Novel islet potency assay

Abstract

Disclosed herein are compositions and methods related to differentiation of stem cells into pancreatic islet cells. In some aspects, the disclosure provides pharmaceutical compositions including the cells generated according to the methods disclosed herein, as well as methods of treatment making use thereof. In some aspects, the disclosure provides for novel assays for assessing β cell potency.

Description

NOVEL ISLET POTENCY ASSAYCROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 642,996, filed May 6, 2024, U.S. Provisional Application No. 63 / 675,636, filed July 25, 2024, and U.S. Provisional Application No. 63 / 712,973, filed October 28, 2024, which are all incorporated by reference herein in their entireties.SEQUENCE LISTING

[0002] The Sequence Listing is submitted as an XML file in the form of the file named “Sequence. xml” (35,701 bytes), which was created on May 5, 2025, which is incorporated by reference herein.BACKGROUND

[0003] Transplantation of pancreas or pancreatic islets has been used for treating diabetes, such as type I diabetes. Prior to administering islet beta-cells to a patient, the potency of the betacells may be assessed. While there are assays for assessing potency of beta-cells in vitro, e.g., a glucose-stimulated insulin secretion (GSIS) assay, there is a need for more potent and / or sensitive in vitro assays for assessing beta-cell potency.INCORPORATION BY REFERENCE

[0004] All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference. Absent any indication otherwise, publications, patents, and patent applications mentioned in this specification are incorporated herein by reference in their entireties.SUMMARY

[0005] In some embodiments, the disclosure provides for a method of treating an in vitro population of cells with arginine, wherein the population of cells is in an assay media and comprises a plurality of islet cells. In some embodiments, the assay media comprises any one or more of: bovine serum albumin, sodium chloride, potassium chloride, calcium chloride, magnesium sulfate, sodium phosphate, potassium phosphate, sodium bicarbonate, and / or HEPES. In some embodiments, the assay media comprises Krebs Buffer. In some embodiments, the assay media has a pH of 5.5-8.5, 6-8, 6.5-7.5, 6.8-7.2, 6.9-7.4, 6.6-7.1, or6.9-7.1. In some embodiments, the assay media does not comprise any glucose. In some embodiments, the assay media comprises glucose (e.g., 2.0 g / L glucose). In some embodiments, the method comprises treating the cells with 0.1-100 mM, 0.1-50 mM, 0.1-20 mM, 0.1-15 mM, 1-100 mM, 1-50 mM, 1-20 mM, 1-12 mM, 5-25 mM, 5-15 mM, 5-12 mM, 8-12 mM, or 9-11 mM of arginine. In some embodiments, the population of islet cells comprises insulin-expressing cells. In some embodiments, the population of islet cells comprises islet cells that are derived from stem cells in vitro. In some embodiments, the population of islet cells comprises cells expressing ISL1. In some embodiments, the population of islet cells comprises cells expressing ISL1 and NKX6.1. In some embodiments, 15-90%, 15-80%, 15-70%, 15-60%, 15-50%, 15-40%, 15-30%, 20-80%, 20- 60%, 20-50%, 30-90%, 30-70%, 30-50% of the cells in the population of cells are ISL1- positive, NKX6.1 -positive cells. In some embodiments, the method further comprises the step of collecting the assay media after a period of time incubating with the arginine (e.g., 2-6 hours, 4-6 hours, 0.25-6 hours, 0.25-4 hours, 0.25-2 hours, 0.25-1 hours, 0.5-1.5 hours, or 0.75-1.25 hours) and assessing the levels of insulin in the assay media. In some embodiments, the insulin levels are assessed by ELISA. In some embodiments, the insulin levels are assessed by AlphaLISA. In some embodiments, the method further comprises the step of comparing the levels of insulin in the assay media to the levels of insulin in a second assay media, wherein the second assay media is taken from a culture comprising a control population of cells substantially similar to the population of cells treated with the arginine, and wherein the control population of cells in the second assay media were not treated with arginine. In some embodiments, the average insulin concentration in the assay media is divided by the average insulin concentration from the second assay media to yield a stimulation index. In some embodiments, prior to treating the population of cells with arginine, the population of cells had been cultured in a culture media for 1-15 days, 1-10 days, 1-8 days, 1-7 days, 1-5 days, 1-3 days, 3-10 days, 3-8 days, 4-7 days, or 5-7 days. In some embodiments, the culture media comprises one or more of: human serum albumin, ascorbic acid, a BMP inhibitor (e.g.., LDN-193189), a TGF-beta receptor inhibitor (e.g., ALK5 Inhibitor II), a thyroid hormone signaling pathway activator (e.g., GC-1), a ROCK inhibitor (e.g., Thiazovivin), a protein kinase inhibitor (e.g., Staurosporine), or a histone methyltransferase inhibitor (e.g., DZNEP). In some embodiments, prior to the cells being cultured in the culture media, the cells had been cryopreserved. In some embodiments, the assay media comprises potassium. In some embodiments, the concentration of potassium in the assay media is 0.1-50 mM, 0.1-40 mM, 0.1-30 mM, 0.1-20 mM, 0.1-10 mM, 0.1-7 mM,30-50 mM, 20-40 mM, 10-25 mM, 2-10 mM, 1-8 mM, 3-7 mM, 4-8 mM, 5-12 mM, or 3-9 mM. In some embodiments, the concentration of potassium is 2-10 mM, 3-7 mM or 5-7 mM. In some embodiments, prior to the cells being treated with the arginine, the cells are in a preservation media (e.g., Hypothermosol). In some embodiments, the preservation media is removed (e.g., at least 50%, 60%, 70%, 80%, 90%, 95%, or 100% or between 50-100%, 50- 95%, 50-90%, 70-95%, 80-95%, 70-80%, or 85-95% or 90-100% of the preservation media is removed) prior to treating the cells with arginine. In some embodiments, the cells are washed with a solution (e.g., a buffer solution or DMEM) following removal of the preservation media. In some embodiments, following removal of the preservation media (and optionally washing the cells), a culture media is added to the cells. In some embodiments, the culture media comprises HEPES, sodium pyruvate, and / or glucose. In some embodiments, the culture media is DMEM media. In some embodiments, the DMEM media is DMEM Fl 2 media. In some embodiments, the culture media comprises human serum albumin (HSA) or bovine serum albumin (BSA). In some embodiments, the culture media comprises 0.01-3%, 0.01-2%, 0.1-2%, 0.1-1.5%, 0.5-1.5%, 0.8-1.2% or 0.9-1.1% HSA or BSA. In some embodiments, the cells are cultured with the culture media for 0.25-48 hours, 0.25-24 hours, 0.25-12 hours, 0.25-6 hours, 0.25-3 hours, 0.25-1.5 hours, 0.75-2 hours, or 0.75-1.25 hours. In some embodiments, the culture media is removed and the assay media is added to the population of cells. In some embodiments, the arginine is arginine-HCl. In some embodiments, the assay media comprises 0.1-3 million, 0.1-2 million, 0.1-1.5 million, 0.5-1.5 million, 0.8- 1.2 million, 0.9-2 million, or 0.9- 1.1 million cells / ml. In some embodiments, the population of cells comprises cell clusters. In some embodiments, 5-10%, 10-50%, 10-40%, 10-30%, 10-20%, 20-50%, 20-40%, or 20-30% or not more than 10%, not more than 20%, not more than 30%, not more than 40%, or not more than 50% of the cells in the population of cells express glucagon. In some embodiments, 5-10%, 10-50%, 10-40%, 10-30%, 10- 20%, 20-50%, 20-40%, or 20-30% or not more than 10%, not more than 20%, not more than 30%, not more than 40%, or not more than 50% of the cells in the population of cells are NKX6.1 -negative, ISLl-positive cells. In some embodiments, the population of cells are not subjected to perifusion when treated with the arginine. In some embodiments, the population of cells are in static culture. In some embodiments, at least 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 60%, 70%, or 80%, or between 10-90%, 10-80%, 10-60%, 10-40%, 10-30%, 20-70%, 20-50%, 20-30%, 30-70%, 30-50%, or 40-65% of the cells in the population of cells are insulin-positive cells. In some embodiments, the population of cells are incubated with the arginine for 2-6 hours, 4-6 hours, 0.25-6 hours, 0.25-4 hours, 0.25-2hours, 0.25-1 hours, 0.5-1.5 hours, or 0.75-1.25 hours. In some embodiments, the population of cells are incubated with the arginine at 35-39, 36-38, 36.5-37.5, or 36.8-37.2 °C.

[0006] In some embodiments, the disclosure provides for a composition comprising an in vitro population of islet cells and a media comprising 1-5 mM, 5-30 mM, 5-25 mM, 5-15 mM, 5- 12 mM, 8-12 mM, or 9-11 mM of arginine. In some embodiments, the media further comprises any one or more of: bovine serum albumin, sodium chloride, potassium chloride, calcium chloride, magnesium sulfate, sodium phosphate, potassium phosphate, sodium bicarbonate, and / or HEPES. In some embodiments, the media comprises Krebs Buffer. In some embodiments, the media has a pH of 5.5-8.5, 6-8, 6.5-7.5, 6.8-7.2, 6.9-7.4, 6.6-7.1, or 6.9-7.1. In some embodiments, the media does not comprise any glucose. In some embodiments, the media comprises glucose (e.g., 2.0 g / L glucose). In some embodiments, the population of islet cells comprises cells expressing ISL1. In some embodiments, the population of islet cells comprises cells expressing ISL1 and NKX6.1. In some embodiments, the arginine is arginine-HCl. In some embodiments, the assay media comprises 0.1-3 million, 0.1-2 million, 0. 1-1.5 million, 0.5-1.5 million, 0.8-1.2 million, 0.9-2 million, or 0.9- 1.1 million cells / ml. In some embodiments, the population of cells comprises cell clusters. In some embodiments, 5-10%, 10-50%, 10-40%, 10-30%, 10-20%, 20-50%, 20-40%, or 20-30% or not more than 10%, not more than 20%, not more than 30%, not more than 40%, or not more than 50% of the cells in the population of cells express glucagon. In some embodiments, 5-10%, 10-50%, 10-40%, 10-30%, 10-20%, 20-50%, 20-40%, or 20- 30% or not more than 10%, not more than 20%, not more than 30%, not more than 40%, or not more than 50% of the cells in the population of cells are NKX6.1 -negative, ISLl-positive cells. In some embodiments, at least 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 60%, 70%, or 80%, or between 10-90%, 10-80%, 10-60%, 10-40%, 10-30%, 20-70%, 20- 50%, 20-30%, 30-70%, 30-50%, or 40-65% of the cells in the population of cells are insulinpositive cells. In some embodiments, the population of islet cells comprises insulinexpressing cells. In some embodiments, the population of islet cells comprises islet cells that are derived from stem cells in vitro. In some embodiments, 15-90%, 15-80%, 15-70%, 15- 60%, 15-50%, 15-40%, 15-30%, 20-80%, 20-60%, 20-50%, 30-90%, 30-70%, 30-50% of the cells in the population of cells are ISLl -positive, NKX6.1 -positive cells. In some embodiments, the composition is in a sterile container. In some embodiments, the composition comprises potassium. In some embodiments, the concentration of potassium in the composition is 0.1-50 mM, 0.1-40 mM, 0.1-30 mM, 0.1-20 mM, 0.1-10 mM, 0.1-7 mM,30-50 mM, 20-40 mM, 10-25 mM, 2-10 mM, 1-8 mM, 3-7 mM, 4-8 mM, 5-12 mM, or 3-9 mM. In some embodiments, the concentration of potassium is 2-10 mM, 3-7 mM or 5-7 mM.

[0007] The details of one or more embodiments of the invention are set forth in the description below. Other features or advantages of the present invention will be apparent from the following drawings and detailed description of several embodiments, and also from the appended claims.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures is represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. In the drawings:

[0009] FIG. 1 is a graph plotting stimulation index results from either a glucose-stimulated insulin secretion (“GSIS”) assay or an arginine-stimulated insulin secretion (“ASIS”) assay using Stage 6, Day 6 SC-islet cells.

[0010] FIG. 2 is a graph plotting stimulation index results from an ASIS assay using arginine or arginine-HCl. “SI” is Stimulation Index.DETAILED DESCRIPTION

[0011] The following description and examples illustrate embodiments of the present disclosure in detail. It is to be understood that this disclosure is not limited to the particular embodiments described herein and as such can vary. Those of skill in the art will recognize that there are numerous variations and modifications of this disclosure, which are encompassed within its scope.

[0012] All terms are intended to be understood as they would be understood by a person skilled in the art. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the disclosure pertains.

[0013] The section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described.

[0014] Although various features of the present disclosure can be described in the context of a single embodiment, the features can also be provided separately or in any suitablecombination. Conversely, although the present disclosure can be described herein in the context of separate embodiments for clarity, the present disclosure can also be implemented in a single embodiment.

[0015] The following definitions supplement those in the art and are directed to the current application and are not to be imputed to any related or unrelated case, e.g., to any commonly owned patent or application. Although any methods and materials similar or equivalent to those described herein can be used in the practice for testing of the present disclosure, the preferred materials and methods are described herein. Accordingly, the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting.

[0016] In this application, the use of the singular includes the plural unless specifically stated otherwise. It must be noted that, as used in the specification, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. As used herein, the term “media” includes a singular medium or multiple media, unless clearly indicated otherwise.

[0017] In this application, the use of “or” means “and / or” unless stated otherwise. The terms “and / or” and “any combination thereof’ and their grammatical equivalents as used herein, can be used interchangeably. These terms can convey that any combination is specifically contemplated. Solely for illustrative purposes, the following phrases “A, B, and / or C” or “A, B, C, or any combination thereof” can mean “A individually; B individually; C individually; A and B; B and C; A and C; and A, B, and C.” The term “or” can be used conjunctively or disjunctively, unless the context specifically refers to a disjunctive use.

[0018] Furthermore, use of the term “including” as well as other forms, such as “include”, “includes,” and “included,” is not limiting.

[0019] Reference in the specification to “some embodiments,” “an embodiment,” “one embodiment” or “other embodiments” means that a particular feature, structure, or characteristic described in connection with the embodiments is included in at least some embodiments, but not necessarily all embodiments, of the present disclosures.

[0020] As used in this specification and claim(s), the words “comprising” (and any form of comprising, such as “comprise” and “comprises”), “having” (and any form of having, such as “have” and “has”), “including” (and any form of including, such as “includes” and “include”) or “containing” (and any form of containing, such as “contains” and “contain”) are inclusive or open-ended and do not exclude additional, unrecited elements or method steps.It is contemplated that any embodiment discussed in this specification can be implemented with respect to any method or composition of the present disclosure, and vice versa. Furthermore, compositions of the present disclosure can be used to achieve methods of the present disclosure.

[0021] The term “about” or “approximately” means within an acceptable error range for the particular value as determined by one of ordinary skill in the art, which will depend in part on how the value is measured or determined, e.g., the limitations of the measurement system. For example, “about” can mean within 1 or more than 1 standard deviation, per the practice in the art. Alternatively, “about” can mean a range of up to 20%, up to 10%, up to 5%, or up to 1% of a given value. In another example, the amount “about 10” includes 10 and any amounts from 9 to 11. In yet another example, the term “about” in relation to a reference numerical value can also include a range of values plus or minus 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, or 1% from that value. Alternatively, particularly with respect to biological systems or processes, the term “about” can mean within an order of magnitude, preferably within 5-fold, and more preferably within 2-fold, of a value. Where particular values are described in the application and claims, unless otherwise stated the term “about” meaning within an acceptable error range for the particular value should be assumed.

[0022] The term “diabetes” and its grammatical equivalents as used herein can refer to is a disease characterized by high blood sugar levels over a prolonged period. For example, the term “diabetes” and its grammatical equivalents as used herein can refer to all or any type of diabetes, including, but not limited to, type 1, type 2, cystic fibrosis-related, surgical, gestational diabetes, and mitochondrial diabetes. In some embodiments, diabetes can be a form of hereditary diabetes. In some embodiments, diabetes can be an autoimmune form of diabetes.

[0023] The term “endocrine cell(s),” if not particularly specified, can refer to hormone-producing cells present in the pancreas of an organism, such as “islet”, “islet cells”, “islet equivalent”, “islet-like cells”, “pancreatic islets” and their grammatical equivalents. In an embodiment, the endocrine cells can be differentiated from pancreatic progenitor cells or precursors. Islet cells can comprise different types of cells, including, but not limited to, pancreatic a cells, pancreatic f> cells, pancreatic 8 cells, pancreatic F cells, and / or pancreatic s cells. Islet cells can also refer to a group of cells, cell clusters, or the like. In particular embodiments, islet cells are stem cell-derived islet cells, e.g., islet cells that are derived from stem cells in vitro.

[0024] The terms “progenitor” and “precursor” cell are used interchangeably herein and refer to cells that have a cellular phenotype that is more primitive e.g., is at an earlier step along adevelopmental pathway or progression than is a fully differentiated cell) relative to a cell which it can give rise to by differentiation. Often, progenitor cells can also have significant or very high proliferative potential. Progenitor cells can give rise to multiple distinct differentiated cell types or to a single differentiated cell type, depending on the developmental pathway and on the environment in which the cells develop and differentiate.

[0025] A “precursor thereof’ as the term related to an insulin-positive endocrine cell can refer to any cell that is capable of differentiating into an insulin-positive endocrine cell, including for example, a pluripotent stem cell, a definitive endoderm cell, a primitive gut tube cell, a pancreatic progenitor cell, or endocrine progenitor cell, that if cultured under suitable conditions will differentiate the precursor cell into the insulin-positive endocrine cell.

[0026] The terms “stem cell-derived cell,” “SC-0 cell,” “functional 0 cell,” “functional pancreatic 0 cell,” “mature SC-0 cell,” “0-like cell” and their grammatical equivalents can refer to cells (e.g., non-native pancreatic 0 cells) that display at least one marker indicative of a pancreatic 0 cell (e.g., PDX-1, ISL1 or NKX6.1), expresses insulin. In some embodiments, the SC-0 cell displays a glucose stimulated insulin secretion (GSIS) response similar or superior to that of an endogenous mature 0 cell (e.g., a mature 0 from a healthy functioning pancreas from a healthy adult non-diabetic patient). In some embodiments, the SC-0 cell displays a arginine stimulated insulin secretion (ASIS) response similar or superior to that of an endogenous mature 0 cell (e.g., a mature 0 from a healthy functioning pancreas from a healthy adult non-diabetic patient). For simplicity, SC-0 cells may be referred to as simply “0 cells” in this disclosure. In some embodiments, the terms “SC-0 cell” and “non-native 0 cell” as used herein are interchangeable. In some embodiments, the “SC-0 cell” expresses lower levels of MAFA than a pancreatic 0 cell from a healthy adult human patient. In some embodiments, the “SC-0 cell” expresses higher levels of MAFB than a pancreatic 0 cell from a healthy adult human patient. In some embodiments, the “SC-0 cell” expresses higher levels of SIX2, HOPX, IAPP and / or UCN3 than a pancreatic 0 cell from a healthy adult human patient. In some embodiments, the “SC-0 cell” comprises a mature pancreatic cell. It is to be understood that the SC-0 cells need not be derived (e.g., directly) from stem cells, as the methods of the disclosure are capable of deriving SC-0 cells from any insulin-positive endocrine cell or precursor thereof using any cell as a starting point (e.g., one can use embryonic stem cells, induced-pluripotent stem cells, progenitor cells such as definitive endoderm cells, partially reprogrammed somatic cells (e.g., a somatic cell which has been partially reprogrammed to an intermediate state between an induced pluripotent stem cell and the somatic cell from which it was derived), multipotent cells, totipotent cells, atransdifferentiated version of any of the foregoing cells, etc., as the invention is not intended to be limited in this manner). In some embodiments, the SC-0 cells exhibit a response to multiple glucose challenges (e.g., at least one, at least two, or at least three or more sequential glucose challenges). In some embodiments, the response resembles the response of endogenous islets (e.g., human islets) to multiple glucose challenges. In some embodiments, the morphology of the SC-0 cell resembles the morphology of an endogenous 0 cell. In some embodiments, the SC-0 cell exhibits an in vitro GSIS (or ASIS) response that resembles the GSIS (or ASIS) response of an endogenous 0 cell. In some embodiments, the SC-0 cell exhibits an in vivo GSIS (or ASIS) response that resembles the GSIS (or ASIS) response of an endogenous 0 cell. In some embodiments, the SC-0 cell exhibits both an in vitro and in vivo GSIS (or ASIS) response that resembles the GSIS (or ASIS) response of an endogenous 0 cell. In some embodiments, the GSIS (or ASIS) response of the SC-0 cell can be observed within two weeks of transplantation of the SC-0 cell into a host (e.g., a human or animal). In some embodiments, the GSIS (or ASIS) response of the SC-0 cell can be observed within three weeks of transplantation of the SC-0 cell into a host (e.g., a human or animal). In some embodiments, the GSIS (or ASIS) response of the SC-0 cell can be observed within four weeks of transplantation of the SC-0 cell into a host (e.g., a human or animal). In some embodiments, the GSIS (or ASIS) response of the SC-0 cell can be observed between one month and three months of transplantation of the SC-0 cell into a host (e.g., a human or animal). In some embodiments, the SC-0 cells package insulin into secretory granules. In some embodiments, the SC-0 cells exhibit encapsulated crystalline insulin granules. In some embodiments, the SC-0 cells exhibit a stimulation index of greater than 1. In some embodiments, the SC-0 cells exhibit a stimulation index of greater than 1.1. In some embodiments, the SC-0 cells exhibit a stimulation index of greater than 2. In some embodiments, the stimulation index of the cell is characterized by the ratio of insulin secreted in response to high glucose concentrations (e.g., 15 mM) compared to low glucose concentrations (e.g., 2.5 mM).

[0027] In some embodiments, the SC-0 cells exhibit cytokine-induced apoptosis in response to cytokines. In some embodiments, insulin secretion from the SC-0 cells is enhanced in response to known antidiabetic drugs (e.g., secretagogues). In some embodiments, the SC-0 cells are monohormonal. In some embodiments, the SC-0 cells do not abnormally co-express other hormones, such as glucagon, somatostatin or pancreatic polypeptide. In some embodiments, the SC-0 cells exhibit a low rate of replication. In some embodiments, the SC- 0 cells increase intracellular Ca2+ in response to glucose.

[0028] The terms “stem cell-derived a cell,” “SC-a cell,” “functional a cell,” “functional pancreatic a cell,” “mature SC-a cell,” “a-like cell” and their grammatical equivalents can refer to cells (e.g., non-native pancreatic a cells) that display at least one marker indicative of a pancreatic a cell (e.g., glucagon, expressing ISL1 but not NKX6.1), expresses glucagon, and is capable of secreting functional glucagon in response to a stimulus that induces an endogenous pancreatic a cell to secrete functional glucagon. In some embodiments, the “SC- a cell” does not express somatostatin. In some embodiments, the “SC-a cell” does not express insulin. In some embodiments, the terms “SC-a cell” and “non-native a cell” as used herein are interchangeable. In some embodiments, the “SC-a cell” comprises a mature pancreatic cell. For short, these cells may be referred to as simply “a cells” in this disclosure.

[0029] The terms “stem cell-derived 3 cell,” “SC-3 cell,” “functional 3 cell,” “functional pancreatic 5 cell,” “mature SC-5 cell,” “5-like cell” and their grammatical equivalents can refer to cells e.g., non-native pancreatic 5 cells) that display at least one marker indicative of a pancreatic 5 cell (e.g., somatostatin), expresses and is capable of secreting somatostatin in response to a stimulus that induces an endogenous pancreatic 5 cell to secrete functional glucagon. For simplicity, SC- 5 cells may be referred to as simply “5 cells” in this disclosure. In some embodiments, “SC-5 cell” does not express glucagon. In some embodiments, “SC-5 cell” does not express insulin. In some embodiments, the terms “SC-5 cell” and “non-native 5 cell” as used herein are interchangeable. In some embodiments, the “SC-5 cell” comprises a mature pancreatic cell.

[0030] The terms “stem cell-derived enterochromaffin (EC) cell,” “SC-EC cell,” and their grammatical equivalents can refer to cells (e.g., non-native pancreatic EC cells) that display at least one marker indicative of a pancreatic EC cell (e.g., VMAT1 (vesicular monoamine transporter 1), expressing NKX6.1 but not ISL1). In some embodiments, the terms “SC-EC cell” and “non-native EC cell” as used herein are interchangeable.

[0031] Similar to SC-f$ cells, it is to be understood that the SC-a, SC-8 cells, and SC-EC cells need not be derived (e.g., directly) from stem cells, as the methods of the disclosure are capable of deriving SC-a cells from other precursor cells generated during in vitro differentiation of SC- cells as a starting point (e.g., one can use embryonic stem cells, induced-pluripotent stem cells, progenitor cells, partially reprogrammed somatic cells (e.g., a somatic cell which has been partially reprogrammed to an intermediate state between an induced pluripotent stem cell and the somatic cell from which it was derived), multipotentcells, totipotent cells, a transdifferentiated version of any of the foregoing cells, etc., as the invention is not intended to be limited in this manner).

[0032] As used herein, the term “insulin producing cell” and its grammatical equivalent refer to a cell differentiated from a pancreatic progenitor, or precursor thereof, which secretes insulin. An insulin-producing cell can include a pancreatic P cell as that term is described herein, as well as pancreatic P-like cells (e.g., insulin-positive, endocrine cells) that synthesize (e.g., transcribe the insulin gene, translate the proinsulin mRNA, and modify the proinsulin mRNA into the insulin protein), express (e.g., manifest the phenotypic trait carried by the insulin gene), or secrete (release insulin into the extracellular space) insulin in a constitutive or inducible manner. A population of insulin producing cells e.g., produced by differentiating insulin-positive endocrine cells or a precursor thereof into SC- cells according to the methods of the present disclosure can be pancreatic P cells or P-like cells (e.g. , cells that have at least one, or at least two least characteristics of an endogenous P cell and exhibit a glucose stimulated insulin secretion (GSIS) response that resembles an endogenous adult P cell). The population of insulin-producing cells, e.g., produced by the methods as disclosed herein can comprise mature pancreatic P cell or SC-P cells, and can also contain non-insulin-producing cells (e.g., cells of cell like phenotype with the exception they do not produce or secrete insulin).

[0033] The terms “insulin-positive 3-like cell,” “insulin-positive endocrine cell,” and their grammatical equivalents can refer to cells (e.g., pancreatic endocrine cells) that display at least one marker indicative of a pancreatic P cell and also expresses insulin but, unless specified otherwise, lack a glucose stimulated insulin secretion (GSIS) or arginine-stimulated insulin secretion (ASIS) response characteristic of an endogenous P cell. Exemplary markers of “insulin-positive endocrine cell” include, but are not limited to, NKX6.1 (NK6 homeobox 1), ISL1 (Isletl), and insulin.

[0034] The term “P cell marker” refers to, without limitation, proteins, peptides, nucleic acids, polymorphism of proteins and nucleic acids, splice variants, fragments of proteins or nucleic acids, elements, and other analyte which are expressed or present in pancreatic P cells. Exemplary P cell markers include, but are not limited to, pancreatic and duodenal homeobox 1 (PDX1) polypeptide, insulin, c-peptide, amylin, E-cadherin, Hnf3p, PCI / 3, B2, Nkx2.2, GLUT2, PC2, ZnT-8, ISL1, Pax6, Pax4, NeuroD, 1 Infib, Hnf-6, Hnf-3beta, VMAT2, NKX6.1, and MafA, and those described in Zhang et al., Diabetes. 50(10) :2231-6 (2001). In some embodiments, the p cell marker is a nuclear P-cell marker. In some embodiments, the pcell marker is PDX1 or PH3. In some embodiments, the 0 cell markers are NKX6.1 and ISLE

[0035] The term “pancreatic endocrine marker” can refer to without limitation, proteins, peptides, nucleic acids, polymorphism of proteins and nucleic acids, splice variants, fragments of proteins or nucleic acids, elements, and other analytes which are expressed or present in pancreatic endocrine cells. Exemplary pancreatic endocrine cell markers include, but are not limited to, Ngn-3, NeuroD and Islet- 1.

[0036] The term “pancreatic progenitor,” “pancreatic endocrine progenitor,” “pancreatic precursor,” “pancreatic endocrine precursor” and their grammatical equivalents are used interchangeably herein and can refer to a stem cell which is capable of becoming a pancreatic hormone expressing cell capable of forming pancreatic endocrine cells, pancreatic exocrine cells or pancreatic duct cells. These cells are committed to differentiating towards at least one type of pancreatic cell, e.g. 0 cells that produce insulin; a cells that produce glucagon; 5 cells (or D cells) that produce somatostatin; and / or F cells that produce pancreatic polypeptide. In some embodiments, such cells can express at least one of the following markers: NGN3, NKX2.2, NeuroD, ISL-1, Pax4, Pax6, or ARX.

[0037] The term “PDX1 -positive pancreatic progenitor” as used herein can refer to a cell which is a pancreatic endoderm (PE) cell which has the capacity to differentiate into SC-0 cells, such as pancreatic P cells. A PDX1 -positive pancreatic progenitor expresses the marker PDX1. Other markers include, but are not limited to Cdcpl, or Ptfl a, or HNF6 or NRx2.2. The expression of PDX1 may be assessed by any method known by the skilled person such as immunochemistry using an anti-PDXl antibody or quantitative RT-PCR. In some embodiments, a PDX1 -positive pancreatic progenitor cell lacks expression of NKX6.1. In some embodiments, a PDXl-positive pancreatic progenitor cell can also be referred to as PDX1 -positive, NKX6.1 -negative pancreatic progenitor cell due to its lack of expression of NKX6.1. In some embodiments, the PDXl-positive pancreatic progenitor cells can also be termed as “pancreatic foregut endoderm cells.”

[0038] The term “pancreatic foregut precursor cells” means a pancreatic endoderm (PE) cell which has the capacity to differentiate into insulin-producing cells, such as pancreatic 0 cells. Pancreatic foregut precursor cells express PDX1 and markers such as NKX6.1, Cdcpl, or Ptfl a, or HNF6 or NRx2.2. In particular embodiments, pancreatic foregut precursor cells are PDXl-positive, NKX6.1 -positive cells. “PDXl-positive, NKX6.1 -positive pancreatic progenitor,” and “NKX6.1 -positive pancreatic progenitor” are used interchangeably herein. The expression of NKX6-1 may be assessed by any method known by the skilled person suchas immunochemistry using an anti-NKX6-l antibody or quantitative RT-PCR. As used herein, the terms “NKX6.1” and “NKX6-1” are equivalent and interchangeable.

[0039] The terms “NeuroD” and “NeuroDl” are used interchangeably and identify a protein expressed in pancreatic endocrine progenitor cells and the gene encoding it.

[0040] The term “differentiated cell” or its grammatical equivalents means any primary cell that is not, in its native form, pluripotent as that term is defined herein. Stated another way, the term “differentiated cell” can refer to a cell of a more specialized cell type derived from a cell of a less specialized cell type (e.g., a stem cell such as an induced pluripotent stem cell) in a cellular differentiation process. Without wishing to be limited to theory, a pluripotent stem cell in the course of normal ontogeny can differentiate first to an endoderm cell that is capable of forming pancreas cells and other endoderm cell types. Further differentiation of an endoderm cell may lead to the pancreatic pathway, where -98% of the cells become exocrine, ductular, or matrix cells, and -2% become endocrine cells. Early endocrine cells are islet progenitors, which can then differentiate further into insulin-producing cells e.g. functional endocrine cells) which secrete insulin, glucagon, somatostatin, or pancreatic polypeptide. Endoderm cells can also be differentiated into other cells of endodermal origin, e.g. lung, liver, intestine, thymus etc.

[0041] As used herein, the term “somatic cell” can refer to any cells forming the body of an organism, as opposed to germline cells. In mammals, germline cells (also known as “gametes”) are the spermatozoa and ova which fuse during fertilization to produce a cell called a zygote, from which the entire mammalian embryo develops. Every other cell type in the mammalian body - apart from the sperm and ova, the cells from which they are made (gametocytes) and undifferentiated stem cells - is a somatic cell: internal organs, skin, bones, blood, and connective tissue are all made up of somatic cells. In some embodiments the somatic cell is a “non-embryonic somatic cell”, by which is meant a somatic cell that is not present in or obtained from an embryo and does not result from proliferation of such a cell in vitro. In some embodiments the somatic cell is an “adult somatic cell”, by which is meant a cell that is present in or obtained from an organism other than an embryo or a fetus or results from proliferation of such a cell in vitro. Unless otherwise indicated the methods for converting at least one insulin-positive endocrine cell or precursor thereof to an insulinproducing, glucose responsive cell can be performed both in vivo and in vitro (where in vivo is practiced when at least one insulin-positive endocrine cell or precursor thereof are present within a subject, and where in vitro is practiced using an isolated at least one insulin-positive endocrine cell or precursor thereof maintained in culture).

[0042] As used herein, the term “adult cell” can refer to a cell found throughout the body after embryonic development.

[0043] The term “endoderm cell” as used herein can refer to a cell which is from one of the three primary germ cell layers in the very early embryo (the other two germ cell layers are the mesoderm and ectoderm). The endoderm is the innermost of the three layers. An endoderm cell differentiates to give rise first to the embryonic gut and then to the linings of the respiratory and digestive tracts (e.g., the intestine), the liver and the pancreas.

[0044] The term “a cell of endoderm origin” as used herein can refer to any cell which has developed or differentiated from an endoderm cell. For example, a cell of endoderm origin includes cells of the liver, lung, pancreas, thymus, intestine, stomach and thyroid. Without wishing to be bound by theory, liver and pancreas progenitors (also referred to as pancreatic progenitors) are developed from endoderm cells in the embryonic foregut. Shortly after their specification, liver and pancreas progenitors rapidly acquire markedly different cellular functions and regenerative capacities. These changes are elicited by inductive signals and genetic regulatory factors that are highly conserved among vertebrates. Interest in the development and regeneration of the organs has been fueled by the intense need for hepatocytes and pancreatic P cells in the therapeutic treatment of liver failure and type I diabetes. Studies in diverse model organisms and humans have revealed evolutionarily conserved inductive signals and transcription factor networks that elicit the differentiation of liver and pancreatic cells and provide guidance for how to promote hepatocyte and p cell differentiation from diverse stem and progenitor cell types.

[0045] The term “definitive endoderm” as used herein can refer to a cell differentiated from an endoderm cell and which can be differentiated into a SC-P cell e.g., a pancreatic P cell). A definitive endoderm cell expresses the marker Sox 17. Other markers characteristic of definitive endoderm cells may include, but are not limited to MIXL2, GATA4, HNF3b, GSC, FGF17, VWF, CALCR, FOXQ1, CXCR4, Cerberus, OTX2, goosecoid, C-Kit, CD99, CMK0R1 and CRIP1. In particular, definitive endoderm cells herein express Soxl7 and in some embodiments Soxl7 and HNF3B, and do not express significant levels of GATA4, SPARC, APF or DAB. Definitive endoderm cells are not positive for the marker PDX1 e.g. they are PDX1 -negative). Definitive endoderm cells have the capacity to differentiate into cells including those of the liver, lung, pancreas, thymus, intestine, stomach and thyroid. The expression of Sox 17 and other markers of definitive endoderm may be assessed by any method known by the skilled person such as immunochemistry, e.g., using an anti-Soxl7 antibody, or quantitative RT-PCR.

[0046] The term “pancreatic endoderm” can refer to a cell of endoderm origin which is capable of differentiating into multiple pancreatic lineages, including pancreatic 0 cells, but no longer has the capacity to differentiate into non-pancreatic lineages.

[0047] The term “pancreatic islet cells” refers to a population of cells that include different types of pancreatic endocrine cells (0-cells, a-cells, 5-cells, e-cells) and enterochromaffin (EC) cells, e.g., as described in Xavier et al. (J Clin Med. 2018 Mar; 7(3): 54), incorporated herein by reference.

[0048] The term “primitive gut tube cell” or “gut tube cell” as used herein can refer to a cell differentiated from an endoderm cell and which can be differentiated into a SC-0 cell e.g., a pancreatic 0 cell). A primitive gut tube cell expresses at least one of the following markers: HNP1-0, HNF3-0 or HNF4-a. In some embodiments, a primitive gut tube cell is FOXA2- positive and SOX2-positive, i.e.. expresses both FOXA2 (also known as HNF3-0) and SOX2. In some embodiments, a primitive gut tube cell is FOXA2 -positive and PDX1 -negative, i.e., expresses FOXA2 but not PDX1. Primitive gut tube cells have the capacity to differentiate into cells including those of the lung, liver, pancreas, stomach, and intestine. The expression of HNF1-0 and other markers of primitive gut tube may be assessed by any method known by the skilled person such as immunochemistry, e.g., using an anti-HNFl-0 antibody.

[0049] The term “phenotype” can refer to one or a number of total biological characteristics that define the cell or organism under a particular set of environmental conditions and factors, regardless of the actual genotype.

[0050] The terms “patient,” “subject,” and “individual” may be used interchangeably and refer to either a human or a non-human animal. The “non-human animals” and “non-human mammals” as used interchangeably herein, includes mammals such as rats, mice, rabbits, sheep, cats, dogs, cows, pigs, and non-human primates. The term “subject” also encompasses any vertebrate including but not limited to mammals, reptiles, amphibians and fish.However, advantageously, the subject is a mammal such as a human, or other mammals such as a domesticated mammal, e.g., dog, cat, horse, and the like, or production mammal, e.g. cow, sheep, pig, and the like. “Patient in need thereof’ or “subject in need thereof is referred to herein as a patient diagnosed with or suspected of having a disease or disorder, for instance, but not restricted to diabetes.

[0051] “Administering” as used herein can refer to providing one or more compositions described herein to a patient or a subject. By way of example and not limitation, composition administration, e.g., injection, can be performed by intravenous (i.v.) injection, sub-cutaneous(s.c.) injection, intradermal (i.d.) injection, intraperitoneal (i.p.) injection, or intramuscular (i.m.) injection. One or more such routes can be employed. Parenteral administration can be, for example, by bolus injection or by gradual perfusion over time. Alternatively, or concurrently, administration can be by the oral route. Additionally, administration can also be by surgical deposition of a bolus or pellet of cells, or positioning of a medical device. In an embodiment, a composition of the present disclosure can comprise engineered cells or host cells expressing nucleic acid sequences described herein, or a vector comprising at least one nucleic acid sequence described herein, in an amount that is effective to treat or prevent proliferative disorders. A pharmaceutical composition can comprise the cell population as described herein, in combination with one or more pharmaceutically or physiologically acceptable carriers, diluents or excipients. Such compositions can comprise buffers such as neutral buffered saline, phosphate buffered saline and the like; carbohydrates such as glucose, mannose, sucrose or dextrans, mannitol; proteins; polypeptides or amino acids such as glycine; antioxidants; chelating agents such as EDTA or glutathione; adjuvants (e.g., aluminum hydroxide); and preservatives.

[0052] The ranges disclosed throughout are sometimes referred to as, for example, “X is administered on or on about day 1 to 2; or 2 to 3 [or any numerical range].” This range includes the numbers themselves e.g., the endpoints of the range) and any individual numbers present in this range.

