Adipocyte maturation

Abstract

The present invention relates to pluripotent stem cell comprising an expression construct for expression of a CEBPα protein and an expression construct for expression of an ADIG protein. The invention further provides for methods of producing adipocytes comprising the pluripotent stem cells and for foodstuff comprising the adipocytes or pluripotent stem cells.

Description

[0001] Adipocyte maturation

[0002] Field of the invention

[0003] The present invention relates to modified pluripotent cells and to methods of differentiating said cell into adipocytes.

[0004] Background of the invention

[0005] According to the most recent United Nations estimations, the current world population is 7.9 billion in July 2022 [https: / / www.worldometers.info / es / poblacion-mundial / #ref-1] and it is expected to reach 10 billion around the year 2056. This increase will be heterogeneously distributed around the globe, with nine countries covering half the projected growth of the global population in the next 30 years, including India, Nigeria, Pakistan, Egypt, and the United States of America. Population and economic growth are major drivers of increased meat consumption. According to the United Nations Food and Agricultural Organization (FAO, https: / / www.oecd- ilibrary.org / agriculture-and-food / oecd-fao-agricultural-outlook-2022-2031_f1 b0b29c-en), an estimated growth of 15% in global meat consumption is projected by 2031 . On the other hand, the correlation between income growth and higher meat consumption is clearly demonstrable at lower income rates but once consumers reach an adequate standard of living, they become more sensitive to environmental, ethical, and animal welfare and health concerns.

[0006] For this reason, there is a growing interest in finding alternative protein sources which ideally will be sustainable and will contain the nutrients normally provided by meat in the human diet. Cultured meat arises as another alternative to traditional animal agriculture that aims to produce the skeletal muscle and adipose tissues that normally comprise animal meats, except using in vitro tissue and biological engineering techniques. Despite efforts to develop robust protocols for scalable generation of animal cell types from easily accessible and renewable sources, the differentiation of animal (pluripotent) stem cells into specific cell types often remains cumbersome, lengthy, and difficult to reproduce and / or has not been established yet.

[0007] Additionally, to date, plant-based and cultured meat alternatives have focused mostly on mimicking the muscle component of meat. However, fat is also a crucial component of meat, contributing to sensory / flavor, textural attributes and palatability (Zhang, Shu, et al. "DNA polymorphisms in bovine fatty acid synthase are associated with beef fatty acid composition 1." Animal genetics 39.1 (2008): 62-70.).

[0008] Modified cell lines that can be differentiated to adipocytes have been previously described by Tontonoz et al (Cell, Vol. 79, 1147-1156 - 30 -12- 1994) wherein a retroviral expression system is used to co-express a combination of two transcription factors into a fibroblast cell line upon which spontaneous differentiation to adipocytes was observed. US2012219530 describes lentivirally transduced human pluripotent cells that have a differentiation efficiency of about 20%. However these protocols have several limitation including heterogeneous adipocyte degree of maturation, lack of scalable process, are not food safe and have long cultivation times of up to 28 days. Accordingly there remains a need in the art for the production and culturing of mature adipocytes that are suitable for human consumption and that can be produced in a scalable and cost effective manner.

[0009] Summary of the invention

[0010] In a first aspect, the invention relates to a pluripotent stem cell comprising: i) an expression construct for expression of a transcriptional regulator protein inserted into a first genetic safe harbour site; ii) an expression construct for expression of a CEBPa protein, wherein the coding sequence for the CEBPa protein is operably linked to an inducible promoter; and, iii) an expression construct for expression of an ADIG protein, wherein the coding sequence for the ADIG protein is operably linked to an inducible promoter; wherein the expression constructs of ii) and iii) are inserted into at least one further genetic safe harbour site that is not the first genetic safe harbour site, and wherein the inducible promotor is regulated by the transcriptional regulator protein.

[0011] In certain embodiments of the invention, the expression constructs of ii) and iii) are both inserted into a second genetic safe harbour site that is different from the first genetic safe harbour site. Preferably, said first and further genomic safe harbour sites are selected from any two of the hROSA26 locus, the AAVS1 locus, the CLYBL gene or the CCR5 gene, preferably wherein the genetic safe harbour site are hROSA26 locus and the AAVS1 locus.

[0012] In certain embodiments of the invention, the cell is selected from the group consisting of embryonic stem cells, induced pluripotent stem cells, embryonic cell lines, and somatic cell lines.

[0013] In certain embodiments of the invention, the pluripotent stem cells are of a livestock or poultry species. Preferably, the livestock species is bovine or porcine, preferably bovine. The pluripotent stem cells may be of the family Bovidae, for example of the subfamily Bovinae, such as of the genus Bos, such as the species B. taurus. The pluripotent stem cells may be of the family Suidae, such as of the genus Sus, such as the species S. domesticus.

[0014] In certain embodiments of the invention, the expression construct that is inserted into the second genetic safe harbour site encodes a CEBPa protein, one or more linkers and an ADIG protein, preferably wherein the linkers is P2A, more preferably wherein the linkers comprise the amino acid sequence set out in SEQ ID NO: 6, optionally encoded a nucleic acid sequence comprising the sequence set out in SEQ ID NO: 5. Preferably, the construct encodes an amino acid sequence comprising the amino acid sequence set out in SEQ ID NO: 8, optionally encoded by a nucleic acid sequence comprising the sequence set out in SEQ ID NO: 7.

[0015] In certain embodiments of the invention, the activity of the transcriptional regulator protein is controlled by an exogenously supplied substance derivative. Preferably, the transcriptional regulator protein is selected from the group consisting of: tetracycline responsive transcriptional activator protein (rtTa), Tetracycline repressor (TetR), VgEcR synthetic receptor or a hybrid transcriptional regulator protein comprising a DNA binding domain from the yeast GAL4 protein, a truncated ligand binding domain from the human progesterone receptor and an activation domain from the human NF-kB, preferably the transcriptional regulator protein is rtTA.

[0016] In certain embodiments, the inducible promoter includes a Tet Responsive Element (TRE).

[0017] In certain embodiments, the inducible promotor is a tetON promotor.

[0018] In a second aspect the invention provides for a method for the production of adipocytes, preferably white adipocytes, comprising a ) culturing the pluripotent stem cell according to any one of the preceding claims in a proliferation medium: followed by b) inducing adipocyte differentiation by adding the exogenous substance as described herein.

[0019] In certain embodiments, the proliferation and / or differentiation medium does not comprise or does not substantially comprise at least one compound selected from the group of insulin, dexamethasone, rosiglitazone and isobutylmethylxanthine. In certain preferred embodiments, the proliferation and / or differentiation medium does not comprise or does not substantially comprise insulin. A proliferation and / or differentiation medium which does not comprise or does not substantially comprise insulin may optionally comprise IGF-1 and / or LR3.

[0020] In certain embodiments, the differentiation phase of the method as described herein is at most 10 days, at most 9 days, 8 days, 7 days, 6 days, 5 days, 4 days, 3 days or 2 days .

[0021] In certain embodiments, the produced adipocytes are for human and non-human dietary consumption.

[0022] In a further aspect, the invention provides for a use of a pluripotent stem cell as described herein or use of the method for producing a adipocyte as described herein for tissue engineering, optionally for the production of cultured meat.

[0023] In yet a further aspect, the invention provides for a food product comprising the pluripotent stem cell as described herein or the adipocytes obtained by the method as described herein. In certain embodiments, the food product is cultured meat.

[0024] Description of the drawings

[0025] Figure 1 shows the full CEBPa-P2A-ADIG_Opti-ox-aavs1 plasmid map in panel A) and the CEBPa-P2A-ADIG construct in panel b).