[0053] All these different combinations are contemplated by the ranges disclosed throughout. All disclosed ranges should be interpreted in this manner, whether it refers to an administration of a therapeutic agent or referring to days, months, years, weight, dosage amounts, etc., unless otherwise specifically indicated to the contrary.Differentiation stages

[0054] Pancreatic differentiation as disclosed herein may be carried out in a step-wise manner. In an exemplary embodiment of the step-wise progression, “Stage 1” or “SI” or “Stl” refers to the first step in the differentiation process, the differentiation of pluripotent stem cells into cells expressing markers characteristic of definitive endoderm cells (“DE”, “Stage 1 cells” or “Stl cells” or “SI cells”). In some embodiments, “Stage 2” refers to the second step, the differentiation of cells expressing markers characteristic of definitive endoderm cells into cells expressing markers characteristic of gut tube cells (“GT”, “Stage 2 cells” “St2 cells” or “S2 cells”). In some embodiments, “Stage 3” refers to the third step, the differentiation of cells expressing markers characteristic of gut tube cells into cells expressing markerscharacteristic of pancreatic progenitor 1 cells (“PPI”, “Stage 3 cells” or “St3 cells” or “S3 cells”). In some embodiments, “Stage 4” refers to the fourth step, the differentiation of cells expressing markers characteristic of pancreatic progenitor 1 cells into cells expressing markers characteristic of pancreatic progenitor 2 cells (“PP2”, “Stage 4 cells” or “St4 cells” or “S4 cells”). In some embodiments, “Stage 5” refers to the fifth step, the differentiation of cells expressing markers characteristic of pancreatic progenitor 2 cells (e.g., PDX. 1+, NKX6.1+) into cells expressing markers characteristic of pancreatic endoderm cells and / or pancreatic endocrine progenitor cells (e.g., insulin+) (“EN”, “Stage 5 cells” or “St5 cells” or “S5 cells”). In some embodiments, “Stage 6” refers to the differentiation of cells expressing markers characteristic of pancreatic endocrine progenitor cells (e.g., insulin) into cells expressing markers characteristic of pancreatic endocrine p cells (“SC- cells”) or pancreatic endocrine a cells (“SC-a cells”). It should be appreciated, however, that not all cells in a particular population progress through these stages at the same rate, i.e., some cells may have progressed less, or more, down the differentiation pathway than the majority of cells present in theparticular population. For example, in some embodiments, SC-P cells can be identified during stage 5, at the conclusion of stage 5, at the beginning of stage 6, etc. Examples of methods of making cells of any one of stages 1 -6 are provided in, for example, US Patent 10,030,229; US Patent 10,443,042; US Patent No. US 11,466,256; published application US 20200332262; and published application US 20210198632, published application US 20220090020, published application US 2022-0233646; published application US 2022- 0090020; published application US 20230218676; and published application WO2022147056, each of which is incorporated by reference in its entirety.Compositions and methods for producing pancreatic islet cells

[0055] In some aspects, the present disclosure provides compositions and methods of differentiating pancreatic islet cells (e.g., differentiating from stem cells such as human embryonic stem cells or human pluripotent stem cells). The compositions and methods provided herein can, in some embodiments, offer pancreatic SC-islet cells, cell populations, or cell clusters containing pancreatic SC-P cells and pancreatic SC-a cells. In some embodiments, such pancreatic SC-islet cells, cell populations or cell clusters exhibit, high insulin content, superior glucose-dependent insulin secretion response, as well as a percentage of pancreatic SC-a, SC- , and SC-8 cells and enterochromaffin (EC) cells, which can resemble native pancreatic islets both structurally and functionally. In some embodiments, a population of pancreatic islet cells (e.g., stem cell derived pancreatic isletcells) produced using the compositions and methods described herein comprises at least 50% pancreatic SC-0 cells, up to 30% pancreatic SC-a cells, 3-10% pancreatic SC-5 cells, and / or less than SC-20% EC cells. In some embodiments, a population of pancreatic islet cells (e.g., stem cell derived pancreatic islet cells) produced using the compositions and methods described herein has improved glucose-stimulated insulin secretion (GSIS) response as compared to cell compositions generated according to conventional methods. In some embodiments, a population of pancreatic islet cells (e.g., stem cell derived pancreatic islet cells) produced using the compositions and methods described herein has dynamic GSIS response similar to native pancreatic islets (e.g., pancreatic islets from a healthy functioning pancreas from a healthy adult non-diabetic subject).

[0056] It should be noted that the disclosure provides for compositions prepared according to any of the methods disclosed herein, and methods of administering any of the reagents to the compositions disclosed herein.

[0057] In some embodiments, any of the methods or compositions disclosed herein comprises a medium, such as a basal media. Such basal media comprises essential nutrients for survival of cells. Such basal media allows survival of at least 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95% or 100% of cells (e.g., 30-100%, 50-100%, 70-100%, 90-100%, 30-80%, 30-60%, 50- 80%, 50-70%, 70-90%, 80-95% or 90-98% of cells) in a culture for at least 12 hours, 1 day, 2 days, 3 days, 4 days or 5 days in culture (e.g., 6-12 hours, 12-24 hours, 1-5 days, 1-4 days, 1- 3 days, 1-2 days). In particular embodiments, basal media may be replaced in a culture after a period of time (e.g., 12-24 hours, 1-5 days, 1-4 days, 1-3 days, 1-2 days). In some embodiments, basal media comprises any one or more of glucose, nucleotides, amino acids, calcium, ascorbic acid, niacin, potassium, iron, manganous sulfate, cuprous sulfate, zinc, nickel, vitamin B-12, Folinic acid, riboflavin, biotin, ethanolamine, transferrin and / or insulin. In some embodiments, the basal media comprises any one of or any combination of StemScale, NutriStem, TeSR-E8, StemFit, StemPro, MCDB-131, ITS-X, GlutaMax, RPMI- 1640, MEM, DMEM (e.g., DMEM-F12), NS-GFs media, MCDB131 medium, and / or CMRL medium.

[0058] The disclosure may refer to a composition that does not comprise, or that lacks, a particular reagent. Such compositions lack exogenous instances of such reagents. For example, if a composition comprising cells does not comprise a growth factor of the TGF- beta superfamily, the composition does not comprise exogenously added growth factor of the TGF-beta superfamily but may include endogenous levels (e.g., low levels) of growth factor secreted by the cells.Methods of producing pancreatic islet cells

[0059] In aspects, the present disclosure relates to compositions and methods of generating endocrine cells from pancreatic progenitor cells or precursors. Certain exemplary detailed protocols of generating endocrine cells to provide at least one SC-0 cell are described in US Patent 10,030,229; US Patent 10,443,042; US Patent No. US 11,466,256; published application US 20200332262; and published application US 20210198632, published application US 20220090020, published application US 2022-0233646; published application US 2022-0090020; published application US 20230218676; and published application WO2022147056, each of which is herein incorporated by reference in its entirety.

[0060] In some embodiments, a method of generating a population of endocrine cells leads to increased percentage of pancreatic a and / or 5 cells and decreased percentage of pancreatic EC cells when generating pancreatic 0 cells. In some embodiments, a method described herein may be used to obtain an enriched population of a cells. In some embodiments, a method described herein may be used to obtain an enriched population of 0 cells. In some embodiments, a method described herein may be used to obtain an enriched population of a cells and 0 cells. In some embodiments, a method described herein may be used to obtain an increased yield of pancreatic endocrine cells.

[0061] The differentiation of hPSC cells to hormone-expressing pancreatic endocrine cells may be conducted by transitioning hPSC cells through major stages of embryonic development; differentiation to mesendoderm and definitive endoderm, establishment of the primitive gut endoderm, patterning of the posterior foregut, and specification and maturation of pancreatic endoderm and endocrine precursors. Through these stages, hPSC cells can obtain pancreatic endocrine phenotype and ability of glucose (or arginine) responsive insulin secretion in vitro.

[0062] Generally, the at least one pancreatic SC-a, SC-0 and / or SC-5 cell or precursor thereof, e.g., pancreatic progenitors produced according to the methods disclosed herein can comprise a mixture or combination of different cells, e.g., for example a mixture of cells such as a PDXl-positive pancreatic progenitors, pancreatic progenitors co-expressing PDX1 and NKX6.1, a Ngn3-positive endocrine progenitor cell, an insulin-positive endocrine cell (e.g., NKX6.1-positive, ISL1 -positive cells, or 0-like cells), and / or other pluripotent or stem cells.

[0063] The at least one pancreatic a, 0 and / or 5 cell or precursor thereof can be produced according to any suitable culturing protocol to differentiate a stem cell or pluripotent cell to a desired stage of differentiation. In some embodiments, the at least one pancreatic a, 0 and / or 5 cell or the precursor thereof are produced by culturing at least one pluripotent cell for aperiod of time and under conditions suitable for the at least one pluripotent cell to differentiate into the at least one pancreatic a, and / or 8 cell or the precursor thereof.

[0064] In some embodiments, the at least one pancreatic a, P and / or 8 cell or precursor thereof is a substantially pure population of pancreatic a, 3 and / or 3 cells or precursors thereof. In some embodiments, a population of pancreatic a, P and / or 6 cells or precursors thereof comprises a mixture of pluripotent cells or differentiated cells. In some embodiments, a population pancreatic a, P and / or 8 cells or precursors thereof are substantially free or devoid of embryonic stem cells or pluripotent cells or iPS cells. In some embodiments, a method described herein produces a population of cells comprising pancreatic a, P and / or 8 cells at a ratio that resembles that of a natural pancreatic islet.

[0065] In some embodiments, in a method described herein, the first medium and / or the second medium further comprises a TGF-P ligand (e.g., activin A). In some embodiments, the first medium further comprises a Wnt signaling pathway activator (e.g., a glycogen synthase kinase 3 (GSK3) inhibitor such as CHIR99021In some embodiments, the first medium and / or the second medium further comprises a water-soluble synthetic polymer (e.g., PVA). In some embodiments, the first medium is supplemented with additional metabolites such as amino acids (e.g., aspartate, glycine, and / or serine) and further comprises a TGF-P ligand (e.g., activin A) and a Wnt signaling pathway activator (e.g., a glycogen synthase kinase 3 (GSK3) inhibitor such as CHIR99021), and / or a water-soluble synthetic polymer (e.g., PVA). In some embodiments, the second medium is supplemented with additional amino acids (e.g., aspartate, glycine, and / or serine) and further comprises a TGF-P ligand (e.g., activin A), and / or a water-soluble synthetic polymer (e.g., PVA), and does not comprise a Wnt signaling pathway activator.

[0066] In some embodiments, in a method described herein, the first medium and / or second medium further comprises a TGF-P ligand (e.g., activin A). In some embodiments, the TGF- P ligand (e.g., activin A) has a concentration of about 1-200 ng / ml (e.g., 1-200, 1-150, 1-125, 1-110, 1-100, 1-90, 1-75, 1-50, 1-25, 1-15, 1-12, 1-10, 1-8, 1-5, 5-200, 5-150, 5-125, 5-110, 5-100, 5-90, 5-75, 5-50, 5-25, 5-15, 5-12, 5-10, 5-8, 8-200, 8-150, 8-125, 8-110, 8-100, 8-90, 8-75, 8-50, 8-25, 8-15, 8-12, 8-10, 10-200, 10-150, 10-125, 10-110, 10-100, 10-90, 10-75, 10-50, 10-25, 10-15, 10-12, 12-200, 12-150, 12-125, 12-110, 12-100, 12-90, 12-75, 12-50, 12-25, 12-15, 15-200, 15-150, 15-125, 15-110, 15-100, 15-90, 15-75, 15-50, 15-25, 25-200, 25-150, 25-125, 25-110, 25-100, 25-90, 25-75, 25-50, 50-200, 50-150, 50-125, 50-110, 50- 100, 50-90, 50-75, 75-200, 75-150, 75-125, 75-110, 75-100, 75-90, 90-200, 90-150, 90-125, 90-110, 90-100, 100-200, 100-150, 100-125, 100-110, 110-200, 110-250, 1 10-125, 125-200,125-150, or 150-200 ng / ml). In some embodiments, the TGF-P ligand (e.g., activin A) has a concentration of about 1-50, 1-25, 5-50, 5-25, 5-15, 8-12, 10-1000, 10-500, 10-250, 10-125, 75-1000, 75-500, 75-250, 75-125, or 90-110 ng / ml. In some embodiments, the TGF-P ligand (e.g., activin A) has a concentration of about 90-1 10 ng / ml (e.g., 90, 95, 100, 105, or 110 ng / ml). In some embodiments, the TGF-P ligand (e.g., activin A) has a concentration of about 8-12 ng / ml (e.g., 8, 9, 10, 11, or 12 ng / ml).

[0067] In some embodiments, in a method described herein, the first medium further comprises a Wnt signaling pathway activator. In some embodiments, the Wnt signaling pathway activator may be a glycogen synthase kinase 3 (GSK3) inhibitor. In some embodiments, the glycogen synthase kinase 3 (GSK3) inhibitor is CHIR99021. In some embodiments, the Wnt signaling pathway activator (e.g., CHIR99021) has a concentration of 0.1-50 pM (e.g., 0.1- 50, 0.1-25, 0.1-10, 0.1-5, 0.1-4, 0.1-3, 0.1-2, 0.1-1, 0.1-0.5, 0.5-50, 0.5-25, 0.5-10, 0.5-5, 0.5- 4, 0.5-3, 0.5-2, 0.5-1, 1-50, 1-25, 1-10, 1-5, 1-4, 1-3, 1-2, 2-50, 2-25, 2-10, 2-5, 2-4, 2-3, 3- 50, 3-25, 3-10, 3-5, 3-4, 4-50, 4-25, 4-10, 4-5, 5-50, 5-25, 5-10, 10-50, 10-25, 25-50 pM). In some embodiments, the Wnt signaling pathway activator (e.g., CHIR99021) has a concentration of 2-4 pM (e.g., 2, 3, or 4 pM).

[0068] In some embodiments, in a method described herein, the first medium and / or second medium further comprises a water-soluble synthetic polymer. In some embodiments, the water-soluble synthetic polymer is polyvinyl alcohol (PVA), poloxamer, polyvinylpyrrolidone, polyethylene glycol (PEG), PEG copolymers, poly(N- isopropylacrylamide), or polyacrylamide, optionally wherein the water-soluble synthetic polymer is polyvinyl alcohol. In some embodiments, the water water-soluble synthetic polymer is polyvinyl alcohol (PVA). In some embodiments, the water-soluble synthetic polymer has a concentration of 0.005% to 0.5% (w / v), 0.01% to 0.2% (w / v), 0.02% to 0.1% (w / v), or 0.03% to 0.08% (w / v) of the culture medium. In some embodiments, the water- soluble synthetic polymer has a concentration of 0.005% (w / v), 0.01% (w / v), 0.05% (w / v), 0.1% (w / v), 0.15% (w / v), 0.2% (w / v), 0.25% (w / v), 0.3% (w / v), 0.35% (w / v), to 0.4% (w / v), 0.45% (w / v), or 0.5% (w / v) of the medium. In some embodiments, the water-soluble synthetic polymer is polyvinyl alcohol (PVA), and the PVA is at most 85% (e.g., 75%-80%) hydrolyzed. In some embodiments, the water-soluble synthetic polymer is polyvinyl alcohol (PVA), and the PVA is about 80% hydrolyzed.

[0069] In some embodiments, in a method described herein, the first population of cells is cultured in the first medium for a period of about 18-48 hours (e.g., about 18-48 hours, 18-42 hours, 18-36 hours, 18-30 hours, 18-24 hours, 24-48 hours, 24-42 hours, 24-36 hours, 24-30hours, 30-48 hours, 30-42 hours, 30-36 hours, 36-48 hours, 36-42 hours, or 42-48 hours). In some embodiments, the first population of cells is cultured in the first medium for a period of about 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, or 48 hours. In some embodiments, the first population of cells is cultured in the first medium for a period of about 24 hours. In some embodiments, culturing the first population of cells in the first media for a contacting period described herein (e.g., 24 hours) results in a second population of cells.

[0070] In some embodiments, a method described herein further comprises culturing the second population of cells with the second medium for a period of 36-72 hours (e.g., 36-72 hours, 36-66 hours, 36-60 hours, 36-54 hours, 36-48 hours, 36-42 hours, 42-72 hours, 42-66 hours, 42-60 hours, 42-54 hours, 42-48 hours, 48-72 hours, 48-66 hours, 48-60 hours, 48-54 hours, 54-72 hours, 54-66 hours, 54-60 hours, 60-72 hours, 60-66 hours, or 66-72 hours). In some embodiments, the second population of cells is cultured in the second medium for a period of about 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, or 72 hours. In some embodiments, the second population of cells is cultured in the second medium for a period of about 48 hours. In some embodiments, culturing the second population of cells in the second media for a contacting period described herein (e.g., 24 hours) results in a third population of cells. In some embodiments, the third population of cells comprise definitive endoderm cells. In some embodiments, the third population of cells further comprise pluripotent stem cells and / or cells that are at a differentiation stage of between pluripotent stem cells and definitive endoderm cells.

[0071] In some embodiments, the pluripotent stem cells used in a method described herein are embryonic stem cells. In some embodiments, the pluripotent stem cells used in a method described herein are induced pluripotent stem cells. In some embodiments, the pluripotent stem cells used in a method described herein are human pluripotent stem cells. In some embodiments, the pluripotent stem cells are ABO blood group type O. In some embodiments, the pluripotent stem cells are genetically modified such that the cell is ABO blood group type O. In some embodiments, the pluripotent stem cells have reduced expression or activity of one or more of beta-2 microglobulin, CIITA, HLA-A, HLA-B, HLA-C, HLA-DP, HLA-DQ, renalase, tissue factor, and HLA-DR, relative to cells that are not genetically modified. In some embodiments, the pluripotent stem cells have increased expression or activity of CD47, PDL1, HLA-G, CD46, CD55, CD59 and CTLA, relative to cells that are not genetically modified.

[0072] In some embodiments, a method described herein further comprises differentiating (e.g., using any methods described herein or known in the art) the definitive endoderm cells to pancreatic endocrine cells (e.g., [> cells, a cells, and 8 cells).Cell types during pancreatic differentiation

[0073] Aspects of the present disclosure provide cell types of the pancreatic lineage obtained during differentiation of stem cells to generate pancreatic islet cells. Such cells include any cell that is capable of differentiating into a pancreatic islet cell, including for example, a pluripotent stem cell, a definitive endoderm cell, a primitive gut tube cell, a pancreatic progenitor cell, or endocrine progenitor cell, when cultured under conditions suitable for differentiating the precursor cell into the pancreatic islet cell.Stem Cells

[0074] “Stem cell” refers to a cell (e.g., plant stem cell, vertebrate stem cell) that has the ability both to self-renew and to generate a differentiated cell type (Morrison et al. (1997) Cell 88:287-298). In the context of cell ontogeny, the adjective “differentiated,” or “differentiating” is a relative term. A “differentiated cell” is a cell that has progressed further down the developmental pathway than the cell it is being compared with. Thus, pluripotent stem cells can differentiate into lineage-restricted progenitor cells (e.g., mesodermal stem cells), which in turn can differentiate into cells that are further restricted (e.g., neuron progenitors), which can differentiate into end-stage cells (i.e., terminally differentiated cells, e.g., neurons, cardiomyocytes, etc.), which play a characteristic role in a certain tissue type, and can or cannot retain the capacity to proliferate further. Stem cells can be characterized by both the presence of specific markers (e.g., proteins, RNAs, etc.) and the absence of specific markers. Stem cells can also be identified by functional assays both in vitro and in vivo, particularly assays relating to the ability of stem cells to give rise to multiple differentiated progeny. In an embodiment, the host cell is an adult stem cell, a somatic stem cell, a non- embryonic stem cell, an embryonic stem cell, hematopoietic stem cell, and include a pluripotent stem cell, and a trophoblast stem cell.

[0075] In some embodiments, the stem cell is a multipotent and is not a pluripotent stem cell. In some embodiments, the stem cell is a stem cell reprogrammed from a primary pancreatic islet cell. In some embodiments, the multipotent stem cell is the SR1423 cell line described in Ratiu et al., 2023, bioRxiv, https: / / doi.org / 10.1101 / 2023.10.20.563345.

[0076] In some embodiments, cells of interest include pluripotent stem cells (PSCs). The term “pluripotent stem cell” or “PSC” is used herein to mean a stem cell capable of producing all cell types of the organism. Therefore, a PSC can give rise to cells of all germ layers of the organism (e.g., the endoderm, mesoderm, and ectoderm of a vertebrate). Pluripotent cells are capable of forming teratomas and of contributing to ectoderm, mesoderm, or endoderm tissues in a living organism. Pluripotent stem cells of plants are capable of giving rise to all cell types of the plant (e.g., cells of the root, stem, leaves, etc.).

[0077] PSCs of animals can be derived in a number of different ways. For example, embryonic stem cells (ESCs) are derived from the inner cell mass of an embryo (Thomson et al., Science. 1998 Nov. 6; 282(5391): 1145-7) whereas induced pluripotent stem cells (iPSCs) are derived from somatic cells (Takahashi et al., Cell. 2007 Nov. 30; 13 1(5): 861-72; Takahashi et al., Nat Protoc. 2007; 2(12):3081-9; Yu et al., Science. 2007 Dec. 21; 318(5858): 1917-20. Epub 2007 Nov. 20). Because the term PSC refers to pluripotent stem cells regardless of their derivation, the term PSC encompasses the terms ESC and iPSC, as well as the term embryonic germ stem cells (EGSC), which are another example of a PSC. PSCs can be in the form of an established cell line, they can be obtained directly from primary embryonic tissue, or they can be derived from a somatic cell.

[0078] By “embryonic stem cell” (ESC) is meant a PSC that is isolated from an embryo, typically from the inner cell mass of the blastocyst. ESC lines are listed in the NIH Human Embryonic Stem Cell Registry, e.g. hESBGN-Ol, hESBGN-02, hESBGN-03, hESBGN-04 (BresaGen, Inc ); HES-1, HES-2, HES-3, HES-4, HES-5, HES-6 (ES Cell International); Miz- hESl (MizMedi Hospital-Seoul National University); HSF-1, HSF-6 (University of California at San Francisco); and Hl, H7, H9, H13, H14 (Wisconsin Alumni Research Foundation (WiCell Research Institute)). Stem cells of interest also include embryonic stem cells from other primates, such as Rhesus stem cells and marmoset stem cells. The stem cells can be obtained from any mammalian species, e.g., human, equine, bovine, porcine, canine, feline, rodent, e.g. mice, rats, hamster, primate, etc. (Thomson et al. (1998) Science 282: 1145; Thomson et al. (1995) Proc. Natl. Acad. Sci USA 92:7844; Thomson et al. (1996) Biol. Reprod. 55:254; Shamblott et al., Proc. Natl. Acad. Sci. USA 95: 13726, 1998). In culture, ESCs typically grow as flat colonies with large nucleo-cytoplasmic ratios, defined borders and prominent nucleoli. In addition, ESCs express SSEA-3, SSEA-4, TRA-1-60, TRA-1-81, and Alkaline Phosphatase, but not SSEA-1 . Examples of methods of generating and characterizing ESCs may be found in, for example, U.S. Pat. No. 7,029,913, U.S. Pat. No. 5,843,780, and U.S. Pat. No. 6,200,806, each of which is incorporated herein by its entirety.Methods for proliferating hESCs in the undifferentiated form are described in WO 99 / 20741, WO 01 / 51616, and WO 03 / 020920, each of which is incorporated herein by its entirety.

[0079] By “embryonic germ stem cell” (EGSC) or “embryonic germ cell” or “EG cell,” it is meant a PSC that is derived from germ cells and / or germ cell progenitors, e.g., primordial germ cells, i.e. those that can become sperm and eggs. Embryonic germ cells (EG cells) are thought to have properties similar to embryonic stem cells as described above. Examples of methods of generating and characterizing EG cells may be found in, for example, U.S. Pat. No. 7, 153,684; Matsui, Y„ et al., (1992) Cell 70:841 ; Shamblott, M., et al. (2001) Proc. Natl. Acad. Sci. USA 98: 113; Shamblott, M„ et al. (1998) Proc. Natl. Acad. Sci. USA, 95: 13726; and Koshimizu, U., et al. (1996) Development, 122: 1235, each of which are incorporated herein by its entirety. By “induced pluripotent stem cell” or “iPSC,” it is meant a PSC that is derived from a cell that is not a PSC (i.e., from a cell this is differentiated relative to a PSC). iPSCs can be derived from multiple different cell types, including terminally differentiated cells. iPSCs have an ES cell-like morphology, growing as flat colonies with large nucleo- cytoplasmic ratios, defined borders and prominent nuclei. In addition, iPSCs express one or more key pluripotency markers known by one of ordinary skill in the art, including but not limited to Alkaline Phosphatase, SSEA3, SSEA4, Sox2, Oct3 / 4, Nanog, TRA160, TRA181, TDGF 1, Dnmt3b, FoxD3, GDF3, Cyp26al, TERT, and zfp42. Examples of methods of generating and characterizing iPSCs can be found in, for example, Patent Publication Nos. US20090047263, US20090068742, US20090191159, US20090227032, US20090246875, and US20090304646, each of which are incorporated herein by its entirety. Generally, to generate iPSCs, somatic cells are provided with reprogramming factors (e.g., Oct4, SOX2, KLF4, MYC, Nanog, Lin28, etc.) known in the art to reprogram the somatic cells to become pluripotent stem cells.

[0080] By ‘ ‘somatic cell,” it is meant any cell in an organism that, in the absence of experimental manipulation, does not ordinarily give rise to all types of cells in an organism. In other words, somatic cells are cells that have differentiated sufficiently that they do not naturally generate cells of all three germ layers of the body, i.e., ectoderm, mesoderm and endoderm. For example, somatic cells can include both neurons and neural progenitors, the latter of which is able to naturally give rise to all or some cell types of the central nervous system but cannot give rise to cells of the mesoderm or endoderm lineages.

[0081] In certain examples, the stem cells can be undifferentiated (e.g., a cell not committed to a specific lineage) prior to exposure to at least one cell maturation factor according to themethods as disclosed herein, whereas in other examples it may be desirable to differentiate the stem cells to one or more intermediate cell types prior to exposure of the at least one cell maturation factor (s) described herein. For example, the stems cells may display morphological, biological or physical characteristics of undifferentiated cells that can be used to distinguish them from differentiated cells of embryo or adult origin. In some examples, undifferentiated cells may appear in the two dimensions of a microscopic view in colonies of cells with high nuclear / cytoplasmic ratios and prominent nucleoli. The stem cells may be themselves (for example, without substantially any undifferentiated cells being present) or may be used in the presence of differentiated cells. In certain examples, the stem cells may be cultured in the presence of suitable nutrients and optionally other cells such that the stem cells can grow and optionally differentiate. For example, embryonic fibroblasts or fibroblastlike cells may be present in the culture to assist in the growth of the stem cells. The fibroblast may be present during one stage of stem cell growth but not necessarily at all stages. For example, the fibroblast may be added to stem cell cultures in a first culturing stage and not added to the stem cell cultures in one or more subsequent culturing stages.

[0082] Stem cells used in all aspects of the present invention can be any cells derived from any kind of tissue (for example embryonic tissue such as fetal or pre-fetal tissue, or adult tissue), which stem cells have the characteristic of being capable under appropriate conditions of producing progeny of different cell types, e.g., derivatives of all of at least one of the 3 germinal layers (endoderm, mesoderm, and ectoderm). These cell types may be provided in the form of an established cell line, or they may be obtained directly from primary embryonic tissue and used immediately for differentiation. Included are cells listed in the NIH Human Embryonic Stem Cell Registry, e.g. hESBGN-Ol, hESBGN-02, hESBGN-03, hESBGN-04 (BresaGen, Inc.); HES-1, HES-2, HES-3, HES-4, HES-5, HES-6 (ES Cell International); Miz- hESl (MizMedi Hospital-Seoul National University); HSF-1, FISF-6 (University of California at San Francisco); and Hl, H7, H9, H13, H14 (Wisconsin Alumni Research Foundation (WiCell Research Institute)). In some embodiments, the source of human stem cells or pluripotent stem cells used for chemically-induced differentiation into mature, insulin positive cells did not involve destroying a human embryo.

[0083] In another embodiment, the stem cells can be isolated from tissue including solid tissue. In some embodiments, the tissue is skin, fat tissue (e.g., adipose tissue), muscle tissue, heart or cardiac tissue. In other embodiments, the tissue is for example but not limited to, umbilical cord blood, placenta, bone marrow, or chondral.

[0084] Stem cells of interest also include embryonic cells of various types, exemplified by human embryonic stem (hES) cells, described by Thomson et al, (1998) Science 282: 1145; embryonic stem cells from other primates, such as Rhesus stem cells (Thomson et al. (1995) Proc. Natl. Acad. Sci. USA 92:7844); marmoset stem cells (Thomson et al. (1996) Biol. Reprod. 55:254); and human embryonic germ (hEG) cells (Shambloft et al., Proc. Natl. Acad. Sci. USA 95: 13726, 1998). Also of interest are lineage committed stem cells, such as mesodermal stem cells and other early cardiogenic cells (see Reyes et al, (2001) Blood 98:2615-2625; Eisenberg & Bader (1996) Circ Res. 78(2):205-16; etc.). The stem cells may be obtained from any mammalian species, e.g., human, equine, bovine, porcine, canine, feline, rodent, e.g., mice, rats, hamster, primate, etc. In some embodiments, a human embryo was not destroyed for the source of pluripotent cell used on the methods and compositions as disclosed herein.

[0085] A mixture of cells from a suitable source of endothelial, muscle, and / or neural stem cells can be harvested from a mammalian donor by methods known in the art. A suitable source is the hematopoietic microenvironment. For example, circulating peripheral blood, preferably mobilized (i.e., recruited), may be removed from a subject. In an embodiment, the stem cells can be reprogrammed stem cells, such as stem cells derived from somatic or differentiated cells. In such an embodiment, the de-differentiated stem cells can be for example, but not limited to, neoplastic cells, tumor cells and cancer cells or alternatively induced reprogrammed cells such as induced pluripotent stem cells or IPS cells.

[0086] In some embodiments, the stem cells are embryonic stem cells. In some embodiments, the stem cells are induced pluripotent stem cells. In some embodiments, the stem cells used in a method described herein are human stem cells. In some embodiments, the stem cells are ABO blood group type O. In some embodiments, the stem cells are genetically modified such that the cell is ABO blood group type O. In some embodiments, the stem cells have reduced expression of one or more of beta-2 microglobulin, CIITA, HLA-A, HLA-B, HLA-C, HLA- DP, HLA-DQ, HLA-DR, renalase, CXCL10, or tissue factor, relative to cells that are not genetically modified. In some embodiments, the stem cells have increased expression or activity of one or more of CD47, PDL1, HLA-G, CD46, CD55, CD59 and CTLA, relative to cells that are not genetically modified.Definitive Endoderm Cells

[0087] The definitive endoderm can be generated in vivo from the inner cell mass by the process of gastrulation of embryogenesis, in which epiblast cells are instructed to form the three germlayers. Definitive endoderm can give rise to diverse cells and tissues that contribute to vital organs as the pancreatic 0 cells, liver hepatocytes, lung alveolar cells, thyroid, thymus, and the epithelial lining of the alimentary and respiratory tract. It is different from the primitive endoderm of extraembryonic tissues, which can give rise to the visceral and parietal endoderm. The definitive endoderm derived from ES cells is theoretically capable of becoming any endoderm derivatives.

[0088] Precise patterning of anterior-posterior axis of the definitive endoderm can eventually form the primitive gut tube. The definitive endoderm-derived primitive gut tube induces the pharynx, esophagus, stomach, duodenum, small and large intestine along the anterior- posterior axis as well as associated organs, including pancreas, lung, thyroid, thymus, parathyroid, and liver. The anterior portion of the foregut of the primitive gut tube becomes lung, thyroid, esophagus, and stomach. The pancreas, liver, and duodenum originate from the posterior portion of the foregut. The midgut and hindgut of primitive gut tube gives rise to the small and large intestine. The anterior foregut expresses developmental markers, NK2 homeobox 1 (NKX2-1) and SRY (sex determining region Y)-box 2 (SOX2); the posterior foregut expresses hematopoietically expressed homeobox (HHEX), pancreatic and duodenal homeobox 1 (PDX1), one cut homeobox 1 (ONECUT1 , known as HNF6), and hepatocyte nuclear factor 4 alpha (HNF4A); and the midgut / hindgut expresses caudal type homeobox 1 (CDX1), caudal type homeobox 2 (CDX2), and motor neuron and pancreas homeobox 1 (MNX1) (3, 19, 20).

[0089] As described herein definitive endoderm cells of use herein can be derived from any source or generated in accordance with any suitable protocol. In some aspects, stem cells, e.g., iPSCs or hESCs, are differentiated to endoderm cells. In some aspects, the endoderm cells (stage 1) are further differentiated, e.g., to primitive gut tube cells (stage 2), PDX1- positive pancreatic progenitor cells (stage 3), NKX6.1 -positive pancreatic progenitor cells (stage 4), or Ngn3-positive endocrine progenitor cells or insulin-positive endocrine cells (stage 5), followed by induction or maturation to SC-0 cells (stage 6). In some embodiments, definitive endoderm cells can be obtained by differentiating at least some stem cells (e.g., pluripotent stem cells) in a population into definitive endoderm cells, e.g., by contacting a population of stem cells with i) at least one growth factor from the TGF-0 superfamily, and ii) a WNT signaling pathway activator, to induce the differentiation of at least some of the pluripotent cells into definitive endoderm cells, wherein the definitive endoderm cells express at least one marker characteristic of definitive endoderm.

[0090] Any growth factor from the TGF-P superfamily capable of inducing the pluripotent stem cells to differentiate into definitive endoderm cells (e.g., alone, or in combination with a WNT signaling pathway activator) can be used in the method provided herein. In some embodiments, the growth factor from the TGF-P superfamily comprises Activin A. In some embodiments, the growth factor from the TGF- superfamily comprises growth differentiating factor 8 (GDF8). Any WNT signaling pathway activator capable of inducing the pluripotent stem cells to differentiate into definitive endoderm cells (e.g., alone, or in combination with a growth factor from the TGF-P superfamily) can be used in the method provided herein. In some embodiments, the WNT signaling pathway activator comprises CHIR99021. In some embodiments, the WNT signaling pathway activator comprises Wnt3a recombinant protein.

[0091] In some embodiments, differentiating at least some stem cells (e.g., pluripotent stem cells) in a population into definitive endoderm cells is achieved by a process of contacting a population of pluripotent cells with i) Activin A, and ii) CHIR99021 for a suitable period of time, e.g., about 2 days, about 3 days, about 4 days, or about 5 days to induce the differentiation of at least some of the pluripotent cells in the population into definitive endoderm cells, wherein the definitive endoderm cells express at least one marker characteristic of definitive endoderm. In some embodiments, the process comprises contacting a population of stem cells (e.g., pluripotent stem cells) with activin A and CHIR99021 for 1 day, and then with activin A (in the absence of CHIR99021) for a further 1 or 2 days.

[0092] In some examples, the method comprises differentiating stem cells (e.g., pluripotent stem cells) into definitive endoderm cells by contacting a population of stem cells (e.g., pluripotent stem cells) with a suitable concentration of the growth factor from the TGF-P superfamily (e.g., Activin A, GDF 8, or GDF11), such as, about 10 ng / mL, about 20 ng / mL, about 50 ng / mL, about 75 ng / mL, about 80 ng / mL, about 90 ng / mL, about 95 ng / mL, about 100 ng / mL, about 110 ng / mL, about 120 ng / mL, about 130 ng / mL, about 140 ng / mL, about 150 ng / mL, about 175 ng / mL, about 180 ng / mL, about 200 ng / mL, about 250 ng / mL, or about 300 ng / mL. In some embodiments, the method comprises use of about 70-130 ng.ml, 80-120 ng / ml, or 90-110 ng / ml Activin A for differentiation of stem cells (e.g., pluripotent stem cells) into definitive endoderm cells. In some embodiments, the method comprises use of about 100 ng / mL Activin A for differentiation of stem cells (e.g., pluripotent stem cells) into definitive endoderm cells. In some embodiments, the method comprises use of about200 ng / mL Activin A for differentiation of stem cells (e.g., pluripotent stem cells) into definitive endoderm cells.

[0093] In some examples, the method comprises differentiating stem cells(e.g., pluripotent stem cells) into definitive endoderm cells by contacting a population of stem cells (e.g., pluripotent stem cells) with a suitable concentration of the WNT signaling pathway activator (e.g., CHIR99021), such as, about 0.01 pM, about 0.05 pM, about 0.1 pM, about 0.2 pM, about 0.5 pM, about 0.8 pM, about 1 pM, about 1.5 pM, about 2 pM, about 2.5 pM, about 3 pM, about 3.5 pM, about 4 pM, about 5 pM, about 8 pM, about 10 pM, about 12 pM, about 15 pM, about 20 pM, about 30 pM, about 50 pM, about 100 pM, or about 200 pM. In some embodiments, the method comprises use of about 1-5 pM or 2-4 pM CHIR99021 for differentiation of stem cells (e.g., pluripotent stem cells) into definitive endoderm cells. In some embodiments, the method comprises use of about 2 pM CHIR99021 for differentiation of stem cells (e.g., pluripotent stem cells) into definitive endoderm cells. In some embodiments, the method comprises use of about 3 pM CHIR99021 for differentiation of stem cells (e.g., pluripotent stem cells) into definitive endoderm cells. In some embodiments, the method comprises use of about 5 pM CHIR99021 for differentiation of stem cells (e.g., pluripotent stem cells) into definitive endoderm cells.

[0094] In some embodiments, the method comprises use of about 1-5 pM or 2-4 pM CHIR99021 for differentiation of stem cells (e.g., pluripotent stem cells) into definitive endoderm cells. In some embodiments, the method comprises use of about 2 pM CHIR99021 for differentiation of stem cells (e.g., pluripotent stem cells) into definitive endoderm cells. In some embodiments, the method comprises use of about 3 pM CHIR99021 for differentiation of stem cells (e.g., pluripotent stem cells) into definitive endoderm cells. In some embodiments, the method comprises use of about 5 pM CHIR99021 for differentiation of stem cells (e.g., pluripotent stem cells) into definitive endoderm cells.

[0095] In some embodiments, the cells are further contacted with a water-soluble synthetic polymer. In some embodiments, the water-soluble synthetic polymer is polyvinyl alcohol. In some cases, the polyvinyl alcohol is at least 78% hydrolyzed, e.g., 79-81% hydrolyzed, 87- 89% hydrolyzed, 87-90% hydrolyzed, or 99% hydrolyzed. In some embodiments, the polyvinyl alcohol is 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% hydrolyzed. In some embodiments, the PVA is 80% hydrolyzed.

[0096] In some embodiments, a definitive endoderm cell produced by the methods as disclosed herein expresses at least one marker selected from the group consisting of: Nodal, Tmprss2, Tmem30b, Stl4, Spink3, Sh3gl2, Ripk4, RablS, Npnt, Clic6, Cldn5, Cacnalb, Bnipl, Anxa4, Emb, FoxAl, Soxl7, and Rbm35a, wherein the expression of at least one marker isupregulated to by a statistically significant amount in the definitive endoderm cell relative to the pluripotent stem cell from which it was derived. In some embodiments, a definitive endoderm cell produced by the methods as disclosed herein does not express by a statistically significant amount at least one marker selected the group consisting of: Gata4, SPARC, AFP and Dab2 relative to the pluripotent stem cell from which it was derived. In some embodiments, a definitive endoderm cell produced by the methods as disclosed herein does not express by a statistically significant amount at least one marker selected the group consisting of: Zicl , Pax6, Flkl and CD31 relative to the pluripotent stem cell from which it was derived. In some embodiments, a definitive endoderm cell produced by the methods as disclosed herein has a higher level of phosphorylation of Smad2 by a statistically significant amount relative to the pluripotent stem cell from which it was derived. In some embodiments, a definitive endoderm cell produced by the methods as disclosed herein has the capacity to form gut tube in vivo. In some embodiments, a definitive endoderm cell produced by the methods as disclosed herein can differentiate into a cell with morphology characteristic of a gut cell, and wherein a cell with morphology characteristic of a gut cell expresses FoxA2 and / or Claudin6. In some embodiments, a definitive endoderm cell produced by the methods as disclosed herein can be further differentiated into a cell of endoderm origin.

[0097] In some embodiments, a population of stem cells (e.g., pluripotent stem cells) are cultured in the presence of at least one P cell differentiation factor prior to any differentiation or during the first stage of differentiation. One can use any stem cell, such as a human pluripotent stem cell, or a human iPS cell or any of pluripotent stem cell as discussed herein or other suitable pluripotent stem cells. In some embodiments, a cell differentiation factor as described herein can be present in the culture medium of a population of stem cells (e.g., pluripotent stem cells) or may be added in bolus or periodically during growth e.g. replication or propagation) of the population of pluripotent stem cells. In certain examples, a population of stem cells (e.g., pluripotent stem cells) can be exposed to at least one P cell differentiation factor prior to any differentiation. In other examples, a population of stem cells (e.g., pluripotent stem cells) may be exposed to at least one P cell differentiation factor during the first stage of differentiation.Primitive Gut Tube Cells

[0098] Aspects of the disclosure involve primitive gut tube cells. Primitive gut tube cells of use herein can be derived from any source or generated in accordance with any suitable protocol. In some aspects, definitive endoderm cells are differentiated to primitive gut tube cells. Insome aspects, the primitive gut tube cells are further differentiated, e.g., to PDXl-positive pancreatic progenitor cells, NKX6.1 -positive pancreatic progenitor cells, Ngn3-positive endocrine progenitor cells, insulin-positive endocrine cells, followed by induction or maturation to SC-P cells.

[0099] In some embodiments, primitive gut tube cells can be obtained by differentiating at least some definitive endoderm cells in a population into primitive gut tube cells, e.g., by contacting definitive endoderm cells with at least one growth factor from the fibroblast growth factor (FGF) family, to induce the differentiation of at least some of the definitive endoderm cells into primitive gut tube cells, wherein the primitive gut tube cells express at least one marker characteristic of primitive gut tube cells.

[0100] Any growth factor from the FGF family capable of inducing definitive endoderm cells to differentiate into primitive gut tube cells (e.g., alone, or in combination with other factors) can be used in the method provided herein. In some embodiments, the at least one growth factor from the FGF family comprises keratinocyte growth factor (KGF). In some embodiments, the at least one growth factor from the FGF family comprises FGF2. In some embodiments, the at least one growth factor from the FGF family comprises FGF8B. In some embodiments, the at least one growth factor from the FGF family comprises FGF10. In some embodiments, the at least one growth factor from the FGF family comprises FGF21.

[0101] In some embodiments, primitive gut tube cells can be obtained by differentiating at least some definitive endoderm cells in a population into primitive gut tube cells, e.g., by contacting definitive endoderm cells with KGF for a certain period of time, e.g., about 1 day, about 2 days, about 3 days, or about 4 days, to induce the differentiation of at least some of the definitive endoderm cells into primitive gut tube cells.

[0102] In some embodiments, the method comprises differentiating definitive endoderm cells into primitive gut tube cells by contacting definitive endoderm cells with a suitable concentration of the growth factor from the FGF family (e.g., KGF), such as, about 10 ng / mL, about 20 ng / mL, about 50 ng / mL, about 75 ng / mL, about 80 ng / mL, about 90 ng / mL, about 95 ng / mL, about 100 ng / mL, about 110 ng / mL, about 120 ng / mL, about 130 ng / mL, about 140 ng / mL, about 150 ng / mL, about 175 ng / mL, about 180 ng / mL, about 200 ng / mL, about 250 ng / mL, or about 300 ng / mL. In some embodiments, the method comprises use of about 20-80 ng / ml, 30-70 ng / ml, or 40-60 ng / mL KGF for differentiation of definitive endoderm cells into primitive gut tube cells. In some embodiments, the method comprises use of about 50 ng / mL KGF for differentiation of definitive endoderm cells into primitive guttube cells. In some embodiments, the method comprises use of about 100 ng / mL KGF for differentiation of definitive endoderm cells into primitive gut tube cells.

[0103] In some embodiments, the cells are further contacted with a water-soluble synthetic polymer. In some embodiments, the water-soluble synthetic polymer is polyvinyl alcohol. In some cases, the polyvinyl alcohol is at least 78% hydrolyzed, e.g., 79-81% hydrolyzed, 87- 89% hydrolyzed, 87-90% hydrolyzed, or 99% hydrolyzed. In some embodiments, the polyvinyl alcohol (PVA) is 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% hydrolyzed. In some embodiments, the PVA is 80% hydrolyzed.PDXl-positive Pancreatic Progenitor Cells

[0104] Aspects of the disclosure involve PDXl-positive pancreatic progenitor cells. PDXl- positive pancreatic progenitor cells of use herein can be derived from any source or generated in accordance with any suitable protocol. In some aspects, primitive gut tube cells are differentiated to PDX1 -positive pancreatic progenitor cells. In some aspects, the PDXl- positive pancreatic progenitor cells are NKX6.1 negative, and can be further differentiated to, e.g., NKX6. 1 -positive pancreatic progenitor cells, Ngn3-positive endocrine progenitor cells, insulin-positive endocrine cells, followed by induction or maturation to SC- cells.

[0105] In some aspects, PDXl-positive pancreatic progenitor cells can be obtained by differentiating at least some primitive gut tube cells in a population into PDXl-positive pancreatic progenitor cells, e.g., by contacting primitive gut tube cells with one or more of i) at least one BMP signaling pathway inhibitor, ii) a growth factor from TGF- superfamily, iii) at least one growth factor from the FGF family, iv) at least one SHH pathway inhibitor, v) at least one retinoic acid (RA) signaling pathway activator; vi) at least one protein kinase C activator, and vii) a ROCK inhibitor to induce the differentiation of at least some of the primitive gut tube cells into PDXl-positive pancreatic progenitor cells, wherein the PDXl- positive pancreatic progenitor cells express PDX1.

[0106] In some aspects, PDXl-positive pancreatic progenitor cells can be obtained by differentiating at least some primitive gut tube cells in a population into PDXl-positive pancreatic progenitor cells, e.g., by contacting primitive gut tube cells with one or more of i) at least one BMP signaling pathway inhibitor, ii) a growth factor from TGF-P superfamily, iii) at least one growth factor from the FGF family, iv) at least one SHH pathway inhibitor, v) at least one retinoic acid (RA) signaling pathway activator; and vi) at least one protein kinase C activator, to induce the differentiation of at least some of the primitive gut tube cells intoPDX1 -positive pancreatic progenitor cells, wherein the PDX1 -positive pancreatic progenitor cells express PDX1.

[0107] In some embodiments, PDX1 -positive pancreatic progenitor cells can be obtained by differentiating at least some primitive gut tube cells in a population into PDX1 -positive pancreatic progenitor cells, e.g., by contacting primitive gut tube cells with one or more of i) at least one BMP signaling pathway inhibitor, ii) at least one growth factor from the FGF family, iii) at least one SHH pathway inhibitor, iv) at least one retinoic acid (RA) signaling pathway activator; and v) at least one protein kinase C activator, to induce the differentiation of at least some of the primitive gut tube cells into PDX1 -positive pancreatic progenitor cells, wherein the PDX1 -positive pancreatic progenitor cells express PDX1.

[0108] In some embodiments, PDX1 -positive pancreatic progenitor cells can be obtained by differentiating at least some primitive gut tube cells in a population into PDX1 -positive pancreatic progenitor cells, e.g., by contacting primitive gut tube cells with i) at least one SHH pathway inhibitor, ii) at least one retinoic acid (RA) signaling pathway activator; and iii) at least one protein kinase C activator, wherein the PDX1 -positive pancreatic progenitor cells express PDX1.

[0109] In some embodiments, PDX1 -positive pancreatic progenitor cells can be obtained by differentiating at least some primitive gut tube cells in a population into PDX1 -positive pancreatic progenitor cells, e.g., by contacting primitive gut tube cells with i) at least one growth factor from the FGF family, and ii) at least one retinoic acid (RA) signaling pathway activator, to induce the differentiation of at least some of the primitive gut tube cells into PDX1 -positive pancreatic progenitor cells, wherein the PDX1 -positive pancreatic progenitor cells express PDX1.

[0110] Any BMP signaling pathway inhibitor capable of inducing primitive gut tube cells to differentiate into PDX1 -positive pancreatic progenitor cells (e.g., alone, or with any combination of a growth factor from TGF-P superfamily, at least one growth factor from the FGF family, at least one SHH pathway inhibitor, at least one retinoic acid signaling pathway activator, at least one protein kinase C activator, and ROCK inhibitor) can be used in the method provided herein. In some embodiments, the BMP signaling pathway inhibitor comprises LDN193189 or DMH-1. In some examples, the method comprises contacting primitive gut tube cells with a concentration of BMP signaling pathway inhibitor (e.g., LDN1931189), such as, about 30 nM, about 40 nM, about 50 nM, about 60 nM, about 70 nM, about 80 nM, about 90 nM, about 100 nM, about 110 nM, about 120 nM, about 130 nM, about 140 nM, about 150 nM, about 160 nM, about 170 nM, about 180 nM, about 190 nM,about 200 nM, about 210 nM, about 220 nM, about 230 nM, about 240 nM, about 250 nM, about 280 nM, about 300 nM, about 400 nM, about 500 nM, or about l|iM. In some examples, the method comprises contacting primitive gut tube cells with a concentration of BMP signaling pathway inhibitor (e.g., DMH-1), such as, about 0.01 pM, about 0.02pM, about 0.05pM, about O.lpM, about 0.2pM, about 0.5 pM, about 0.8 pM, about 1 pM, about 1.2 pM, about 1.5pM, about 1.75pM, about 2 pM, about 2.2 pM, about 2.5pM, about 2.75pM, about 3 pM, about 3.25 pM, about 3.5 pM, about 3.75 pM, about 4 pM, about 4.5 pM, about 5 pM, about 8 pM, about 10 pM, about 15 pM, about 20 pM, about 30 pM, about 40 pM, about 50 pM, or about 100 pM. In some examples, the method comprises contacting primitive gut tube cells with a concentration of BMP signaling pathway inhibitor (e.g., DMH- 1), such as, about 220-280 nM, about 230-270 nM, about 240-260 nM, or about 245-255 nM. In some examples, the method comprises contacting primitive gut tube cells with a concentration of BMP signaling pathway inhibitor (e.g., DMH-1) about 250 nM.

[0111] Any growth factor from the TGF- superfamily capable of inducing primitive gut tube cells to differentiate into PDX1 -positive pancreatic progenitor cells (e.g., alone, or with any combination of at least one BMP signaling pathway inhibitor, a growth factor from the FGF family, at least one SHH pathway inhibitor, at least one retinoic acid signaling pathway activator, at least one protein kinase C activator, and ROCK inhibitor) can be used. In some embodiments, the growth factor from TGF-P family comprises Activin A. In some embodiments, the growth factor from TGF-P family comprises GDF8. In some examples, the method comprises contacting primitive gut tube cells with a concentration of a growth factor from TGF-P superfamily (e.g., Activin A), such as, about 5 ng / mL, about 7.5 ng / mL, about 8 ng / mL, about 9 ng / mL, about 10 ng / mL, about 11 ng / mL, about 12 ng / mL, about 13 ng / mL, about 14 ng / mL, about 15 ng / mL, about 16 ng / mL, about 17 ng / mL, about 18 ng / mL, about 19 ng / mL, about 20 ng / mL, about 21 ng / mL, about 22 ng / mL, about 23 ng / mL, about 24 ng / mL, about 25 ng / mL, about 26 ng / mL, about 27 ng / mL, about 28 ng / mL, about 29 ng / mL, about 30 ng / mL, about 35 ng / mL, about 40 ng / mL, about 50 ng / mL, or about 100 ng / mL. In some examples, the method comprises contacting primitive gut tube cells with a concentration of a growth factor from TGF-P superfamily (e.g., Activin A), such as, about 17-23 ng / ml, about 18-22 ng / ml, or about 19-21 ng / ml. In some examples, the method comprises contacting primitive gut tube cells with a concentration of a growth factor from TGF-P superfamily (e.g., Activin A) of about 20 ng / ml. In some embodiments, the method does not comprise contacting primitive gut tube cells with any TGF-beta superfamily growth factor.

[0112] Any growth factor from the FGF family capable of inducing primitive gut tube cells to differentiate into PDX1 -positive pancreatic progenitor cells (e.g., alone, or with any combination of at least one BMP signaling pathway inhibitor, a growth factor from TGF-P superfamily, at least one SHH pathway inhibitor, at least one retinoic acid signaling pathway activator, at least one protein kinase C activator, and ROCK inhibitor) can be used. In some embodiments, the at least one growth factor from the FGF family comprises keratinocyte growth factor (KGF). In some embodiments, the at least one growth factor from the FGF family is selected from the group consisting of FGF2, FGF8B, FGF10, and FGF21 . In some examples, the method comprises contacting primitive gut tube cells with a concentration of a growth factor from FGF family (e.g., KGF), such as, about 10 ng / mL, about 20 ng / mL, about 50 ng / mL, about 75 ng / mL, about 80 ng / mL, about 90 ng / mL, about 95 ng / mL, about 100 ng / mL, about 110 ng / mL, about 120 ng / mL, about 130 ng / mL, about 140 ng / mL, about 150 ng / mL, about 175 ng / mL, about 180 ng / mL, about 200 ng / mL, about 250 ng / mL, or about 300 ng / mL. In some examples, the method comprises contacting primitive gut tube cells with a concentration of a growth factor from FGF family e.g., KGF), such as, about 20-80 ng / ml, about 30-70 ng / ml, about 40-60 ng / ml, or about 45-55 ng / ml. In some examples, the method comprises contacting primitive gut tube cells with a concentration of a growth factor from FGF family (e.g., KGF) of about 50 ng / ml.

[0113] Any SHH pathway inhibitor capable of inducing primitive gut tube cells to differentiate into PDX1 -positive pancreatic progenitor cells (e.g., alone, or with any combination of at least one BMP signaling pathway inhibitor, at least one growth factor from the FGF family, a growth factor from TGF-P superfamily, at least one retinoic acid signaling pathway activator, at least one protein kinase C activator, and ROCK inhibitor) can be used. In some embodiments, the SHH pathway inhibitor comprises Santl. In some examples, the method comprises contacting primitive gut tube cells with a concentration of a SHH pathway inhibitor (e.g., Santl), such as, about 0.001 pM, about 0.002 pM, about 0.005 pM, about 0.01 pM, about 0.02 pM, about 0.03pM, about 0.05pM, about 0.08 pM, about O.lpM, about 0.12 pM, about 0.13 pM, about 0.14 pM, about 0.15 pM, about 0.16 pM, about 0.17 pM, about 0.18 pM, about 0.19 pM, about 0.2 pM, about 0.21 pM, about 0.22 pM, about 0.23 pM, about 0.24 pM, about 0.25 pM, about 0.26 pM, about 0.27 pM, about 0.28 pM, about 0.29 pM, about 0.3 pM, about 0.31 pM, about 0.32 pM, about 0.33 pM, about 0.34 pM, about 0.35 pM, about 0.4 pM, about 0.45 pM, about 0.5 pM, about 0.6 pM, about 0.8 pM, about 1 pM, about 2 pM, or about 5 pM. In some examples, the method comprises contacting primitive gut tube cells with a concentration of a SHH pathway inhibitor (e.g., Santl), suchas, about 220-280 nM, about 230-270 nM, about 240-260 nM, or about 245-255 nM. In some examples, the method comprises contacting primitive gut tube cells with a concentration of a SHH pathway inhibitor (e.g., Santl) of about 250 nM.

[0114] Any RA signaling pathway activator capable of inducing primitive gut tube cells to differentiate into PDXl-positive pancreatic progenitor cells (e.g., alone, or with any combination of at least one BMP signaling pathway inhibitor, at least one growth factor from the FGF family, at least one SHH pathway inhibitor, at least one protein kinase C activator, and ROCK inhibitor) can be used. In some embodiments, the RA signaling pathway activator comprises retinoic acid. In some examples, the method comprises contacting primitive gut tube cells with a concentration of an RA signaling pathway activator (e.g., retinoic acid), such as, about 0.02 pM, about O.lpM, about 0.2 pM, about 0.25 pM, about 0.3 pM, about 0.4 pM, about 0.45 pM, about 0.5 pM, about 0.55 pM, about 0.6 pM, about 0.65 pM, about 0.7 pM, about 0.75 pM, about 0.8 pM, about 0.85 pM, about 0.9 pM, about 1 pM, about 1.1 pM, about 1.2 pM, about 1.3 pM, about 1.4 pM, about 1.5 pM, about 1.6 pM, about 1.7 pM, about 1.8 pM, about 1.9 pM, about 2 pM, about 2.1 pM, about 2.2 pM, about 2.3 pM, about 2.4 pM, about 2.5 pM, about 2.6 pM, about 2.7 pM, about 2.8 pM, about 3 pM, about 3.2 pM, about 3.4 pM, about 3.6 pM, about 3.8 pM, about 4 pM, about 4.2 pM, about 4.4 pM, about 4.6 pM, about 4.8 pM, about 5 pM, about 5.5 pM, about 6 pM, about 6.5 pM, about 7 pM, about 7.5 pM, about 8 pM, about 8.5 pM, about 9 pM, about 9.5 pM, about 10 pM, about 12 pM, about 14 pM, about 15 pM, about 16 pM, about 18 pM, about 20 pM, about 50 pM, or about 100 pM. In some examples, the method comprises contacting primitive gut tube cells with a concentration of an RA signaling pathway activator (e.g., retinoic acid), such as, about 1.7-2.3 pM, about 1.8-2.2 pM, or about 1.9-2.1 pM. In some examples, the method comprises contacting primitive gut tube cells with a concentration of an RA signaling pathway activator (e.g., retinoic acid) of about 2 pM.

[0115] Any PKC activator capable of inducing primitive gut tube cells to differentiate into PDXl-positive pancreatic progenitor cells (e.g., alone, or with any combination of at least one BMP signaling pathway inhibitor, at least one growth factor from the FGF family, at least one SHH pathway inhibitor, at least one RA signaling pathway activator, and ROCK inhibitor) can be used. In some embodiments, the PKC activator comprises PdBU. In some embodiments, the PKC activator comprises TPPB. In some examples, the method comprises contacting primitive gut tube cells with a concentration of a PKC activator (e.g., PdBU or TPPB), such as, about 10 nM, 50 nM, 100 nM, 150 nM, 200 nM, 250 nM, 300 nM, 350 nM, 400 nM, 450 nM, 500 nM, 550 nM, 600 nM, 650 nM, 700 nM, 750 nM, 800 nM, 850 nM,900 nM, 950 nM, 1 pM, 10 pM, about 20 pM, about 50 pM, about 75 pM, about 80 pM, about 100 pM, about 120 pM, about 140 pM, about 150 pM, about 175 pM, about 180 pM, about 200 pM, about 210 pM, about 220 pM, about 240 pM, about 250 pM, about 260 pM, about 280 pM, about 300 pM, about 320 pM, about 340 pM, about 360 pM, about 380 pM, about 400 pM, about 420 pM, about 440 pM, about 460 pM, about 480 pM, about 500 pM, about 520 pM, about 540 pM, about 560 pM, about 580 pM, about 600 pM, about 620 pM, about 640 pM, about 660 pM, about 680 pM, about 700 pM, about 750 pM, about 800 pM, about 850 pM, about 900 pM, about 1 mM, about 2 mM, about 3 mM, about 4 mM, or about 5 mM. In some embodiments, the method comprises contacting primitive gut tube cells with a concentration of a PKC activator (e. ., PdBU or TPPB) of 10 nM-1 mM, 10 nM-500 pM,10 nM-1 pM, 10-800 nM, 100-900 nM, 300-800 nM, 300-600 nM, 400-600 nM, 450-550 nM, or about 500 nM. In some examples, the method comprises contacting primitive gut tube cells with a concentration of a PKC activator (e.g., PdBU or TPPB), such as, about 450- 550 mM, about 475-525 nM, about 490-510 nM, or about 495-505 nM. In some examples, the method comprises contacting primitive gut tube cells with a concentration of a PKC activator (e.g., PdBU or TPPB) of about 500 nM. In some embodiments, primitive gut tube cells are not treated with a PKC activator (e.g., PDBU).

[0116] Any ROCK inhibitor capable of inducing primitive gut tube cells to differentiate into PDXl-positive pancreatic progenitor cells e.g., alone, or with any combination of at least one BMP signaling pathway inhibitor, at least one growth factor from the FGF family, at least one SHH pathway inhibitor, PKC activator, and at least one RA signaling pathway activator) can be used. In some embodiments, the ROCK inhibitor comprises Thiazovivin, Y-27632, Fasudil / HA1077, or H-l 152. In some embodiments, the ROCK inhibitor comprises Y-27632. In some embodiments, the ROCK inhibitor comprises Thiazovivin. In some examples, the method comprises contacting primitive gut tube cells with a concentration of a ROCK inhibitor (e.g., Y-27632 or Thiazovivin), such as, about 0.2 pM, about 0.5 pM, about 0.75 pM, about 1 pM, about 2 pM, about 3 pM, about 4 pM, about 5 pM, about 6 pM, about 7 pM, about 7.5 pM, about 8 pM, about 9 pM, about 10 pM, about11 pM, about 12 pM, about 13 pM, about 14 pM, about 15 pM, about 16 pM, about 17 pM, about 18 pM, about 19 pM, about 20 pM, about 21 pM, about 22 pM, about 23 pM, about 24 pM, about 25 pM, about 26 pM, about 27 pM, about 28 pM, about 29 pM, about 30 pM, about 35 pM, about 40 pM, about 50 pM, or about 100 pM. In some examples, the method comprises contacting primitive gut tube cells with a concentration of a ROCK inhibitor (e.g., Y-27632 or Thiazovivin), such as, about 2.2-2.8 pM, about 2.3-2.7 pM, or about 2.4-2.6 pM.In some examples, the method comprises contacting primitive gut tube cells with a concentration of a ROCK inhibitor (e.g., Y-27632 or Thiazovivin) of about 2.5 pM.

[0117] In some embodiments, the cells are further contacted with a water-soluble synthetic polymer. In some embodiments, the water-soluble synthetic polymer is polyvinyl alcohol. In some cases, the polyvinyl alcohol is at least 78% hydrolyzed, e.g., 79-81% hydrolyzed, 87- 89% hydrolyzed, 87-90% hydrolyzed, or 99% hydrolyzed. In some embodiments, the polyvinyl alcohol (PVA) is 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% hydrolyzed. In some embodiments, the PVA Is 80% hydrolyzed.

[0118] In some embodiments, PDX1 -positive pancreatic progenitor cells can be obtained by differentiating at least some primitive gut tube cells in a population into PDX1 -positive pancreatic progenitor cells, e.g., by contacting primitive gut tube cells with retinoic acid, KGF, Santl, DMH-1, PdBU, thiazovivin, and Activin A, for a suitable period of time, e.g., about 1 day, about 2 days, about 3 days, or about 4 days. In some embodiments, PDX1- positive pancreatic progenitor cells can be obtained by differentiating at least some primitive gut tube cells in a population into PDX1 -positive pancreatic progenitor cells, e.g., by contacting primitive gut tube cells with retinoic acid, KGF, Santl, DMH-1, PdBU, thiazovivin, and Activin A, for about 2 days. In some embodiments, PDXl-positive pancreatic progenitor cells can be obtained by differentiating at least some primitive gut tube cells in a population into PDXl-positive pancreatic progenitor cells, e.g., by contacting primitive gut tube cells with retinoic acid, KGF, Santl, DMH-1, PdBU, thiazovivin, and Activin A for 1 day, followed by contacting the cells with retinoic acid, KGF, Santl, PdBU, thiazovivin, and Activin A for 1 day (in the absence of DMH-1).NKX6.1 -positive Pancreatic Progenitor Cells

[0119] Aspects of the disclosure involve NKX6.1 -positive pancreatic progenitor cells.NKX6. 1 -positive pancreatic progenitor cells of use herein can be derived from any source or generated in accordance with any suitable protocol. In some aspects, PDXl-positive, NKX6.1 -negative pancreatic progenitor cells are differentiated to PDXl-positive, NKX6.1- positive pancreatic progenitor cells. In some aspects, the NKX6.1-positive pancreatic progenitor cells are further differentiated, e.g., to Ngn3-positive endocrine progenitor cells, or insulin-positive endocrine cells, followed by induction or maturation to SC- cells.

[0120] In some aspects, a method of producing a NKX6.1-positive pancreaticprogenitor cell from a PDX1 -positive pancreatic progenitor cell comprises contacting a population of cells (e.g., under conditions that promote cell clustering and / or promoting cell survival) comprising PDX1 -positive pancreatic progenitor cells with at least two cell-differentiation factors comprising a) at least one growth factor from the fibroblast growth factor (FGF) family, b) a sonic hedgehog pathway inhibitor, and optionally c) a low concentration of a retinoic acid (RA) signaling pathway activator, to induce the differentiation of at least one PDX1 -positive pancreatic progenitor cell in the population into NKX6.1-positive pancreatic progenitor cells, wherein the NKX6.1 -positive pancreatic progenitor cells expresses NKX6.1.

[0121] In some embodiments, the PDX1 -positive, NKX6.1-positive pancreatic progenitor cells are obtained by contacting PDX1 -positive pancreatic progenitor cells with i) at least one growth factor from the FGF family, ii) at least one SHH pathway inhibitor, and optionally iii) a RA signaling pathway activator, to induce the differentiation of at least some of the PDX1- positive pancreatic progenitor cells into PDX1 -positive, NKX6.1 -positive pancreatic progenitor cells, wherein the PDX 1 -positive, NKX6.1- positive pancreatic progenitor cells express PDX1 and NKX6.1.

[0122] In some embodiments, the PDX 1 -positive, NKX6.1-positive pancreatic progenitor cells are obtained by contacting PDX 1 -positive pancreatic progenitor cells with i) at least one growth factor from the FGF family, ii) at least one SHH pathway inhibitor, and optionally iii) a RA signaling pathway activator, iv) ROCK inhibitor, and v) at least one growth factor from the TGF- superfamily, to induce the differentiation of at least some of the PDXl-positive pancreatic progenitor cells into PDXl-positive, NKX6. 1 -positive pancreatic progenitor cells. In some embodiments, following 3, 4, or 5 days of contacting the PDXl-positive, NKX6.1- positive pancreatic progenitor cells are obtained by contacting PDXl-positive pancreatic progenitor cells with i) at least one growth factor from the FGF family, ii) at least one SHH pathway inhibitor, and optionally iii) a RA signaling pathway activator, iv) ROCK inhibitor, and v) at least one growth factor from the TGF-0 superfamily; the cells are then contacted with i) at least one growth factor from the FGF family, ii) at least one SHH pathway inhibitor, and optionally iii) a RA signaling pathway activator, iv) ROCK inhibitor, and v) at least one growth factor from the TGF- superfamily, and vi) a PKC activator and optionally vii) a gamma-secretase inhibitor. In some embodiments, the PDXl-positive, NKX6.1- positive pancreatic progenitor cells are obtained by contacting PDXl-positive pancreatic progenitor cells under conditions that promote cell clustering with at least one growth factor from the FGF family. In some embodiments, the growth factor from the FGF family is KGF.

[0123] In some embodiments, the disclosure provides for a method in which a first population of cells comprising PDX1 -positive, NKX6.1 -negative cells is cultured in a media comprising any one or combination of: i) at least one growth factor from the FGF family, ii) at least one SHH pathway inhibitor, iii) a RA signaling pathway activator, iv) a ROCK inhibitor, and v) a growth factor from the TGF-P superfamily for a period of about 1, 2, 3, 4 or 5 days (e.g., 2-4,3-4, or 4-5 days); thereby generating a second population of cells. In some embodiments, the second population of cells is then incubated in a composition comprising any one or combination of: i) at least one growth factor from the FGF family, ii) at least one SHH pathway inhibitor, iii) a RA signaling pathway activator, iv) a ROCK inhibitor, v) a growth factor from the TGF-P superfamily, vi) a PKC activator, vii) a FoxOl inhibitor, and optionally viii) a notch signaling inhibitor for about 1, 2, or 3 days (e.g., 1-2, 1-3, or 2-3 days).

[0124] In some embodiments, in the media for culturing the first population of cells, the growth factor from the FGF family is present at a concentration of about 45-55 ng / ml, about 46-54 ng / ml, about 47-53 ng / ml, about 48-52 ng / ml, or about 49-51 ng / ml, the SHH pathway inhibitor is present at a concentration of about 200-300 nM, about 220-280 nM, or about 240- 260 nM, the RA signaling pathway activator is present at a concentration of about 1.7-2.3 pM, about 1.8-2.2 pM, or about 1.9-2.1 pM, the ROCK inhibitor is present at a concentration of about 2-3 pM, about 2.2-2.8 pM, or about 2.4-2.6 pM, and / or the growth factor from the TGF-P superfamily is present at a concentration of about 2-8 ng / ml, about 3-7 ng / ml or about4-6 ng / ml.

[0125] In some embodiments, in the media for culturing the second population of cells, the growth factor from the FGF family is present at a concentration of about 45-55 ng / ml, about 46-54 ng / ml, about 47-53 ng / ml, about 48-52 ng / ml, or about 49-51 ng / ml, the SHH pathway inhibitor is present at a concentration of about 200-300 nM, about 220-280 nM, or about 240- 260 nM, the RA signaling pathway activator is present at a concentration of about 1.7-2.3 pM, about 1.8-2.2 pM, or about 1.9-2.1 pM, the ROCK inhibitor is present at a concentration of about 2-3 pM, about 2.2-2.8 pM, or about 2.4-2.6 pM, the growth factor from the TGF-P superfamily is present at a concentration of 2 about -8 ng / ml, about 3-7 ng / ml or about 4-6 ng / ml, the PKC activator is present at a concentration of about 0.2-0.8 pM, about 0.3-0.7 pM, or about 0.4-0.6 pM, and the FoxOl inhibitor is present at a concentration of about 0.7-1.3 pM, about 0.8-1.2 pM, or about 0.9-1.1 pM, and optionally the notch signaling inhibitor is present at a concentration of about 1.7-2.3 pM, about 1.8-2.2 pM, or about 1.9-2. 1 pM.

[0126] In some embodiments, the PDX1 -positive pancreatic progenitor cells are produced from a population of pluripotent cells. In some embodiments, the PDX1 -positive pancreatic progenitor cells are produced from a population of iPS cells. In some embodiments, the PDX1 -positive pancreatic progenitor cells are produced from a population of ESC cells. In some embodiments, the PDXl-positive pancreatic progenitor cells are produced from a population of definitive endoderm cells. In some embodiments, the PDXl-positive pancreatic progenitor cells are produced from a population of primitive gut tube cells.

[0127] Any growth factor from the FGF family capable of inducing PDXl -positive pancreatic progenitor cells to differentiate into NKX6.1 -positive pancreatic progenitor cells (e.g., alone, or with any combination of at least one SHH pathway inhibitor, a ROCK inhibitor, a growth factor from the TGF- superfamily, and at least one retinoic acid signaling pathway activator) can be used in the method provided herein. In some embodiments, the at least one growth factor from the FGF family comprises keratinocyte growth factor (KGF). In some embodiments, the at least one growth factor from the FGF family is selected from the group consisting of FGF8B, FGF 10, and FGF21. In some examples, the method comprises contacting PDXl-positive pancreatic progenitor cells with a concentration of a growth factor from FGF family e.g., KGF), such as, about 10 ng / mL, about 20 ng / mL, about 50 ng / mE, about 75 ng / mE, about 80 ng / mL, about 90 ng / mL, about 95 ng / mL, about 100 ng / mL, about 110 ng / mL, about 120 ng / mL, about 130 ng / mL, about 140 ng / mL, about 150 ng / mL, about 175 ng / mL, about 180 ng / mL, about 200 ng / mL, about 250 ng / mL, or about 300 ng / mL. In some examples, the method comprises contacting PDXl-positive pancreatic progenitor cells with a concentration of a growth factor from FGF family (e.g., KGF), such as, about 20-80 ng / ml, about 30-70 ng / ml, about 40-60 ng / ml, or about 45-55 ng / ml. In some examples, the method comprises contacting PDXl-positive pancreatic progenitor cells with a concentration of a growth factor from FGF family (e.g., KGF) of about 50 ng / ml.

[0128] Any SHH pathway inhibitor capable of inducing PDXl-positive pancreatic progenitor cells to differentiate into NKX6.1 -positive pancreatic progenitor cells (e.g., alone, or with any combination of at least one growth factor from the FGF family, a retinoic acid signaling pathway activator, ROCK inhibitor, and at least one growth factor from the TGF-P superfamily) can be used in the method provided herein. In some embodiments, the SHH pathway inhibitor comprises Santl. In some examples, the method comprises contacting PDXl-positive pancreatic progenitor cells with a concentration of a SHH pathway inhibitor (e.g., Santl), such as, about 0.001 pM, about 0.002 pM, about 0.005 pM, about 0.01 pM, about 0.02 pM, about 0.03pM, about 0.05pM, about 0.08 pM, about 0.1 pM, about 0.12 pM,about 0.13 pM, about 0.14 pM, about 0.15 pM, about 0.16 pM, about 0.17 pM, about 0.18 pM, about 0.19 pM, about 0.2 pM, about 0.21pM, about 0.22pM, about 0.23pM, about 0.24 M, about 0.25 M, about 0.26 pM, about 0.27 pM, about 0.28 pM, about 0.29 pM, about 0.3 pM, about 0.31 pM, about 0.32 pM, about 0.33 pM, about 0.34 pM, about 0.35 pM, about 0.4 pM, about 0.45 pM, about 0.5 pM, about 0.6 pM, about 0.8 pM, about 1 pM, about 2 pM, or about 5 pM. In some examples, the method comprises contacting PDXl-positive pancreatic progenitor cells with a concentration of a SHH pathway inhibitor (e.g., Santl), such as, about 220-280 nM, about 230-270 nM, about 240-260 nM, or about 245-255 nM. In some examples, the method comprises contacting PDXl-positive pancreatic progenitor cells with a concentration of a SHH pathway inhibitor (e.g., Santl) of about 250 nM.

[0129] Any RA signaling pathway activator capable of inducing PDXl-positive pancreatic progenitor cells to differentiate into NKX6.1 -positive pancreatic progenitor cells e.g., alone, or with any combination of at least one growth factor from the FGF family, at least one SHH pathway inhibitor, ROCK inhibitor, and at least one growth factor from the TGF-P superfamily) can be used. In some embodiments, the RA signaling pathway activator comprises retinoic acid. In some examples, the method comprises contacting PDXl-positive pancreatic progenitor cells with a concentration of an RA signaling pathway activator (e.g., retinoic acid), such as, about 0.02 pM, about 0.1 pM, about 0.2 pM, about 0.25 pM, about 0.3 pM, about 0.4 pM, about 0.45 pM, about 0.5 pM, about 0.55 pM, about 0.6 pM, about 0.65 pM, about 0.7 pM, about 0.75 pM, about 0.8 pM, about 0.85 pM, about 0.9 pM, about 1 pM, about 1.1 pM, about 1.2 pM, about 1.3 pM, about 1.4 pM, about 1.5 pM, about 1.6 pM, about 1.7 pM, about 1.8 pM, about 1.9 pM, about 2 pM, about 2.1 pM, about 2.2 pM, about 2.3 pM, about 2.4 pM, about 2.5 pM, about 2.6 pM, about 2.7 pM, about 2.8 pM, about 3 pM, about 3.2 pM, about 3.4 pM, about 3.6 pM, about 3.8 pM, about 4 pM, about 4.2 pM, about 4.4 pM, about 4.6 pM, about 4.8 pM, about 5 pM, about 5.5 pM, about 6 pM, about 6.5 pM, about 7 pM, about 7.5 pM, about 8 pM, about 8.5 pM, about 9 pM, about 9.5 pM, about 10 pM, about 12 pM, about 14 pM, about 15 pM, about 16 pM, about 18 pM, about 20 pM, about 50 pM, or about 100 pM. In some examples, the method comprises contacting PDXl-positive pancreatic progenitor cells with a concentration of an RA signaling pathway activator (e.g., retinoic acid), such as, about 70-130 nM, about 80-120 nM, about 90-110 nM, or about 95-105 nM. In some examples, the method comprises contacting PDXl-positive pancreatic progenitor cells with a concentration of an RA signaling pathway activator (e.g., retinoic acid) of about 100 nM.

[0130] Any ROCK inhibitor capable of inducing PDXl-positive pancreatic progenitor cells to differentiate into NKX6.1 -positive pancreatic progenitor cells (e.g., alone, or with any combination of at least one growth factor from the FGF family, at least one SHH pathway inhibitor, a RA signaling pathway activator, and at least one growth factor from the TGF-P superfamily) can be used. In some embodiments, the ROCK inhibitor comprises Thiazovivin, Y-27632, Fasudil / HA1077, or 14-1152. In some examples, the method comprises contacting PDXl-positive pancreatic progenitor cells with a concentration of a ROCK inhibitor (e.g., Y- 27632 or Thiazovivin), such as, about 0.2 pM, about 0.5 pM, about 0.75 pM, about 1 pM, about 2 pM, about 3 pM, about 4 pM, about 5 pM, about 6 pM, about 7 pM, about 7.5 pM, about 8 pM, about 9 pM, about 10 pM, about 11 pM, about 12 pM, about 13 pM, about 14 pM, about 15 pM, about 16 pM, about 17 pM, about 18 pM, about 19 pM, about 20 pM, about 21 pM, about 22 pM, about 23 pM, about 24 pM, about 25 pM, about 26 pM, about 27 pM, about 28 pM, about 29 pM, about 30 pM, about 35 pM, about 40 pM, about 50 pM, or about 100 pM. In some examples, the method comprises contacting PDXl-positive pancreatic progenitor cells with a concentration of a ROCK inhibitor (e.g., Y-27632 or Thiazovivin), such as, about 2.2-2.8 pM, about 2.3-2.7 pM, or about 2.4-2.6 pM. In some examples, the method comprises contacting PDXl-positive pancreatic progenitor cells with a concentration of a ROCK inhibitor (e.g., Y-27632 or Thiazovivin) of about 2.5 pM.

[0131] Any activator from the TGF-P superfamily capable of inducing PDXl-positive pancreatic progenitor cells to differentiate into NKX6. 1 -positive pancreatic progenitor cells (e.g., alone, or with any combination of at least one growth factor from the FGF family, at least one SHH pathway inhibitor, a RA signaling pathway activator, and ROCK inhibitor) can be used. In some embodiments, the activator from the TGF-P superfamily comprises Activin A or GDF8. In some examples, the method comprises contacting PDXl-positive pancreatic progenitor cells with a concentration of a growth factor from TGF- superfamily (e.g., Activin A), such as, about 0.1 ng / mL, about 0.2 ng / mL, about 0.3 ng / mL, about 0.4 ng / mL, about 0.5 ng / mL, about 0.6 ng / mL, about 0.7 ng / mL, about 0.8 ng / mL, about 1 ng / mL, about 1.2 ng / mL, about 1.4 ng / mL, about 1.6 ng / mL, about 1.8 ng / mL, about 2 ng / mL, about 2.2 ng / mL, about 2.4 ng / mL, about 2.6 ng / mL, about 2.8 ng / mL, about 3 ng / mL, about 3.2 ng / mL, about 3.4 ng / mL, about 3.6 ng / mL, about 3.8 ng / mL, about 4 ng / mL, about 4.2 ng / mL, about 4.4 ng / mL, about 4.6 ng / mL, about 4.8 ng / mL, about 5 ng / mL, about 5.2 ng / mL, about 5.4 ng / mL, about 5.6 ng / mL, about 5.8 ng / mL, about 6 ng / mL, about 6.2 ng / mL, about 6.4 ng / mL, about 6.6 ng / mL, about 6.8 ng / mL, about 7 ng / mL, about 8 ng / mL, about 9 ng / mL, about 10 ng / mL, about 20 ng / mL, about 30 ng / mL, orabout 50 ng / mL. In some examples, the method comprises contacting PDXl-positive pancreatic progenitor cells with a concentration of a growth factor from TGF- superfamily (e.g., Activin A), such as, about 2-8 ng / ml, about 3-7 ng / ml, about 4-6 ng / ml, or about 4.5-5.5 ng / ml. In some examples, the method comprises contacting PDXl-positive pancreatic progenitor cells with a concentration of a growth factor from TGF-P superfamily e.g., Activin A), such as, about 5 ng / mL.

[0132] Any FoxOl inhibitor capable of inducing PDXl-positive pancreatic progenitor cells to differentiate into NKX6. 1 -positive pancreatic progenitor cells (e.g., alone, or with any combination of at least one growth factor from the FGF family, at least one retinoic acid signaling pathway activator, ROCK inhibitor, at least one growth factor from the TGF-P superfamily, PKC activator, and Notch signaling inhibitor) can be used in the method provided herein. In some embodiments, the FoxOl inhibitor is AS 1842856.