[0026] Figure 2 Immunofluorescent images (20X) of bEplSCs Opti-Ox CEBPa -ADIG and bEplSCs Opti- Ox CEBPa -PPARg (control) A) Cells stained in dapi_blue, Phalloidin_green, Lipitox_red (merged images). B) Cells stained with Phalloidin_green and Lipidtox_red. From day 4 on, induction of transcription of the corresponding combination of transcription factors; bEplSCs Opti-Ox CEBPa - ADIG shows a remarkable higher production of Lipid droplets compared to control cells. As detected by the lipid dye lipidtox in red.

[0027] Figure 3 Immunofluorescent images (20X) of pEplSCs Opti-Ox CEBPa -ADIG and pEplSCs Opti- Ox CEBPa -PPARg (control) A) Cells stained in dapi_blue, Phalloidin_green, Lipitox_red (merged images). B) Cells stained with Phalloidin_green and Lipidtox_red. From day 2 on, induction of transcription of the corresponding combination of transcription factors; pEplSCs Opti-Ox CEBPa - ADIG shows a remarkable higher production of Lipid droplets compared to control cells. As detected by the lipid dye lipidtox in red.

[0028] Figure 4: Light microscopy images (10x) of bEplSCs Opti-Ox CEBPa -PPARy (control) (P) (upper row)_ Day2, Day4 and Day 5 differentiation (P-D2, P-D4.P-D5) and of bEplSCs Opti-Ox CEBPoc - ADIG (lower row) Day2, Day4 and Day 5 differentiation (A-D2, A-D4.A-D5). As depicted in the images at day 6 of induction a formation of big lipid droplets structures is observed in of bEplSCs Opti-Ox CEBPoc -ADIG, such structures was never observed in control cells even after 8 days of differentiation.

[0029] Figure 5: Two Principal component analysis (PCA) gene expression data of differentiation towards adipocytes (right-above direction: Fat tissue) of A: bEplSCs Opti-Ox CEBPoc -ADIG (represented in the figure by AO, A2, A4, A6 and A8_A:ADIG-cebpa_0,2,4,6 or 8: Days after induction) or P: bEplSCs Opti-Ox CEBPoc -PPARy (control) (represented in the figure by P0, P2, P4, P6 and P at_0,2,4,6 or 8: Days after induction). The numbers after A and P indicate the number of days with induction.

[0030] Description of the sequences

[0031] Description of the invention

[0032] Definitions

[0033] Unless defined otherwise, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. One skilled in the art will recognize many methods and materials similar or equivalent to those described herein, which could be used in the practice of the present invention. Indeed, the present invention is in no way limited to the method.

[0034] In this document and in its claims, the verb "to comprise" and its conjugations is used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. In addition, reference to an element by the indefinite article "a" or "an" does not exclude the possibility that more than one of the elements is present, unless the context clearly requires that there be one and only one of the elements. The indefinite article "a" or "an" thus usually means "at least one". As used herein, the term "and / or" indicates that one or more of the stated cases may occur, alone or in combination with at least one of the stated cases, up to with all of the stated cases.

[0035] As used herein, with "At least" a particular value means that particular value or more. For example, "at least 2" is understood to be the same as "2 or more" i.e., 2, 3, 4, 5, 6, 7, 8, 9, 10, 1 1 , 12, 13, 14, 15, ... ,etc. The word “about” or “approximately” when used in association with a numerical value (e.g. about 10) preferably means that the value may be the given value (of 10) more or less 0.1 % of the value.

[0036] The term "heterologous" when used with respect to a nucleic acid (DNA or RNA) or protein refers to a nucleic acid or protein that does not occur naturally as part of the organism, cell, genome or DNA or RNA sequence in which it is present, or that is found in a cell or location or locations in the genome or DNA or RNA sequence that differ from that in which it is found in nature. Heterologous nucleic acids or proteins are not endogenous to the cell into which it is introduced, but has been obtained from another cell or synthetically or recombinantly produced. Generally, though not necessarily, such nucleic acids encode proteins that are not normally produced by the cell in which the DNA is transcribed or expressed. Similarly exogenous RNA encodes for proteins not normally expressed in the cell in which the exogenous RNA is present. Heterologous nucleic acids and proteins may also be referred to as foreign nucleic acids or proteins. Any nucleic acid or protein that one of skill in the art would recognize as heterologous or foreign to the cell in which it is expressed is herein encompassed by the term heterologous nucleic acid or protein. The term heterologous also applies to non-natural combinations of nucleic acid or amino acid sequences, i.e. combinations where at least two of the combined sequences are foreign with respect to each other.

[0037] The terms "expression vector" or “expression construct" refer to nucleotide sequences that are capable of effecting expression of one or more genes in host cells or host organisms compatible with such sequences. These expression vectors typically include at least suitable transcription regulatory sequences and optionally, 3' transcription termination signals. Additional factors necessary or helpful in effecting expression may also be present, such as expression enhancer elements

[0038] As used herein, the term “operably linked” refers to a linkage of polynucleotide elements in a functional relationship. A nucleic acid is “operably linked” when it is placed into a functional relationship with another nucleic acid sequence. For instance, a transcription regulatory sequence is operably linked to a coding sequence if it affects the transcription of the coding sequence. Operably linked means that the DNA sequences being linked are typically contiguous and, where necessary to join two protein encoding regions, contiguous and in reading frame, inducible promoter

[0039] As used herein, the term "promoter" refers to a nucleic acid fragment that functions to control the transcription of one or more coding sequences, and is located upstream with respect to the direction of transcription of the transcription initiation site of the coding sequence, and is structurally identified by the presence of a binding site for DNA-dependent RNA polymerase, transcription initiation sites and any other DNA sequences, including, but not limited to transcription factor binding sites, repressor and activator protein binding sites, and any other sequences of nucleotides known to one of skill in the art to act directly or indirectly to regulate the amount of transcription from the promoter. A "constitutive" promoter is a promoter that is active in most tissues under most physiological and developmental conditions. An "inducible" promoter is a promoter that is physiologically or developmentally regulated, e.g. by the application of a chemical inducer. In the case of the present invention, the control is effected by the transcriptional regulator protein. Any reference to nucleotide or amino acid sequences accessible in public sequence databases herein refers to the version of the sequence entry as available on the filing date of this document.

[0040] All patent and literature references cited in the present specification are hereby incorporated by reference in their entirety.

[0041] The inventors have surprisingly found that the time period required for differentiation of pluripotent cells into mature adipocytes can dramatically be reduced by using a modified pluripotent stem cells that comprise an expression construct for expression of a CEBPa protein and an expression construct for expression of an ADIG protein. As shown in the examples described herein, by using these modified pluripotent cell lines, full differentiation into mature adipocytes can be achieved in less than 10 days. Apart from significantly reducing the culturing time and the associated cost involved, the use of the herein describe pluripotent cells also provides for a more reliable and scalable production of mature adipocyte as compared to what has been previously described.

[0042] Accordingly, in a first aspect the invention relates to a pluripotent stem cell comprising: i) an expression construct for expression of a transcriptional regulator protein inserted into a first genetic safe harbour site; ii) an expression construct for expression of a CEBPa protein, wherein the coding sequence for the CEBPa protein is operably linked to an inducible promoter; and, iii) an expression construct for expression of an ADIG protein, wherein the coding sequence for the ADIG protein is operably linked to an inducible promoter; wherein the expression constructs of ii) and iii) are inserted into at least one further genetic safe harbour site that is not the first genetic safe harbour site, and wherein the inducible promotor is regulated by the transcriptional regulator protein.