[0133] In some examples, the method comprises contacting PDXl-positive pancreatic progenitor cells with a concentration of a FoxOl inhibitor, such as, about 0.1 pM, about 0.12 pM, about 0.13 pM, about 0.14 pM, about 0.15 pM, about 0.16 pM, about 0.17 pM, about 0.18 pM, about 0.19 pM, about 0.2 pM, about 0.21pM, about 0.22pM, about 0.23pM, about 0.24 pM, about 0.25 pM, about 0.26 pM, about 0.27 pM, about 0.28 pM, about 0.29 pM, about 0.3 pM, about 0.31 pM, about 0.32 pM, about 0.33 pM, about 0.34 pM, about 0.35 pM, about 0.4 pM, about 0.45 pM, about 0.5 pM, about 0.6 pM, about 0.8 pM, about 1 pM, about 2 pM, or about 5 pM. In some examples, the method comprises contacting PDXl- positive pancreatic progenitor cells with a concentration of a FoxOl inhibitor, such as, about 0.7-1.3 pM, about 0.8-1.2 pM, about or 0.9-1.1 pM. In some examples, the method comprises contacting PDXl-positive pancreatic progenitor cells with a concentration of a FoxOl inhibitor, such as, about 1 pM.

[0134] Any PKC activator capable of inducing PDXl-positive pancreatic progenitor cells to differentiate into NKX6. 1 -positive pancreatic progenitor cells (e.g., alone, or with any combination of at least one growth factor from the FGF family, at least one retinoic acid signaling pathway activator, ROCK inhibitor, at least one growth factor from the TGF-P superfamily, FoxOl inhibitor, and Notch signaling inhibitor) can be used in the method provided herein. In some embodiments, the PKC activator is PDBU. In some examples, the method comprises contacting PDXl-positive pancreatic progenitor cells with a concentration of a PKC activator (e.g., PDBU), such as, about O.lpM, about 0.12 pM, about 0.13 pM, about 0.14 pM, about 0.15 pM, about 0.16 pM, about 0.17 pM, about 0.18 pM, about 0.19 pM, about 0.2 pM, about 0.21pM, about 0.22pM, about 0.23pM, about 0.24 pM, about 0.25pM, about 0.26 pM, about 0.27 pM, about 0.28 pM, about 0.29 pM, about 0.3 pM, about 0.31 pM, about 0.32 pM, about 0.33 pM, about 0.34 pM, about 0.35 pM, about 0.4 pM, about 0.45 pM, about 0.5 pM, about 0.6 pM, about 0.8 pM, about 1 pM, about 2 pM, or about 5 pM. In some examples, the method comprises contacting PDXl-positive pancreatic progenitor cells with a concentration of a PKC activator (e.g., PDBU), such as, about 0.2-0.8 pM, about 0.3-0.7 pM, about 0.4-0.6 pM. In some examples, the method comprises contacting PDXl-positive pancreatic progenitor cells with a concentration of a PKC activator (e.g., PDBU), such as, about 0.5 pM.

[0135] Any Notch signaling inhibitor capable of inducing PDXl-positive pancreatic progenitor cells to differentiate into NKX6.1 -positive pancreatic progenitor cells (e.g., alone, or with any combination of at least one growth factor from the FGF family, at least one retinoic acid signaling pathway activator, ROCK inhibitor, at least one growth factor from the TGF-P superfamily, FoxOl inhibitor, and PKC activator) can be used in the method provided herein. In some embodiments, the Notch signaling inhibitor is XXI. In some examples, the method comprises contacting PDXl-positive pancreatic progenitor cells with a concentration of a Notch signaling inhibitor (e.g., XXI), such as, about O.lpM, about 0.12 pM, about 0.13 pM, about 0.14 pM, about 0.15 pM, about 0.16 pM, about 0.17 pM, about 0.18 pM, about 0.19 pM, about 0.2 pM, about 0.21 pM, about 0.22 pM, about 0.23 pM, about 0.24 pM, about 0.25 pM, about 0.26 pM, about 0.27 pM, about 0.28 pM, about 0.29 pM, about 0.3 pM, about 0.31 pM, about 0.32 pM, about 0.33 pM, about 0.34 pM, about 0.35 pM, about 0.4 pM, about 0.45 pM, about 0.5 pM, about 0.6 pM, about 0.8 pM, about 1 pM, about 2 pM, or about 5 pM. In some examples, the method comprises contacting PDXl-positive pancreatic progenitor cells with a concentration of a Notch signaling inhibitor (e.g., XXI), such as, about 1.7-2.3 pM, about 1.8-2.2 pM, or about 1.9- 2.1 pM. In some examples, the method comprises contacting PDXl-positive pancreatic progenitor cells with a concentration of a Notch signaling inhibitor (e.g., XXI), such as, about 2 pM.

[0136] In some embodiments, the cells are further contacted with a water-soluble synthetic polymer. In some embodiments, the water-soluble synthetic polymer is polyvinyl alcohol. In some cases, the polyvinyl alcohol is at least 78% hydrolyzed, e.g., 79-81% hydrolyzed, 87- 89% hydrolyzed, 87-90% hydrolyzed, or 99% hydrolyzed. In some embodiments, the polyvinyl alcohol (PVA) is 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% hydrolyzed. In some embodiments, the PVA is 80% hydrolyzed.

[0137] In some embodiments, the PDX1 -positive, NKX6.1 -positive pancreatic progenitor cells are obtained by contacting PDX1 -positive pancreatic progenitor cells under conditions that promote cell clustering with KGF, Santl, and RA, for a period of 5 days or 6 days. In some embodiments, the PDX1 -positive, NKX6. 1 -positive pancreatic progenitor cells are obtained by contacting PDX1 -positive pancreatic progenitor cells under conditions that promote cell clustering with KGF, Santl, RA, thiazovivin, and Activin A, for a period of 5 or 6 days. In some embodiments, the PDX1 -positive, NKX6.1 -positive pancreatic progenitor cells are obtained by contacting PDX1 -positive pancreatic progenitor cells under conditions that promote cell clustering with KGF for a period of 5 days. In some embodiments, the PDX1- positive, NKX6. 1 -positive pancreatic progenitor cells are obtained by contacting PDX1- positive pancreatic progenitor cells under conditions that promote cell clustering with KGF for a period of 6 days. In some embodiments, the PDX1 -positive, NKX6.1 -positive pancreatic progenitor cells are obtained by: a) contacting PDX1 -positive pancreatic progenitor cells with KGF, Santl, RA, thiazovivin, and Activin A, for a period of 3, 4 or 5 days (e.g., 4 days), followed by; b) contacting the cells of a) with PDBU, XXI, KGF, Santl, RA, thiazovivin, and Activin A and optionallyderivatives thereof for a period of 1, 2 or 3 days (e.g., 2 days).Insulin-positive Endocrine Cells

[0138] Aspects of the disclosure involve insulin-positive endocrine cells (e.g., [3-like cells) and additional methods of generating insulin-positive endocrine cells. Insulin-positive endocrine cells of use herein can be derived from any source or generated in accordance with any suitable protocol. In some aspects, pancreatic foregut precursor cells are differentiated toinsulin-positive endocrine cells (e.g., P-like cells), In some aspects, the insulin-positive endocrine cells are further differentiated, e.g., by induction or maturation to SC-P cells.

[0139] In some aspects, a method of producing an insulin-positive endocrine cell from a pancreatic foregut precursor cell comprises contacting a population of cells (e.g., under conditions that promote cell clustering) comprising pancreatic foregut precursor cells with a) a TGF-P signaling pathway inhibitor, b) a thyroid hormone signaling pathway activator, c) a BMP pathway inhibitor, and / or d) a protein kinase inhibitor to induce the differentiation of at least one pancreatic foregut precursor cell in the population into an insulin-positive endocrine cell, wherein the insulin-positive endocrine ceil expresses insulin. In some embodiments, insulin-positive endocrine cells express PDX1, NKX6.1, ISL1, NKX2.2, Mafb, glis3, Suri, Kir6.2, Znt8, SLC2A1, SLC2A3 and / or insulin.

[0140] Any TGF-P signaling pathway inhibitor capable of inducing the differentiation of pancreatic foregut precursor cells to differentiate into insulin-positive endocrine cells e.g., alone, or in combination with other P cell-differentiation factors, e.g., a thyroid hormone signaling pathway activator) can be used. In some embodiments, the TGF-P signaling pathway comprises TGF-P receptor type 1 kinase signaling. In some embodiments, the TGF-P signaling pathway inhibitor comprises Alk5 inhibitor II. In some examples, the method comprises contacting pancreatic foregut precursor cells with a concentration of a TGF-P signaling pathway inhibitor (e.g., Alk5 inhibitor such as Alk5 inhibitor II), such as, about 0.1 pM, about 0.5 pM, about 1 pM, about 1.5 pM, about 2 pM, about 2.5 pM, about 3 pM, about 3.5 pM, about 4 pM, about 4.5 pM, about 5 pM, about 5.5 pM, about 6 pM, about 6.5 pM, about 7 pM, about 7.5 pM, about 8 pM, about 8.5 pM, about 9 pM, about 9.5 pM, about 10 pM, about 10.5 pM, about 11 pM, about 11.5 pM, about 12 pM, about 12.5 pM, about 13 pM, about 13.5 pM, about 14 pM, about 14.5 pM, about 15 pM, about 15.5 pM, about 16 pM, about 16.5 pM, about 17 pM, about 17.5 pM, about 18 pM, about 18.5pM, about 19 pM, about 19.5 pM, about 20 pM, about 25 pM, about 30 pM, about 35 pM, about 40 pM, about 45 pM, or about 50 pM. In some examples, the method comprises contacting pancreatic foregut precursor cells with a concentration of a TGF-P signaling pathway inhibitor (e.g., Alk5 inhibitor such as Alk5 inhibitor II), such as, about 7-13 pM, about 8-12 pM, about 9-11 pM. In some examples, the method comprises contacting pancreatic foregut precursor cells with a concentration of a TGF- signaling pathway inhibitor (e.g., Alk5 inhibitor such as Alk5 inhibitor II), such as, about 10 pM.

[0141] Any thyroid hormone signaling pathway activator capable of inducing the differentiation of pancreatic foregut precursor cells to differentiate into insulin-positive endocrine cells (e.g.,alone, or in combination with other 0 cell-differentiation factors, e.g., a TGF-0 signaling pathway inhibitor) can be used. In some embodiments, the thyroid hormone signaling pathway activator comprises triiodothyronine (T3). In some embodiments, the thyroid hormone signaling pathway activator comprises GC-1. In some examples, the method comprises contacting pancreatic foregut precursor cells with a concentration of thyroid hormone signaling pathway activator (e.g., GC-1), such as, about O.lpM, about 0.12 pM, about 0.13 pM, about 0.14 pM, about 0.15 pM, about 0.16 pM, about 0.17 pM, about 0.18 pM, about 0.19 pM, about 0.2 pM, about 0.21 pM, about 0.22pM, about 0.23pM, about 0.24 pM, about 0.25 pM, about 0.26 pM, about 0.27 pM, about 0.28 pM, about 0.29 pM, about 0.3 pM, about 0.31 pM, about 0.32 pM, about 0.33 pM, about 0.34 pM, about 0.35 pM, about 0.4 pM, about 0.45 pM, about 0.5 pM, about 0.6 pM, about 0.8 pM, about 1 pM, about 2 pM, or about 5 pM. In some examples, the method comprises contacting pancreatic foregut precursor cells with a concentration of thyroid hormone signaling pathway activator (e.g., GC-1), such as, about 0.7-1.3 pM, about 0.8-1.2 pM, or about 0.9-1.1 pM. In some examples, the method comprises contacting pancreatic foregut precursor cells with a concentration of thyroid hormone signaling pathway activator (e.g., GC-1), such as, about 1 pM.

[0142] In some embodiments, the method comprises contacting the population of cells (e.g., pancreatic foregut precursor cells) with at least one additional factor. In some embodiments, the method comprises contacting the pancreatic foregut precursor cells with at least one of i) a SHH pathway inhibitor, ii) a y-secretase inhibitor, iii) at least one growth factor from the epidermal growth factor (EGF) family, iv) a TGF-0 signaling pathway inhibitor, or vii) a thyroid hormone signaling pathway activator. In some embodiments, the method comprises contacting the population of cells (e.g., pancreatic foregut precursor cells) with at least one additional factor. In some embodiments, the method comprises contacting the pancreatic foregut precursor cells with at least one of i) a SHH pathway inhibitor, ii) a RA signaling pathway activator, iii) a y-secretase inhibitor, iv) at least one growth factor from the epidermal growth factor (EGF) family, v) a protein kinase inhibitor, vi) a TGF-0 signaling pathway inhibitor, vii) a thyroid hormone signaling pathway activator, viii) a wnt signaling pathway inhibitor, or ix) a PKC activator.

[0143] In some embodiments, the method comprises contacting the pancreatic foregut precursor cells with at least one of i) a SHH pathway inhibitor, ii) a RA signaling pathway activator, iii) a y-secretase inhibitor, iv) at least one growth factor from the epidermal growth factor (EGF) family, v) at least one bone morphogenetic protein (BMP) signaling pathway inhibitor, vi) aTGF-P signaling pathway inhibitor, vii) a thyroid hormone signaling pathway activator, viii) a protein kinase inhibitor, or ix) a ROCK inhibitor.

[0144] In some embodiments, the method comprises contacting the pancreatic foregut precursor cells with at least one of i) a SHH pathway inhibitor, ii) a RA signaling pathway activator, iii) a y-secretase inhibitor, iv) at least one growth factor from the epidermal growth factor (EGF) family, v) at least one bone morphogenetic protein (BMP) signaling pathway inhibitor, vi) a TGF-P signaling pathway inhibitor, vii) a thyroid hormone signaling pathway activator, viii) an epigenetic modifying compound, ix) a protein kinase inhibitor, or x) a ROCK inhibitor. In some embodiments, the method comprises contacting the pancreatic foregut precursor cells in a culture with a i) a SHH pathway inhibitor, ii) a RA signaling pathway activator, iii) a y- secretase inhibitor, iv) at least one growth factor from the epidermal growth factor (EGF) family, v) at least one bone morphogenetic protein (BMP) signaling pathway inhibitor, vi) a TGF-P signaling pathway inhibitor, vii) a thyroid hormone signaling pathway activator, viii) an epigenetic modifying compound, ix) a protein kinase inhibitor, x) a ROCK inhibitor, xi) a PKC activator and xii) a Wnt signaling pathway inhibitor for 1, 2, or 3 days (e.g., 1-2, 1-3, or 2-3 days), and then contacting the cells in the culture with i) a y-secretase inhibitor, ii) at least one growth factor from the epidermal growth factor (EGF) family, iii) at least one bone morphogenetic protein (BMP) signaling pathway inhibitor, iv) a TGF-P signaling pathway inhibitor, v) a thyroid hormone signaling pathway activator, vi) an epigenetic modifying compound, vii) a protein kinase inhibitor, and viii) a ROCK inhibitor for a period of 1, 2, 3, 4, 5, 6, or 7 days (e.g., 1-7, 1-5, 1-3, 3-7, 3-5, 5-7, or 4-6 days) in the absence of a SHH pathway inhibitor, a RA signaling pathway activator, a Wnt signaling pathway inhibitor, PKC activator, and / or growth factor from the epidermal growth factor (EGF) family.

[0145] In some embodiments, in the method of generating the insulin-positive endocrine cells from the pancreatic foregut precursor cells, some of the differentiation factors are present only for the first 1, 2, 3, 4, or 5 days during the differentiation step. In some embodiments, some of the differentiation factors, such as the SHH pathway inhibitor, the RA signaling pathway activator, the PKC activator, and the at least one growth factor from the EGF family are removed from the culture medium after the first 1, 2, or 3 days of incubation.

[0146] Any y-secretase inhibitor that is capable of inducing the differentiation of pancreatic foregut precursor cells in a population into insulin-positive endocrine cells (e.g., alone, or in combination with any of a TGF-P signaling pathway inhibitor and / or a thyroid hormone signaling pathway activator) can be used. In some embodiments, the y-secretase inhibitor comprises XXL In some embodiments, the y-secretase inhibitor comprises DAPT. In someexamples, the method comprises contacting pancreatic foregut precursor cells with a concentration of a y-secretase inhibitor (<?.g., XXI), such as, about 0.01 pM, about 0.02 pM, about 0.05 pM, about 0.075 pM, about 0.1 pM, about 0.2 pM, about 0.3 pM, about 0.4 pM, about 0.5 pM, about 0.6 pM, about 0.7 pM, about 0.8 pM, about 0.9 pM, about 1 pM, about1.1 pM, about 1.2 pM, about 1.3 pM, about 1.4 pM, about 1.5 pM, about 1.6 pM, about 1.7 pM, about 1.8 pM, about 1.9 pM, about 2 pM, about 2.1 pM, about 2.2 pM, about 2.3 pM, about 2.4 pM, about 2.5 pM, about 2.6 pM, about 2.7 pM, about 2.8 pM, about 2.9 pM, about 3 pM, about 3.2 pM, about 3.4 pM, about 3.6 pM, about 3.8 pM, about 4 pM, about4.2 pM, about 4.4 pM, about 4.6 pM, about 4.8 pM, about 5 pM, about 5.2 pM, about 5.4 pM, about 5.6 pM, about 5.8 pM, about 6 pM, about 6.2 pM, about 6.4 pM, about 6.6 pM, about 6.8 pM, about 7 pM, about 8 pM, about 9 pM, about 10 pM, about 20 pM, about 30 pM, or about 50 pM. In some examples, the method comprises contacting pancreatic foregut precursor cells with a concentration of a y-secretase inhibitor (e.g., XXI), such as, about 1.7-2.3 pM, about 1.8-2.2 pM, or about 1.9-2.1 pM. In some examples, the method comprises contacting pancreatic foregut precursor cells with a concentration of a y-secretase inhibitor (e.g., XXI), such as about 2 pM.

[0147] Any growth factor from the EGF family capable of inducing the differentiation of pancreatic foregut precursor cells in a population into insulin-positive endocrine cells (e.g., alone, or in combination with any of a TGF-P signaling pathway inhibitor and / or a thyroid hormone signaling pathway activator) can be used. In some embodiments, the at least one growth factor from the EGF family comprises betacellulin. In some embodiments, at least one growth factor from the EGF family comprises EGF. In some examples, the method comprises contacting pancreatic foregut precursor cells with a concentration of a growth factor from EGF family (e.g., betacellulin), such as, about 1 ng / mL, about 2 ng / mL, about 4 ng / mL, about 6 ng / mL, about 8 ng / mL, about 10 ng / mL, about 12 ng / mL, about 14 ng / mL, about 16 ng / mL, about 18 ng / mL, about 20 ng / mL, about 22 ng / mL, about 24 ng / mL, about 26 ng / mL, about 28 ng / mL, about 30 ng / mL, about 40 ng / mL, about 50 ng / mL, about 75 ng / mL, about 80 ng / mL, about 90 ng / mL, about 95 ng / mL, about 100 ng / mL, about 150 ng / mL, about 200 ng / mL, about 250 ng / mL, or about 300 ng / mL. In some examples, the method comprises contacting pancreatic foregut precursor cells with a concentration of a growth factor from EGF family (e.g., betacellulin), such as, about 17-23 ng / ml, about 18-22 ng / ml, or about 19-21 ng / ml. In some examples, the method comprises contacting NKX6.1- positive pancreatic progenitor cells with a concentration of a growth factor from EGF family (e.g., betacellulin), such as, about 20 ng / ml.

[0148] Any RA signaling pathway activator capable of inducing the differentiation of pancreatic foregut precursor cells to differentiate into insulin-positive endocrine cells (e.g., alone, or in combination with any of a TGF-P signaling pathway inhibitor and / or a thyroid hormone signaling pathway activator) can be used. In some embodiments, the RA signaling pathway activator comprises RA. In some examples, the method comprises contacting pancreatic foregut precursor cells with a concentration of an RA signaling pathway activator (e.g., retinoic acid), such as, about 0.02 pM, about 0.05 pM, about 0.1 pM, about 0.2 pM, about 0.25 pM, about 0.3 pM, about 0.4 pM, about 0.45 pM, about 0.5 pM, about 0.55 pM, about 0.6 pM, about 0.65 pM, about 0.7 pM, about 0.75 pM, about 0.8 pM, about 0.85 pM, about 0.9 pM, about 1 pM, about 1.1 pM, about 1.2 pM, about 1.3 pM, about 1.4 pM, about 1.5 pM, about 1.6 pM, about 1.7 pM, about 1.8 pM, about 1.9 pM, about 2 pM, about 2.1 pM, about 2.2 pM, about 2.3 pM, about 2.4 pM, about 2.5 pM, about 2.6 pM, about 2.7 pM, about 2.8 pM, about 3 pM, about 3.2 pM, about 3.4 pM, about 3.6 pM, about 3.8 pM, about 4 pM, about 4.2 pM, about 4.4 pM, about 4.6 pM, about 4.8 pM, about 5 pM, about 5.5 pM, about 6 pM, about 6.5 pM, about 7 pM, about 7.5 pM, about 8 pM, about 8.5 pM, about 9 pM, about 9.5 pM, about 10 pM, about 12 pM, about 14 pM, about 15 pM, about 16 pM, about 18 pM, about 20 pM, about 50 pM, or about 100 pM. In some examples, the method comprises contacting pancreatic foregut precursor cells with a concentration of an RA signaling pathway activator e.g., retinoic acid), such as, about 20-80 nM, about 30-70 nM, or about 40-60 nM. In some examples, the method comprises contacting pancreatic foregut precursor cells with a concentration of an RA signaling pathway activator e.g., retinoic acid), such as, about 50 nM.

[0149] Any SHH pathway inhibitor capable of inducing the differentiation of pancreatic foregut precursor cells to differentiate into insulin-positive endocrine cells (e.g., alone, or in combination with any of a TGF- signaling pathway inhibitor and / or a thyroid hormone signaling pathway activator) can be used in the method provided herein. In some embodiments, the SHH pathway inhibitor comprises Santl. In some examples, the method comprises contacting pancreatic foregut precursor cells with a concentration of a SHH pathway inhibitor (e.g., Santl), such as, about 0.001 pM, about 0.002 pM, about 0.005 pM, about 0.01 pM, about 0.02 pM, about 0.03pM, about 0.05pM, about 0.08 pM, about O.lpM, about 0.12 pM, about 0.13 pM, about 0.14 pM, about 0.15 pM, about 0.16 pM, about 0.17 pM, about 0.18 pM, about 0.19 pM, about 0.2 pM, about 0.21pM, about 0.22pM, about 0.23pM, about 0.24 pM, about 0.25 pM, about 0.26 pM, about 0.27 pM, about 0.28 pM, about 0.29 pM, about 0.3 pM, about 0.31 pM, about 0.32 pM, about 0.33 pM, about 0.34 pM, about 0.35 pM, about 0.4 pM, about 0.45 pM, about 0.5 pM, about 0.6 pM, about 0.8 pM, about 1 pM, about 2 pM, or about 5 pM. In some examples, the method comprises contacting pancreatic foregut precursorcells with a concentration of a SHH pathway inhibitor (e.g., Santl), such as, about 220-280 nM, about 230-270 nM, about 240-260 nM, or about 245-255 nM. In some examples, the method comprises contacting pancreatic foregut precursor cells with a concentration of a SHH pathway inhibitor (e.g., Santl), such as, about 250 nM.

[0150] Any BMP signaling pathway inhibitor capable of inducing the differentiation of pancreatic foregut precursor cells to differentiate into insulin-positive endocrine cells (e.g., alone, or in combination with any of a TGF- signaling pathway inhibitor and / or a thyroid hormone signaling pathway activator) can be used. In some embodiments, the BMP signaling pathway inhibitor comprises LDN193189 or DMH-1. In some examples, the method comprises contacting pancreatic foregut precursor cells with a concentration of BMP signaling pathway inhibitor (e.g., LDN 1931189), such as, about 30 nM, about 40 nM, about 50 nM, about 60 nM, about 70 nM, about 80 nM, about 90 nM, about 100 nM, about 110 nM, about 120 nM, about 130 nM, about 140 nM, about 150 nM, about 160 nM, about 170 nM, about 180 nM, about 190 nM, about 200 nM, about 210 nM, about 220 nM, about 230 nM, about 240 nM, about 250 nM, about 280 nM, about 300 nM, about 400 nM, about 500 nM, or about IpM. In some examples, the method comprises contacting pancreatic foregut precursor cells with a concentration of BMP signaling pathway inhibitor (e.g., LDN1931189), such as, about 70-130 nM, about 80-120 nM, about 90-1 10 nM. In some examples, the method comprises contacting pancreatic foregut precursor cells with a concentration of BMP signaling pathway inhibitor (e.g., LDN1931189), such as, about 100 nM.

[0151] Any ROCK inhibitor that is capable of inducing the differentiation of pancreatic foregut precursor cells in a population into insulin-positive endocrine cells (e.g., alone, or in combination with any of a TGF-[3 signaling pathway inhibitor and / or a thyroid hormone signaling pathway activator) can be used. In some embodiments, the ROCK inhibitor comprises Thiazovivin, Y-27632, Fasudil / HA1077, or H-1152. In some embodiments, the ROCK inhibitor comprises Y-27632. In some embodiments, the ROCK inhibitor comprises Thiazovivin. In some examples, the method comprises contacting PDX1 -positive, NKX6.1 -positive pancreatic progenitor cells with a concentration of a ROCK inhibitor (e.g., Y-27632 or Thiazovivin), such as, about 0.2 pM, about 0.5 pM, about 0.75 pM, about 1 pM, about 2 pM, about 3 pM, about 4 pM, about 5 pM, about 6 pM, about 7 pM, about 7.5 pM, about 8 pM, about 9 pM, about 10 pM, about 11 pM, about 12 pM, about 13 pM, about 14 pM, about 15 pM, about 16 pM, about 17 pM, about 18 pM, about 19 pM, about 20 pM, about 21 pM, about 22 pM, about 23 pM, about 24 pM, about 25 pM, about 26 pM, about 27 pM, about 28 pM, about 29 pM, about 30 pM, about 35 pM, about 40 pM, about 50 pM, or about 100 pM. In some embodiments, the ROCK inhibitor comprises Thiazovivin. In some examples, the method comprises contacting PDX1 -positive, NKX6.1 -positive pancreatic progenitor cells with a concentration of a ROCK inhibitor (e.g., Y-27632 or Thiazovivin), such as, about 2.2-2.8 pM, about 2.3-2.7 pM, or about 2.4-2.6 pM. In some embodiments, the ROCK inhibitor comprises Thiazovivin.In some examples, the method comprises contacting pancreatic foregut precursor cells with a concentration of a ROCK inhibitor (e.g., Y-27632 or Thiazovivin), such as, about 2.5 pM.

[0152] Any epigenetic modifying compound that is capable of inducing the differentiation of pancreatic foregut precursor cells in a population into insulin-positive endocrine cells (e.g., alone, or in combination with any of a TGF-P signaling pathway inhibitor and / or a thyroid hormone signaling pathway activator) can be used. In some embodiments, the epigenetic modifying compound comprises a histone methyltransferase inhibitor or a HD AC inhibitor. In some embodiments, the epigenetic modifying compound comprises a histone methyltransferase inhibitor, e.g., DZNep. In some embodiments, the epigenetic modifying compound comprises a HDAC inhibitor, e.g., KD5170. In some examples, the method comprises contacting pancreatic foregut precursor cells with a concentration of an epigenetic modifying compound (e.g., DZNep or KD5170), such as, about 0.01 pM, about 0.025 pM, about 0.05 pM, about 0.075 pM, about 0.1 pM, about 0.15 pM, about 0.2 pM, about 0.5 pM, about 0.75 pM, about 1 pM, about 2 pM, about 3 pM, about 4 pM, about 5 pM, about 6 pM, about 7 pM, about 7.5 pM, about 8 pM, about 9 pM, about 10 pM, about 15 pM, about 20 pM, about 25 pM, about 30 pM, about 35 pM, about 40 pM, about 50 pM, or about 100 pM. In some examples, the method comprises contacting pancreatic foregut precursor cells with a concentration of an epigenetic modifying compound (e.g., DZNep or KD5170), such as, about 70-1 0 nM, about 80- 120 nM, or about 90-110 nM. In some examples, the method comprises contacting pancreatic foregut precursor cells with a concentration of an epigenetic modifying compound (e.g., DZNep or KD5170), such as, about 100 nM.

[0153] Any Wnt signaling pathway inhibitor that is capable of inducing the differentiation of pancreatic foregut precursor cells in a population into insulin-positive endocrine cells (e.g., alone, or in combination with any of a TGF- signaling pathway inhibitor and / or a thyroid hormone signaling pathway activator) can be used. In some embodiments, the Wnt signaling pathway inhibitor comprises a tankyrase inhibitor. In some embodiments, the tankyrase inhibitor is NVP-TNKS656. In some examples, the method comprises contacting pancreatic foregut precursor cells with a concentration of a Wnt signaling pathway inhibitor (e.g., a tankyrase inhibitor such as NVP- TNKS656), such as, about O.lpM, about 0.15 pM, about 0.2 pM, about 0.25 pM, about 0.3 pM, about 0.35 pM, about 0.4 pM, about 0.45 pM, about 0.5 pM, about 0.55 pM, about 0.6 pM, about 0.65 pM, about 0.7 pM, about 0.75 pM, about 0.8 pM, about 0.85 pM, about 0.9 pM, about 0.95 pM, about 1 pM, about 1.5 pM, about 2 pM, about 2.5 pM, about 3 pM, about 3.5 pM, about 4 pM, about 4.5 pM, or about 5 pM. In some examples, the method comprises contacting pancreatic foregut precursor cells with a concentration of a Wnt signaling pathway inhibitor (e.g., a tankyrase inhibitor such as NVP-TNKS656), such as, about 1.7-2.3 pM, about 1.8-2.2 pM, or about 1.9-2.1 pM. In some examples, the method comprises contacting pancreatic foregut precursor cells with a concentration of a Wnt signaling pathway inhibitor (e.g., a tankyrase inhibitor such as NVP-TNKS656), such as, about 2 pM.

[0154] Any PKC activator that is capable of inducing the differentiation of pancreatic foregut precursor cells in a population into insulin-positive endocrine cells (e.g., alone, or in combination with any of a TGF- signaling pathway inhibitor and / or a thyroid hormone signaling pathway activator) can be used. In some embodiments, the PKC activator is TPB or PDBU. In some examples, the method comprises contacting pancreatic foregut precursor cells with a concentration of a PKC activator (TPB or PDBU), such as, about 0.01 pM, about 0.025 pM, about 0.05 pM, about 0.075 pM, about 0.1 pM, about 0.15 pM, about 0.2 pM, about 0.25 pM, about 0.3 pM, about 0.35 pM, about 0.4 pM, about 0.45 pM, about 0.5 pM, about 0.55 pM, about 0.6 pM, about 0.65 pM, about 0.7 pM, about 0.75 pM, about 0.8 pM, about 0.85 pM, about 0.9 pM, about 0.95 pM, about 1 pM, about 2 pM, about 3 pM, about 4 pM, about 5 pM, about 6 pM, about 7 pM, about 7.5 pM, about 8 pM, about 9 pM, about 10 pM, about 15 pM, or about 20 pM. In some examples, the method comprises contacting pancreatic foregut precursor cells with a concentration of a PKC activator (TPB or PDBU), such as, about 450-550 mM, about 475-525 nM, about 490-510 nM, or about 495-505 nM. In some examples, the method comprises contacting pancreatic foregut precursor cells with a concentration of a PKC activator (TPB or PDBU), such as, about 500 nM.

[0155] In some embodiments, the population of cells is optionally contacted with a protein kinase inhibitor. In some embodiments, the population of cells is not contacted with the protein kinase inhibitor. In some embodiments, the population of cells is contacted with the protein kinase inhibitor. Any protein kinase inhibitor that is capable of inducing the differentiation of pancreatic foregut precursor cells in a population into insulin-positive endocrine cells (e.g., alone, or in combination with any of a TGF-[3 signaling pathway inhibitor and / or a thyroid hormone signaling pathway activator). In some embodiments, the protein kinase inhibitor comprises staurosporine. In some examples, the method comprises contacting pancreatic foregut precursor cells with a concentration of a protein kinase inhibitor (e.g., staurosporine), such as, about 0.1 nM, about 0.2 nM, about 0.3 nM, about 0.4 nM, about 0.5 nM, about 0.6 nM, about 0.7 nM, about 0.8 nM, about 0.9 nM, about 1 nM, about 1.1 nM, about 1.2 nM, about 1.3 nM, about 1.4 nM, about 1.5 nM, about 1.6 nM, about 1.7 nM, about 1.8 nM, about 1.9 nM, about 2.0 nM, about 2.1 nM, about 2.2 nM, about 2.3 nM, about 2.4 nM, about 2.5 nM, about 2.6 nM, about 2.7 nM, about 2.8 pM, about 2.9 nM, about 3 nM, about 3.1 nM, about 3.2 nM, about 3.3 nM, about 3.4 nM, about 3.5 nM, about 3.6 nM, about 3.7 nM, about 3.8 nM, about 3.9 nM, about 4.0 nM, about 4.1 nM, about 4.2 nM, about 4.3 nM, about 4.4 nM, about 4.5 nM, about 4.6 nM, about 4.7 nM, about 4.8 pM, about 4.9 nM, or about 5 nM. In some examples, the method comprises contacting pancreatic foregut precursor cells with a concentration of a protein kinase inhibitor (e.g., staurosporine), such as, about 1-5 nM, about 2-4 nM, or about 2.5-3.5 nM. In some examples, the method comprises contacting pancreatic foregut precursor cells with a concentration of a protein kinase inhibitor (e.g., staurosporine), such as, about 3 nM.

[0156] In some embodiments, the cells are further contacted with a water-soluble synthetic polymer. In some embodiments, the water-soluble synthetic polymer is polyvinyl alcohol. In somecases, the polyvinyl alcohol is at least 78% hydrolyzed, e.g., 79-81% hydrolyzed, 87-89% hydrolyzed, 87-90% hydrolyzed, or 99% hydrolyzed. In some embodiments, the polyvinyl alcohol (PVA) is 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% hydrolyzed. In some embodiments, the PVA is 89% hydrolyzed.

[0157] In some embodiments, the method comprises contacting the population of cells (e.g., pancreatic foregut precursor cells) with XXI, Alk5i, T3 or GC-1, RA, Santl, and betacellulin, PDBU, and NVP-TNKS656 for a period of 7 days, to induce the differentiation of at least one NKX6.1- positive pancreatic progenitor cell in the population into an insulin-positive endocrine cell, wherein the insulin-positive endocrine cell expresses insulin. In some embodiments, the method comprises contacting the population of cells (e.g., pancreatic foregut precursor cells ) with XXI, Alk5i, T3 or GC-1, RA, Santl, betacellulin, and LDN193189 for a period of 7 days, to induce the differentiation of at least one pancreatic foregut precursor cell in the population into an insulin-positive endocrine cell, wherein the insulin-positive endocrine cell expresses insulin. In some embodiments, one or more differentiation factors are added in a portion of the Stage 5, for instance, only the first 1, 2, 3, 4, 5, or 6 days of the period of time for Stage 5, or the last 1, 2, 3, 4, 5, or 6 days of the period of time for Stage 5. In one example, the cells are contacted with SHH signaling pathway inhibitor the PKC activator, the retinoic acid, and / or the wnt signaling pathway inhibitor for only the first 2, 3, 4, or 5 days during Stage 5, after which the SHH signaling pathway inhibitor, the PKC activator, the retinoic acid, and / or the wnt signaling pathway inhibitor are not included in or removed from the culture medium. In another example, the cells are contacted with BMP signaling pathway inhibitor for only the first 1, 2, or 3 days during Stage 5, after which the BMP signaling pathway inhibitor is removed from the culture medium.

[0158] In some embodiments, the method comprises contacting the population of cells (e.g., pancreatic foregut precursor cells) with one or more metabolites. In some embodiments, the method comprises contacting the population of cells (e.g., pancreatic foregut precursor cells) with one or more of an acetyl CoA-related metabolite, a vitamin, histone deacetylase inhibitor (HDACi), a redox homeostasis regulator, a one carbon metabolism pathway intermediate, and / or glutamine. Examples of metabolites include glutamine, taurine, acetate, beta-hydroxybutyrate, biotin, and formate.

[0159] In some embodiments, a composition (e.g., medium) of the disclosure comprises an acetyl CoA-related metabolite. Exemplary acetyl CoA-related metabolites include, but are not limited to acetate, pyruvate, ketogenic amino acids, valine, leucine, isoleucine, phenylalanine, tyrosine, lysine, tryptophan, fatty acids, CoA, Isovaleryl-CoA, and [3-hydroxybutyrate. In some embodiments, the acetyl CoA-related metabolite is acetate. In some embodiments, the acetyl CoA-related metabolite is present in or is added to a composition of the disclosure at a concentration of about 10 nM, about 50 nM, about 80 nM, about 100 nM, about 120 nM, about 140 nM, about 150 nM, about 200 nM, about 300 nM, about 500 nM, about 800 nM, about 1 pM, about 10 pM, about 100 pM, about 500 pM, about 800 pM, about 900 pM, about 1 mM, about 2 mM, about 3 mM, about 5 mM, or about 10 mM.In some embodiments, the acetyl CoA-related metabolite is present in or is added to a composition of the disclosure at a concentration of about 0.01-50 mM, 0.1-50 mM, 0.5-50 mM, 0.01-20 mM, 0.1-20 mM, 0.5-20 mM, 0.01-10 mM, 0.1-10 mM, 0.5-10 mM, 0.8-25 mM, 0.8-10 mM, 0.8-5 mM, 0.8-2 mM, 0.8-1.5 mM, 0.8-1.2 mM, 0.9-1.1 mM, or 0.95-1.05 mM. In some embodiments, the acetyl CoA- related metabolite is acetate present at a concentration of about 1 mM. In some embodiments, the acetyl CoA-related metabolite is acetate present at a concentration of about 50-1000 nM, 50-800 nM, 50-500 nM, 50-300 nM, 50-250 nM, 100-200 nM, or 125-175 nM. In some embodiments, the acetyl CoA-related metabolite is acetate present at a concentration of about 160 nM.

[0160] In some embodiments, a composition (e.g., medium) of the disclosure comprises one or more vitamins. Exemplary vitamins include, but are not limited to vitamin C, biotin, vitamin B 1 (thiamine), vitamin B2 (riboflavin), vitamin B3 (niacin), vitamin B6 (pyridoxine) and vitamin B 12 (cyanocobalamin). In some embodiments the vitamin modulates fatty acid synthesis. In some embodiments the vitamin modulates branched-chain amino acid metabolism. In some embodiments the vitamin modulates or participates as a co-factor in the TCA cycle, e.g., as a cofactor for pyruvate carboxylase. In some embodiments, the vitamin is biotin. In some embodiments, the vitamin is present in or is added to a composition of the disclosure at a concentration of about 100 nM, about 300 nM, about 500 nM, about 600 nM, about 700 nM, about 800 nM, about 900 nM, about 1 pM, about 1.5 pM, about 3 pM, about 5 pM, about 10 pM, or about 100 pM. In some embodiments, the vitamin is biotin present at a concentration of about 800 nM. In some embodiments, the vitamin is present in or is added to a composition of the disclosure at a concentration of about 1 nM to 500 pM, 1 nM to 100 pM, 1 nM to 10 pM, 1 nM to 1 pM, 1 nM to 800 nM, 1 nM to 600 nM, 1 nM to 400 nM, 1 nM to 300 nM, 1 nM to 200 nM, 25 nM to 500 pM, 25 nM to 100 pM, 25 nM to 10 pM, 25 nM to 1 pM, 25 nM to 800 nM, 25 nM to 600 nM, 25 nM to 400 nM, 25 nM to 300 nM, 25 nM to 200 nM, 50 nM to 500 pM, 50 nM to 100 pM, 50 nM to 10 pM, 50 nM to 1 pM, 50 nM to 800 nM, 50 nM to 600 nM, 50 nM to 400 nM, 50 nM to 300 nM, 50 nM to 200 nM, 100 nM to 500 pM, 100 nM to 100 pM, 100 nM to 10 pM, 100 nM to 1 pM, 100 nM to 800 nM, 100 nM to 600 nM, 100 nM to 400 nM, 100 nM to 300 nM, or 100 nM to 200 nM.