[0043] CCAAT / enhancer-binding protein alpha (CEBPa) is a protein encoded by the CEBPA gene in humans. The protein encoded by this intronless gene is a bZIP transcription factor which can bind as a homodimer to certain promoters and gene enhancers. It can also form heterodimers with the related proteins CEBP-beta and CEBP-gamma, as well as distinct transcription factors such as c-Jun. The encoded protein is a key regulator of adipogenesis (the process of forming new fat cells) and the accumulation of lipids in those cells, as well as in the metabolism of glucose and lipids in the liver. In certain embodiments, the coding sequence for the CEBPa may comprise the sequence of SEQ ID NO: 1 . The CEBPa protein may comprise the amino acid sequence set out in SEQ ID NO: 2.

[0044] Adipogenin (ADIG) is an adipocyte-enriched transmembrane protein encoded by the ADIG gene. It is also known as Small Adipocyte Factor 1 (SMAF1) and is known to play a role in stimulating adipocyte differentiation, development and proliferation. ADIG is a transcription factors also known as lipid-producing protein that has been shown to have an effect in the upregulation of PPARg expression. In certain embodiments, the coding sequence for the ADIG has the sequence of SEQ ID NO: 3. The CEBPa protein may comprise the amino acid sequence set out in SEQ ID NO: 4. A pluripotent stem cell of the invention may comprise: i) an expression construct for expression of a transcriptional regulator protein inserted into a first genetic safe harbour site; ii) an expression construct for expression of a CEBPa protein, wherein the coding sequence for the CEBPa protein is operably linked to an inducible promoter; iii) an expression construct for expression of an ADIG protein, wherein the coding sequence for the ADIG protein is operably linked to an inducible promoter; and, iv) an expression construct for expression of an PPARy protein, wherein the coding sequence for the PPARy protein is operably linked to an inducible promoter; wherein the expression constructs of ii), iii) and iv) are inserted into at least one further genetic safe harbour site that is not the first genetic safe harbour site, and wherein the inducible promotor is regulated by the transcriptional regulator protein.

[0045] Peroxisome proliferator- activated receptor gamma (PPAR-y) is a type II nuclear receptor functioning as a transcription factor that in humans is encoded by the PPARG gene. PPARG is mainly present in adipose tissue, colon and macrophages. Two isoforms of PPARG are detected in the human and in the mouse: PPAR-y1 (found in nearly all tissues except muscle) and PPAR-y2 (mostly found in adipose tissue and the intestine). In certain embodiments, the coding sequence of PPAR-y of the invention encodes PPAR-y2. PPARG regulates fatty acid storage and glucose metabolism. The genes activated by PPARG stimulate lipid uptake and adipogenesis by fat cells. PPARG knockout mice are devoid of adipose tissue, establishing PPARG as a master regulator of adipocyte differentiation.

[0046] In certain embodiments, the nucleic acid molecules encoding the proteins according to the invention are codon-optimized for expression in mammalian cells. Methods of codon-optimization are known and have been described previously (e.g. WO 96 / 09378 for mammalian cells). A sequence is considered codon-optimized if at least one non-preferred codon as compared to a wildtype sequence is replaced by a codon that is more preferred. Herein, a non-preferred codon is a codon that is used less frequently in an organism than another codon coding for the same amino acid, and a codon that is more preferred is a codon that is used more frequently in an organism than a non-preferred codon. The frequency of codon usage for a specific organism can be found in codon frequency tables, such as in http: / / www.kazusa.or.jp / codon. Preferably more than one nonpreferred codon, preferably most or all non-preferred codons, are replaced by codons that are more preferred. Preferably the most frequently used codons in an organism are used in a codon- optimized sequence. Replacement by preferred codons generally leads to higher expression.

[0047] A transcriptional regulator protein is a protein that bind to DNA, preferably sequence- specifically to a DNA site located in or near a promoter, and either facilitating the binding of the transcription machinery to the promoter, and thus transcription of the DNA sequence (a transcriptional activator) or blocks this process (a transcriptional repressor). Such entities are also known as transcription factors. The DNA sequence that a transcriptional regulator protein binds to is called a transcription factor-binding site or response element, and these are found in or nearthe promoter of the regulated DNA sequence.

[0048] Transcriptional activator proteins bind to a response element and promote gene expression. Such proteins are preferred in the methods of the present invention for controlling inducible cassette expression.

[0049] A genetic safe harbour (GSH) site is a locus within the genome wherein a gene or other genetic material may be inserted without any deleterious effects on the cell or on the inserted genetic material. Most beneficial is a GSH site in which expression of the inserted gene sequence is not perturbed by any read-through expression from neighboring genes and expression of the inducible cassette minimizes interference with the endogenous transcription program. More formal criteria have been proposed that assist in the determination of whether a particular locus is a GSH site in future (Papapetrou et al, 201 1 , Nature Biotechnology, 29(1), 73-8. doi: 1 0. 1 038 / nbt. 1 71 7.) These criteria include a site that is (i) 50 kb or more from the 5’ end of any gene, (ii) 300 kb or more from any gene related to cancer, (iii) 300 kb or more from any microRNA(miRNA), (iv) located outside a transcription unit and (v) located outside ultra-conserved regions (UCR). It may not be necessary to satisfy all of these proposed criteria, since GSH already identified do not fulfil all of the criteria. It is thought that a suitable GSH will satisfy at least 2, 3, 4 or all of these criteria.

[0050] In certain embodiments of the invention, the first and further genomic safe harbour sites are selected from any two of the hROSA26 locus, the AAVS1 locus, the CLYBL gene or the CCR5 gene. In certain embodiments the first and further genomic safe harbour sites are located on chr1 : 152,360,840-152,360,859, chr1 : 175,942,362 -175,942,381 , chr1 :231 ,999,396-231 ,999,415, chr2: 45,708,354 - 45, 708, 373; chr8: 68,720,172 - 68,720,191 of the human genome.

[0051] In certain embodiments of the invention, the first and further genomic safe harbour sites are selected from any two of the bovine safe harbour sites ROSA26, AAVS1 , the CLYBL gene and the CCR5 gene.

[0052] Preferably, the genetic safe harbour sites are hROSA26 locus and the AAVS1 locus.

[0053] In certain embodiments of the invention, the expression construct for expression of CEBPa protein as described herein and the expression construct for expression of a ADIG protein as described herein are both inserted into a second genetic safe harbour site that is different from the first genetic safe harbour site. In certain embodiments, the expression construct that is inserted into the second genetic safe harbour site is capable of expressing both the CEBPa protein and the ADIG protein simultaneously.

[0054] As used herein, the term "pluripotent stem cells" includes embryonic stem cells, embryo- derived stem cells, induced pluripotent stem cells and somatic cells, regardless of the method by which the pluripotent stem cells are derived. Accordingly, in certain embodiments the pluripotent stem cell is selected from the group consisting of embryonic stem cells, induced pluripotent stem cells, embryonic cell lines, and somatic cell lines. In certain embodiments, the pluripotent stem cells are epiblast-derived stem cells (EpiSC). In certain embodiments epiblast-derived stem cells (EpiSC) are preferred. In certain embodiments, pluripotent stem cells express one or more markers selected from the group consisting of: OCT-4, Sox2, Klf4, c-MYC, Nanog, Lin28, alkaline phosphatase, SSEA-3, SSEA-4, TRA-1-60, and TRA-1-81 . Exemplary pluripotent stem cells can be generated using, methods known in the art. "Induced pluripotent stem cells" (iPS cells or iPSC) can be produced by protein transduction of reprogramming factors in a somatic cell.

[0055] The pluripotent stem cell according to the invention can be from any species. Embryonic stem cells have been successfully derived in, for example, mice, multiple species of non-human primates, and humans, and embryonic stem-like cells have been generated from numerous additional species. Thus, one of skill in the art can generate embryonic stem cells and embryo- derived stem cells from any species, including but not limited to, human, non-human primates, rodents (mice, rats), ungulates (cows, sheep, etc.), dogs (domestic and wild dogs), cats (domestic and wild cats such as lions, tigers, cheetahs), rabbits, hamsters, gerbils, squirrel, guinea pig, goats, elephants, panda (including giant panda), pigs, raccoon, horse, zebra, marine mammals (dolphin, whales, etc.) and the like.

[0056] Similarly, iPS cells can be from any species. These iPS cells have been successfully generated using mouse and human cells. Furthermore, iPS cells have been successfully generated using embryonic, fetal, newborn, and adult tissue. Accordingly, one can readily generate iPS cells using a donor cell from any species. Thus, one can generate iPS cells from any species, including but not limited to, human, non-human primates, rodents (mice, rats), ungulates (cows, sheep, pigs etc.), dogs (domestic and wild dogs), cats (domestic and wild cats such as lions, tigers, cheetahs), rabbits, hamsters, goats, elephants, panda (including giant panda), pigs, raccoon, horse, zebra, marine mammals (dolphin, whales, etc.) and the like.

[0057] In certain embodiments, the pluripotent stem cell according to the invention, or for use in the invention is an animal cell. In certain embodiments the pluripotent stem cell according to the invention, or for use in the invention if from an edible animal species.

[0058] Preferably, the pluripotent stem cell according to the invention, or for use in the invention is from a livestock or poultry animal. Livestock species include but are not limited to domestic cattle, pigs, sheep, goats, lamb, camels, water buffalo and rabbits.

[0059] Preferably, the pluripotent stem cell according to the invention, or for use in the invention is a bovine or porcine pluripotent stem cell, most preferably, a bovine pluripotent stem cell. In certain embodiments, the stem cell according to the invention is a bovine epiblast stem cell (bEpiSCs) or a porcine epiblast stem cell (pEpiSCs).

[0060] Poultry species include but are not limited to domestic chicken, turkeys, ducks, geese and pigeons. In certain embodiments, the cells originate from common game species such as wild deer, gallinaceous fowl, waterfowl and hare. Preferably a pluripotent stem cell according to the invention, or for use in the invention, is not a human cell.

[0061] Transcriptional repressor proteins bind to a response element and prevent gene expression.

[0062] Transcriptional regulator proteins may be activated or deactivated by a number of mechanisms including binding of a substance, interaction with other transcription factors (e.g., homo- or hetero-dimerization) or coregulatory proteins, phosphorylation, and / or methylation. The transcriptional regulator may be controlled by activation or deactivation.

[0063] If the transcriptional regulator protein is a transcriptional activator protein, it is preferred that the transcriptional activator protein requires activation. This activation may be through any suitable means, but it is preferred that the transcriptional regulator protein is activated through the addition to the cell of an exogenous substance. The supply of an exogenous substance to the cell can be controlled, and thus the activation of the transcriptional regulator protein can be controlled. Alternatively, an exogenous substance can be supplied in order to deactivate a transcriptional regulator protein, and then supply withdrawn in orderto activate the transcriptional regulator protein.

[0064] If the transcriptional regulator protein is a transcriptional repressor protein, it is preferred that the transcriptional repressor protein requires deactivation. Thus, a substance is supplied to prevent the transcriptional repressor protein repressing transcription, and thus transcription is permitted.

[0065] Any suitable transcriptional regulator protein may be used, preferably one that is activatable or deactivatable. It is preferred that an exogenous substance may be supplied to control the transcriptional regulator protein. Such transcriptional regulator proteins are also called inducible transcriptional regulator proteins.

[0066] Accordingly, in certain embodiments, the pluripotent stem cell according to the invention is controlled by an exogenously supplied substance.

[0067] In certain embodiments, the exogenously supplied substance is selected from the group consisting of peptides (such as described by Klotzsche, et al; Journal of Biological Chemistry 280.26 (2005): 24591-24599 or Schlicht et al.; Applied and environmental microbiology 72.8 (2006): 5637- 5642) or the inducers described in Goeke, et al. Journal of molecular biology 416.1 (2012): 33-45; incorporated herein by reference), an aptamer (such as the RNA aptamer described in Hunsicker et al. “Chemistry & biology 16.2 (2009): 173-180; incorporated herein by reference), tetracycline, and anhydroteracyclin or a derivative thereof. Preferably, the exogenously supplied substance is doxycycline.

[0068] In certain embodiments, the transcriptional regulator protein as described herein is selected from the group consisting of tetracycline responsive transcriptional activator protein (rtTa), Tetracycline repressor (TetR), VgEcR synthetic receptor or a hybrid transcriptional regulator protein comprising a DNA binding domain from the yeast GAL4 protein, a truncated ligand binding domain from the human progesterone receptor or an activation domain from the human NF-kB.

[0069] Tetracycline-Controlled Transcriptional Activation is a method of inducible gene expression well known in the art where transcription is reversibly turned on or off in the presence of the antibiotic tetracycline or one of its derivatives (e.g. doxycycline which is more stable). In this system, the transcriptional activator protein is tetracycline - responsive transcriptional activator protein (rtTa) ora derivative thereof. The rtTA protein is able to bind to DNA at specific TetO operator sequences. Several repeats of such TetO sequences are placed upstream of a minimal promoter (such as the CMV promoter), which together form a tetracycline response element (TRE). There are two forms of this system, depending on whether the addition of tetracycline or a derivative activates (Tet-On) or deactivates (Tet-Off) the rTA protein.

[0070] In a Tet-Off system, tetracycline or a derivative thereof binds rTA and deactivates the rTA, rendering it incapable of binding to TRE sequences, thereby preventing transcription of TRE- controlled genes. The Tet-On system is composed of two components; (1) the constitutively expressed tetracycline - responsive transcriptional activator protein (rtTa) and the rtTa sensitive inducible promoter (Tet Responsive Element, TRE). This may be bound by tetracycline or its more stable derivatives, including doxycycline (dox), resulting in activation of rtTa, allowing it to bind to TRE sequences and inducing expression of TRE-controlled genes. In preferred embodiments of the invention the transcriptional regulator protein is rtTA.

[0071] If the transcriptional regulator protein is rtTA, then the inducible promoter inserted into the at least one further GSH hat is not the first GSH site includes the tetracycline response element (TRE). Thus, in certain embodiments the inducible promoter includes a Tet Responsive Element (TRE).

[0072] In some embodiments, where the transcriptional regulator protein is rtTA and includes TRE the exogenously supplied substance is the antibiotic tetracycline or one of its derivatives.

[0073] In certain embodiments of the invention, the expression construct that is inserted into the second genetic safe harbour site is a fusion protein that encodes both the CEBPa protein and the ADIG protein as described herein. In certain embodiments, expression construct that is inserted into the second genetic safe harbour site encodes a CEBPa protein, a linker and a ADIG protein, in preferred embodiments, the construct comprises or consists of the coding sequence set out in SED NO: 5, encoding the linker sequence comprising or consisting of the amino acid sequence set out in SEQ ID NO: 6.