[0161] In some embodiments, a composition (e.g., medium) of the disclosure comprises a histone deacetylase inhibitor (HDACi). Exemplary histone deacetylase inhibitors (HDACi) include, but are not limited to -Hydroxybutyrate, butyric acid, class I HDACi, class IIA HDACi, class IIB HDACi, class III HDACi, class IV HDACi, HDAC-1, HD AC-2, HD AC-3, HD AC-4, HD AC-5, HD AC-6, HDAC-7, HDAC-8, HD AC-9, HDAC-10, HDAC-11, sirtuins, SIRT1, SIRT2, SIRT3, SIRT4, SIRT5, SIRT6, SIRT7, Vorinostat (suberoylanilide hydroxamic acid, SAHA, MK0683), Entinostat (MS-275, SNDX-275), Panobinostat (LBH589, NVP-LBH589), Trichostatin A (TSA), Mocetinostat (MGCD0103, MG0103), GSK3117391 (GSK3117391A, HDAC-IN-3), BRD33O8, BRD3308, Tubastatin A TFA (Tubastatin A trifluoroacetate salt), Tubastatin A, SIS 17, NKL 22, BML-210 (CAY10433), TC-H 106, SR-4370, Belinostat (PXD101, NSC726630, PX-105684), Romidepsin(FK228, Depsipeptide, FR 901228, NSC 630176), MC1568, Givinostat (ITF2357), Dacinostat (LAQ824, NVP-LAQ824), CUDC-101, Quisinostat (JNJ-26481585), Pracinostat (SB939), PCI- 34051, Droxinostat (NS 41080), Abexinostat (PCI- 24781), Abexinostat (PCI-24781, CRA-024781), RGFP966, AR-42 (HDAC-42), Ricolinostat (ACY-1215, Rocilinostat), Valproic acid sodium salt (Sodium valproate), Tacedinaline (CI994, PD- 123654, GOE-5549, Acetyldinaline), Fimepinostat (CUDC-907), Sodium butyrate (NaB), Curcumin, Diferuloylmethane, M344, Tubacin, RG2833 (RGFP109), RG2833 (RGFP109), Resminostat (RAS241O), Divalproex Sodium, Scriptaid (GCK 1026), Sodium Phenylbutyrate, Sinapinic acid (Sinapic acid), TMP269, Santacruzamate A (CAY10683), TMP195 (TFMO 2), Valproic acid (VPA), UF010, Tasquinimod (ABR-215050), SKLB-23bb, Isoguanosine, Sulforaphane, BRD73954, Citarinostat (ACY-241, HDAC-IN-2), Suberohydroxamic acid, Splitomicin, HPOB, LMK-235, Biphenyl-4-sulfonyl chloride (p- Phenylbenzenesulfonyl, 4- Phenylbenzenesulfonyl, p-Biphenylsulfonyl), Nexturastat A, TH34, Tucidinostat (Chidamide, HBI-8000, CS-055), (-)-Parthenolide, WT161, CAY10603, CAY10603, ACY-738, Raddeanin A, Tinostamustine(EDO-SlOl), Domatinostat (4SC-202), and BG45. In some embodiments, the HDACi is P-Hydroxybutyrate. In some embodiments, the HDACi is present in or is added to a composition of the disclosure at a concentration of about 100 nM, about 300 nM, about 500 nM, about 600 nM, about 700 nM, about 800 nM, about 900 nM, about 1 pM, about 1 .5 pM, about 3 pM, about 5 pM, about 10 pM, or about 100 pM. In some embodiments, the HDACi is - Hydroxybutyrate present at a concentration of about 200 nM. In some embodiments, the HDACi is present in or is added to a composition of the disclosure at a concentration of about 1 nM to 500 pM, 1 nM to 100 pM, 1 nM to 10 pM, 1 nM to 1 pM, 1 nM to 800 nM, 1 nM to 600 nM, 1 nM to 400 nM, 1 nM to 300 nM, 1 nM to 200 nM, 5 nM to 500 pM, 25 nM to 100 pM, 25 nM to 10 pM, 25 nM to 1 pM, 25 nM to 800 nM, 25 nM to 600 nM, 25 nM to 400 nM, 25 nM to 300 nM, 25 nM to 200 nM, 50 nM to 500 pM, 50 nM to 100 pM, 50 nM to 10 pM, 50 nM to 1 pM, 50 nM to 800 nM, 50 nM to 600 nM, 50 nM to 400 nM, 50 nM to 300 nM, 50 nM to 200 nM, 100 nM to 500 pM, 100 nM to 100 pM, 100 nM to 10 pM, 100 nM to 1 pM, 100 nM to 800 nM, 100 nM to 600 nM, 100 nM to 400 nM, 100 nM to 300 nM, or 100 nM to 200 nM.

[0162] In some embodiments, a composition (e.g., medium) of the disclosure comprises a redox homeostasis regulator. Exemplary redox homeostasis regulators include, but are not limited to taurine, respiratory chain regulators, free radical scavengers, regulators of mitochondrial protein synthesis, allium sulphur compounds, anthocyanins, beta-carotene, catechins, copper, cryptoxanthins, flavonoids, indoles, isoflavonoids, lignans, lutein, lycopene, alpha lipoic acid, ellagic acid, manganese, polyphenols, selenium, glutathione, vitamin A, vitamin C, vitamin E, zinc, superoxide disutases, GSHPx, Prx-I, catalase, and co-enzyme Q10. In some embodiments, the redox homeostasis regulator is taurine. In some embodiments, the redox homeostasis regulator is present in or is added to a composition of the disclosure at a concentration of about 100 nM, about 500 nM, 1 pM, about 10 pM, about 20 pM, about 30 pM, about 40 pM, about 50 pM, about 60 pM, about 70 pM, about 80pM, about 90 pM, about 100 pM, about 110 pM, about 110 M, about 150 pM, or about 200 pM. In some embodiments, the redox homeostasis regulator is taurine. In some embodiments, the redox homeostasis regulator is taurine present at a concentration of about 90 pM. In some embodiments, the redox homeostasis regulator intermediate is present or is added at a concentration of about 100 nM to 1 mM, 500 nM to 1 mM, 1 pM to 1 mM, 10 pM to 1 mM, 20 pM to 1 mM, 30 pM to 1 mM, 30 pM to 1 mM, 40 pM to 1 mM, 50 pM to 1 mM, 60 pM to 1 mM, 70 pM to 1 mM, 80 pM to 1 mM, 100 nM to 250 pM, 500 nM to 250 pM, 1 pM to 250 pM, 10 pM to 250 pM, 20 pM to 250 pM, 30 pM to 250 pM, 30 pM to 250 pM, 40 pM to 250 pM, 50 pM to 250 pM, 60 pM to 250 pM, 70 pM to 250 pM, 100 nM to 100 pM, 500 nM to 100 pM, 1 pM to 100 pM, 10 pM to 100 pM, 20 pM to 100 pM, 30 pM to 100 pM, 40 pM to 100 pM, 50 pM to 100 pM, 60 pM to 100 pM, 70 pM to 100 pM, or 80 pM to 100 pM.L0163J In some embodiments, a composition (e.g., medium) of the disclosure comprises a one carbon metabolism pathway intermediate. Exemplary one carbon metabolism pathway intermediates include, but are not limited to formate, tetrahydrofolate (THF), 10-formylTHF; 5,10-meTHF; 5,10- meTHF; and 10-formylTHF. In some embodiments, the one carbon metabolism pathway intermediate is formate present at a concentration of about 50 pM. In some embodiments, the one carbon metabolism pathway intermediate is present or is added at a concentration of about 100 nM to 1 mM, 500 nM to 1 mM, 1 pM to 1 mM, 10 pM to 1 mM, 20 pM to 1 mM, 30 pM to 1 mM, 100 nM to 250 pM, 500 nM to 250 pM, 1 pM to 250 pM, 10 pM to 250 pM, 20 pM to 250 pM, 30 pM to 250 pM, 100 nM to 100 pM, 500 nM to 100 pM, 1 pM to 100 pM, 10 pM to 100 pM, 20 pM to 100 pM, 30 pM to 100 pM, 100 nM to 60 pM, 500 nM to 60 pM, 1 pM to 60 pM, 10 pM to 60 pM, 20 pM to 60 pM, 30 pM to 60 pM, 40 pM to 60 pM, or 45 pM to 55 pM.

[0164] In some embodiments, a composition (e.g., medium) of the disclosure comprises glutamine. Thus in some embodiments, compositions and methods of the disclosure utilize glutamine in a form with increased bioavailability, such as a free glutamine form, such as a non-dipeptide form, a non-alanine-glutamine dipeptide form (e.g., a non-alanyl-l-glutamine form), a non-glycine- glutamine dipeptide form (e.g., a non-glycyl-l-glutamine form), a form that in which glutamine is not conjugated to another amino acid or stabilizing moiety, a monomeric form, a free form, or a combination thereof. In some embodiments, glutamine is provided as a protein hydrolysate. In some embodiments, glutamine is present or is added to a composition of the disclosure at a concentration of from 0.5-20 mM, 0.5-10 mM, 0.5-5 mM, 1-5 mM, 2-5 mM, or 1 mM to 10 mM. In some embodiments, glutamine is present or is added to a composition of the disclosure at a concentration of 3.8-4.2 mM. In some embodiments, glutamine is present or is added to a composition of the disclosure at a concentration of 1-10, 1-7, 1-8, 1-6, 1-5, 1-4, 2-10, 2-7, 2-8, 2-6, 2-5, 2-4, 3-10, 3-7, 3- 8, 3-6, 3-5, 3-4, 3.5-4.5, 3.8-4.2, or 3.9-4.1 mM. In some embodiments, glutamine is present or is added to a composition of the disclosure at a concentration of about 4 mM. In some embodiments, at least 0.5 mM, 0.6 mM, 0.7 mM, 0.8 mM, 0.9 mM, 1 mM, 1.5 mM, 2 mM, 2.5 mM, 3 mM, 3.5 mM, 4mM, 4.5 mM, or 5 mM of the glutamine is not in a dipeptide form. In some embodiments, at least 500 pM, at least 750 pM, at least 1 mM, at least 1.5 mM, at least 2 mM, at least 2.5 mM, at least 2.6 mM, at least 2.7 mM, at least 2.8 mM, at least 2.9 mM, at least 3 mM, at least 3.1 mM, at least 3.2 mM, at least 3.3 mM, at least 3.4 mM, at least 3.5 mM, at least 3.6 mM, at least 3.7 mM, at least 3.8 mM, at least 3.9 mM, at least 4 mM, at least 5 mM, at least 5.5 mM, at least 6 mM, at least 6.5 mM, at least 7 mM, at least 7.5 mM, at least 8 mM, at least 8.5 mM, at least 9 mM, at least 9.5 mM, or at least10 mM of the glutamine is in a free form.

[0165] In some embodiments, the method comprises culturing the population of cells (e.g., pancreatic foregut precursor cells) in a medium, to induce the differentiation of at least one pancreatic foregut precursor cell in the population into an insulin-positive endocrine cell, wherein the insulinpositive endocrine cell expresses insulin.

[0166] Aspects of the disclosure involve treatment of cell population comprising pancreatic foregut precursor cells with PKC activator and / or wnt signaling pathway inhibitor, which can lead to increase in percentage of pancreatic a cells, increase in percentage of pancreatic 5 cells, increase in percentage of pancreatic [3 cells, reduction in percentage of EC cells, or any combination thereof, in the cell population of pancreatic endocrine cells generated according to the method disclosed herein.

[0167] In some embodiments, the method comprises contacting a population of cells comprising pancreatic foregut precursor cells with a first composition comprising a FOXO1 inhibitor, notch signaling inhibitor, a PKC activator, a ROCK inhibitor, a growth factor from TGF0 superfamily, a growth factor from FGF family, a RA signaling pathway activator, and a SHH pathway inhibitor, for one to two days, thereby obtaining a first transformation cell population comprising pancreatic foregut precursor cells; and contacting the first transformation cell population comprising pancreatic foregut precursor cells with a second composition comprising the PKC activator, notch signaling inhibitor, a TGF-0 signaling pathway inhibitor, a TH signaling pathway activator, BMP pathway inhibitor, ROCK inhibitor, retinoic acid, and EGF-family growth factor, wnt signaling pathway inhibitor, and / or an epigenetic modifying compound, for one to two days, thereby obtaining a second transformation cell population comprising pancreatic foregut precursor cells.Pancreatic i> Cells

[0168] Aspects of the disclosure involve generating pancreatic 0 cells (e.g., non-native pancreatic 0 cells / SC-0 cells) and additional methods of generating them. Non-native pancreatic 0 cells, In some embodiments, resemble endogenous mature 0 cells in form and function, but nevertheless are distinct from native 0 cells.

[0169] In some embodiments, the insulin-positive pancreatic endocrine cells generated using the method provided herein can form a cell cluster, alone or together with other types of cells, e.g., precursors thereof, e.g., stem cell, definitive endoderm cells, primitive gut tube cell, PDXl-positive pancreatic progenitor cells, or pancreatic foregut precursor cells.

[0170] In some embodiments, any of the cells or populations of cells disclosed herein are in a cell cluster. In some aspects, provided herein are cell clusters that resemble the functions and characteristics of endogenous pancreatic islets. Such cell clusters can mimic the function of endogenous pancreatic islets in regulating metabolism, e.g., glucose metabolism in a subject.

[0171] In some embodiments, a composition or cell population of the present disclosure comprises SC-0 cells that express lower levels of MAFA than SC-beta cells from the pancreas of a healthy control adult subject. In some embodiments, the composition or cell population comprises SC- cells that express higher levels of MAFB than S P cells from the pancreas of a healthy control adult subject. In some embodiments, the composition or cell population comprises S P cells that express higher levels of SIX2, HOPX, IAPP and / or UCN3 than S P cells from the pancreas of a healthy control adult subject.

[0172] In some embodiments, a composition or cell population of the present disclosure comprises SC-P cells that do not express MAFA. In some embodiments, the composition or cell population comprises NKX6.1 -positive, ISL-positive cells that express MAFB.

[0173] In some embodiments, the cell population comprising the insulin-positive endocrine cells can be directly induced to mature into SC-P cells without addition of any exogenous differentiation factors (such as inhibitor of TGF-P signaling pathway, thyroid hormone signaling pathway activator, PKC activator, growth factors from TGF-P superfamily, FGF family, or EGF family, SHH signaling pathway inhibitor, y-secretase inhibitor, ROCK inhibitor, or BMP signaling pathway inhibitor). In some embodiments, the method provided herein comprises contacting a cell population comprising NKX6.1 -positive, ISL1 -positive endocrine cells with a serum albumin protein, a TGF-P signaling pathway inhibitor, a SHH pathway inhibitor, a TH signaling pathway activator, a protein kinase inhibitor, a ROCK inhibitor, a BMP signaling pathway inhibitor, and / or an epigenetic modifying compound. In some embodiments, the method provided herein comprises contacting a cell population comprising NKX6.1 -positive, ISL1 -positive endocrine cells with human serum albumin protein. In some embodiments, the method provided herein comprises contacting a cell population comprising NKX6.1 -positive, ISL1 -positive endocrine cells with a PKC activator.

[0174] In some embodiments, the cell population comprising the insulin-positive endocrine cells can be induced to mature into SC-0 cells by contacting the insulin-positive endocrine cells with differentiation factors. The differentiation factors can comprise at least one inhibitor of TGF-0 signaling pathway and thyroid hormone signaling pathway activator as described herein. In some embodiments, SC-0 cells can be obtained by contacting a population of cells comprising insulinpositive endocrine cells with Alk5i and T3 or GC-1.

[0175] In some embodiments, the method provided herein comprises contacting a cell population comprising NKX6.1 -positive, ISLl-positive endocrine cells with (i) a TGF-0 signaling pathway inhibitor, (ii) a thyroid hormone signaling pathway activator, (iii) an epigenetic modifying compound,(iv) a BMP signaling pathway inhibitor, (v) a ROCK inhibitor, and / or (vi) a protein kinase inhibitor (e.g., staurosporine).

[0176] In some embodiments, the method provided herein comprises contacting a cell population comprising NKX6.1 -positive, ISL1 -positive endocrine cells with (i) a growth factor from the FGF family, (ii) a TGF- signaling pathway inhibitor, (iii) a thyroid hormone signaling pathway activator, (iv) an epigenetic modifying compound, (v) a protein kinase inhibitor, (vi) a ROCK inhibitor, (vii) a BMP signaling pathway inhibitor, and (viii) a lipase inhibitor for about one two five days. In some embodiments, the contacting is for about three days.

[0177] Any TGF-P signaling pathway inhibitor capable of inducing the differentiation of insulinpositive endocrine cells to mature into SC-P cells (e.g., alone, or in combination with other p celldifferentiation factors, e.g., a thyroid hormone signaling pathway activator) can be used. In some embodiments, the TGF-P signaling pathway comprises TGF-P receptor type I kinase signaling. In some embodiments, the TGF-P signaling pathway inhibitor comprises Alk5 inhibitor II. In some examples, the method comprises contacting insulin-positive endocrine cells with a concentration of a TGF-P signaling pathway inhibitor (e.g., Alk5 inhibitor such as Alk5 inhibitor II), such as, about 0.1 pM, about 0.5 pM, about 1 pM, about 1.5 pM, about 2 pM, about 2.5 pM, about 3 pM, about 3.5 pM, about 4 pM, about 4.5 pM, about 5 pM, about 5.5 pM, about 6 pM, about 6.5 pM, about 7 pM, about 7.5 pM, about 8 pM, about 8.5 pM, about 9 pM, about 9.5 pM, about 10 pM, about 10.5 pM, about 11 pM, about 11.5 pM, about 12 pM, about 12.5 pM, about 13 pM, about 13.5 pM, about 14 pM, about 14.5 pM, about 15 pM, about 15.5 pM, about 16 pM, about 16.5 pM, about 17 pM, about 17.5 pM, about 18 pM, about 18.5pM, about 19 pM, about 19.5 pM, about 20 pM, about 25 pM, about 30 pM, about 35 pM, about 40 pM, about 45 pM, or about 50 pM. In some examples, the method comprises contacting insulin-positive endocrine cells with a concentration of a TGF- signaling pathway inhibitor (e.g., Alk5 inhibitor such as Alk5 inhibitor II), such as, about 7-13 pM, about 8-12 pM , or about 9-11 pM. In some examples, the method comprises contacting insulinpositive endocrine cells with a concentration of a TGF-P signaling pathway inhibitor (e.g., Alk5 inhibitor such as Alk5 inhibitor II), such as, about 10 pM.

[0178] Any thyroid hormone signaling pathway activator capable of inducing the differentiation of insulin-positive endocrine cells to mature into SC-P cells (e.g., alone, or in combination with other P cell-differentiation factors, e.g., a TGF- signaling pathway inhibitor) can be used. In some embodiments, the thyroid hormone signaling pathway activator comprises triiodothyronine (T3). In some embodiments, the thyroid hormone signaling pathway activator comprises GC-1. In some examples, the method comprises contacting insulin-positive endocrine cells with a concentration of thyroid hormone signaling pathway activator (e.g., GC-1), such as, about O.lpM, about 0.12 pM, about 0.13 pM, about 0.14 pM, about 0.15 pM, about 0.16 pM, about 0.17 pM, about 0.18 pM, about 0.19 pM, about 0.2 pM, about 0.21pM, about 0.22pM, about 0.23pM, about 0.24 pM, about 0.25 pM, about 0.26 pM, about 0.27 pM, about 0.28 pM, about 0.29 pM, about 0.3 pM, about 0.31 pM,about 0.32 pM, about 0.33 pM, about 0.34 pM, about 0.35 pM, about 0.4 pM, about 0.45 jiM, about 0.5 pM, about 0.6 jiM, about 0.8 jiM, about 1 pM, about 2 pM, or about 5 pM. In some examples, the method comprises contacting insulin-positive endocrine cells with a concentration of thyroid hormone signaling pathway activator (e.g., GC-1), such as, about 0.7- 1.3 pM, about 0.8- 1.2 pM, or about 0.9-1.1 pM.

[0179] Any BMP signaling pathway inhibitor capable of inducing the differentiation of insulinpositive endocrine cells to mature into SC- cells (e.g., alone, or in combination with any of a TGF-0 signaling pathway inhibitor and / or a thyroid hormone signaling pathway activator) can be used. In some embodiments, the BMP signaling pathway inhibitor comprises LDN193189 or DMH-1. In some examples, the method comprises contacting insulin-positive endocrine cells with a concentration of BMP signaling pathway inhibitor (e.g., LDN1931189), such as, about 30 nM, about 40 nM, about 50 nM, about 60 nM, about 70 nM, about 80 nM, about 90 nM, about 100 nM, about 110 nM, about 120 nM, about 130 nM, about 140 nM, about 150 nM, about 160 nM, about 170 nM, about 180 nM, about 190 nM, about 200 nM, about 210 nM, about 220 nM, about 230 nM, about 240 nM, about 250 nM, about 280 nM, about 300 nM, about 400 nM, about 500 nM, or about IpM. In some examples, the method comprises contacting insulin-positive endocrine cells with a concentration of BMP signaling pathway inhibitor (e.g., LDN1931 189), such as, about 70-130 nM, about 80-120 nM, about 90-110 nM. In some examples, the method comprises contacting NKX6.1 -positive pancreatic progenitor cells with a concentration of BMP signaling pathway inhibitor (e.g., LDN1931189), such as, about 100 nM.

[0180] Any ROCK inhibitor that is capable of inducing the differentiation of insulin-positive endocrine cells to mature into SC-0 cells (e.g., alone, or in combination with any of a TGF-0 signaling pathway inhibitor and / or a thyroid hormone signaling pathway activator) can be used. In some embodiments, the ROCK inhibitor comprises Thiazovivin, Y-27632, Fasudil / HA1077, or H-l 152. In some embodiments, the ROCK inhibitor comprises Y-27632. In some embodiments, the ROCK inhibitor comprises Thiazovivin. In some examples, the method comprises contacting insulin-positive endocrine cells with a concentration of a ROCK inhibitor (e.g., Y-27632 or Thiazovivin), such as, about 0.2 pM, about 0.5 pM, about 0.75 pM, about 1 pM, about 2 pM, about 3 pM, about 4 pM, about 5 pM, about 6 pM, about 7 pM, about 7.5 pM, about 8 pM, about 9 pM, about 10 pM, about 11 pM, about 12 pM, about 13 pM, about 14 pM, about 15 pM, about 16 pM, about 17 pM, about 18 pM, about 19 pM, about 20 pM, about 21 pM, about 22 pM, about 23 pM, about 24 pM, about 25 pM, about 26 pM, about 27 pM, about 28 pM, about 29 pM, about 30 pM, about 35 pM, about 40 pM, about 50 pM, or about 100 pM. In some embodiments, the ROCK inhibitor comprises Thiazovivin. In some examples, the method comprises contacting insulin-positive endocrine cells with a concentration of a ROCK inhibitor (e.g., Y-27632 or Thiazovivin), such as, about 2.2-2.8 pM, about 2.3-2.7 pM, or about 2.4-2.6 pM. In some embodiments, the ROCK inhibitor comprises Thiazovivin.In some examples, the method comprises contacting insulin-positive endocrine cells with a concentration of a ROCK inhibitor (e.g., Y-27632 or Thiazovivin), such as, about 2.5 pM.

[0181] Any epigenetic modifying compound that is capable of inducing the differentiation of insulin-positive endocrine cells to mature into SC-[3 cells (e.g., alone, or in combination with any of a TGF-0 signaling pathway inhibitor and / or a thyroid hormone signaling pathway activator) can be used. In some embodiments, the epigenetic modifying compound comprises a histone methyltransferase inhibitor or a HDAC inhibitor. In some embodiments, the epigenetic modifying compound comprises a histone methyltransferase inhibitor, e.g., DZNep. In some embodiments, the epigenetic modifying compound comprises a HDAC inhibitor, e.g., KD5170. In some examples, the method comprises contacting insulin-positive endocrine cells to mature into SC-P cells with a concentration of an epigenetic modifying compound (e.g., DZNep or KD5170), such as, about 0.01 M, about 0.025 pM, about 0.05 pM, about 0.075 pM, about 0.1 pM, about 0.15 pM, about 0.2 pM, about 0.5 pM, about 0.75 pM, about 1 pM, about 2 pM, about 3 pM, about 4 pM, about 5 pM, about 6 pM, about 7 pM, about 7.5 pM, about 8 pM, about 9 pM, about 10 pM, about 15 pM, about 20 pM, about 25 pM, about 30 pM, about 35 pM, about 40 pM, about 50 pM, or about 100 pM. In some examples, the method comprises contacting insulin-positive endocrine cells to mature into SC-P cells with a concentration of an epigenetic modifying compound (e.g., DZNep or KD5170), such as, about 70-130 nM, about 80-120 nM, or about 90-110 nM. In some examples, the method comprises contacting insulin-positive endocrine cells to mature into SC-P cells with a concentration of an epigenetic modifying compound (e.g., DZNep or KD5170), such as, about 100 nM.

[0182] Any protein kinase inhibitor that is capable of inducing the differentiation insulin-positive endocrine cells to mature into SC-P cells (e.g., alone, or in combination with any of a TGF-P signaling pathway inhibitor and / or a thyroid hormone signaling pathway activator). In some embodiments, the protein kinase inhibitor comprises staurosporine. In some examples, the method comprises contacting insulin-positive endocrine cells with a concentration of a protein kinase inhibitor (e.g., staurosporine), such as, about 0.1 nM, about 0.2 nM, about 0.3 nM, about 0.4 nM, about 0.5 nM, about 0.6 nM, about 0.7 nM, about 0.8 nM, about 0.9 nM, about 1 nM, about 1.1 nM, about 1.2 nM, about 1.3 nM, about1.4 nM, about 1.5 nM, about 1.6 nM, about 1.7 nM, about 1.8 nM, about 1.9 nM, about 2.0 nM, about2.1 nM, about 2.2 nM, about 2.3 nM, about 2.4 nM, about 2.5 nM, about 2.6 nM, about 2.7 nM, about2.8 pM, about 2.9 nM, about 3 nM, about 3.1 nM, about 3.2 nM, about 3.3 nM, about 3.4 nM, about3.5 nM, about 3.6 nM, about 3.7 nM, about 3.8 nM, about 3.9 nM, about 4.0 nM, about 4.1 nM, about4.2 nM, about 4.3 nM, about 4.4 nM, about 4.5 nM, about 4.6 nM, about 4.7 nM, about 4.8 pM, about4.9 nM, or about 5 nM. In some examples, the method comprises contacting insulin-positive endocrine cells with a concentration of a protein kinase inhibitor (e.g., staurosporine), such as, about 1-5 nM, about 2-4 nM, or about 2.5-3.5 nM. In some examples, the method comprises contacting insulin-positive endocrine cells with a concentration of a protein kinase inhibitor (e.g., staurosporine), such as, about 3 nM.

[0183] In some embodiments, the method comprises contacting the population of cells (e.g., NKX6.1 -positive, ISL1 -positive, insulin-positive cells) with one or more metabolites. In some embodiments, the method comprises contacting the population of cells (e.g., NKX6.1 -positive, ISL1- positive, insulin-positive cells) with one or more of an acetyl CoA-related metabolite, a vitamin, histone deacetylase inhibitor (HDACi), a redox homeostasis regulator, a one carbon metabolism pathway intermediate, glutamate, and / or carnitine. Examples of metabolites include taurine, acetate, beta-hydroxybutyrate, biotin, carnitine, glutamate, and formate.

[0184] In some embodiments, a composition (e.g., medium) of the disclosure comprises an acetyl CoA-related metabolite. Exemplary acetyl CoA-related metabolites include, but are not limited to acetate, pyruvate, ketogenic amino acids, valine, leucine, isoleucine, phenylalanine, tyrosine, lysine, tryptophan, fatty acids, CoA, Isovaleryl-CoA, and [3-hydroxybutyrate. In some embodiments, the acetyl CoA-related metabolite is acetate. In some embodiments, the acetyl CoA-related metabolite is present in or is added to a composition of the disclosure at a concentration of about 10 nM, about 50 nM, about 80 nM, about 100 nM, about 120 nM, about 140 nM, about 150 nM, about 200 nM, about 300 nM, about 500 nM, about 800 nM, about 1 pM, about 10 pM, about 100 pM, about 500 pM, about 800 pM, about 900 pM, about 1 mM, about 2 mM, about 3 mM, about 5 mM, or about 10 mM. In some embodiments, the acetyl CoA-related metabolite is present in or is added to a composition of the disclosure at a concentration of about 0.01-50 mM, 0.1-50 mM, 0.5-50 mM, 0.01-20 mM, 0.1-20 mM, 0.5-20 mM, 0.01-10 mM, 0.1-10 mM, 0.5-10 mM, 0.8-25 mM, 0.8-10 mM, 0.8-5 mM, 0.8-2 mM, 0.8-1.5 mM, 0.8-1.2 mM, 0.9-1.1 mM, or 0.95-1.05 mM. In some embodiments, the acetyl CoA- related metabolite is acetate present at a concentration of about 1 mM. In some embodiments, the acetyl CoA-related metabolite is acetate present at a concentration of about 50-1000 nM, 50-800 nM, 50-500 nM, 50-300 nM, 50-250 nM, 100-200 nM, or 125-175 nM. In some embodiments, the acetyl CoA-related metabolite is acetate present at a concentration of about 160 nM.

[0185] In some embodiments, a composition (e.g., medium) of the disclosure comprises one or more vitamins. Exemplary vitamins include, but are not limited to biotin, vitamin Bl (thiamine), vitamin B2 (riboflavin), vitamin B3 (niacin), vitamin B6 (pyridoxine) and vitamin B12 (cyanocobalamin). In some embodiments the vitamin modulates fatty acid synthesis. In some embodiments the vitamin modulates branched-chain amino acid metabolism. In some embodiments the vitamin modulates or participates as a co-factor in the TCA cycle, e.g., as a cofactor for pyruvate carboxylase. In some embodiments, the vitamin is biotin. In some embodiments, the vitamin is present in or is added to a composition of the disclosure at a concentration of about 100 nM, about 300 nM, about 500 nM, about 600 nM, about 700 nM, about 800 nM, about 900 nM, about 1 pM, about 1.5 pM, about 3 pM, about 5 pM, about 10 pM, or about 100 pM. In some embodiments, the vitamin is biotin present at a concentration of about 800 nM. In some embodiments, the vitamin is present in or is added to a composition of the disclosure at a concentration of about 1 nM to 500 pM, 1 nM to 100 pM, 1 nM to 10 pM, 1 nM to 1 pM, 1 nM to 800 nM, 1 nM to 600 nM, 1 nM to 400 nM,1 nM to 300 nM, 1 nM to 200 nM, 25 nM to 500 pM, 25 nM to 100 pM, 25 nM to 10 pM, 25 nM to 1 pM, 25 nM to 800 nM, 25 nM to 600 nM, 25 nM to 400 nM, 25 nM to 300 nM, 25 nM to 200 nM, 50 nM to 500 pM, 50 nM to 100 pM, 50 nM to 10 pM, 50 nM to 1 pM, 50 nM to 800 nM, 50 nM to 600 nM, 50 nM to 400 nM, 50 nM to 300 nM, 50 nM to 200 nM, 100 nM to 500 pM, 100 nM to 100 pM, 100 nM to 10 pM, 100 nM to 1 pM, 100 nM to 800 nM, 100 nM to 600 nM, 100 nM to 400 nM, 100 nM to 300 nM, or 100 nM to 200 nM.

[0186] In some embodiments, a composition (e.g., medium) of the disclosure comprises a histone deacetylase inhibitor (HDACi). Exemplary histone deacetylase inhibitors (HDACi) include, but are not limited to P-Hydroxybutyrate, butyric acid, class I HDACi, class IIA HDACi, class IIB HDACi, class III HDACi, class IV HDACi, HDAC-1, HD AC-2, HD AC-3, HD AC-4, HD AC-5, HD AC-6, HDAC-7, HDAC-8, HD AC-9, HDAC-10, HDAC-11, sirtuins, SIRT1, SIRT2, SIRT3, SIRT4, SIRT5, SIRT6, S1RT7, Vorinostat (suberoylanilide hydroxamic acid, SAHA, MK0683), Entinostat (MS-275, SNDX-275), Panobinostat (LBH589, NVP-LBH589), Trichostatin A (TSA), Mocetinostat (MGCD0103, MG0103), GSK3117391 (GSK3117391 A, HDAC-IN-3), BRD33O8, BRD3308, Tubastatin A TFA (Tubastatin A trifluoroacetate salt), Tubastatin A, SIS 17, NKL 22, BML-210 (CAY10433), TC-H 106, SR-4370, Belinostat (PXD101, NSC726630, PX-105684), Romidepsin (FK228, Depsipeptide, FR 901228, NSC 630176), MC1568, Givinostat (ITF2357), Dacinostat (LAQ824, NVP-LAQ824), CUDC-101, Quisinostat (JNJ-26481585), Pracinostat (SB939), PCI- 34051, Droxinostat (NS 41080), Abexinostat (PCI- 24781), Abexinostat (PCI- 24781, CRA-024781), RGFP966, AR-42 (HDAC-42), Ricolinostat (ACY-1215, Rocilinostat), Valproic acid sodium salt (Sodium valproate), Tacedinaline (CI994, PD- 123654, GOE-5549, Acetyldinaline), Fimepinostat (CUDC-907), Sodium butyrate (NaB), Curcumin, Diferuloylmethane, M344, Tubacin, RG2833 (RGFP109), RG2833 (RGFP109), Resminostat (RAS2410), Divalproex Sodium, Scriptaid (GCK 1026), Sodium Phenylbutyrate, Sinapinic acid (Sinapic acid), TMP269, Santacruzamate A (CAY10683), TMP195 (TFMO 2), Valproic acid (VPA), UF010, Tasquinimod (ABR-215050), SKLB-23bb, Isoguanosine, Sulforaphane, BRD73954, Citarinostat (ACY-241, HDAC-IN-2), Suberohydroxamic acid, Splitomicin, HPOB, LMK-235, Biphenyl-4-sulfonyl chloride (p- Phenylbenzenesulfonyl, 4- Phenylbenzenesulfonyl, p-Biphenylsulfonyl), Nexturastat A, TH34, Tucidinostat (Chidamide, HBI-8000, CS-055), (-)-Parthenolide, WT161, CAY10603, CAY10603, ACY-738, Raddeanin A, Tinostamustine(EDO-SlOl), Domatinostat (4SC-202), and BG45. In some embodiments, the HDACi is P-Hydroxybutyrate. In some embodiments, the HDACi is present in or is added to a composition of the disclosure at a concentration of about 100 nM, about 300 nM, about 500 nM, about 600 nM, about 700 nM, about 800 nM, about 900 nM, about 1 |iM, about 1.5 |1M, about 3 |1M, about 5 |1M, about 10 pM, or about 100 pM. In some embodiments, the HDACi is P- Hydroxybutyrate present at a concentration of about 200 nM. In some embodiments, the HDACi is present in or is added to a composition of the disclosure at a concentration of about 1 nM to 500 pM, 1 nM to 100 pM, 1 nM to 10 pM, 1 nM to 1 pM, 1 nM to 800 nM, 1 nM to 600 nM, 1 nM to 400 nM,1 nM to 300 nM, 1 nM to 200 nM, 25 nM to 500 pM, 25 nM to 100 pM, 25 nM to 10 pM, 25 nM to 1 pM, 25 nM to 800 nM, 25 nM to 600 nM, 25 nM to 400 nM, 25 nM to 300 nM, 25 nM to 200 nM, 50 nM to 500 pM, 50 nM to 100 pM, 50 nM to 10 pM, 50 nM to 1 pM, 50 nM to 800 nM, 50 nM to 600 nM, 50 nM to 400 nM, 50 nM to 300 nM, 50 nM to 200 nM, 100 nM to 500 pM, 100 nM to 100 pM, 100 nM to 10 pM, 100 nM to 1 pM, 100 nM to 800 nM, 100 nM to 600 nM, 100 nM to 400 nM, 100 nM to 300 nM, or 100 nM to 200 nM.

[0187] In some embodiments, a composition (e.g., medium) of the disclosure comprises a redox homeostasis regulator. Exemplary redox homeostasis regulators include, but are not limited to taurine, respiratory chain regulators, free radical scavengers, regulators of mitochondrial protein synthesis, allium sulphur compounds, anthocyanins, beta-carotene, catechins, copper, cryptoxanthins, flavonoids, indoles, isoflavonoids, lignans, lutein, lycopene, alpha lipoic acid, ellagic acid, manganese, polyphenols, selenium, glutathione, vitamin A, vitamin C, vitamin E, zinc, superoxide disutases, GSHPx, Prx-I, catalase, and co-enzyme Q10. In some embodiments, the redox homeostasis regulator is taurine. In some embodiments, the redox homeostasis regulator is present in or is added to a composition of the disclosure at a concentration of about 100 nM, about 500 nM, 1 pM, about 10 pM, about 20 pM, about 30 pM, about 40 pM, about 50 pM, about 60 pM, about 70 pM, about 80 pM, about 90 pM, about 100 pM, about 1 10 pM, about 1 10 pM, about 150 pM, or about 200 pM. In some embodiments, the redox homeostasis regulator is taurine. In some embodiments, the redox homeostasis regulator is taurine present at a concentration of about 90 pM. In some embodiments, the redox homeostasis regulator intermediate is present or is added at a concentration of about 100 nM to 1 mM, 500 nM to 1 mM, 1 pM to 1 mM, 10 pM to 1 niM, 20 pM to 1 mM, 30 pM to 1 mM, 30 pM to 1 mM, 40 pM to 1 mM, 50 pM to 1 mM, 60 pM to 1 mM, 70 pM to 1 mM, 80 pM to 1 mM, 100 nM to 250 pM, 500 nM to 250 pM, 1 pM to 250 pM, 10 pM to 250 pM, 20 pM to 250 pM, 30 pM to 250 pM, 30 pM to 250 pM, 40 pM to 250 pM, 50 pM to 250 pM, 60 pM to 250 pM, 70 pM to 250 pM, 100 nM to 100 pM, 500 nM to 100 pM, 1 pM to 100 pM, 10 pM to 100 pM, 20 pM to 100 pM, 30 pM to 100 pM, 40 pM to 100 pM, 50 pM to 100 pM, 60 pM to 100 pM, 70 pM to 100 pM, or 80 pM to 100 pM.

[0188] In some embodiments, a composition (e.g., medium) of the disclosure comprises a one carbon metabolism pathway intermediate. Exemplary one carbon metabolism pathway intermediates include, but are not limited to formate, tetrahydrofolate (THF), 10-formylTHF; 5,10-meTHF; 5,10- meTHF; and 10-formylTHF. In some embodiments, the one carbon metabolism pathway intermediate is formate present at a concentration of about 50 pM. In some embodiments, the one carbon metabolism pathway intermediate is present or is added at a concentration of about 100 nM to 1 mM, 500 nM to 1 mM, 1 pM to 1 mM, 10 pM to 1 mM, 20 pM to 1 mM, 30 pM to 1 mM, 100 nM to 250 pM, 500 nM to 250 pM, 1 pM to 250 pM, 10 pM to 250 pM, 20 pM to 250 pM, 30 pM to 250 pM, 100 nM to 100 pM, 500 nM to 100 pM, 1 pM to 100 pM, 10 pM to 100 pM, 20 pM to 100 pM,30 pM to 100 pM, 100 nM to 60 pM, 500 nM to 60 pM, 1 pM to 60 pM, 10 pM to 60 pM, 20 pM to 60 M, 30 pM to 60 pM, 40 pM to 60 pM, or 45 pM to 55 pM.

[0189] In some embodiments, a composition (e.g., medium) of the disclosure comprises glutamate (e.g., L-glutamate). In some embodiments, glutamate can be present in a composition of the disclosure at a concentration of about 100 pM, about 200 pM, about 300 pM, about 400 pM, about 450 pM, about 500 pM, about 550 pM, about 600 pM, about 700 pM, about 800 pM, about 900 pM, about 1 mM, about 1.5 mM, about 2 mM, about 2.5 mM, about 3 mM, about 4 mM, or about 5 mM. In some embodiments, glutamate is present or is added to a composition of the disclosure at a concentration of about 500 pM. In some embodiments, glutamate is present or is added to a composition of the disclosure at a concentration of from about 100 pM to 5mM, 200 pM to 5mM, 300 pM to 5mM, 400 pM to 5mM, 100 pM to 3mM, 200 pM to 3mM, 300 pM to 3mM, 400 pM to 3mM, 100 pM to 2mM, 200 pM to 2mM, 300 pM to 2mM, 400 pM to 2mM, 100 pM to ImM, 200 pM to ImM, 300 pM to ImM, 400 pM to ImM, 100 pM to 700 pM, 200 pM to 700 pM, 300 pM to 700 pM, 400 pM to 700 pM, 100 pM to 600 pM, 200 pM to 600 pM, 300 pM to 600 pM, or 400 pM to 600 pM.