[0074] In certain embodiments, the linker sequence may be a cleavable linker. That is, the linker sequence may comprise a sequence of amino acids which is capable of being cleaved. For example, the linker sequence may comprise a sequence capable of acting as a substrate for an enzyme capable of cleaving peptide bonds--i.e. a cleavage site. Many such cleavage sites are known to and can be employed by the person skilled in the art of molecular biology. In some embodiments, the cleavable linker may comprise an autocleavage site. Autocleavage sites are automatically cleaved without the need for treatment with enzymes. For example the family of 2A self-cleaving peptides, or 2A peptides have been described, which includes 2A peptides P2A, E2A, F2A, and T2A. F2A is derived from foot-and-mouth disease virus; E2A is derived from equine rhinitis A virus; P2A is derived from porcine teschovirus-1 2A; T2A is derived from thosea asigna virus 2A. In certain embodiments, the cleavable linker is thus selected from the group consisting of P2A, E2A, F2A, and T2A.

[0075] In some preferred embodiments the expression construct comprises a Picornavirus 2A (P2A) linker. Preferably, the expression construct comprises a linker comprising or consisting of the sequence of SEQ ID NO: 5, encoding the linker sequence comprising or consisting of the amino acid sequence set out in SEQ ID NO: 6. In certain embodiments, the expression construct that is inserted into the second genetic safe harbour site encoding a CEBPa protein, a linker and an ADIG protein as described herein comprises or consists of the sequence of SEQ ID NO: 7 encoding a sequence comprising or consisting of the amino acid sequence set out in SEQ ID NO: 8.

[0076] In certain embodiments, the inducible promotor that is operably linked to the CEBPa protein is different than the inducible promotor that is linked to the ADIG protein. In certain embodiments, the inducible promotor that is operably linked to the CEBPa protein is the same at the inducible promotor that is linked to the ADIG protein. Inducible promotors are well-known in the art, examples include but are not limited to CMV, CAG, CBh, PGK, SV40, Ferritin heavy or light chains, etc.

[0077] In certain embodiments, the inducible promotor used in the present invention a tetOn promotor. Preferably a 3rdgeneration TetOn promotor.

[0078] Culturing methods

[0079] The inventors of present application have surprisingly found that the differentiation time needed to obtain adipocytes can dramatically be reduced by using the pluripotent cells as described herein. Accordingly, in a further aspect the invention relates to a method for the production of adipocytes, comprising a ) culturing the pluripotent stem cell as described herein in a proliferation medium: followed by b) inducing adipocyte differentiation by adding an exogenous substance as described herein.

[0080] In certain embodiments, the method of the invention is an ex vivo method.

[0081] In certain embodiments, the method is for the production of mature adipocytes. Mature adipocytes are herein defined as adipocytes which show lipid accumulation and / or express detectable levels of PPARy FABP4, PLIN1 and adiponectin.

[0082] In certain embodiments, the method of the invention relates to a method for production of white adipocytes. In certain embodiments, the proliferation and / or differentiation medium does not comprise or does not substantially comprise at least one compound selected from the group of insulin dexamethasone, rosiglitazone and isobutylmethylxanthine. In preferred embodiments, the proliferation and / or differentiation medium does not comprise or does not substantially comprise insulin.

[0083] A proliferation and / or differentiation medium which does not comprise or does not substantially comprise insulin may optionally comprise IGF-1 and / or LR3.

[0084] A proliferation and / or differentiation medium may comprise up to about 20 pg / mL insulin, for example up to about 10 pg / mL insulin, such as about 5 pg / mL insulin, for example 1 pg / mL insulin”.

[0085] The inventors have surprisingly found that use of the pluripotent cell as described herein obviates the need to culture the cells with a commitment induction step. Normally, when adipocytes are cultured several culturing phases can be distinguished. The commitment or determination phase involves the formation of preadipocytes, which have lost the potential to differentiate into other cell types. Differentiation of preadipocytes to adipocytes is promoted by a highly regulated network of transcription factors chronologically expressed to promote adipocyte morphologic and biochemical features such as insulin responsiveness, lipid transport and synthesis, and secretory capacity. The differentiation phase is also divided into four stages: growth arrest, mitotic clonal expansion, early differentiation, and terminal differentiation. Use of the pluripotent stem cells as described herein in the method as described herein allows the differentiation of the pluripotent stem cells to mature adipocytes without needing a commitment induction step and without forcing overexpression. The ability of the cells to skip this commitment induction step is particularly advantageous as it reduces the amount of compounds and small molecules that are normally required to be present in the differentiation medium. It was for example found that the cells as described herein are able to differentiate without the presence of BMP-4, Activin A and FGF2 which are normally required for satisfactory differentiation. The ability to leave out these compounds and small molecules from the differentiation medium reduces the medium costs and eases the way to regulatory acceptance. The term differentiation phase and differentiation stage are used interchangeably herein.

[0086] Accordingly, in certain embodiments the method as described herein does not comprise an additional commitment phase induction step.

[0087] The method as described herein reduces the differentiation time of the pluripotent cells as described herein to mature adipocytes dramatically. In certain embodiments, the time to produce mature adipocytes using the method as claimed is at most 10 days, 9 days, 8 days, 7 days, 6 days, 5 days, 4 days, 3 days or 2 days. Using the pluripotent cells as described in the method as described, the inventors have observed a conversion rate of at least 95% by day 4 of culture, meaning that at least 95% of the cells are mature after 4 days of culture. Accordingly, in certain embodiments the time to produce at least 95% mature adipocytes is at most 4 days.

[0088] In a further aspect, the invention provides for adipocytes, preferably mature adipocytes, as obtained by the method as described herein.

[0089] Culturing the cells as described herein can be performed under so called 2D culturing conditions, which is considered the conventional approach to culturing cells. However, the method as described can also easily be adapted to allow culturing under 3D conditions as shown in the examples below.

[0090] 3D cell culture is an artificially-created environment which enables cells to grow or interact with their surroundings in three dimensions. In such culture, cells typically form 3D colonies, which may be referred to as "spheroids". The 3D culture approach may more accurately model the cells' in vivo growth and behaviour. The skilled person is readily able to carry out 3D cell culture, for example by taking advantage of any of a number of commercially-available culturing tools. For example, the 3D culture may be carried out using scaffold or scaffold-free techniques. Scaffoldbased techniques make use of supports such as solid scaffolds and hydrogels to enable the cells to form a 3D culture. Such scaffolds may aim to mimic the natural extracellular matrix (ECM), which is present in vivo. Scaffold-free techniques dispense with the use of the scaffold on which to grow the cells. Instead, 3D spheroids may be established through the use of, for example, low-adhesion plates, hanging-drop plates, micro-patterned surfaces, rotating bioreactors, magnetic levitation and magnetic 3D bioprinting.

[0091] Cells that have been transduced with lentiviral vectors are not considered food safe or not safe for human and non-human dietary consumption. The pluripotent cells as described herein of the method as described herein obviates the need to use lentivirally transduced cells. Accordingly, in certain embodiments, the adipocytes that are produced according to the method as disclosed herein are for human and non-human dietary consumption. In certain embodiments, the produced adipocytes can be used in the production of cultured meat for human consumption.

[0092] In a further aspect, the invention provides for a use of a pluripotent stem cell as described herein or the adipocytes obtained by the method as described herein for tissue engineering. In certain embodiments the method as described herein is for ex vivo or in vivo tissue engineering.

[0093] In certain aspect, the use is for the production of cultured meat. That is to say, the invention provides for a use of a pluripotent stem cell as described herein or the adipocytes obtained by the method as described herein for the production of cultured meat.

[0094] In yet a further aspect, the invention provides for a food product (also referred to as “foodstuff’) comprising the pluripotent stem cells as described herein or the adipocytes produced and / or obtained by the method as described. In certain embodiments, the food product is or further comprises an edible composition for human or non-human consumption. The edible composition for human or non-human consumption for example comprises at least one of myocytes, mature muscle cells, minerals, synthetic substances, flavoring substances (such as for examples herbs and spices), plant based proteins or proteins from microbial origin such as yeast proteins. Plant based proteins and yeast proteins suitable for the use in food products are known to the skilled person in the art. In certain embodiments, the food product is cultured meat or a cultured meat product.

[0095] In yet a further aspect, the invention provides for a method of producing a food product, the method comprising combining the pluripotent stem cells as described herein or the produced and / or obtained adipocytes with an edible composition for human consumption or non-human consumption as described herein. In certain embodiments, the food product is cultured meat.

[0096] Examples

[0097] The present invention is further described by the following examples which should not be construed as limiting the scope of the invention.

[0098] Materials and Methods

[0099] Bovine Epiblast-derived Stem Cells (bEplSCs) and porcine Epiblast-derived Stem Cells (pEplSCs) differentiation to adipocytes.

[0100] Undifferentiated bEplSCs and pEplSCs (Opti-Ox CEBPa-PPARy (control) and Opti-Ox CEBP-ADIG) are grown in, for example, N2B27 proliferation media (50% DMEM Ham’s F-12 (L0093-500, Biowest), 50% Neurobasal media (21103049, Thermofisher), B27 supplement (17504044, Thermofisher), N2 supplement (17502001 , Thermofisher), glutamax (35050061 , Thermofisher), 10 mM 2-Mercaptoethanol (31350010, Thermofisher), 0,02pg / mL Activin A (QK001 , Q-kine), 0,10 pg / mL FGF2 (QK002, Q-kine), 0,625 pg / mL XAV939 (X3004, Sigma Aldrich) on hESC-qualified geltrex (A1413301 .Thermo Scientific)-coated plates. For 2D adipocyte differentiation, single cells were obtained after gentle cell dissociation reagent (07174, STEMCELL technologies) treatment and cell number and viability assessed. Single bEplSCs and pEplSCs cells were seeded in the corresponding cell culture plates at a density of 50000-150000 cells / cm2. After an overnight incubation in proliferation media with 10 pm Rock Inhibitor (Y-27632 (HBF2297, HelloBio), cells were cultivated in StemPro-34 SFM media (10639011 , Thermo Scientific) supplemented with 25 ng / mL Activin A (120-14E, PeproTech), 10 ng / mL BMP4 (120-05ET, PeproTech), 4 ng / mL FGF2 (Qk002, Qkine) and 50 mg / mL Ascorbic acid (A8960, Sigma Aldrich) for 48 hours to enhance stem cells commitment to adipocyte lineage. On day 2, media was replaced by adipocyte maturation media composed of DMEM Ham’s F-12 (L0093-500, Biowest) containing 15% Knockout Serum Replacement (10828-028, Thermofisher), 1 pg / mL insulin (12585014, Thermofisher) and 1 pM Dexamethasone (D1756, Sigma Adrich). bEplSCs and p were differentiated for the specified amount of days. Media was refreshed every two days. Doxycycline (1 pg / mL, D9891 , Sigma Aldrich) was added to the differentiation media to activate the Opti-OX system in these cells.

[0101] For spheroids or aggregates differentiation experiments, undifferentiated single-bEplSCs or - pEplSCs (Opti-Ox CEBPoc PPARy (control) and Opti-Ox CEBPa-ADIG) were seeded at 3 million cells / mL in 250 mL shaker flasks containing 25 mL of proliferation media (containing 50% DMEM Ham’s F-12 (L0093-500, Biowest), 50% Neurobasal media (21103049, Thermofisher), B27 supplement (17504044, Thermofisher), N2 supplement (17502001 , Thermofisher), glutamax (35050061 , Thermofisher), 10 mM 2-Mercaptoethanol (31350010, Thermofisher) , 0,02pg / mL Activin A (QK001 , Q-kine), 0,10 pg / mL FGF2 (QK002, Q-kine), 0,625 pg / mL XAV939 (X3004, Sigma Aldrich), 2X % Knockout Serum Replacement (10828-028, Thermofisher)KSR and 10ng / mLX FGF2). Next day, once small spheroids are formed, media was replaced by supplemented StemPro-34 SFM. In the same way, maturation media was added at day 2 of differentiation and was refreshed every two days until the end of the experiment.

[0102] LipidTOX Staining

[0103] Undifferentiated and differentiated bEplSCs or pEPISCs Opti-Ox CEBPa-PPARy (control) and bEplSCs or pEPISCs Opti-Ox CEBPa-ADIG are stained with LipidTOX (Thermo Fischer). Briefly, cells in culture or in aggregates were washed with phosphate buffered saline (PBS) and fixed with 4 paraformaldehyde (PFA) for 40 minutes at room temperature. After being washed 3 times with PBS and permeabilized with 60% isopropanol, cells were stained with LipidTOX according to manufacturer’s instructions. Thereafter, bEplSCs and pEPISCs were washed several times with deionized water until only lipid droplets were properly stained with the dye. Undifferentiated and differentiated cells were photographed under an inverted bright fieldlight microscope (Oxion Inverso, Euromex) or under fluorescent microcopya (EVOS M7000, Thermo Fisher Scientific). Triglyceride content of bEplSCs or pEplSCs Opti-Ox CEBPa-PPARy (control) and bEplSCs or pEplSCs CEBPa-ADIG were estimated at different check points during adipogenesis by extracting LipidTOX dye from the cells with 100% isopropanol and measuring spectrophotometrically the resulting solution at 540 mM (Glomax Discover, Promega). LipidTOX data were adjusted by an estimation of the number of cells spectrophotometrically measured by HOESCH 33342 staining (H1399, Thermo Fisher Scientific), according to the manufacturer’s instructions. bEplSCs or pEplSCs Opti-Ox CEBPa-PPARy (control) and bEplSCs or pEplSCs CEBPa- ADIG differentiated in aggregates or spheroids were stained following the same protocol previously described. Two different approaches were followed for imaging acquisition. For a quick check on adipocyte quality, stained aggregates were transferred to a slide. After removing excess buffer, the slides werecoverslipped using hard set mounting medium (P36984, Thermo Fisher Scientific). In this process the spheroid aggregates were flattened, resulting in an overview of lipid presence and an estimation of its distribution. For a more accurate analysis, unstained and fixed cell aggregates were cryopreserved in sucrose solution. The frozen samples were then sectioned at 20 pm with a cryostat (CM 1950, Leica). The cryosections were stained using the LipidTOX staining according to manufacturer’s instructions. Measurements included total cell number, total lipid number per cell, lipid size and shape, total intensity (within lipid objects).

[0104] Triglyceride content

[0105] Intracellular triglyceride content was quantified from undifferentiated and differentiated cultured / aggregates bEplSCs or pEplSCs Opti-Ox CEBPa-PPARy (control) and bEplSCs or pEplSCs CEBPa-ADIG using Triglyceride Quantification Colorimetric / Fluorometric Kit (MAK266- 1 KT, Sigma Aldrich) according to manufacturer's instructions. Briefly, total lipids were extracted with 5% Nonidet P40 Substitute (11754599001 , Sigma Aldrich) solution in deionized water under heating. By adding lipase, glycerol is released from triglycerides and subsequently reacted to generate colour, which can be measured spectrophotometrically at 570nm (Glomax Discover, Promega). TG concentrations were calculated based upon a standard curve made from TG standards and normalized to total cellular protein content.