[0190] In some embodiments, a composition (e.g., medium) of the disclosure comprises carnitine. In some embodiments, carnitine is present in or is added to a composition of the disclosure at a concentration of about 100 nM, about 500 nM, about 1 pM, about 10 pM, about 15 pM, about 20 pM, about 25 pM, about 30 pM, about 35 pM, about 40 pM, about 45 pM, about 50 pM, about 55 pM, about 60 pM, about 75 pM, or about 100 pM. In some embodiments, carnitine is present or is added at a concentration of about 40 pM. In some embodiments, carnitine is present in or is added to a composition of the disclosure at a concentration of about 100 nM to 1 mM, 500 nM to 1 mM,l pM to 1 mM, 10 pM to 1 mM, 20 pM to 1 mM, 30 pM to 1 mM, 100 nM to 250 pM, 500 nM to 250 pM, 1 pM to 250 pM, 10 pM to 250 pM, 20 pM to 250 pM, 30 pM to 250 pM, 100 nM to 100 pM, 500 nM to 100 pM, 1 pM to 100 pM, 10 pM to 100 pM, 20 pM to 100 pM, 30 pM to 100 pM, 100 nM to 60 pM, 500 nM to 60 pM, 1 pM to 60 pM, 10 pM to 60 pM, 20 pM to 60 pM, 30 pM to 60 pM, 35 pM to 60 pM, or 30 pM to 50 pM.

[0191] In some embodiments, the method comprises contacting the population of cells (e.g., NKX6.1 -positive, ISL1 -positive, insulin-positive cells) with a serum albumin protein (e.g., HSA). In some embodiments, the serum albumin is present at a concentration of 0.01-2% HSA. In some embodiments, the serum albumin is present at a concentration of 0.03-0.1%, 0.03-0.07%, or 0.04- 0.05%. In some embodiments, the serum albumin is present at a concentration of 0.05%. In some embodiments, the serum albumin is present at a concentration of 0.7-1.3%, 0.8-1.2%, 0.9-1.1% or at 1%. In some embodiments, the serum albumin is present at a concentration of 1%.

[0192] In some embodiments, the method comprises contacting the population of cells (e.g., NKX6.1 -positive, ISL1 -positive, insulin-positive cells) with ZnSO i. In some embodiments, the method comprises contacting the cells with 1-100 pM, 1-50 pM, 1-20 pM, 1-12 pM, 5-15 pM, 8-12pM or 9-11 (iM of ZnSC In some embodiments, the method comprising contacting the cells with about 10 pM of ZnSCU

[0193] In some embodiments, the method comprises contacting the population of cells (e.g., NKX6.1 -positive, ISL1 -positive, insulin-positive cells) with one or more of an a serum albumin protein, a TGF-P signaling pathway inhibitor, a TH signaling pathway activator, a protein kinase inhibitor, a ROCK inhibitor, a BMP signaling pathway inhibitor, an epigenetic modifying compound, acetyl CoA-related metabolite, a vitamin, histone deacetylase inhibitor ('HDACi), a redox homeostasis regulator, a one carbon metabolism pathway intermediate, glutamate, and / or carnitine for a first period of 1, 2, 3, 4, 5, 6, or 7 days (e.g., 4 days). In some embodiments, the method further comprises contacting the population of cells following the first period with one or more of a serum albumin protein, an acetyl CoA-related metabolite, a vitamin, histone deacetylase inhibitor (HDACi), a redox homeostasis regulator, a one carbon metabolism pathway intermediate, glutamate, and / or carnitine for a second period of 1, 2, 3, 4, 5, 6, or 7 days (e.g., 3 days) or more in the absence of a TGF-P signaling pathway inhibitor, a TH signaling pathway activator, a protein kinase inhibitor, a ROCK inhibitor, a BMP signaling pathway inhibitor, and / or an epigenetic modifying compound. In some embodiments, the cells are contacted with a higher concentration of the serum albumin in the second period as compared to the first period. In some embodiments, the compositions further comprise ZnSOzi. In some embodiments, the method further comprises contacting the population of cells following the first period with human serum albumin, but in the absence of a TGF-P signaling pathway inhibitor, a TH signaling pathway activator, a protein kinase inhibitor, a ROCK inhibitor, a BMP signaling pathway inhibitor, an epigenetic modifying compound, an acetyl CoA-related metabolite, a vitamin, histone deacetylase inhibitor (HDACi), a redox homeostasis regulator, a one carbon metabolism pathway intermediate, glutamate, and / or carnitine.

[0194] In some embodiments, the method comprises contacting the population of cells (e.g., NKX6.1 -positive, ISL1 -positive, insulin-positive cells) with one or more of HSA, Alk5 inhibitor II, GC-1, staurosporine, thiazovivin, LDN193189, DZNEP, taurine, acetate, beta-hydroxybutyrate, biotin, carnitine, glutamate, and formate for a first period of 1, 2, 3, 4, 5, 6, or 7 days (e.g., 4 days). In some embodiments, the method further comprises contacting the population of cells following the first period with one or more of HSA, taurine, acetate, beta-hydroxybutyrate, biotin, carnitine, glutamate, and formate for a second period of 1, 2, 3, 4, 5, 6, or 7 days (e.g., 3 days) or more in the absence of an Alk5 inhibitor II, GC-1, staurosporine, thiazovivin, LDN193189, DZNEP. In some embodiments, the compositions further comprise ZnSO4. In some embodiments, the cells are contacted with a higher concentration of the HSA (e.g., about 1.0%) in the second period as compared to the first period (e.g., about 0.05%).

[0195] In some examples, insulin-positive endocrine cells can be matured in a NS-GFs medium, MCDB131 medium, DMEM medium, or CMRL medium. In some embodiments, the insulin-positive endocrine cells can be matured in a CMRL medium supplemented with 10% FBS. In someembodiments, the insulin-positive endocrine cells can be matured in a DMEM / F12 medium supplemented with 1% HSA. In other cases, SC- cells can be obtained by culturing the population of cells containing the insulin-positive endocrine cells in a MCDB131 medium that can be supplemented by 2% BSA. In some embodiments, the MCDB131 medium with 2% BSA for maturation of insulin-positive endocrine cells into SC-[3 cells can be comprise no small molecule factors as described herein. In some case, the MCDB131 medium with 2% BSA for maturation of insulin-positive endocrine cells into SC-0 cells can comprise no serum (e.g., no FBS). In other cases, SC- cells can be obtained by culturing the population of cells containing the insulin-positive endocrine cells in a MCDB131 medium that can be supplemented by 0.05% HSA and vitamin C. In some embodiments, SC-P cells can be obtained by culturing the population of cells containing the insulin-positive endocrine cells in a MCDB131 medium that can be supplemented by 0.05% HSA, 1TS-X, vitamin C, and glutamine (Gin, e.g., 4mM). In some embodiments, the type of culture medium may be changed during S6. For instance, the S6 cells are cultured in a MCDB131 medium that can be supplemented by 0.05% HSA and vitamin C for the first two to four days, and then followed by a DMEM / F12 medium supplemented with 1% HSA. In some embodiments, additional factors are introduced into the culture medium. For instance, S6 cells can be cultured in a MCDB131 medium that can be supplemented by 0.05% HSA, ITS-X, vitamin C, and glutamine (Gin, e.g., 4mM) throughout the 10-12 days, during which ZnSOi is introduced from day 4 of S6.

[0196] In some embodiments, the medium used to culture the cells as described herein can be xeno-free. A xeno-free medium for culturing cells and / or cell clusters of originated from an animal can have no product from other animals. In some embodiments, a xeno-free medium for culturing human cells and / or cell clusters can have no products from any non-human animals. For example, a xeno-free medium for culturing human cells and / or cell clusters can comprise human platelet lysate (PLT) instead of fetal bovine serum (FBS). For example, a medium can comprise from about 1% to about 20%, from about 5% to about 15%, from about 8% to about 12%, from about 9 to about 11% serum. In some embodiments, medium can comprise about 10% of serum. In some embodiments, the medium can be free of small molecules and / or FBS. For example, a medium can comprise MCDB131 basal medium supplemented with 2% BSA. In some embodiments, the medium is serum-free. In some examples, a medium can comprise no exogenous small molecules or signaling pathway agonists or antagonists, such as, growth factor from fibroblast growth factor family (FGF, such as FGF2, FGF8B, FGF 10, or FGF21), Sonic Hedgehog Antagonist (such as Santl, Sant2, Sant4, Sant4, Cur61414, forskolin, tomatidine, AY9944, triparanol, cyclopamine, or derivatives thereof), Retinoic Acid Signaling agonist (e.g.. retinoic acid, CD1530, AM580, TTHPB, CD437, Ch55, BMS961, AC261066, AC55649, AM80, BMS753, tazarotene, adapalene, or CD2314), inhibitor of Rho- associated, coiled-coil containing protein kinase (ROCK) (e.g.. Thiazovivin, Y-27632, Fasudil / HA1077, or 14-1152), activator of protein kinase C (PKC) (e.g., phorbol 12, 13 -dibutyrate (PDBU) , TPB, phorbol 12-myristate 13-acetate, bryostatin 1, or derivatives thereof), antagonist ofTGF P super family (e.g., Alk5 inhibitor II (CAS 446859-33-2), A83-O1, SB431542, D4476, GW788388, LY364947, LY580276, SB505124, GW6604, SB-525334, SD-208, SB-505124, or derivatives thereof), inhibitor of Bone Morphogenetic Protein (BMP) type 1 receptor (e.g., LDN193189 or derivatives thereof), thyroid hormone signaling pathway activator (e.g., T3, GC-1 or derivatives thereof), gamma-secretase inhibitor (e.g., XXI, DAPT, or derivatives thereof), activator of TGF- signaling pathway (e.g., WNT3a or Activin A) growth factor from epidermal growth factor (EGF) family (e.g., betacellulin or EGF), broad kinase (e.g., staurosporine or derivatives thereof), non-essential amino acids, vitamins or antioxidants (e.g.. cyclopamine, vitamin D, vitamin C, vitamin A, or derivatives thereof), or other additions like N- acetyl cysteine, zinc sulfate, or heparin. In some embodiments, the reaggregation medium can comprise no exogenous extracellular matrix molecule. In some embodiments, the reaggregation medium does not comprise Matrigel™. In some embodiments, the reaggregation medium does not comprise other extracellular matrix molecules or materials, such as, collagen, gelatin, poly-L-lysine, poly-D-lysine, vitronectin, laminin, fibronectin, PLO laminin, fibrin, thrombin, and RetroNectin and mixtures thereof, for example, or lysed cell membrane preparations.

[0197] A person of ordinary skill in the art will appreciate that the concentration of serum albumin supplemented into the medium may vary. For example, a medium (e.g., MCDB131 ) can comprise about 0.01%, 0.05%, 0.1%, 1%, about 2%, about 3%, about 4%, about 5%, about 10%, or about 15% BSA. In other cases, a medium can comprise about 0.01%, 0.05%, 0.1%, 1%, about 2%, about 3%, about 4%, about 5%, about 10%, or about 15% HSA. The medium used (e.g., MCDB131 medium) can contain components not found in traditional basal media, such as trace elements, putrescine, adenine, thymidine, and higher levels of some amino acids and vitamins. These additions can allow the medium to be supplemented with very low levels of serum or defined components. The medium can be free of proteins and / or growth factors, and may be supplemented with EGF, hydrocortisone, and / or glutamine. The medium can comprise one or more extracellular matrix molecules (e.g., extracellular proteins). Non-limiting exemplary extracellular matrix molecules used in the medium can include collagen, placental matrix, fibronectin, laminin, merosin, tenascin, heparin, heparin sulfate, chondroitin sulfate, dermatan sulfate, aggrecan, biglycan, thrombospondin, vitronectin, and decorin. In some embodiments, the medium comprises laminin, such as LN-332. In some embodiments, the medium comprises heparin.

[0198] The medium can be changed periodically in the culture, e.g., to provide optimal environment for the cells in the medium. When culturing the cells dissociated from the first cell cluster for re-aggregation, the medium can be changed at least or about every 4 hours, 12 hours, 24 hours, 48 hours, 3 days or 4 days. For example, the medium can be changed about every 48 hours.

[0199] In some embodiments, cells can be cultured under dynamic conditions (e.g., under conditions in which the cells are subject to constant movement or stirring while in the suspension culture). For dynamic culturing of cells, the cells can be cultured in a container (e.g., an non-adhesivecontainer such as a spinner flask (e.g., of 200 ml to 3000 ml, for example 250 ml; of 100 ml; or in 125 ml Erlenmeyer), which can be connected to a control unit and thus present a controlled culturing system. Alternatively, the cells can be cultured in a bioreactor. In some embodiments, cells can be cultured under non-dynamic conditions (e.g., a static culture) while preserving their proliferative capacity. For non-dynamic culturing of cells, the cells can be cultured in an adherent culture vessel. An adhesive culture vessel can be coated with any of substrates for cell adhesion such as extracellular matrix (ECM) to improve the adhesiveness of the vessel surface to the cells. The substrate for cell adhesion can be any material intended to attach stem cells or feeder cells (if used). The substrate for cell adhesion includes collagen, gelatin, poly-L-lysine, poly-D-lysine, vitronectin, laminin, fibronectin, PLO laminin, fibrin, thrombin, and RetroNectin and mixtures thereof, for example, Matrigel™, and lysed cell membrane preparations.L0200J Medium in a dynamic cell culture vessel (e.g.. a spinner flask or bioreactor) can be stirred (e.g., by a stirrer). The spinning speed can correlate with the size of the re-aggregated second cell cluster. The spinning speed can be controlled so that the size of the second cell cluster can be similar to an endogenous pancreatic islet. In some embodiments, the spinning speed is controlled so that the size of the second cell cluster can be from about 75 pm to about 250 pm. The spinning speed of a dynamic cell culture vessel (e.g., a spinner flask or bioreactor) can be about 20 rounds per minute (rpm) to about 100 rpm, e.g., from about 30 rpm to about 90 rpm, from about 40 rpm to about 60 rpm, from about 45 rpm to about 50 rpm. In some embodiments, the spinning speed can be about 50 rpm.

[0201] Stage 6 cells as provided herein may or may not be subject to the dissociation and reaggregation process as described herein. In some embodiments, the cell cluster comprising the insulin-positive endocrine cells can be reaggregated. The reaggregation of the cell cluster can enrich the insulin-positive endocrine cells. In some embodiments, the insulin-positive endocrine cells in the cell cluster can be further matured into pancreatic [> cells. For example, after reaggregation, the second cell cluster can exhibit in vitro GSIS, resembling native pancreatic islet. For example, after reaggregation, the second cell cluster can comprise non-native pancreatic f> cell that exhibits in vitro GSIS. In some embodiments, the reaggregation process can be performed according to the disclosure of PCT application PCT / US2018 / 043179, which is incorporated herein by reference in its entirety.

[0202] Stage 6 cells obtained according to methods provided herein can have high recovery yield after cryopreservation and reaggregation procedures. In some embodiments, stage 6 cells that are obtained in a differentiation process that involves treatment of a BMP signaling pathway inhibitor (e.g., DMH-1 or LDN) and a growth factor from TGF- superfamily (e.g., Activin A) at stage 3 and treatment of an epigenetic modifying compound (e.g., histone methyltransferase inhibitor, e.g., EZH2 inhibitor, e.g., DZNep) at stage 5 can have a higher recovery yield after cryopreservation post stage 5, as compared to a corresponding cell population without such treatment. In some embodiments, stage 6 cells that are obtained in a differentiation process that involves treatment of a BMP signaling pathway inhibitor (e.g., DMH-1 or LDN) and a growth factor from TGF- superfamily (e.g., ActivinA) at stage 3 and treatment of an epigenetic modifying compound (e.g., histone methyltransferase inhibitor, e.g., EZH2 inhibitor, e.g., DZNep) at stage 5 can have a higher recovery yield after cryopreservation post stage 5, as compared to a corresponding cell population without treatment of a BMP signaling pathway inhibitor (e.g., DMH-1 or LDN) and a growth factor from TGF-P superfamily (e.g., Activin A) at stage 3. In some embodiments, stage 6 cells that are obtained in a differentiation process that involves treatment of a BMP signaling pathway inhibitor (e.g., DMH-1 or LDN) and a growth factor from TGF-P superfamily (e.g., Activin A) at stage 3 and treatment of an epigenetic modifying compound (e.g., histone methyltransferase inhibitor, e.g., EZH2 inhibitor, e.g., DZNep) at stage 5 can have a recovery yield after cryopreservation post stage 5 that is at least about 35%, 37.5%, 40%, 42.5%, 45%, 47.5%, 48%, 49%, or 50%. The recovery yield can be calculated as a percentage of cells that survive and form reaggregated cell clusters after cryopreservation, thawing and recovery, and reaggregation procedures, as compared to the cells before the cryopreservation.

[0203] In some embodiments, the present disclosure relates to cryopreservation of the non-native pancreatic P cells or precursors thereof obtained using the methods provided herein. In particular embodiments, the cells are cryopreserved following stage 5 and before stage 6. In some embodiments, the cell population comprising non-native pancreatic P cells can be stored via cryopreservation. For instances, the cell population comprising non-native P cells, e.g., Stage 6 cells are thawed. In some embodiments, the cells can be dissociated into cell suspension, e.g., single cell suspension, and the cell suspension can be cryopreserved, e.g., frozen in a cryopreservation solution. The dissociation of the cells can be conducted by any of the technique provided herein, for example, by enzymatic treatment. The cells can be frozen at a temperature of at highest -20 °C, at highest -30 °C, at highest -40 °C, at highest -50 °C, at highest -60 °C, at highest -70 °C, at highest -80 °C, at highest -90 °C, at highest -100 °C, at highest -110 °C, at highest -120 °C, at highest -130 °C, at highest -140 °C, at highest -150 °C, at highest -160 °C, at highest -170 °C, at highest -180 °C, at highest -190 °C, or at highest -200 °C. In some embodiments, the cells are frozen at a temperature of about -80 °C. In some embodiments, the cells are frozen at a temperature of about -195 °C. Any cooling methods can be used for providing the low temperature needed for cryopreservation, such as, but not limited to, electric freezer, solid carbon dioxide, and liquid nitrogen. In some embodiments, any cryopreservation solution available to one skilled in the art can be used for incubating the cells for storage at low temperature, including both custom made and commercial solutions. For example, a solution containing a cryoprotectant can be used. The cryoprotectant can be an agent that is configured to protect the cell from freezing damage. For instance, a cryoprotectant can be a substance that can lower the glass transition temperature of the cry opreservation solution. Exemplary cryoprotectants that can be used include DMSO (dimethyl sulfoxide), glycols (e.g., ethylene glycol, propylene glycol and glycerol), dextran (e.g., dextran-40), and trehalose. Additional agents can be added into the cryopreservation solution for other effects. In some embodiments, commercially available cryopreservation solutions can be used in the method provided herein, for instance,FrostaLife™, pZerve™, Prime-XV®, Gibco Synth-a-Freeze Cryopreservation Medium, STEMCELLBANKER®, CryoStor® Freezing Media, HypoThermosol® FRS Preservation Media, and CryoDefend® Stem Cells Media.

[0204] During the differentiation process, the cells can be subject to irradiation treatment as provided herein. In some embodiments, the cell population at Stage 6, e.g., the cell population or cell cluster that has cells being differentiated from insulin-positive endocrine cells into pancreatic 0 cells, is irradiated for a period of time. In some embodiments, the cell population at Stage 6 after reaggregation following the recovery from cryopreservation is irradiated for a period of time. In some embodiments, the cryopreserved cells (e.g., the cells that are cryopreserved at the end of Stage 5) are irradiated for a certain period of time prior to thawing and recovery for subsequent differentiation process.

[0205] In some embodiments, the stage 6 cells comprise NKX6.1 -positive, insulin-positive cells. In some embodiments, the stage 6 cells comprise NKX6.1-positive, insulin-negative cells. In some embodiments, the stage 6 cells comprise C-peptide positive cells. In some embodiments, Stage 6 cells or cells that have characteristics of stage 6 cells are incubated in NS-GFs medium, MCDB131 medium, DMEM medium, or CMRL medium. In some embodiments, the stage 6 cells or cells that have characteristics of stage 6 cells are contacted with any one or more of a vitamin or anti-oxidant (e.g., vitamin C), an albumin protein (e.g., a human serum albumin protein), a TGF-beta pathway inhibitor (e.g., an ALK5 inhibitor II), a bone morphogenic protein (BMP) type 1 receptor inhibitor (e.g., LDN193189), a Rho-associated coiled-coil containing protein kinase (ROCK) inhibitor (e.g., thiazovivin), a histone methyltransferase inhibitor (e.g., DZNEP), and a protein kinase inhibitor (e.g., staurosporine). See, e.g.., W02020264072. In some embodiments, the stage 6 cells are contacted with a PKC activator (see, e.g., WO2019217487, which is incorporated by reference herein in its entirety).Differentiation / Growth factors

[0206] Aspects of the disclosure relate to contacting progenitor cells (e.g., stem cells, e.g., iPS cells, definitive endoderm cells, primitive gut tube cells, PDXl-positive pancreatic progenitor cells, NKX6.1-positive pancreatic progenitor cells, insulin-positive endocrine cells) with [5 cell differentiation or growth factors, for example, to induce the maturation of the insulin-positive endocrine cells or differentiation of other progenitor cells into SC- cells (e.g., mature pancreatic 0 cells). In some embodiments, the differentiation factor can induce the differentiation of pluripotent cells (e.g., iPSCs or hESCs) into definitive endoderm cells, e.g., in accordance with a method described herein. In some embodiments, the differentiation factor can induce the differentiation of definitive endoderm cells into primitive gut tube cells, e.g., in accordance with a method described herein. In some embodiments, the differentiation factor(s) can induce the differentiation of primitive gut tube cells into PDXl-positive pancreatic progenitor cells, e.g., in accordance with a methoddescribed herein. In some embodiments, the differentiation factor(s) can induce the differentiation of PDX1 -positive pancreatic progenitor cells into NKX6-1 -positive pancreatic progenitor cells, e.g., in accordance with a method described herein. In some embodiments, the differentiation factor(s) can induce the differentiation of NKX6-1 -positive pancreatic progenitor cells into insulin-positive endocrine cells, e.g., in accordance with a method described herein. In particular embodiments, any of the differentiation / growth factors may be combined with any other differentiation / growth factor disclosed herein. In some embodiments, the differentiation factor(s) can induce the maturation of insulin-positive endocrine cells into pancreatic islet cells, e.g., in accordance with a method described herein.

[0207] At least one differentiation factor described herein can be used alone, or in combination with other differentiation actors, to generate pancreatic islet cells (e.g., SC-beta cells) according to the methods as disclosed herein. In some embodiments, at least two, at least three, at least four, at least five, at least six, at least seven, at least eight, at least nine, or at least ten differentiation factors described herein are used in the methods of generating pancreatic islet cells.

[0208] In some embodiments, a composition described herein does not comprise one or more of the differentiation factors provided herein.Amino acids

[0209] Aspects of the disclosure relate to the use of culture media supplemented with additional amino acids for differentiation. As described herein, the term “amino acid” may broadly refer to compounds containing both a carboxyl group and an amino group and may refer to an amino acid in its many different chemical forms including a single administration amino acid, its physiologically active salts or esters, its combinations with its various salts, its tautomeric, polymeric and / or isomeric forms, its analog forms, its derivative forms, its products of biosynthesis, and / or its decarboxylation products. Amino acids may describe both essential amino acids and / or non-essential amino acids. As described herein, an “essential amino acid” may refer to an amino acid that cannot be made by the body and is consumed through diet. In some embodiments essential amino acids may include histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. As described herein, a “non-essential amino acid” may refer to an amino acid that can be made by the body and does not need to be obtained directly through dietary intake. In some embodiments, non-essential amino acids may include alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, proline, serine, and tyrosine.

[0210] In some embodiments, in a method described herein comprises a medium supplemented with additional amino acids including aspartate, glycine or serine, or combinations thereof. As described herein, “aspartate” or “aspartic acid” may refer to a non-essential amino acid that has a side chain (CHzCOOH). Aspartate may be present in two forms, or enantiomers. These two forms may include either D-aspartic acid or L-aspartic acid. In some embodiments, aspartic acid maybe present in a racemic mixture “DL-aspartic acid”. As described herein, “glycine” may refer to an amino acid that has a single hydrogen atom as its side chain. As described herein, “serine” may refer to an-amino acid that has a side chain of a hydroxymethyl group.Forkhead Box 01 (FoxOl ) inhibitor

[0211] Aspects of the disclosure relate to the use of Forkhead Box O1 (FoxOl) inhibitors as differentiation factors. In some embodiments, the FoxOl inhibitor used in the compositions and methods described herein is a compound of Formula (I):or a pharmaceutically acceptable salt, solvate, hydrate, polymorph, co-crystal, tautomer, stereoisomer, isotopically labeled derivative, prodrug, composition, or mixture thereof, wherein:

[0212] R1is hydrogen, optionally substituted acyl, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted aryl, optionally substituted heteroaryl, or an oxygen protecting group;

[0213] R2is hydrogen, optionally substituted acyl, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted aryl, optionally substituted heteroaryl, or a nitrogen protecting group;

[0214] each instance of R3is independently optionally substituted acyl, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted aryl, optionally substituted heteroaryl, or a nitrogen protecting group; or optionally two instances of R3are taken together with their intervening atoms to form a substituted or unsubstituted heterocyclic or substituted or unsubstituted heteroaryl ring;

[0215] each instance of R4is independently halogen, optionally substituted acyl, optionally substituted alkyl, optionally substituted heteroalkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted aryl, optionally substituted heteroaryl, -ORC1, -NO2, -N(Rc2)2, -SRC1, -CN, or -SCN;

[0216] R5is hydrogen, optionally substituted acyl, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted carbocyclyl, optionallysubstituted heterocyclyl, optionally substituted aryl, optionally substituted heteroaryl, or a nitrogen protecting group;

[0217] each instance of R6is independently halogen, optionally substituted acyl, optionally substituted alkyl, optionally substituted heteroalkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted aryl, optionally substituted heteroaryl, -ORC1, -NO2, -N(Rc2)2, -SRC1, -CN, or -SCN;

[0218] wherein RC1is hydrogen, optionally substituted acyl, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted aryl, optionally substituted heteroaryl, an oxygen protecting group when attached to an oxygen atom, or a sulfur protecting group when attached to a sulfur atom;

[0219] wherein each instance of Rc2is independently hydrogen, optionally substituted acyl, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted aryl, optionally substituted heteroaryl, or a nitrogen protecting group; or optionally two instances of Rc2are taken together with their intervening atoms to form a substituted or unsubstituted heterocyclic or substituted or unsubstituted heteroaryl ring;

[0220] x is 0, 1, or 2;

[0221] y is 0 or 1; and

[0222] z is 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, as valency permits.

[0223] In some embodiments, the compound is of Formula (I- A):or a pharmaceutically acceptable salt, solvate, hydrate, polymorph, co-crystal, tautomer, stereoisomer, isotopically labeled derivative, prodrug, composition, or mixture thereof, wherein:

[0224] R1is hydrogen, optionally substituted alkyl, optionally substituted alkenyl, or optionally substituted alkynyl;

[0225] R2is hydrogen, optionally substituted alkyl, optionally substituted alkenyl, or optionally substituted alkynyl;

[0226] each instance of R3is independently hydrogen, optionally substituted alkyl, optionally substituted alkenyl, or optionally substituted alkynyl;

[0227] R4is halogen, optionally substituted acyl, optionally substituted alkyl, optionally substituted heteroalkyl, optionally substituted alkenyl; and

[0228] R5is hydrogen, optionally substituted alkyl, optionally substituted alkenyl, or optionally substituted alkynyL

[0229] In some embodiments, R1is hydrogen. In some embodiments, R2is optionally substituted alkyl. In some embodiments, R2is ethyl. In some embodiments, at least one instance of R3is hydrogen. In some embodiments, both instances of R3are hydrogen. In some embodiments, at least one instance of R1is halogen. In some embodiments, at least one instance of R1is fluorine. In some embodiments, x is 1. In some embodiments, R5is hydrogen. In some embodiments, y is 1. In some embodiments, z is 0.

[0230] In some embodiments, the compound is of formula:or a pharmaceutically acceptable salt, solvate, hydrate, polymorph, co-crystal, tautomer, stereoisomer, isotopically labeled derivative, prodrug, composition, or mixture thereof.

[0231] In some embodiments, the compound is AS 1842856.

[0232] In some embodiments, a medium described herein does not comprise a FoxOl inhibitor.Transforming Growth Factor-f (TGF-fi) Superfamily

[0233] Aspects of the disclosure relate to the use of growth factors from the transforming growth factor-|3 (TGF-P) superfamily as differentiation factors. The “TGF- superfamily” means proteins having structural and functional characteristics of known TGF family members. The TGF family of proteins can include the TGF series of proteins, the Inhibins (including Inhibin A and Inhibin B), the Activins (including Activin A, Activin B, and Activin AB), MIS (Mullerian inhibiting substance), BMP (bone morphogenetic proteins), dpp (decapentaplegic), Vg-1, MNSF (monoclonal nonspecific suppressor factor), and others. Activity of this family of proteins can be based on specific binding to certain receptors on various cell types. Members of this family can share regions of sequence identity, particularly at the C-terminus, that correlate to their function. The TGFP family can include more than one hundred distinct proteins, all sharing at least one region of amino acid sequence identity. Members of the family that can be used in the method disclosed herein can include, but are not limited to, the following proteins, as identified by their GenBank accession numbers: P07995, P18331, P08476, Q04998, P03970, P43032, P55102, P27092, P42917, P09529, P27093, P04088, Q04999, P17491, P55104, Q9WUK5, P55103, 088959, 008717, P58166, 061643, P35621, P09534, P48970, Q9NR23, P25703, P30884, P12643, P49001, P21274, 046564, 019006, P22004, P20722, Q04906, Q07104, P30886, P18075, P23359, P22003, P34821, P49003, Q90751, P21275, Q06826, P30885, P34820, Q29607, P12644, Q90752, 046576, P27539, P48969, Q26974, P07713, P91706,P91699, P27091, 042222, Q24735, P20863, 018828, P55106, Q9PTQ2, 014793, 008689, 042221, 018830, 018831, 018836, 035312, 042220, P43026, P43027, P43029, 095390, Q9R229, 093449, Q9Z1W4, Q9BDW8, P43028, Q7Z4P5, P50414, P17246, P54831, P04202, P01137, P09533, P18341, 019011, Q9Z1Y6, P07200, Q9Z217, 095393, P55105, P30371, Q9MZE2, Q07258, Q96S42, P97737, AAA97415.1, NP-776788.1, NP-058824.1, EAL24001.1, 1 S4Y, NP-001009856.1, NP-1- 032406.1, NP-999193.1, XP-519063.1, AAG17260.1, CAA40806.1, NP- 1-001009458.1, AAQ55808.1, AAK40341.1, AAP33019.1, AAK21265.1, AAC59738.1, CAI46003.1, B40905, AAQ55811.1, AAK40342.1, XP-540364.1, P55102, AAQ55810.1, NP-990727.1, CAA51163.1, AAD50448.1, JC4862, PN0504, BAB17600.1, AAH56742.1, BAB17596.1, CAG06183.1, CAG05339.1, BAB17601.1, CAB43091.1, A36192, AAA49162.1, AAT42200.1, NP-789822.1, AAA59451.1, AAA59169.1, XP-541000.1, NP-990537.1, NP- 1-002184.1, AAC14187.1, AAP83319.1, AAA59170.1, BAB16973.1, AAM66766.1, WFPGBB, 1201278C, AAH30029.1, CAA49326.1, XP-344131.1, AA-148845.1, XP-1-148966.3, 148235, B41398, AAH77857.1, AAB26863.1, 1706327A, BAA83804.1, NP-571143.1, CAG00858.1, BAB17599.1, BAB17602.1, AAB61468.1, PN0505, PN0506, CAB43092.1, BAB17598.1, BAA22570.1, BAB16972.1, BAC81672.1, BAA12694.1, BAA08494.1, B36192, C36192, BAB16971.1, NP-034695.1,A A A49160.1 , C A A62347.1 , A A A49161 .1 , A AD301 2.1 , C A A58290. 1 , NP-005529.1 , XP-522443.1 , AAM27448.1, XP-538247.1, AAD30133. 1, AAC36741.1, AAH10404.1, NP-032408.1, AAN03682.1, XP-509161.1, AAC32311.1, NP-651942.2, AAL51005.1, AAC39083.1, AAH85547.1, NP-571023.1, CAF94113.1, EAL29247.1, AAW30007.1, AAH90232.1, A29619, NP-001007905.1, AAH73508.1, AADO2201.1, NP-999793.1, NP-990542.1, AAF19841.1, AAC97488.1, AAC60038.1, NP 989197.1, NP-571434.1, EAL41229.1, AAT07302.1, CAI19472.1, NP-031582.1, AAA40548.1, XP-535880.1, NP- 1-037239.1, AAT72007.1, XP-418956.1, CAA41634.1, BAC30864.1, CAA3885O.1, CAB81657.2, CAA45018.1, CAA45019.1, BAC28247.1, NP-031581.1, NP-990479.1, NP-999820.1, AAB27335.1, S45355, CAB82007.1, XP-534351.1, NP-058874.1, NP-031579.1, 1REW, AAB96785.1, AAB46367.1, CAAO5O33.1, BAA89012.1, IES7, AAP20870.1, BAC24087.1, AAG09784.1, BAC06352.1, AAQ89234.1, AAM27000.1, AAH30959.1, CAGO1491.1, NP- 571435.1, 1REU, AAC60286.1, BAA24406.1, A36193, AAH55959.1, AAH54647.1, AAH90689.1, CAG09422.1, BAD16743.1, NP-032134.1, XP-532179.1, AAB24876.1, AAH57702.1, AAA82616.1, CAA40222.1, CAB90273.2, XP-342592.1, XP-534896.1, XP-534462.1, 1LXI, XP-417496.1, AAF34179.1, AAL73188.1, CAF96266.1, AAB34226.1, AAB33846.1, AAT12415.1, AA033819.1, AAT72008.1, AAD38402.1, BAB68396.1, CAA45021.1, AAB27337.1, AAP69917.1, AATI2416.1, NP-571396.1, CAA53513.1, AA033820.1, AAA48568.1, BAC02605.1, BAC02604.1, BAC02603.1, BAC02602.1, BAC02601.1, BAC02599.1, BAC02598.1, BAC02597.1, BAC02595.1, BAC02593.1, BAC02592.1, BAC02590.1, AAD28039.1, AAP74560.1, AAB94786.1, NP-001483.2, XP-528195.1, NP-571417.1, NP-001001557. 1, AAH43222.1, AAM33143.1, CAG1O381.1, BAA31132.1, EAL39680.1, EAA12482.2, P34820, AAP88972.1, AAP74559.1, CAI16418.1, AAD30538.1, XP-345502.1, NP-1-038554.1, CAG04089.1, CAD60936.2, NP-031584.1, B55452, AAC60285.1, BAA06410.1, AAH52846.1, NP-O3158O.1, NP- 1-036959.1, CAA45836.1, CAA45020.1, Q29607, AAB27336.1, XP-547817.1, AAT12414.1, AAM54049.1, AAH78901.1, AA025745.1, NP-570912.1, XP-392194.1, AAD20829.1, AAC97113.1, AAC61694.1, AAH60340.1, AAR97906.1, BAA32227.1, BAB68395.1, BAC02895.1, AAWS 1451.1, AAF82188.1, XP-544189.1, NP-990568.1, BAC80211.1, AAW82620.1, AAF99597.1, NP-571062.1, CAC44179.1, AAB97467.1, AAT99303.1, AAD28038.1, AAH52168.1, NP-001004122.1, CAA72733.1, NP-032133.2, XP-394252.1, XP-224733.2, JH0801, AAP97721.1, NP-989669.1, S43296, P43029, A55452, AAH32495.1, XP-542974.1, NP-032135.1, AAK30842.1, AAK27794.1, BAC30847.1, EAA12064.2, AAP97720.1, XP-525704.1, AAT07301.1, BAD07014.1, CAF94356.1, AAR27581.1, AAG13400.1, AAC60127.1, CAF92055.1, XP-540103.1, AA020895.1, CAF97447.1, AAS01764.1, BAD08319.1, CAA10268.1, NP-998140.1, AAR03824.1, AAS48405.1, AAS48403.1, AAK53545.1, AAK84666.1, XP-395420.1, AAK56941.1, AAC47555.1, AAR88255.1, EAL33036.1, AAW47740.1, AAW29442.1, NP-722813.1, AARO8901.1, AAO 15420.2, CAC59700.1, AAL26886.1, AAK71708.1, AAK71707.1, CAC51427.2, AAK67984.1, AAK67983.1, AAK28706.1, P07713, P91706, P91699, CAG02450.1, AAC47552.1, NP-005802.1, XP-343149.1, AW34055.1, XP-538221.1, AAR27580.1, XP-125935.3, AAF21633.1, AAF21630.1, AAD05267.1, Q9Z1 W4, NP-1 -031585.2, NP-571094.1, CAD43439.1 , CAF99217.1, CAB63584.1, NP-722840.1, CAE46407.1, XP-1-417667.1, BAC53989.1, BAB19659.1, AAM46922.1, AAA81169.1, AAK28707.1, AAL05943.1, AAB17573.1, CAH25443.1, CAG10269.1, BAD16731.1, EAA00276.2, AAT07320.1, AAT07300.1, AAN15037.1, CAH25442.1, AAK08152.2, 2009388A, AAR12161.1, CAGO1961.1, CAB63656.1, CAD67714.1, CAF94162.1, NP-477340.1, EAL24792.1, NP- 1-001009428.1, AAB86686.1, AAT40572.1, AAT40571.1, AAT40569.1, NP-033886.1, AAB49985.1, AAG39266.1, Q26974, AAC77461.1, AAC47262.1, BAC05509.1, NP-055297.1, XP-546146.1, XP-525772.1, NP-060525.2, AAH33585.1, AAH69080.1, CAG12751.1, AAH74757.2, NP-034964.1, NP-038639.1, 042221, AAF02773.1, NP-062024.1, AAR18244.1, AAR14343.1, XP-228285.2, AAT40573.1, AAT94456.1, AAL35278.1, AAL35277.1, AAL17640.1, AAC08035.1, AAB86692.1, CAB40844.1, BAC38637.1, BAB16046.1, AAN63522.1, NP-571041.1, AAB04986.2, AAC26791.1, AAB95254.1, BAA11835.1, AAR18246.1, XP-538528.1, BAA31853.1, AAK18000.1, XP- 1-420540.1, AAL35276.1, AAQ98602.1, CAE71944.1, AAW50585.1, AAV63982.1, AAW29941.1, AAN87890.1, AAT40568.1, CAD57730.1, AAB81508.1, AAS00534.1, AAC59736.1, BAB79498.1, AAA97392.1, AAP85526.1, NP-999600.2, NP-878293.1, BAC82629.1, CAC60268.1, CAG04919.1, AAN10123.1, CAA07707.1 AAK20912.1, AAR88254.1, CAC34629.1, AAL35275.1, AAD46997. 1, AAN03842.1, NP-571951.2, CAC50881.1, AAL99367.1, AAL49502.1, AAB71839.1, AAB65415.1, NP-624359.1, NP-990153.1, AAF78069.1,AAK49790.1, NP-919367.2, NP-001192.1, XP-544948.1, AAQ18013.1, AAV38739.1, NP-851298.1, CAA67685.1, AAT67171.1, AAT37502.1, AAD27804.1, AAN76665.1, BAC11909.1, XP-1-421648.1, CAB63704.1, NP-037306.1, A55706, AAF02780.1, CAG09623.1, NP-067589.1, NP-035707.1, AAV30547.1, AAP49817.1, BAC77407.1, AAL87199.1, CAG07172.1, B36193, CAA33024.1, NP-1-001009400.1, AAP36538.1, XP-512687.1, XP-510080.1, AAH05513.1, 1KTZ, AAH14690.1, AAA31526.1.

[0234] The growth factor from the TGF- superfamily in the methods and compositions provided herein can be naturally obtained or recombinant. In some embodiments, the growth factor from the TGF-0 superfamily comprises Activin A. The term “Activin A” can include fragments and derivatives of Activin A. The sequence of an exemplary Activin A is provided as SEQ ID NO: 1. Other nonlimiting examples of Activin A are provided in SEQ ID NO: 3-16, and non-limiting examples of nucleic acids encoding Activin A are provided in SEQ ID NO: 2, SEQ ID NO: 17, and SEQ ID NO: 18 . In some embodiments, the growth factor from the TGF-[3 superfamily comprises a polypeptide comprising an amino acid sequence that is at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 98% or at least 99% identical to the amino acid sequence of any one of SEQ ID NOs: 1 and 3-16, or functional fragments thereof. In some embodiments, the growth factor from the TGF-0 superfamily comprises a polypeptide comprising the amino acid any one of SEQ ID NOs: 1 and 3-16.

[0235] SEQ ID NO: 1 - Homo sapiens Inhibin beta A subunit (Activin A) amino acid sequence: GLECDGKVNICCKKQFFVSFKDIGWNDWIIAPSGYHANYCEGECPSHIAGTSGSSLSFHSTVIN HYRMRGHSPFANLKSCCVPTKLRPMSMLYYDDGQNIIKKDIQNMIVEECGCS

[0236] SEQ ID NO: 2 - Homo sapiens Inhibin beta A chain (Activin A) nucleic acid sequence: GGCTTGGAGTGTGATGGCAAGGTCAACATCTGCTGTAAGAAACAGTTCTTTGTCAGTTTC AAGGACATCGGCTGGAATGACTGGATCATTGCTCCCTCTGGCTATCATGCCAACTACTGC GAGGGTGAGTGCCCGAGCCATATAGCAGGCACGTCCGGGTCCTCACTGTCCTTCCACTCA ACAGTCATCAACCACTACCGCATGCGGGGCCATAGCCCCTTTGCCAACCTCAAATCGTGC TGTGTGCCCACCAAGCTGAGACCCATGTCCATGTTGTACTATGATGATGGTCAAAACATC ATCAAAAAGGACATTCAGAACATGATCGTGGAGGAGTGTGGGTGCTCATAG

[0237] SEQ ID NO: 3 - Homo sapiens Erythroid differentiation protein (EDF) ovarian amino acid sequence: MPLLWLRGFLLASCWIIVRSSPTPGSEGHSAAPDCPSCALAALPKDVPNSQPEMVEAVKKHIL NMLHLKKRPDVTQPVPKAALLNAIRKLHVGKVGENGYVEIEDDIGRRAEMNELMEQTSEIIT FAESGTARKTLHFEISKEGSDLSVVERAEVWLFLKVPKANRTRTKVTIRLFQQQKHPQGSLDT GEEAEEVGLKGERSELLLSEKVVDARKSTWHVFPVSSSIQRLLDQGKSSLDVRIACEQCQESG ASLVLLGKKKKKEEEGEGKKKGGGEGGAGADEEKEQSHRPFLMLQARQSEDHPHRRRRRG LECDGKVNICCKKQFFVSFKDIGWNDWIIAPSGYHANYCEGECPSHIAGTSGSSLSFHSTVINH YRMRGHSPFANLKSCCVPTKLRPMSMLYYDDGQNIIKKDIQNMIVEECGCS

[0238] SEQ ID NO: 4 - Homo sapiens Inhibin B subunit amino acid sequence:ARQSEDHPHRRRRRGLECDGKVNICCKKQFFVSFKDIGWNDWIIAPSGYHANYCEGECPSHIAGTSGSSLSFHSTVINHYRMRGHSPFANLKSCCVPTKLRPMSMLYYDDGQNUKKDIQNMIVEECGCS

[0239] SEQ ID NO: 5 - Homo sapiens Inhibin B subunit in testis Homo sapiens amino acid sequence:GLECDGKVNICCKKQFFVSFKDIGWNDWIIAPSGYHANYCEGECPSHIAGTSGSSLSFHSTVINHYACGHSPFANLKSCCVPTKLRPMSMLYYDDGQNIIKKDIQNMIVEECGCS

[0240] SEQ ID NO: 6 - Homo sapiens Inhibin B subunit erythroid differentiation protein (EDF), amino acid sequence:MPLLWLRGFLLASCWIIVRSSPTPGSEGHSAAPDCPSCALAALPKDVPNSQPEMVEAVKKHILNMLHLKKRPDVTQPVPKAALLNAIRKLHVGKVGENGYVEIEDDIGRRAEMNELMEQTSEIITFAESGTARKTLHFEISKEGSDLSVVERAEVWLFLKVPKANRTRTKVTIRLFQQQKHPQGSLDTGEEAEEVGLKGERSELLLSEKVVDARKSTWHVFPVSSSIQRLLDQGKSSLDVRIACEQCQESGASLVLLGKKKKKEEEGEGKKKGGGEGGAGADEEKEQSHRPFLMLQARQSEDHPHRRRRRGLECDGKVNICCKKQFFVSFKDIGWNDWIIAPSGYHANYCEGECPSHIAGTSGSSLSFHSTVINHYRMRGHSPFANLKSCCVPTKLRPMSMLYYDDGQNIIKKDIQNMIVEECGCS

[0241] SEQ ID NO: 7 - Mus musculus (Mouse) Inhibin beta A chain (Activin beta-A chain) amino acid sequence:MPLLWLRGFLLASCWIIVRSSPTPGSEGHGSAPDCPSCALATLPKDGPNSQPEMVEAVKKHILNMLHLKKRPDVTQPVPKAALLNAIRKLHVGKVGENGYVEIEDDIGRRAEMNELMEQTSEIITFAESGTARKTLHFEISKEGSDLSVVERAEVWLFLKVPKANRTRTKVTIRLFQQQKHPQGSLDTGDEAEEMGLKGERSELLLSEKVVDARKSTWHIFPVSSSIQRLLDQGKSSLDVRIACEQCQESGASLVLLGKKKKKEVDGDGKKKDGSDGGLEEEKEQSHRPFLMLQARQSEDHPHRRRRRGLECDGKVNICCKKQFFVSFKDIGWNDWIIAPSGYHANYCEGECPSHIAGTSGSSLSFHSTVINHYRMRGHSPFANLKSCCVPTKLRPMSMLYYDDGQNIIKKDIQNMIVEECGCS

[0242] SEQ ID NO: 8 - Rattus norvegicus (Rat) Inhibin beta A chain (Activin beta-A chain) amino acid sequence:MPLLWLRGFLLASCWIIVRSSPTPGSEGHGAAPDCPSCALATLPKDGPNSQPEMVEAVKKHILNMLHLKKRPDVTQPVPKAALLNAIRKLHVGKVGENGYVEIEDDIGRRAEMNELMEQTSEIITFAESGTARKTLHFEISKEGSDLSVVERAEVWLFLKVPKANRTRTKVTIRLFQQQKHPQGSLDMGDEAEEMGLKGERSELLLSEKVVDARKSTWHIFPVSSSIQRLLDQGKSSLDVRIACEQCQESGASLVLLGKKKKKEVDGDGKKKDGSDGGLEEEKEQSHRPFLMLQARQSEDHPHRRRRRGLECDGKVNICCKKQFFVSFKDIGWNDWIIAPSGYHANYCEGECPSHIAGTSGSSLSFHSTVINHYRMRGHSPFANLKSCCVPTKLRPMSMLYYDDGQNIIKKDIQNMIVEECGCS

[0243] SEQ ID NO: 9 - Gallus gallus (Chicken) Inhibin beta A chain (Activin beta-A chain) amino acid sequence:MPLLWKRGFLLVICWIIVRSSPTPGSEGHSSVADCPSCALTTLSKDVPSSQPEMVEAVKKHILNMLHLRDRPNITQPVPKAALLNATKKLHVGKVGDDGYVEIEDDVGRRAEMNEVVEQTSEIITFAESGTPKKTLHFEISKEGSELSVVEHAEVWLFLKVSKANRSRTKVTIRLFQQQRQPKGNSEAAEDMEDMGLKGERSETLISEKAVDARKSTWHIFPISSSVQRLLDQGQSSLDVRIACDLCQETGASLVLLGKKKKKEDDGEGKEKDGGELTGEEEKEQSHRPFLMMLARHSEDRQHRRRERGLECDGKVNICCKKQFFVSFKDIGWSDWIIAPTGYHANYCEEECPSHIAGTSGSSLSFHSTVINHYRMRGHSPFANLKSCCVPTKLRPMSMLYYDDGQNIIKKDIQNMIVEECGCS

[0244] SEQ ID NO: 10 - Bos taurus (Bovine) Inhibin beta A chain (Activin beta-A chain) amino acid sequence:MPLLWLRGFLLASCWIIVRSSPTPGSEGHSAAPDCPSCALATLPKDVPNSQPEMVEAVKKHILNMLHLKKRPDVTQPVPKAALLNAIRKLHVGKVGENGYVEIEDDIGRRAEMNELMEQTSEIITFAESGTARKTLHFEISKEGSDLSVVERAEIWLFLKVPKANRTRSKVTIRLFQQQKHLQGSLDAGEEAEEVGLKGEKSEMLISEKVVDARKSTWHIFPVSSCIQRLLDQGKSSLDIRIACEQCQETGASLVLLGKKKKKEEEGEGKKRDGEGGAGGDEEKEQSHRPFLMLQARQSEDHPHRRRRRGLECDGKVNICCKKQFFVSFKDIGWNDWIIAPSGYHANYCEGECPSHIAGTSGSSLSFHSTVINHYRMRGHSPFANLKSCCVPTKLRPMSMLYYDDGQNIIKKDIQNMIVEECGCS

[0245] SEQ ID NO: 1 1 - Equus caballus (Horse) Inhibin beta A chain (Activin beta-A chain) amino acid sequence:MPLLWLRGFLLASCWIIVKSSPTPGSEGHSAAPNCPSCALATLPKDVPNAQPEMVEAVKKHILNMLHLKKRPDVTQPVPKAALLNAIRKLHVGKVGENGYVEIEDDIGRRAEMNELMEQTSEIITFAESGTARKTLHFEISKEGSDLSVVERAEVWLFLKVPKANRTRSKVTIRLLQQQKHPQGSSDTREEAEEADLMEERSEQLISEKVVDARKSTWHIFPVSSSIQRLLDQGKSSLDIRIACDQCHETGASLVLLGKKKKKEEEGEGKKKDGGEAGAGVDEEKEQSHRPFLMLQARQSEDHPHRRRRRGLECDGKVNICCKKQFFVSFKDIGWNDWIIAPSGYHANYCEGECPSHIAGTSGSSLSFHSTVINQYRLRGHNPFANLKSCCVPTKLRPMSMLYYDDGQNIIKKDIQNMIVEECGCS

[0246] SEQ ID NO: 12 - Sus scrofa (Pig) Inhibin beta A chain (Activin beta-A chain) amino acid sequence:MPLLWLRGFLLASCWIIVRSSPTPGSGGHSAAPDCPSCALATLPKDVPNSQPEMVEAVKKHILNMLHLKKRPDVTQPVPKAALLNAIRKLHVGKVGENGYVELEDDIGRRAEMNELMEQTSEIITFAEAGTARKTLRFEISKEGSDLSVVERAEIWLFLKVPKANRTRTKVSIRLFQQQRRPQGSADAGEEAEDVGFPEEKSEVLISEKVVDARKSTWHIFPVSSSIQRLLDQGKSALDIRTACEQCHETGASLVLLGKKKKKEEEAEGRKRDGEGAGVDEEKEQSHRPFLMLQARQSEEHPHRRRRRGLECDGKVNICCKKQFFVSFKDIGWNDWIIAPSGYHANYCEGECPSHIAGTSGSSLSFHSTVINHYRMRGHSPFANLKSCCVPTKLRPMSMLYYDDGQNIIKKDIQNMIVEECGCS

[0247] SEQ ID NO: 13 - Ovis aries (Sheep) Inhibin beta A chain (Activin beta-A chain) amino acid sequence:MPLLWLRGFLLASCWIIVRSSPTPGSEGHSAAPDCPSCALATLPKDVPNSQPEMVEAVKKHIL NMLHLKKRPDVTQPVPKAALLNAIRKLHVGKVGENGYVEIEDDIGRRAEMNELMEQTSEIIT FAESGTARKTLHFEISQEGSDLSVVERAEIWLFLKVPKANRTRSKVTIRLFQQQKHLQGSLDA GEEAEEVGLKGEKSEMLISEKVVDARKSTWHIFPVSSCIQRLLDQGKSSLDIRIACEQCQETG ASLVLLGKKKRKEEEGEGKKRDGEGGAGGDEEKEQSHRPFLMLQARQSEDHPHRRRRRGLECDGKVNICCKKQFYVSFKDIGWNDWIIAPSGYHANYCEGECPSHIAGTSGSSLSFHSTVINHY RMRGHSPFANLKSCCVPTKLRPMSMLYYDDGQNIIKKDIQNMIVEECGCS

[0248] SEQ ID NO: 14 - Felis catus (cat) Inhibit! beta A chain (Activin beta-A chain) amino acid sequence:MPLLWLRGFLLASCWIIVRSSPTPGSEGPGAAPDCPSCALATLPKDVPNSQPEMVEAVKKHILNMLHLKKRPEVTQPVPKAALLNAIRKLHVGKVGENGYVEIEDDIGRRAEMNELMEQTSEIIT FAESGTARKTLHFEISKEGSDLSVVERAEVWLFLKVPKANRTRTKVTIQLLQKQPQGGVDAG EEAEEMGLMEERNEVLISEKVVDARKSTWHIFPVSSSIQRLLDQGKSSLDVRIACEQCHETGA SLVLLGKKKKKEEEGEGKKKDGGDGGAGADEDKEQSHRPFLMLQARQSEDHPHRRRRRGL ECDGKVNICCKKQFFVSFKDIGWNDWIIAPSGYHANYCEGECPSHIAGTSGSSLSFHSTVINHYRMRGHSPFANLKSCCVPTKLRPMSMLYYDDGQNIIKKDIQNMIVEECGCS

[0249] SEQ ID NO: 15 - Danio rerio (zebrafish) Inhibin beta A chain (Activin beta-A chain) amino acid sequence:MSPLPLLSGILLLLIRSCSLSAMVTKGSLPMSEQQAGATVCPSCALARFRKGVSESEDEGAQQDVVEAVKRHILNMLHLQERPNITHPVPRAALLNAIRKVHVGRVAKDGSVLIEDEASNRAETE QAEQTEIITFAETGEAPGIVNFLISKEGGEMSVVDQANVWIFLRLPKGNRTRANVNIRLLLQQ GAGEKILAEKSVDTRRSGWHTFPASESVQSLLQRGGSTLSLRVSCPLCADARATPVLVSPGGS EREQSHRPFLMAVVRQMDELSLRRRRKRGLECDGKARVCCKRQFYVNFKDIGWNDWIIAPS GYHANYCEGDCASNVASITGNSLSFHSTVISHYRIRGYSPFTNIKSCCVPTRLRAMSMLYYNEEQKIVKKDIQNMIVEECGCS

[0250] SEQ ID NO: 16 - Carassius auratus (goldfish) Inhibin beta A chain (Activin beta-A chain) amino acid sequence:MSSLTLVNRGTAALRLFVRGLLTHSSREWLSGDGEPDDPVTPCPSCALAQRQKDSEEQTDM VEAVKRHILNMLHLNTRPNVTHPVPRAALLNAIRRLHVGRVGEDGTVEMEEDGGGLGEHREQSEEQPFEIITFAEPGDAPDIMKFDISMEGNTLSVVEQANVWLLLKVAKGSRGKGKVSVQLL QHGKADPGSADGPQEAVVSEKTVDTRRSGWHTLPVSRTVQTLLDGDSSMLSLRVSCPMCAE AGAVPILVPTESNKGKEREQSHRPFLMVVLKPAEEHPHRRSKRGLECDGKIRVCCKRQFYVN FKDIGWSDWIIAPSGYHANYCEGDCPSHVASITGSALSFHSTVINHYRMRGYSPFNNIKSCCV PTRLRAMSMLYYNEEQKIIKKDIQNMIVEECGCS

[0251] SEQ ID NO: 17 - Recombinant Inhibin B subunit nucleic acid sequenceGCCCGGCAGTCTGAAGACCACCCTCATCGCCGGCGTCGGCGGGGCTTGGAGTGTGATGGCAAGGTCAACATCTGCTGTAAGAAACAGTTCTTTGTCAGTTTCAAGGACATCGGCTGGAATGACTGGATCATTGCTCCCTCTGGCTATCATGCCAACTACTGCGAGGGTGAGTGCCCGAG CCATATAGCAGGCACGTCCGGGTCCTCACTGTCCTTCCACTCAACAGTCATCAACCACTA CCGCATGCGGGGCCATAGCCCCTTTGCCAACCTCAAATCGTGCTGTGTGCCCACCAAGCT GAGACCCATGTCCATGTTGTACTATGATGATGGTCAAAACATCATCAAAAAGGACATTCA GAACATGATCGTGGAGGAGTGTGGGTGCTCATAGAGTTGCCCAGCCCAGGGGGAAAGGG AGCAAGA

[0252] SEQ ID NO : 18 - Homo sapiens mature subunit beta(A) inhibin in testis nucleic acid sequence GGCCTGGAGTGCGACGGCAAGGTCAACATCTGCTGTAAGAAACAGTTCTTTGTCAGTTTC AAGGACATCGGCTGGAATGACTGGATCATTGCTCCCTCTGGCTATCATGCCAACTACTGC GAGGGTGAGTGCCCGAGCCATATAGCAGGCACGTCCGGGTCCTCACTGTCCTTCCACTCA ACAGTCATCAACCACTACGCATGCGGCCATAGCCCCTTTGCCAACCTCAAATCGTGCTGT GTGCCCACCAAGCTGAGACCCATGTCCATGTTGTACTATGATGATGGTCAAAACATCATC AAAAAGGACATTCAGAACATGATCGTGGAGGAGTGCGGGTGCTCCTAA

[0253] In some embodiments, the growth factor from the TGF-P superfamily comprises growth differentiation factor 8 (GDF8). The term “GDF8” can include fragments and derivatives of GDF8. The sequences of GDF8 polypeptides are available to the skilled artisan. In some embodiments, the growth factor from the TGF-P superfamily comprises a polypeptide having an amino acid sequence at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, or at least 99%, or greater identical to the human GDF8 polypeptide sequence (GenBank Accession EAX1O88O).

[0254] In some embodiments, the growth factor from the TGF-P superfamily comprises a growth factor that is closely related to GDF8, e.g., growth differentiation factor 11 (GDF11). In some embodiments, the growth factor from the TGF-P superfamily comprises a polypeptide having an amino acid sequence at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, or at least 99%, or greater identical to the human GDF11 polypeptide sequence (GenBank Accession AAF21630).

[0255] In some embodiments, the growth factor from the TGF-P superfamily can be replaced with an agent mimics the at least one growth factor from the TGF-P superfamily. Exemplary agents that mimic the at least one growth factor from the TGF-P superfamily, include, without limitation, IDE1 and IDE2.

[0256] In some embodiments, a medium described herein does not comprise a TGF-P superfamily protein.Bone Morphogenetic Protein (BMP) Signaling Pathway Inhibitors

[0257] Aspects of the disclosure relate to the use of BMP signaling pathway inhibitors (which also may be referred to as “BMP inhibitors” herein) as cell differentiation factors. The BMP signalingfamily is a diverse subset of the TGF- superfamily (Sebald et al. Biol. Chem. 385:697-710, 2004). Over twenty known BMP ligands are recognized by three distinct type II (BMPRII, ActRIIa, and ActRIIb) and at least three type I (ALK2, ALK3, and ALK6) receptors. Dimeric ligands facilitate assembly of receptor heteromers, allowing the constitutively-active type II receptor serine / threonine kinases to phosphorylate type I receptor serine / threonine kinases. Activated type I receptors phosphorylate BMP-responsive (BR-) SMAD effectors (SMADs 1, 5, and 8) to facilitate nuclear translocation in complex with SMAD4, a co-SMAD that also facilitates TGF signaling. In addition, BMP signals can activate intracellular effectors such as MAPK p38 in a SMAD-independent manner (Nohe et al. Cell Signal 16:291-299, 2004). Soluble BMP antagonists such as noggin, chordin, gremlin, and follistatin limit BMP signaling by ligand sequestration.

[0258] In some embodiments, the BMP signaling pathway inhibitor in the methods and composition provided herein comprises DMH-1, or a derivative, analogue, or variant thereof. In some embodiments, the BMP signaling pathway inhibitor in the methods and composition provided herein comprises the following compound or a derivative, analogue, or variant of the following compound:

[0259] In some embodiments, the BMP signaling pathway inhibitor in the methods and composition provided herein comprises LDN193189 (also known as LDN193189, 1062368-24-4, LDN-193189, DM 3189, DM-3189, IUPAC Name: 4-[6-(4-piperazin-l-ylphenyl)pyrazolo[l,5- a]pyrimidin-3-yl]quinolone). In some embodiments, the BMP signaling pathway inhibitor in the methods and composition provided herein comprises the following compound or a derivative, analogue, or variant of the following compound:N .A . AH

[0260] In some embodiments, DMH-1 can be more selective as compared to LDN193189. In some embodiments of the present disclosure, DMH-1 can be particularly useful for the methods provided herein. In some embodiments, the methods and compositions provided herein, or specific stages of the methods disclosed herein (e.g., stage 3), exclude use of LDN193189. In some embodiments, the methods and compositions provided herein exclude use of LDN193189, or a derivative, analogue, or variant thereof for generating PDXl-positive pancreatic progenitor cells from primitive gut tube cells. In some embodiments, the methods and compositions provided herein relate to use of DMH-1, or a derivative, analogue, or variant thereof for generating PDXl-positive pancreatic progenitor cells from primitive gut tube cells.

[0261] In some embodiments, the BMP signaling pathway inhibitor in the methods and composition provided herein comprise an analog or derivative of LDN193189, e.g., a salt, hydrate, solvent, ester, or prodrug of LDN193189. In some embodiments, a derivative (e.g., salt) of LDN193189 comprises LDN193189 hydrochloride.

[0262] In some embodiments, the BMP signaling pathway inhibitor is dorsomorphin. In some embodiments, the BMP inhibitor is noggin, LDN-212854, or ML347.

[0263] In some embodiments, the BMP signaling pathway inhibitor in the methods and composition provided herein comprises a compound of Formula I from U.S. Patent Publication No. 2011 / 0053930.

[0264] In some embodiments, a medium described herein does not comprise a BMP signaling pathway inhibitor.TGF-fi Signaling Pathway Inhibitors

[0265] Aspects of the disclosure relate to the use of TGF-P signaling pathway inhibitors as cell differentiation factors.

[0266] In some embodiments, the TGF-P signaling pathway comprises TGF-P receptor type I kinase (TGF-P RI) signaling. In some embodiments, the TGF-P signaling pathway inhibitor comprises ALK5 inhibitor II (CAS 446859-33-2, an ATP-competitive inhibitor of TGF-B RI kinase,also known as RepSox, IUPAC Name: 2-[5-(6-methylpyridin-2-yl)-lH-pyrazol-4-yl]-l,5- naphthyridine. In some embodiments, the TGF-P signaling pathway inhibitor is an analog or derivative of ALK5 inhibitor II.

[0267] In some embodiments, the analog or derivative of ALK5 inhibitor II (also named “ALK5i”) is a compound of Formula I as described in U.S. Patent Publication No. 2012 / 0021519, incorporated by reference herein in its entirety.

[0268] In some embodiments, the TGF- signaling pathway inhibitor in the methods and compositions provided herein is a TGF-P receptor inhibitor described in U.S. Patent Publication No. 2010 / 0267731. In some embodiments, the TGF-P signaling pathway inhibitor in the methods and compositions provided herein comprises an ALK5 inhibitor described in U.S. Patent Publication Nos. 2009 / 0186076 and 2007 / 0142376. In some embodiments, the TGF-P signaling pathway inhibitor in the methods and compositions provided herein is A 83-01. In some embodiments, the TGF-P signaling pathway inhibitor in the methods and compositions provided herein is not A 83-01. In some embodiments, the compositions and methods described herein exclude A 83-01. In some embodiments, the TGF-P signaling pathway inhibitor in the methods and compositions provided herein is SB 431542. In some embodiments, the TGF-P signaling pathway inhibitor is not SB 431542. In some embodiments, the compositions and methods described herein exclude SB 4 1542. In some embodiments, the TGF-P signaling pathway inhibitor in the methods and compositions provided herein is D 4476. In some embodiments, the TGF-P signaling pathway inhibitor is not D 4476. In some embodiments, the compositions and methods described herein exclude D 4476. In some embodiments, the TGF-P signaling pathway inhibitor in the methods and compositions provided herein is GW 788388. In some embodiments, the TGF-P signaling pathway inhibitor is not GW 788388. In some embodiments, the compositions and methods described herein exclude GW 788388. In some embodiments, the TGF-P signaling pathway inhibitor in the methods and compositions provided herein is LY 364947. In some embodiments, the TGF-P signaling pathway inhibitor is not LY 364947. In some embodiments, the compositions and methods described herein exclude LY 364947. In some embodiments, the TGF-P signaling pathway inhibitor in the methods and compositions provided herein is LY 580276. In some embodiments, the TGF-P signaling pathway inhibitor is not LY 580276. In some embodiments, the compositions and methods described herein exclude LY 580276. In some embodiments, the TGF-P signaling pathway inhibitor in the methods and compositions provided herein is SB 525334. In some embodiments, the TGF-P signaling pathway inhibitor is not SB 525334. In some embodiments, the compositions and methods described herein exclude SB 525334. In some embodiments, the TGF-P signaling pathway inhibitor in the methods and compositions provided herein is SB 505124. In some embodiments, the TGF-P signaling pathway inhibitor is not SB 505124. In some embodiments, the compositions and methods described herein exclude SB 505124. In some embodiments, the TGF-P signaling pathway inhibitor in the methods and compositions provided herein is SD 208. In some embodiments, the TGF-P signaling pathwayinhibitor is not SD 208. In some embodiments, the compositions and methods described herein exclude SD 208. In some embodiments, the TGF- signaling pathway inhibitor in the methods and compositions provided herein is GW 6604. In some embodiments, the TGF- signaling pathway inhibitor is not GW 6604. In some embodiments, the compositions and methods described herein exclude GW 6604. In some embodiments, the TGF-0 signaling pathway inhibitor in the methods and compositions provided herein is GW 788388. In some embodiments, the TGF- signaling pathway inhibitor in the methods and compositions provided herein is not GW 788388. In some embodiments, the compositions and methods described herein exclude GW 788388.

[0269] From the collection of compounds described above, the following can be obtained from various sources: LY-364947, SB-525334, SD-208, and SB-505124 available from Sigma, P.O. Box 14508, St. Louis, Mo., 63178-9916; 616452 and 616453 available from Calbiochem (EMD Chemicals, Inc.), 480 S. Democrat Road, Gibbstown, N.J., 08027; GW788388 and GW6604 available from GlaxoSmithKline, 980 Great West Road, Brentford, Middlesex, TW8 9GS, United Kingdom; LY580276 available from Lilly Research, Indianapolis, Ind. 46285; and SM16 available from Biogen Idee, P.O. Box 14627, 5000 Davis Drive, Research Triangle Park, N.C., 27709-4627.

[0270] In some embodiments, a medium described herein does not comprise a TGF-P signaling pathway inhibitor.WNT Signaling Pathway

[0271] Aspects of the disclosure relate to the use of activators of the WNT signaling pathway as cell differentiation factors.

[0272] In some embodiments, the WNT signaling pathway activator in the methods and compositions provided herein comprises CHIR99021. In some embodiments, the WNT signaling pathway activator in the methods and compositions provided herein comprises a derivative of CHIR99021, e.g., a salt of CHIR99021, e.g., trihydrochloride, a hydrochloride salt of CHIR99021. In some embodiments, the WNT signaling pathway activator in the methods and compositions provided herein comprises Wnt3a recombinant protein. In some embodiments, the WNT signaling pathway activator in the methods and compositions provided herein comprises a glycogen synthase kinase 3 (GSK3) inhibitor. Exemplary GSK3 inhibitors include, without limitation, 3F8, A 1070722, AR-A 014418, BIO, BlO-acetoxime, FRATide, lOZ-Hymenialdisine, Indirubin-3 'oxime, kenpaullone, L8O3, L803-mts, lithium carbonate, NSC 693868, SB 216763, SB 415286, TC-G 24, TCS 2002, TCS 21311, TWS 119, and analogs or derivatives of any of these. In certain embodiments, the methods, compositions, and kits disclosed herein exclude a WNT signaling pathway activator.

[0273] In some embodiments, a medium described herein does not comprise a Wnt signaling pathway activator.

[0274] Aspects of the disclosure relate to the use of inhibitors of the WNT signaling pathway as [> cell differentiation factors.

[0275] In some embodiments, the WNT signaling inhibitor is a tankyrase inhibitor that inhibits expression or activity of at least one tankyrase (TNKS) protein. In some embodiments, the at least one tankyrase protein is tankyrase 1 or tankyrase 2. In some embodiments, the WNT signaling inhibitor inhibits binding of a substrate to a nicotinamide subsite or an adenosine subsite, or both, of a tankyrase protein. In some embodiments, the tankyrase inhibitor is AZ 6102, JW55, MN64, IWR-1- endo, TC-E5001, WIKI4, TNKS 22, TNKS 49, 2X-121 (E7449), XAV-939 (XAV), G007-LK, NVP- TNKS656, decernotinib, (VX-509), vismodegib (GDC-0449), IM- 12, GSK429286A, INO-1001, Ofloxacin, TG101209, FG-4592, l-BET-762, LY2157299, MK- 0752, Wnt-C59 (C59), MC1568, Pacritinib (SB 1518), SB415286, Drocinostat, IWR-l-endo, Norfloxacin, SH-4-54, Nexturastat A, SB216763, UNCO 79, dephnetin, GF109203X, RepSox, Sotrastaurin, SB431542, tofacitinib (CP- 690550, Tasocitinib), AG- 14361, CI994 (tacedinaline), Ro 31-8220 mesylate, resveratrol, NVP- TNKS656, or YO-01027. In some embodiments, said tankyrase inhibitor is AZ 6102, NVP- TNKS656, or IWR-l-endo. In some embodiments, the tankyrase inhibitor is NVP-TNKS656 (NVP). In some embodiments, the tankyrase inhibitor selectively inhibits tankyrase 1 over tankyrase 2. In some embodiments, the tankyrase inhibitor selectively inhibits tankyrase 2 over tankyrase 1.

[0276] In some embodiments, a medium described herein does not comprise a Wnt signaling pathway inhibitor.Fibroblast Growth Factor (FGF) Family

[0277] Aspects of the disclosure relate to the use of growth factors from the FGF family as cell differentiation factors.

[0278] In some embodiments, the growth factor from the FGF family in the methods and compositions provided herein comprises keratinocyte growth factor (KGF). The polypeptide sequences of KGF are available to the skilled artisan. An example of human KGF amino acid sequence is provided in GenBank Accession No. AAB21431, provided as SEQ ID NO: 19).

[0279] In some embodiments, the growth factor from the FGF family comprises a polypeptide comprises an amino acid sequence that is at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 98% or at least 99% identical to the amino acid sequence of SEQ ID NO: 19, or a functional fragment thereof. In some embodiments, the growth factor from the FGF family comprises a polypeptide comprising the amino acid sequence of SEQ ID NO: 19.

[0280] Human KGF amino acid sequence (GenBank Accession AAB21431; SEQ ID NO: 19) MHKWIETWIEPTEEYRSCFHIICEVGTISEACNDMTPEQMATNVNCSSPERHTRSYDYMEGG DIRVRREFCRTQWYERIDKRGKVKGTQEMKNNYNIMEIRTVAVGIVAIKGVESEFYEAMNKE GKEYAKKECNEDCNFKEEIEENHYNTYASAKWTHNGGEMFVAENQKGIPVRGKKTKKEQK TAHFEPMAIT

[0281] In some embodiments, the growth factor from the FGF family in the methods and composition provided herein comprises FGF2. The polypeptide sequences of FGF2 are available to the skilled artisan. In some embodiments, the growth factor from the FGF family comprises a polypeptide having an amino acid sequence at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, or at least 99%, or greater identical to the human FGF2 polypeptide sequence (GenBank Accession NP—001997).

[0282] In some embodiments, the at least one growth factor from the FGF family in the methods and composition provided herein comprises FGF8B. The polypeptide sequences of FGF8B are available to the skilled artisan. In some embodiments, the growth factor from the FGF family comprises a polypeptide having an amino acid sequence at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, or at least 99%, or greater identical to the human FGF8B polypeptide sequence (GenBank Accession AAB40954).

[0283] In some embodiments, the at least one growth factor from the FGF family in the methods and composition provided herein comprises FGF10. The polypeptide sequences of FGF10 are available to the skilled artisan. In some embodiments, the growth factor from the FGF family comprises a polypeptide having an amino acid sequence at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, or at least 99%, or greater identical to the human FGF10 polypeptide sequence (GenBank Accession CAG46489).

[0284] In some embodiments, the at least one growth factor from the FGF family in the methods and composition provided herein comprises FGF21. The polypeptide sequences of FGF21 are available to the skilled artisan. In some embodiments, the growth factor from the FGF family comprises a polypeptide having an amino acid sequence at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, or at least 99%, or greater identical to the human FGF21 polypeptide sequence (GenBank Accession AAQ89444.1).

[0285] In some embodiments, a medium described herein does not comprise a FGF family protein.Sonic Hedgehog ( SHH) Signaling Pathway

[0286] Aspects of the disclosure relate to the use of SHH signaling pathway inhibitors as cell differentiation factors.

[0287] In some embodiments, the SHH signaling pathway inhibitor in the methods and composition provided herein comprises Santl. In some embodiments, the SHH signaling pathway inhibitor in the methods and composition provided herein comprises SANT2. In some embodiments, the SHH signaling pathway inhibitor in the methods and composition provided herein comprises SANT3. In some embodiments, the SHH signaling pathway inhibitor in the methods and composition provided herein comprises SANT4. In some embodiments, the SHH signaling pathway inhibitor comprises Cur61414. In some embodiments, the SHH signaling pathway inhibitor in the methods andcomposition provided herein comprises forskolin. In some embodiments, the SHH signaling pathway inhibitor in the methods and composition provided herein comprises tomatidine. In some embodiments, the SHH signaling pathway inhibitor in the methods and composition provided herein comprises AY9944. In some embodiments, the SHH signaling pathway inhibitor in the methods and composition provided herein comprises triparanol. In some embodiments, the SHH signaling pathway inhibitor in the methods and composition provided herein comprises compound A or compound B (as disclosed in U.S. Pub. No. 2004 / 0060568). In some embodiments, the SHH signaling pathway inhibitor in the methods and composition provided herein comprises a steroidal alkaloid that antagonizes hedgehog signaling (e.g., cyclopamine or a derivative thereof) as disclosed in U.S. Pub. No. 2006 / 0276391. In certain embodiments, the methods, compositions, and kits disclosed herein exclude a SHH signaling pathway inhibitor.A7w Kinase (ROCK) Signaling Pathway

[0288] Aspects of the disclosure relate to the use of ROCK signaling pathway inhibitors (ROCK inhibitors) as cell differentiation factors.

[0289] In some embodiments, the ROCK inhibitor in the methods and composition provided herein comprises Y-27632 or Thiazovivin. In some embodiments, the ROCK inhibitor in the methods and composition provided herein comprises Thiazovivin. In some embodiments, the ROCK inhibitor in the methods and composition provided herein comprises Y-27632. In some embodiments, the ROCK inhibitor in the methods and composition provided herein comprises the following compound or a derivative thereof:

[0290] In some embodiments, the ROCK inhibitor in the methods and composition provided herein comprises the following compound or a derivative thereof:

[0291] Non-limiting examples of ROCK inhibitor that can be used in the methods and compositions provided herein include Thiazovivin, Y-27632, Fasudil / HA1077, H-l 152, Ripasudil,Y39983, Wf-536, SLx-2119, Azabenzimidazole-aminofurazans, DE-104, Olefins, Isoquinolines, Indazoles, and pyridinealkene derivatives, ROKa inhibitor, XD-4000, HMN-1152, 4-(l-aminoalkyl)- N-(4-pyridyl)cyclohexane-carboxamides, Rhostatin, BA-210, BA-207, BA-215, BA-285, BA-1037, Ki-23095, VAS-012, and quinazoline.

[0292] In some embodiments, a medium described herein does not comprise a ROCK inhibitor.Retinoic Acid Signaling Pathway

[0293] Aspects of the disclosure relate to the use of modulators of retinoic acid signaling as cell differentiation factors.

[0294] In some embodiments, the modulator of retinoic acid signaling in the methods and composition provided herein comprises an activator of retinoic acid signaling. In some embodiments, the RA signaling pathway activator in the methods and composition provided herein comprises retinoic acid. In some embodiments, the RA signaling pathway activator in the methods and composition provided herein comprises a retinoic acid receptor agonist. Exemplary retinoic acid receptor agonists in the methods and composition provided herein include, without limitation, CD 1530, AM 580, TTNPB, CD 437, Ch 55, BMS 961, AC 261066, AC 55649, AM 80, BMS 753, tazarotene, adapalene, and CD 2314.

[0295] In some embodiments, the modulator of retinoic acid signaling in the methods and composition provided herein comprises an inhibitor of retinoic acid signaling. In some embodiments, the retinoic acid signaling pathway inhibitor comprises DEAB (IUPAC Name: 2-[2- (diethylamino)ethoxy]-3-prop-2-enylbenzaldehyde). In some embodiments, the retinoic acid signaling pathway inhibitor comprises an analog or derivative of DEAB.

[0296] In some embodiments, the retinoic acid signaling pathway inhibitor in the methods and composition provided herein comprises a retinoic acid receptor antagonist. In some embodiments, the retinoic acid receptor antagonist in the methods and composition provided herein comprises (E)-4-[2- (5,6-dihydro-5,5-dimethyl-8-phenyl-2-naphthalenyl)ethenyl]benzoic acid, (E)-4-[[(5,6-dihydro-5,5- dimethyl-8-phenylethynyl)-2-naphthalenyl]ethenyl]benzoic acid, (E)-4-[2-[5,6-dihydro-5,5-dimethyl- 8-(2-naphthalenyl)-2-naphthalenyl]ethenyl]-benzoic acid, and (E)-4-[2-[5,6-dihydro-5,5-dimethyl-8- (4-methoxyphenyl)-2-naphthalenyl]ethenyl]benzoic acid. In some embodiments, the retinoic acid receptor antagonist comprises BMS 195614 (CAS#253310-42-8), ER 50891 (CAS#187400-85-7), BMS 493 (CAS#170355-78-9), CD 2665 (CAS#170355-78-9), LE 135 (CAS#155877-83-l), BMS 453 (CAS #166977-43-1), or MM 11253 (CAS#345952-44-5).

[0297] In certain embodiments, the methods, compositions, and kits disclosed herein exclude a modulator of retinoic acid signaling. In certain embodiments, the methods, compositions, and kits disclosed herein exclude a retinoic acid signaling pathway activator. In certain embodiments, the methods, compositions, and kits disclosed herein exclude a retinoic acid signaling pathway inhibitor.

[0298] In some embodiments, a medium described herein does not comprise retinoic acid.Protein Kinase C Activator

[0299] Aspects of the disclosure relate to the use of protein kinase C activators as cell differentiation factors. Protein kinase C is one of the largest families of protein kinase enzymes and is composed of a variety of isoforms. Conventional isoforms include a, pi, 011, y; novel isoforms include 5, e, r], 0; and atypical isoforms include and t / Z. PKC enzymes are primarily cytosolic but translocate to the membrane when activated. In the cytoplasm, PKC is phosphorylated by other kinases or autophosphorylated. In order to be activated, some PKC isoforms (e.g., PKC-e) require a molecule to bind to the diacylglycerol (“DAG”) binding site or the phosphatidylserine (“PS”) binding site. Others are able to be activated without any secondary binding messengers at all. PKC activators that bind to the DAG site include, but are not limited to, bryostatin, picologues, phorbol esters, aplysiatoxin, and gnidimacrin. PKC activators that bind to the PS site include, but are not limited to, polyunsaturated fatty acids and their derivatives. It is contemplated that any protein kinase C activator that is capable, either alone or in combination with one or more other cell differentiation factors, of inducing the differentiation of at least one insulin-producing, endocrine cell or precursor thereof into a SC- cell can be used in the methods, compositions, and kits described herein.