[0106] Real-time quantitative PCR analysis (RT-qPCR)

[0107] Total RNA from undifferentiated and differentiated bEplSCs or pEplSCs Opti-Ox CEBPa- PPARy (control) and bEplSCs or pEplSCs CEBPa-ADIG was extracted using Reliaprep Cell Miniprep System (Z6012, Promega) according to the manufacturer's instructions. RNA concentration and quality was determined with a Microvolume Spectrophotometer DS-11 (DeNovix). Five hundred nanograms of purified total RNA from every sample was first treated with DNase I to remove possible genomic DNA contamination and were subsequently reverse transcribed into cDNA using iScript gDNA Clear cDNA Synthesis Kit (1725035BUN, BioRad). Specific primers for bovine or porcine pluripotency and mature adipocyte markers are designed to perform real-time quantitative PCR analysis. At least three samples from two independent experiments were amplified in triplicates in an (thermocycler) system using PowerTrack SYBR Green Master Mix (A46112, Thermofisher) according to manufacturer’s guidelines. RT-qPCR conditions were 95 °C for 30 seconds, followed by 40 cycles of of 15 s at 95°C and 1 min at 60°C. The YWHAZ gene was used as a housekeeping gene to normalize the target gene expression levels. Relative gene quantification was calculated by the 2-AACt method.

[0108] Results

[0109] Example 1: Development of an Inducible Transgene Overexpression Method by Dual GSH Targeting in Animal Cells

[0110] The Opti-ox approach to generating cells in which transcription may be controlled as described in WO2018096343A1 was employed in these Examples. This approach involves insertion of an inducible cassette so that transcription of the genetic material within that inducible cassette may be controlled by using a dual genomic safe harbour targeted system.

[0111] To explore the potential of OPTi-OX for forward programming of bovine pluripotent stem cells (bPSCs) and porcine pluripotent stem cells (pPSCs), CEBPa and ADIG are selected for use in a combined cellular reprogramming strategy. Using the OPTi-OX approach to generate bPSCs and pPSCs, we sequentially targeted the rtTA cassette into the bovine or porcine ROSA26 GSH under control of a CAG promoter and a knock-in that has CEBPa, a P2A “self-cleaving” peptide linker and ADIG all in one open reading frame to simultaneously express CEBPa and ADIG by doxycycline induction into the AAVS1 GSH. 2A peptide linkers are well-characterized short peptide linkers of 18-22 amino acids that result in two separate gene products expressed from a single open reading frame due to ribosome skipping during translation. The bovine construct for targeting to the ROSA locus is shown in Fig. 1 .

[0112] Stable knock-ins in the AAVS1 GSH were selected by incorporation of a puromycin- resistance cassette and selected with puromycin addition to the cell culture medium (data not shown). Following selection, single bEpiSC cells were plated and clonal cell lines isolated for outgrowth and analysis.

[0113] Incorporation of doxycycline-inducible CEBPa-P2A-ADIG was subsequently confirmed using PCR genomic analysis. Using the dual GSH-targeting approach, clonal lines were selected that carry two copies of each of the transgenes (data not shown).

[0114] Example 2: EpiSCs- CEBPa-AD / G 2D short-term differentiation into adipocytes. bEplSCs or pEplSCs Opti-Ox CEBPa -ADIG were proliferated and differentiated with doxycycline for up to 8 days (short-term) as described previously in W02024 / 084082. Pictures were taken from the undifferentiated cells (day 0) and during differentiation (at days 2, 4, 6 and 8 (for short term differentiation) using bright-field microscopy to determine lipid droplet size. The lipid droplet size is compared to control bEplSCs comprising Opti-Ox CEBPa-PPARy, i.e. cells expressing o CEBPa and PPARy. Figure 2A shows the results in bovine cells. Figure 3A shows the results in porcine cells.

[0115] Also, the total triglyceride content from the undifferentiated and differentiated cells using LipidTox staining was determined (Figure 2B bovine, Figure 3B porcine). LipidTox is a fat-soluble dye that stains neutral triglycerides and lipids. As can be seen (Figure 2A and 2B), from day 4 on, in bovine cells a remarkable higher production of Lipid droplets is observed in Opti-Ox CEBPa -ADIG cells as compared to the control Opti-Ox CEBPa-PPARy cells. In porcine cells, the same remarkable difference is observed already at two days post differentiation (Figure 3A and 3B).

[0116] This difference is further confirmed by Light microscopy images wherein formation of big lipid droplets structures is observed in CEBPa -ADIG cells at day 6 whereas such structures were never observed in CEBPa-PPARy cells even after 8 days of differentiation (Figure 4, results in bovine cells shown).

[0117] Example 3: RNAseq

[0118] Table I : RNAseq analysis of gene expression markers that are indicative of a lipid rich environment.

[0119] Days indicated the number of days with induction

[0120] P.: bEplSCs CEBPa-PPARy A.: pEplSCs CEBPa -ADIG

[0121] Overall there is a very clear correlation between higher induction of all the markers by ADIG relative to the induction by PPARy. PLD’s: controlling cellular signaling regulated by lipid products; AGPAT: Regulates biosynthesis of triglycerides; FRAS1 : Upregulated by lipid droplet formation; AAK1 : Regulates lipid droplets size; FREM’s: Regulates lipid droplet formation at the ER.

[0122] Figure 5 represents a Two Principal component analysis (PCA) gene expression data of differentiation towards adipocytes (right-above direction: Fat tissue) of bovine CEBPa-ADIG cells (represented in the figure by A0, A2, A4, A6 and A8_at 0,2, 4, 6 or 8: Days after induction) or Bovine control Opti-Ox CEBPa- PPARy (represented in the figure by P0, P2, P4, P6 and P8 at 0,2, 4, 6 or 8: Days after induction).

[0123] At day 0, as expected (not yet induced) Line 147 harbouring CEBPa -ADIG cells and Line 156 harbouring CEBPa-PPARy remained in a same cluster (most left) indicating they are genetically similar and clustering together with EpiSC (Line146 and Line 157). At Day 2, Line 158 (P2) moves to the right indicating genetic variability and moving in the direction of Fat tissue genetic profile; in contrast Line 149 (A2) moves not only to the right but also above quicker towards the intended genetic phenotype, as shown A2 already cluster on day 4. At Day 4, Line 160 (P4) keeps moving to the right in the direction of Fat tissue but not above, in contrast Line 151 (A4) moves still quicker to the right and above towards the intended genetic phenotype, as shown A4 cluster already on day 6. At Day 6, Line 163 (P6) keeps moving to the right in the direction of Fat tissue but not above, in contrast Line 153 (A6) moves still quicker to the right and above towards the intended genetic phenotype, as shown A6 clustering already in day 8. At Day 8, Line 165 (P8) finally catch up to the right and above in the direction of Fat tissue, in contrast Line 153 (A6) and Line 154 (A8) were clustering already in day 8 after only 6 days . Overall, the samples expressing CEBPa -ADIG combination are 2 days quicker (right) in advance towards a stronger (above) differentiation genetic phenotype / profile to FAT tissue in comparison to the combination CEBPa-PPARy.

[0124] Example 4: 3D culture of EpiSCs-CEBPa-ADIG

[0125] In suspension culture of cells in 3D is a necessary step to scale up to large volumes and generate the amounts of adipocytes needed for a cultivated meat product at cost competitive prices (for example in shakers and / or bioreactors). Although in suspension culture of cells in 3D allows the cells to grow in an environment that more closely mimics the physiological in vivo environment of the cells the transition from 2D to 3D culture needs to be properly performed and differentiation data obtained from 2D experiments need to be validated in 3D.