[0300] In some embodiments, any of the PKC activators disclosed herein is a PKC activator capable of binding to a DAG binding site on a PKC. In some embodiments, the PKC activator is capable of binding to a Cl domain of a PKC. In some embodiments, the PKC activator is a benzolactam-derivative. In some embodiments, the benzolactam-derivative is ((2S,5S)-(E,E)-8-(5-(4- (Trifluoromethyl)phenyr)-2,4-pentadienoylamino)benzolactam), which may be referred to herein as TPPB or TPB. In some embodiments, contacting a population of cells with a benzolactam-derivative PKC activator (e.g., TPPB) increases cell yield as compared to a population of cells not treated with the benzolactam-derivative PKC activator. In some embodiments, the PKC activator is a phorbol ester. In some embodiments, the phorbol ester is Phorbol 12, 13 -dibutyrate, which may be referred to herein as PDBU or PdbU. In some embodiments, contacting a population of cells with a benzolactam-derivative PKC activator (e.g., TPPB) increases cell yield as compared to a population of cells treated with a phorbol ester PKC activator (e.g., PdbU). In some embodiments, the PKC activator in the methods and composition provided herein comprises PdbU. In some embodiments, the PKC activator in the methods and composition provided herein comprises TPB. In some embodiments, the PKC activator in the methods and composition provided herein comprises cyclopropanated polyunsaturated fatty acids, cyclopropanated monounsaturated fatty acids, cyclopropanated polyunsaturated fatty alcohols, cyclopropanated monounsaturated fatty alcohols, cyclopropanated polyunsaturated fatty acid esters, cyclopropanated monounsaturated fatty acid esters, cyclopropanated polyunsaturated fatty acid sulfates, cyclopropanated monounsaturated fatty acid sulfates, cyclopropanated polyunsaturated fatty acid phosphates, cyclopropanated monounsaturated fatty acid phosphates, macrocyclic lactones, DAG derivatives, isoprenoids, octylindolactam V,gnidimacrin, iripallidal, ingenol, napthalenesulfonamides, diacylglycerol kinase inhibitors, fibroblast growth factor 18 (FGF-18), insulin growth factor, hormones, and growth factor activators, as described in WIPO Pub. No. WO / 2013 / 071282. In some embodiments, the bryostain comprises bryostatin-1, bryostatin-2, bryostatin-3, bryostatin-4, bryostatin-5, bryostatin-6, bryostatin-7, bryostatin-8, bryostatin-9, bryostatin-10, bryostatin-11, bryostatin-12, bryostatin-13, bryostatin-14, bryostatin-15, bryostatin-16, bryostatin-17, or bryostatin-18. In certain embodiments, the methods, compositions, and kits disclosed herein exclude a protein kinase C activator.

[0301] In some embodiments, a medium described herein does not comprise a protein kinase C activator. y-Secretase Inhibitors

[0302] Aspects of the disclosure relate to the use of y-secretase inhibitors as cell differentiation factors.

[0303] In some embodiments, the y-secretase inhibitor in the methods and composition provided herein comprises XXI. In some embodiments, the y-secretase inhibitor in the methods and composition provided herein comprises DAPT. Additional exemplary y-secretase inhibitors in the methods and composition provided herein include, without limitation, the y-secretase inhibitors described in U.S. Pat. Nos. 7,049,296, 8,481,499, 8,501,813, and WIPO Pub. No. WO / 2013 / 052700. In certain embodiments, the methods, compositions, and kits disclosed herein exclude a y-secretase inhibitor.

[0304] In some embodiments, a medium described herein does not comprise a y-secretase inhibitor.Thyroid Hormone Signaling Pathway Activators

[0305] Aspects of the disclosure relate to the use of thyroid hormone signaling pathway activators as cell differentiation factors.

[0306] In some embodiments, the thyroid hormone signaling pathway activator in the methods and composition provided herein comprises triiodothyronine (T3). In some embodiments, the thyroid hormone signaling pathway activator in the methods and composition provided herein comprises GC- 1. In some embodiments, the thyroid hormone signaling pathway activator in the methods and composition provided herein comprises an analog or derivative of T3 or GC-1. Exemplary analogs of T3 in the methods and composition provided herein include, but are not limited to, selective and non- selective thyromimetics, TRp selective agonist-GC-1, GC-24,4-Hydroxy-PCB 106, MB07811, MB07344,3,5-diiodothyropropionic acid (DITPA); the selective TR- agonist GC-1; 3- lodothyronamine (T(l)AM) and 3,3',5-triiodothyroacetic acid (Triac) (bioactive metabolites of the hormone thyroxine (T(4)); KB-2115 and KB-141; thyronamines; SKF L-94901; DIBIT; 3'-AC-T2; tetraiodothyroacetic acid (Tetrac) and triiodothyroacetic acid (Triac) (via oxidative deamination anddecarboxylation of thyroxine [T4] and triiodothyronine [T3] alanine chain), 3,3',5'-triiodothyronine (rT3) (via T4 and T3 deiodination), 3, 3 '-diiodo thyronine (3,3'-T2) and 3, 5 -diiodothyronine (T2) (via T4, T3, and rT3 deiodination), and 3-iodothyronamine (T1AM) and thyronamine (TOAM) (via T4 and T3 deiodination and amino acid decarboxylation), as well as for TH structural analogs, such as 3,5,3'- triiodothyropropionic acid (Triprop), 3,5-dibromo-3-pyridazinone-l-thyronine (L-940901), N-[3,5- dimethyl-4-(4'-hydroxy-3'-isopropylphenoxy)-phenyl]-oxamic acid (CGS 23425), 3,5-dimethyl-4- [(4'-hydroxy-3'-isopropylbenzyl)-phenoxy]acetic acid (GC-1), 3,5-dichloro-4-[(4-hydroxy-3- isopropylphenoxy)phenyl] acetic acid (KB-141), and 3,5-diiodothyropropionic acid (DITPA).

[0307] In some embodiments, the thyroid hormone signaling pathway activator in the methods and composition provided herein comprises a prodrug or prohormone of T3, such as T4 thyroid hormone (e.g., thyroxine or L-3,5,3',5'-tetraiodothyronine).

[0308] In some embodiments, the thyroid hormone signaling pathway activator in the methods and composition provided herein is an iodothyronine composition described in U.S. Pat. No. 7,163,918.

[0309] In some embodiments, a medium described herein does not comprise a thyroid hormone.Epidermal Growth Factor ( EGF) Family

[0310] Aspects of the disclosure relate to the use of growth factors from the EGF family as cell differentiation factors.

[0311] In some embodiments, the at least one growth factor from the EGF family in the methods and composition provided herein comprises betacellulin. An example of human betacellulin amino acid sequence is provided in GenBank Accession No.: AAB25452.1 (SEQ ID NO: 20). In some embodiments, the growth factor from the EGF family used in the compositions and methods described herein comprises an amino acid sequence that is at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 98% or at least 99% identical to the amino acid sequence of SEQ ID NO: 20, or a functional fragment thereof. In some embodiments, the growth factor from the EGF family used in the compositions and methods described herein comprises the amino acid sequence of SEQ ID NO: 20.

[0312] Human betacellulin amino acid sequence (GenBank: AAB25452.1; SEQ ID NO: 20) MDRAARCSGASSLPLLLALALGLVILHCVVADGNSTRSPETNGLLCGDPEENCAATTTQSKR KGHFSRCPKQYKHYCIKGRCRFVVAEQTPSCVCDEGYIGARCERVDLFYLRGDRGQILVICLI AVMVVFIILVIGVCTCCHPLRKRRKRKKKEEEMETLGKDITPINEDIEETN

[0313] In some embodiments, at least one growth factor from the EGF family in the methods and composition provided herein comprises EGF. Epidermal growth factor (EGF) is a 53 amino acid cytokine which is proteolytically cleaved from a large integral membrane protein precursor. In some embodiments, the growth factor from the EGF family in the methods and composition provided herein comprises a variant EGF polypeptide, for example an isolated epidermal growth factor polypeptidehaving at least 90% amino acid identity to the human wild-type EGF polypeptide sequence, as disclosed in U.S. Pat. No. 7,084,246. In some embodiments, the growth factor from the EGF family in the methods and composition provided herein comprises an engineered EGF mutant that binds to and agonizes the EGF receptor, as is disclosed in U.S. Pat. No. 8,247,531. Non-limiting examples of amino acid sequences of growth factors from the EGF family that may be used in the compositions and methods described are provided below. In some embodiments, the growth factor from the EGF family used in the compositions and methods described herein comprises an amino acid sequence that is at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 98% or at least 99% identical to the amino acid sequence of any one of SEQ ID NOs: 21-32, or a functional fragment thereof. In some embodiments, the growth factor from the EGF family used in the compositions and methods described herein comprises the amino acid sequence of any one of SEQ ID NO: 21-32.

[0314] Homo sapiens epidermal growth factor (WT) (Genbank: AAS83395.1; SEQ ID NO: 21) NSDSECPLSHDGYCLHDGVCMYIEALDKYACNCVVGYIGERCQYRDLKWWELR

[0315] Homo sapiens epidermal growth factor (mutant) (SEQ ID NO: 22) NSDSECPLSHDGYCLHGGVCMYIKAVDRYACNCVVGYIGERCQYRDLTWWGPR

[0316] Homo sapiens epidermal growth factor (mutant) (SEQ ID NO: 23)NSDSECPLSHDGYCLHDGVCMYIKALDKYACNCVVGYTGERCQYRDLRWWGRR

[0317] Homo sapiens epidermal growth factor (mutant) (SEQ ID NO: 24)NSNSECPLSHDGYCLHDGVCRYIEALDRYACNCVVGYIGERCQYGDLRWWGRR

[0318] Homo sapiens epidermal growth factor (mutant) (SEQ ID NO: 25)NSDSGCPLSHSGYCLHDGVCMYIKALDRYACNCVVGYAGERCQYRDLRWWARR

[0319] Homo sapiens epidermal growth factor (mutant) (SEQ ID NO: 26)TRGSECPLSHDGYCLHDGVCMYIGALDRYACNCVVGYTGERCQYRDLRWWARR

[0320] Homo sapiens epidermal growth factor (mutant) (SEQ ID NO: 27)NSDFGCPLSYDGYCLHDGVCMYIKALDKYACNCVVGYAGERCQYRDLRWWGRR

[0321] Homo sapiens epidermal growth factor (mutant) (SEQ ID NO: 28)SRGSKCPPSHDGYCLHDGVCMYIEALDRYACNCVVGYAGERCQYRDLRWWARR

[0322] Homo sapiens epidermal growth factor (mutant) (SEQ ID NO: 29)SSGSECPSSHDGYCLHDGACMYIEALDRYACNCAVGYAGERCQYRDLRWWGRR

[0323] Homo sapiens epidermal growth factor (mutant) (SEQ ID NO: 30)SSNSECPPSHDGYCLHDGVCMYIEALDRYACNCVVGYAGERCQYRDLRWWARR

[0324] Homo sapiens epidermal growth factor (mutant) (SEQ ID NO: 31)NSYSECPPSYDGYCLHDGVCRYIEALDSYACNCVVGYAGERCQYRDLRWWGRR

[0325] Homo sapiens epidermal growth factor (mutant) (SEQ ID NO: 32)SSGSECPLSHDGYCLNDGVCMYIEALDKYACNCVVGYVGERCQYRDLRWWARR

[0326] In some embodiments, the at least one growth factor from the EGF family in the methods and composition provided herein is replaced with an agent that activates a signaling pathway in the EGF family. In some embodiments, the growth factor from the EGF family in the methods and composition provided herein comprises a compound that mimics EGF. In certain embodiments, the methods, compositions, and kits disclosed herein exclude a growth factor from the EGF family.

[0327] In some embodiments, a medium described herein does not comprise a EGF family growth factor.Epigenetic Modifying Compounds

[0328] Aspects of the disclosure relate to the use of epigenetic modifying compound as cell differentiation factors.

[0329] The term “epigenetic modifying compound” can refer to a chemical compound that can make epigenetic changes genes, i.e., change gene expression(s) without changing DNA sequences. Epigenetic changes can help determine whether genes are turned on or off and can influence the production of proteins in certain cells, e.g., beta-cells. Epigenetic modifications, such as DNA methylation and histone modification, can alter DNA accessibility and chromatin structure, thereby regulating patterns of gene expression. These processes can be cruci l to normal development and differentiation of distinct cell lineages in the adult organism. They can be modified by exogenous influences, and, as such, can contribute to or be the result of environmental alterations of phenotype or pathophenotype. Importantly, epigenetic modification can have a crucial role in the regulation of pluripotency genes, which become inactivated during differentiation. Non-limiting exemplary epigenetic modifying compound include a DNA methylation inhibitor, a histone acetyltransferase inhibitor, a histone deacetylase inhibitor, a histone methyltransferase inhibitor, a bromodomain inhibitor, or any combination thereof.

[0330] In an embodiment, the histone methyltransferase inhibitor is an inhibitor of enhancer of zeste homolog 2 (EZH2). EZH2 is a histone-lysine N-methyltransferase enzyme. Non-limiting examples of an EZH2 inhibitor that can be used in the methods provided herein include 3- deazaneplanocin A (DZNep), EPZ6438, EPZ005687 (an S-adenosylmethionine (SAM) competitive inhibitor), Ell, GSK126, and UNC1999. DZNep can inhibit the hydrolysis of S-adenosyl-L- homocysteine (SAH), which is a product-based inhibitor of all protein methyltransferases, leading to increased cellular concentrations of SAH which in turn inhibits EZH2. DZNep may not be specific to EZH2 and can also inhibit other DNA methyltransferases. GSK126 is a SAM-competitive EZH2 inhibitor that has 150-fold selectivity over EZH1. UNC1999 is an analogue of GSK126, and it is less selective than its counterpart GSK126.

[0331] In an embodiment, the histone methyltransferase inhibitor is DZNep. In an embodiment, the HD AC inhibitor is a class I HDAC inhibitor, a class II HD AC inhibitor, or a combination thereof. In an embodiment, the HDAC inhibitor is KD5170 (mercaptoketone-based HDAC inhibitor),MC1568 (class Ila HDAC inhibitor), TMP195 (class Ila HDAC inhibitor), or any combination thereof. In some embodiments, HDAC inhibitor is vorinostat, romidepsin (Istodax), chidamide, panobinostat (farydak), belinostat (PXD101), panobinostat (LBH589), valproic acid, mocetinostat (MGCD0103), abexinostat (PCI-24781), entinostat (MS-275), SB939, resminostat (4SC-201), givinostat (ITF2357), quisinostat (JNJ-26481585), HBI-8000, (a benzamide HDI), kevetrin, CUDC- 101, AR-42, CHR-2845, CHR-3996, 4SC-202, CG200745, ACY-1215, ME-344, sulforaphane, or any variant thereof.

[0332] In some embodiments, a medium described herein does not comprise an epigenetic modifying compound.Protein Kinase Inhibitors

[0333] Aspects of the disclosure relate to the use of protein kinase inhibitors as cell differentiation factors.

[0334] In some embodiments, the protein kinase inhibitor in the methods and composition provided herein comprises staurosporine. In some embodiments, the protein kinase inhibitor in the methods and composition provided herein comprises an analog of staurosporine. Exemplary analogs of staurosporine in the methods and composition provided herein include, without limitation, Ro-31 - 8220, a bisindolylmaleimide (Bis) compound, 10'-{5"-[(methoxycarbonyl)amino]-2"-methyl}- phenylaminocarbonylstaurosporine, a staralog (see, e.g., Lopez et al., “Staurosporine-derived inhibitors broaden the scope of analog-sensitive kinase technology”, J. Am. Chem. Soc. 2013;135(48): 18153-18159), and, cgp41251.

[0335] In some embodiments, the protein kinase inhibitor in the methods and composition provided herein is an inhibitor of PKC . In some embodiments, the protein kinase inhibitor in the methods and composition provided herein is an inhibitor of PKC0 with the following structure or a derivative, analogue or variant of the compound as follows:

[0336] In some embodiments, the inhibitor of PKCf> is a GSK-2 compound with the following structure or a derivative, analogue or variant of the compound as follows:

[0337] In some embodiments, the inhibitor of PKC in the methods and composition provided herein is a bisindolylmaleimide. Exemplary bisindolylmaleimides include, without limitation, bisindolylmaleimide I, bisindolylmaleimide II, bisindolylmaleimide Ill, hydrochloride, or a derivative, analogue or variant thereof.

[0338] In some embodiments, the PKC inhibitor in the methods and composition provided herein is a pseudohypericin, or a derivative, analogue, or variant thereof. In some embodiments, the PKC inhibitor in the methods and composition provided herein is indorublin-3-monoximc, 5-Iodo or a derivative, analogue or variant thereof. In certain embodiments, the methods, compositions, and kits disclosed herein exclude a protein kinase inhibitor.

[0339] In some embodiments, a medium described herein does not comprise a protein kinase inhibitor, or more specifically, does not comprise staurosporine.Acetyl CoA-related metabolite

[0340] In some embodiments, a composition (e.g., medium) of the disclosure comprises an acetyl CoA-related metabolite. Metabolism of acetyl-coenzyme A (acetyl-CoA) can confer numerous metabolic functions, including energy production, lipid synthesis, and protein acetylation.

[0341] Exemplary acetyl CoA-related metabolites include, but arc not limited to acetate, pyruvate, ketogenic amino acids, valine, leucine, isoleucine, phenylalanine, tyrosine, lysine, tryptophan, fatty acids, Co A, Isovaleryl-CoA, and -hydroxybutyrate. In some embodiments, the acetyl CoA-related metabolite is acetate. In some embodiments, a composition of the disclosure contains two or more different acetyl CoA related metabolites, for example, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more different acetyl CoA-related metabolites. In some embodiments, the acetyl CoA-related metabolite is acetate.

[0342] In some embodiments, a medium described herein does not include an acetyl CoA-related metabolite (e.g., does not include acetate).Histone deacetylase inhibitor (HDACi)

[0343] In some embodiments, a composition (e.g., medium) of the disclosure comprises a histone deacetylase inhibitor (HDACi). Histone deacetylase inhibitors (HDACi) are a class ofcompounds that increase acetylation of lysine residues on histone proteins as well as other, nonhistone, proteins by inhibiting the activity of HD AC enzymes.

[0344] Exemplary histone deacetylase inhibitors (HDACi) include, but are not limited to P-Hydroxybutyrate, butyric acid, class I HDACi, class IIA HDACi, class IIB HDACi, class III HDACi, class IV HDACi, HDAC-1, HD AC-2, HD AC-3, HDAC-4, HDAC-5, HDAC-6, HD AC-7, HDAC-8, HDAC-9, HDAC-10, HDAC-11, sirtuins, SIRT1, SIRT2, SIRT3, SIRT4, SIRT5, SIRT6, SIRT7, Vorinostat (suberoylanilide hydroxamic acid, SAHA, MK0683), Entinostat (MS-275, SNDX-275), Panobinostat (LBH589, NVP-LBH589), Trichostatin A (TSA), Mocetinostat (MGCD0103, MG0103), GSK3117391 (GSK3117391A, HDAC-IN-3), BRD3308, BRD33O8, Tubastatin A TFA (Tubastatin A trifluoroacetate salt), Tubastatin A, SIS17, NKL 22, BML-210 (CAY10433), TC-H 106, SR-4370, Belinostat (PXD101, NSC726630, PX-105684), Romidepsin (FK228, Depsipeptide, FR 901228, NSC 630176), MC1568, Givinostat (ITF2357), Dacinostat (LAQ824, NVP-LAQ824), CUDC-101, Quisinostat (JNJ-26481585), Pracinostat (SB939), PCI-34051, Droxinostat (NS 41080), Abexinostat (PCI-24781), Abexinostat (PCI-24781, CRA-024781), RGFP966, AR-42 (HD AC-42), Ricolinostat (ACY-1215, Rocilinostat), Valproic acid sodium salt (Sodium valproate), Tacedinaline (CI994, PD- 123654, GOE-5549, Acetyldinaline), Fimepinostat (CUDC-907), Sodium butyrate (NaB), Curcumin, Diferuloylmethane, M344, Tubacin, RG2833 (RGFP109), RG2833 (RGFP109), Resminostat (RAS2410), Divalproex Sodium, Scriptaid (GCK 1026), Sodium Phenylbutyrate, Sinapinic acid (Sinapic acid), TMP269, Santacruzamate A (CAY10683), TMP195 (TFMO 2), Valproic acid (VPA), UF010, Tasquinimod (ABR-215050), SKLB-23bb, Isoguanosine, Iforaphane, BRD73954, Citarinostat (ACY-241, HDAC-IN-2), Suberohydroxamic acid, plitomicin, HPOB, LMK-235, Biphenyl-4- sulfonyl chloride (p-Phenylbenzenesulfonyl, 4-henylbenzenesulfonyl, p-Biphenylsulfonyl), Nexturastat A, TH34, Tucidinostat (Chidamide, HBI-8000, CS-055), (-)-Parthenolide, WT161, CAY10603, CAY10603, ACY-738, RaddeaninA, Tinostamustine(EDO-SlOl), Domatinostat (4SC- 202), and BG45.

[0345] In some embodiments, the HDACi is -Hydroxybutyrate. P-Hydroxybutyric acid is a ketone body that, along with butyric acid, is an agonist of hydroxycarboxylic acid receptor 2 (HCA2), a Gi / o-coupled GPCR. In some embodiments, an HDACi inhibitor is an agonist of hydroxycarboxylic acid receptor 2.

[0346] In some embodiments, a medium described herein does not comprise anHDACi (e.g., does not include P-Hydroxybutyrate).Redox homeostasis regulator

[0347] In some embodiments, a composition (e.g., medium) of the disclosure comprises a redoxhomeostasis regulator.

[0348] Exemplary redox homeostasis regulators include, but are not limited to taurine, respiratory chain regulators, free radical scavengers, regulators of mitochondrial protein synthesis, allium sulphurcompounds, anthocyanins, beta-carotene, catechins, copper, cryptoxanthins, flavonoids, indoles, isoflavonoids, lignans, lutein, lycopene, alpha lipoic acid, ellagic acid, manganese, polyphenols, selenium, glutathione, vitamin A, vitamin C, vitamin E, zinc, superoxide disutases, GSHPx, Prx-I, catalase, and co-enzyme Q10.

[0349] In some embodiments, the redox homeostasis regulator is taurine.

[0350] In some embodiments, a medium described herein does not comprise a redox homeostasis regulator.

[0351] Taurine is a non-proteinogenic B-aminosulfonic acid that can be derived from methionine and cysteine metabolism. In some embodiments, taurine can inhibit ROS generation within the respiratory chain.

[0352] In some embodiments, a medium described herein does not comprise a redox homeostasis regulator (e.g., does not include taurine).One carbon metabolism pathway intermediate

[0353] In some embodiments, a composition (e.g., medium) of the disclosure comprises a one carbon metabolism pathway intermediate. One-carbon metabolism mediated by folate cofactors, supports multiple physiological processes including amino acid homeostasis (methionine, glycine and serine), biosynthesis of nucleotides (purines, thymidine), epigenetic maintenance, and redox defense.

[0354] Exemplary one carbon metabolism pathway intermediates include, but are not limited to formate, tetrahydrofolate (THF), 10-formylTHF; 5,10-meTHF; 5,10-meTHF; and 10-formylTHF.

[0355] In some embodiments, a medium described herein does not comprise a one carbon metabolism pathway intermediate (e.g., does not include formate).Glutamine

[0356] In some embodiments, a composition (e.g., medium) of the disclosure comprises glutamine. Glutamine (Gin or Q) is an alpha-amino acid. Glutamine can be an essential amino acid within in vitro cell cultures. Glutamine supports the growth of cells, including cells that have high energy demands and synthesize large amounts of proteins and nucleic acids. It is an alternative energy source for rapidly dividing cells and cells that use glucose inefficiently.

[0357] In some embodiments, compositions and methods of the disclosure utilize glutamine in a form with increased bioavailability. Because of its chemical instability and importance for cell growth and function, it is important that delivery of L-glutamine be tailored to each unique cell culture process. Glutamine (e.g., L-glutamine) in a free form can be unstable at physiological pH in liquid media, breaking down to ammonium and pyroglutamate at rates that make it a problem in many cell culture and biomanufacturing applications. Therefore, many cell culture media contain stabilized forms of glutamine, including dipeptide forms, such as alanyl-l-glutamine and glycyl-l-glutamine. However, these more stable forms of L-glutamine can also have limited bioavailability, for example,due to a requirement for processing by enzymes, such as cell surface peptidases. Thus in some embodiments, compositions and methods of the disclosure utilize glutamine in a form with increased bioavailability, such as a free glutamine form, such as a non-dipeptide form, a non-alanine-glutamine dipeptide form (e.g., a non-alanyl-l-glutamine form), a non-glycine-glutamine dipeptide form (e.g., a non-glycyl-l-glutamine form), a form that in which glutamine is not conjugated to another amino acid or stabilizing moiety, a monomeric form, a free form, or a combination thereof. In some embodiments, glutamine is provided as a protein hydrolysate.

[0358] In some embodiments, a basal media contains glutamine. In some embodiments, glutamine in a form as disclosed herein is added to a media that already contains glutamine. In some embodiments, glutamine in a form as disclosed herein is added to a basal media that contains no glutamine or only low levels of glutamine to increase the bioavailability of glutamine.

[0359] In some embodiments, a medium described herein does not comprise glutamine.Glutamate

[0360] In some embodiments, a composition (e.g., medium) of the disclosure comprises glutamate (e.g., L-glutamate). Glutamate can be converted into, for example, g-amino butyric acid (GABA), ornithine, 2-oxoglutarate, glucose or glutathione. Glutamate and metabolites generated therefrom can contribute to, for example, redox homeostasis, cell signaling, nitrogen assimilation, amine catabolism, amino acid biosynthesis, nucleoside biosynthesis, and cofactor production.

[0361] In some embodiments, contacting cells with glutamate can improve production of SC- cells in vitro, for example, providing higher cell yields and recoveries, increased numbers and relative percentages of SC-3 cells, enhanced stability and shelf-life of SC-3 cells, SC-islet clusters with advantageous characteristics such as reduced size and increased uniformity, improved function of the SC- cells in vitro, improved cell viability, improved cell function, reduced immunogenicity after transplantation, or a combination thereof, e.g., relative to a composition that lacks glutamate, or contains a lower concentration of glutamate.

[0362] In some embodiments, a medium described herein does not comprise glutamate.Vitamins

[0363] In some embodiments, a composition (e.g., medium) of the disclosure comprises one or more vitamins.

[0364] Exemplary vitamins include, but are not limited to ascorbic acid, biotin, vitamin B 1 (thiamine), vitamin B2 (riboflavin), vitamin B3 (niacin), vitamin B6 (pyridoxine) and vitamin B 12 (cyanocobalamin). In some embodiments the vitamin modulates fatty acid synthesis. In some embodiments the vitamin modulates branched-chain amino acid metabolism. In some embodiments the vitamin modulates or participates as a co-factor in the TCA cycle, e.g., as a cofactor for pyruvate carboxylase. In some embodiments, the vitamin is biotin. In some embodiments, a composition of thedisclosure contains two or more different vitamins, for example, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more different vitamins.

[0365] In some embodiments, a medium described herein does not comprise a vitamin.'Water-soluble synthetic polymer

[0366] Water-soluble polymer described herein can refer to any polymer that has hydrophilic property and is soluble in aqueous solution at room temperature. The water-soluble polymer can be either naturally occurring or synthetic. In some embodiments, a water-soluble polymer is an albumin protein (e.g., human serum albumin or bovine serum albumin). In some embodiments, the water- soluble polymer is a water-soluble synthetic polymer. Water-soluble synthetic polymers described herein can refer to any synth...

Claims

CLAIMSWhat is claimed is:

1. A method, comprising treating an in vitro population of cells with arginine, wherein the population of cells is in an assay medium and comprises a plurality of islet cells2. The method of claim 1, wherein the assay medium comprises any one or more of: bovine serum albumin, human serum albumin, sodium chloride, potassium chloride, calcium chloride, magnesium sulfate, sodium phosphate, potassium phosphate, sodium bicarbonate, and / or HEPES.

3. The method of claim 1 or 2, wherein the assay medium comprises Krebs Buffer.

4. The method of any one of claims 1-3, wherein the assay medium has a pH of 5.5-8.5, 6-8, 6.5-7.5, 6.8-7.2, 6.9-7.4, 6.6-7.1, or 6.9-7.1.

5. The method of any one of claims 1-4, wherein the assay medium does not comprise any glucose.

6. The method of any one of claims 1-5, wherein the assay medium comprises glucose.

7. The method of any one of claims 1-6, wherein the method comprises treating the population of cells with 0.1-100 mM, 0.1-50 mM, 0.1-20 mM, 0.1-15 mM, 1-100 mM, 1-50 mM, 1-20 mM, 1-12 mM, 5-25 mM, 5-15 mM, 5-12 mM, 8-12 mM, or 9-1 1 mM of arginine.

8. The method of any one of claims 1-7, wherein the plurality of islet cells comprises insulinexpressing cells.

9. The method of any one of claims 1-8, wherein the plurality of islet cells comprises islet cells that are derived from stem cells in vitro.

10. The method of any one of claims 1-9, wherein the population of cells comprises cells expressing ISLE11. The method of claim 9 or claim 10, wherein the plurality of islet cells comprises cells expressing ISL1 and NKX6.1.

12. The method of any one of claims 1-11, wherein 15-90%, 15-80%, 15-70%, 15-60%, 15-50%, 15- 40%, 15-30%, 20-80%, 20-60%, 20-50%, 30-90%, 30-70%, 30-50% of the cells in the population of cells are ISLl-positive, NKX6.1 -positive cells.

13. The method of any one of claims 1-12, wherein the method further comprises the step of collecting the assay medium after a period of time incubating with the arginine, such as 2-6 hours, 4-6 hours, 0.25-6 hours, 0.25-4 hours, 0.25-2 hours, 0.25-1 hours, 0.5-1.5 hours, or 0.75-1.25 hours, and assessing a level of insulin in the assay medium.

14. The method of claim 13, wherein the insulin level is assessed by an enzyme-linked immunosorbent assay (ELISA).

15. The method of claim 13, wherein the insulin levels are assessed by a no-wash immunoassay, such as ALPHALISA®.

16. The method of any one of claims 13-15, further comprising the step of comparing the level of insulin in the assay medium to the levels of insulin in a second assay medium, wherein the second assay media is taken from a culture comprising a control population of cells substantially similar to the population of cells treated with the arginine, and wherein the control population of cells in the second assay medium were not treated with arginine.

17. The method of claim 16, wherein the average insulin concentration in the assay medium is divided by the average insulin concentration from the second assay medium to yield a stimulation index.

18. The method of any one of claims 1-17, wherein prior to treating the population of cells with arginine, the population of cells had been cultured in a culture medium for 1-15 days, 1-10 days, 1-8 days, 1-7 days, 1-5 days, 1-3 days, 3-10 days, 3-8 days, 4-7 days, or 5-7 days.

19. The method of claim 18, wherein the culture medium comprises one or more of: human serum albumin, ascorbic acid, a BMP inhibitor (e.g.., LDN-193189), a TGF-beta receptor inhibitor (e.g., ALK5 Inhibitor II), a thyroid hormone signaling pathway activator (e.g., GC-1), a ROCK inhibitor (e.g., Thiazovivin), a protein kinase inhibitor (e.g., Staurosporine), or a histone methyltransferase inhibitor (e.g., DZNEP).

20. The method of claim 18 or 19, wherein prior to the population of cells being cultured in the culture media, the population of cells had been cryopreserved.

21. The method of any one of claims 1-20, wherein the assay medium comprises potassium.

22. The method of claim 21, wherein the concentration of potassium in the assay medium is 0.1-50 mM, 0.1-40 mM, 0.1-30 mM, 0.1-20 mM, 0.1-10 mM, 0.1-7 mM, 30-50 mM, 20-40 mM, 10-25 mM, 2-10 mM, 1-8 mM, 3-7 mM, 4-8 mM, 5-12 mM, or 3-9 mM.

23. The composition of claim 22, wherein the concentration of potassium in the assay medium is 2-10 mM, 3-7 mM or 5-7 mM.

24. The method of any one of claims 1-23, wherein prior to the population cells being treated with the arginine, the cells were in a preservation media (e.g., Hypothermosol).

25. The method of claim 24, wherein the preservation medium was removed (e.g., at least 50%, 60%, 70%, 80%, 90%, 95%, or 100% or between 50-100%, 50-95%, 50-90%, 70-95%, 80-95%, 70-80%, 85-95%, or 90-100% of the preservation medium is removed) prior to treating the cells with arginine.

26. The method of claim 25, wherein the cells were washed with a solution (e.g., a buffer solution or DMEM) following removal of the preservation medium.

27. The method of claim 25 or 26, wherein following removal of the preservation medium (and optionally washing the cells), a culture media was added to the cells.

28. The method of claim 27, wherein the culture medium comprises HEPES, sodium pyruvate, and / or glucose.

29. The method of claim 27, wherein the culture medium is DMEM medium.

30. The method of claim 29, wherein the DMEM medium is DMEM F12 medium.

31. The method of any one of claims 27-30, wherein the culture medium comprises human serum albumin (HSA) or bovine serum albumin (BSA).

32. The method of claim 31, wherein the culture media comprises 0.01-3%, 0.01-2%, 0.1-2%, 0.1- 1.5%, 0.5-1.5%, 0.8-1.2% or 0.9-1.1% HSA or BSA.

33. The method of any one of claims 27-32, wherein the cells were cultured with the culture medium for 0.25-48 hours, 0.25-24 hours, 0.25-12 hours, 0.25-6 hours, 0.25-3 hours, 0.25-1.5 hours, 0.75-2 hours, or 0.75-1.25 hours.

34. The method of any one of claims 27-33, wherein the culture medium was removed and the assay media was added to the population of cells.

35. The method of any one of claims 1-34, wherein the arginine is arginine-HCl.

36. The method of any one of claims 1-35, wherein the assay media comprises 0.1-3 million, 0.1-2 million, 0.1 -1.5 million, 0.5- 1.5 million, 0.8- 1.2 million, 0.9-2 million, or 0.9- 1.1 million cells / ml.

37. The method of any one of claims 1-36, wherein the population of cells comprises cell clusters.

38. The method of any one of claims 1-37, wherein: a) 5-10%, 10-50%, 10-40%, 10-30%, 10-20%, 20-50%, 20-40%, or 20-30% of cells in the population of cells express glucagon, or b) not more than 10%, not more than 20%, not more than 30%, not more than 40%, or not more than 50% of the cells in the population of cells express glucagon.

39. The method of any one of claims 1-37, wherein: a) 5-10%, 10-50%, 10-40%, 10-30%, 10-20%, 20-50%, 20-40%, or 20-30% of the cells in the population of cells are NKX6.1 -negative, ISLl-positive cells, or b) not more than 10%, not more than 20%, not more than 30%, not more than 40%, or not more than 50% of the cells in the population of cells are NKX6.1 -negative, ISLl-positive cells.

40. The method of any one of claims 1-39, wherein the population of cells is not subjected to perifusion when treated with the arginine.

41. The method of any one of claims 1-40, wherein the population of cells are in static culture.

42. The method of any one of claims 1-41, wherein: a) at least 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 60%, 70%, or 80% of the cells in the population of cells are insulin-positive cells, or b) 10-90%, 10-80%, 10-60%, 10-40%, 10-30%, 20-70%, 20-50%, 20-30%, 30-70%, 30-50%, or 40- 65% of the cells in the population of cells are insulin-positive cells.

43. The method of any one of claims 1-42, wherein the population of cells is incubated with the arginine for 2-6 hours, 4-6 hours, 0.25-6 hours, 0.25-4 hours, 0.25-2 hours, 0.25-1 hours, 0.5-1.5 hours, or 0.75-1.25 hours.

44. The method of claim 43, wherein the population of cells is incubated with the arginine at 35-39 °C, 36-38 °C, 36.5-37.5 °C, or 36.8-37.2 °C.

45. A composition comprising an in vitro population of islet cells and a medium comprising 1-5 mM, 5-30 mM, 5-25 mM, 5-15 mM, 5-12 mM, 8-12 mM, or 9-11 mM of arginine.

46. The composition of claim 45, wherein the medium further comprises one or more of: bovine serum albumin, sodium chloride, potassium chloride, calcium chloride, magnesium sulfate, sodium phosphate, potassium phosphate, sodium bicarbonate, and / or HEPES.

47. The composition of claim 45 or 46, wherein the medium comprises Krebs Buffer.

48. The composition of any one of claims 45-47, wherein the medium has a pH of 5.5-8.5, 6-8, 6.5- 7.5, 6.8-7.2, 6.9-7.4, 6.6-7.1, or 6.9-7.1.

49. The composition of any one of claims 45-48, wherein the medium does not comprise any glucose.

50. The composition of any one of claims 45-48, wherein the medium comprises glucose (e.g., 2.0 g / L glucose).

51. The composition of any one of claims 45-50, wherein the population of islet cells comprises cells expressing ISLE52. The composition of any one of claims 45-51, wherein the population of islet cells comprises cells expressing ISL1 and NKX6.1.

53. The composition of any one of claims 45-52, wherein the arginine is arginine-HCL54. The composition of any one of claims 45-53, wherein the medium comprises 0.1-3 million, 0.1-2 million, 0.1 -1.5 million, 0.5- 1.5 million, 0.8- 1.2 million, 0.9-2 million, or 0.9- 1.1 million cells / ml.

55. The composition of any one of claims 45-54, wherein the population of cells comprises cell clusters.

56. The composition of any one of claims 45-55, wherein: a) 5-10%, 10-50%, 10-40%, 10-30%, 10-20%, 20-50%, 20-40% of the cells in the population of cells express glucagon, or b) 20-30% or not more than 10%, not more than 20%, not more than 30%, not more than 40%, or not more than 50% of the cells in the population of cells express glucagon.

57. The composition of any one of claims 45-56, wherein: a) 5-10%, 10-50%, 10-40%, 10-30%, 10-20%, 20-50%, 20-40%, or 20-30% of the cells in the population of cells are NKX6.1 -negative, ISLl-positive cells, or b) not more than 10%, not more than 20%, not more than 30%, not more than 40%, or not more than 50% of the cells in the population of cells are NKX6.1 -negative, ISLl-positive cells.

58. The composition of any one of claims 45-57, wherein: a) at least 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 60%, 70%, or 80% of the cells in the population of cells are insulin-positive cells, or b) between 10-90%, 10-80%, 10-60%, 10-40%, 10-30%, 20-70%, 20-50%, 20-30%, 30-70%, 30-50%, or 40-65% of the cells in the population of cells are insulin-positive cells.

59. The composition of any one of claims 45-58, wherein the population of islet cells comprises insulin-expressing cells.

60. The composition of any one of claims 45-59, wherein the population of islet cells comprises islet cells that are derived from stem cells in vitro.

61. The composition of any one of claims 45-60, wherein 15-90%, 15-80%, 15-70%, 15-60%, 15- 50%, 15-40%, 15-30%, 20-80%, 20-60%, 20-50%, 30-90%, 30-70%, 30-50% of the cells in the population of cells are ISLl-positive, NKX6.1 -positive cells.

62. The composition of any one of claims 45-61, wherein the composition is in a sterile container.

63. The composition of any one of claims 45-62, wherein the composition comprises potassium.

64. The composition of claim 63, wherein the concentration of potassium in the composition is 0.1-50 mM, 0.1-40 mM, 0.1-30 mM, 0.1-20 mM, 0.1-10 mM, 0.1-7 mM, 30-50 mM, 20-40 mM, 10-25 mM, 2-10 mM, 1-8 mM, 3-7 mM, 4-8 mM, 5-12 mM, or 3-9 mM.

65. The composition of claim 63, wherein the concentration of potassium in the composition is 2-10 mM, 3-7 mM or 5-7 mM.

66. The composition of any one of claims 45-65, wherein the composition is not in a perifusion apparatus or perifusion chamber.

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