[0126] For this reason, bEpiSCs-CEBPa-ADIG are adapted to 3D suspension cell growth and grown as aggregates; bEpiSCs-CEBPa-ADIG expanded in an adherent 6-well cell plate are single celled with Accumax (00-4666-56, ThermoFisher Scientific) according to the manufacturer’s instructions and transferred to shaker flask in media and a RHO / ROCK pathway inhibitor and thereafter expanded for at a number of cycles. Media during expansion in 3D is refreshed daily. 3D adapted bEpiSCs- CEBPa-ADIG are subsequently used in shaker and bioreactor experiments. are

[0127] To explore adipogenesis performance in 3D, cells are inoculated in a shaker flask containing media and bEpiSCs-CEBPa-ADIG are differentiated. Media is changed every second day. Cells are collected during differentiation at day 6, stained with Oil Red O and DAPI and visualized by fluorescent microcopy. mRNA relative gene expression for bovine CEBPa and ADIG Opti-Ox-derived mRNA and bovine endogenous PPARy, CEBPa, adiponectin, LPL, Perilipin-1 , FABP4, CD36 and CEBPp are also analyzed.

[0128] Embodiments

[0129] The present invention provides at least the following numbered statements / embodiments: 1 . A pluripotent stem cell comprising: i) an expression construct for expression of a transcriptional regulator protein inserted into a first genetic safe harbour site; ii) an expression construct for expression of a CEBPa protein, wherein the coding sequence for the CEBPa protein is operably linked to an inducible promoter; and, iii) an expression construct for expression of a ADIG protein, wherein the coding sequence for the ADIG protein is operably linked to an inducible promoter; wherein the expression constructs of ii) and iii) are inserted into at least one further genetic safe harbour site that is not the first genetic safe harbour site, and wherein the inducible promotor is regulated by the transcriptional regulator protein.

[0130] 2. A pluripotent stem cell according to embodiment 1 , wherein the expression constructs of ii) and iii) are both inserted into a second genetic safe harbour site that is different from the first genetic safe harbour site.

[0131] 3. The pluripotent stem cell according to embodiment 1 or 2, wherein the cell is selected from the group consisting of induced pluripotent stem cells, and embryonic cell lines.

[0132] 4. The pluripotent stem cell according to any one of embodiments 1 -3, wherein the pluripotent stem cells are of a livestock or poultry species.

[0133] 5. The pluripotent stem cell according to embodiment 4, wherein the livestock species is porcine or bovine, preferably bovine.

[0134] 6. The pluripotent stem cell according to any one of embodiments 2-5, wherein the expression construct that is inserted into the second genetic safe harbour site encodes a CEBPa protein, a linker and an ADIG protein, preferably wherein the linker is P2A, more preferably wherein the linker comprises the amino acid sequence of SEQ ID NO: 6.

[0135] 7. The pluripotent stem cell according to embodiment 6, wherein the construct comprises the nucleic acid sequence of SEQ ID NO: 7.

[0136] 8. The pluripotent stem cell according to any one of the preceding embodiments, wherein the activity of the transcriptional regulator protein is controlled by an exogenously supplied substance derivative.

[0137] 9. The pluripotent stem cell according to any one of the preceding embodiments, wherein the transcriptional regulator protein is selected from the group consisting of: tetracycline responsive transcriptional activator protein (rtTa), Tetracycline repressor (TetR), VgEcR synthetic receptor or a hybrid transcriptional regulator protein comprising a DNA binding domain from the yeast GAL4 protein, a truncated ligand binding domain from the human progesterone receptor and an activation domain from the human NF-kB, preferably the transcriptional regulator protein is rtTA.

[0138] 10. The pluripotent stem cell according to any one of the preceding embodiments, wherein the inducible promoter includes a Tet Responsive Element (TRE).

[0139] 11 . The pluripotent stem cell according to any one of the preceding embodiments, wherein the inducible promotor is a tetON promotor.

[0140] 12. The pluripotent stem cell according to any one of the preceding embodiments, wherein said first and further genomic safe harbour sites are selected from any two of the hROSA26 locus, the AAVS1 locus, the CLYBL gene or the CCR5 gene, preferably wherein the genetic safe harbour site are hROSA26 locus and the AAVS1 locus.

[0141] 13. A method for the production of adipocytes, preferably white adipocytes, comprising a ) culturing the pluripotent stem cell according to any one of the preceding embodiments in a proliferation medium: followed by b) inducing adipocyte differentiation by adding the exogenous substance according to embodiment 8, preferably the proliferation and / or differentiation medium does not comprise insulin and / or dexamethasone.

[0142] 14. The method according to embodiment 13, wherein the differentiation phase is at most 10 days, at most 9 days, 8 days, 7 days, 6 days, 5 days, 4 days or 3 days.

[0143] 15. The method according to embodiments 13 or 14 wherein the produced adipocytes are for human and non-human dietary consumption.

[0144] 16. Use of a pluripotent stem cell according to any one of embodiments 1 -12 or use of the method for producing a adipocyte according to any one of embodiments 13-15 for tissue engineering, optionally for the production of cultured meat.

[0145] 17. A food product comprising the pluripotent stem cell according to any one of embodiments 1-12 or the adipocytes obtained by the method according to any one of embodiments 13-15.

[0146] 18. The food product according to embodiment 17, wherein the food product is cultured meat.

Claims

Claims1 . A pluripotent stem cell comprising: i) an expression construct for expression of a transcriptional regulator protein inserted into a first genetic safe harbour site; ii) an expression construct for expression of a CEBPa protein, wherein the coding sequence for the CEBPa protein is operably linked to an inducible promoter; and, iii) an expression construct for expression of a ADIG protein, wherein the coding sequence for the ADIG protein is operably linked to an inducible promoter; wherein the expression constructs of ii) and iii) are inserted into at least one further genetic safe harbour site that is not the first genetic safe harbour site, and wherein the inducible promotor is regulated by the transcriptional regulator protein.

2. A pluripotent stem cell according to claim 1 , wherein the expression constructs of ii) and iii) are both inserted into a second genetic safe harbour site that is different from the first genetic safe harbour site.

3. The pluripotent stem cell according to claim 1 or 2, wherein the cell is selected from the group consisting of induced pluripotent stem cells, and embryonic cell lines.

4. The pluripotent stem cell according to any one of claims 1 -3, wherein the pluripotent stem cells are of a livestock or poultry species.

5. The pluripotent stem cell according to claim 4, wherein the livestock species is porcine or bovine, preferably bovine.

6. The pluripotent stem cell according to any one of claims 2-5, wherein the expression construct that is inserted into the second genetic safe harbour site encodes a CEBPa protein, a linker and an ADIG protein, preferably wherein the linker is P2A, more preferably wherein the linker comprises the amino acid sequence of SEQ ID NO: 6.

7. The pluripotent stem cell according to claim 6, wherein the construct comprises the nucleic acid sequence of SEQ ID NO: 7.

8. The pluripotent stem cell according to any one of the preceding claims, wherein the activity of the transcriptional regulator protein is controlled by an exogenously supplied substance derivative.

9. The pluripotent stem cell according to any one of the preceding claims, wherein the transcriptional regulator protein is selected from the group consisting of: tetracycline responsive transcriptional activator protein (rtTa), Tetracycline repressor (TetR), VgEcR synthetic receptor or a hybridtranscriptional regulator protein comprising a DNA binding domain from the yeast GAL4 protein, a truncated ligand binding domain from the human progesterone receptor and an activation domain from the human NF-kB, preferably the transcriptional regulator protein is rtTA.

10. The pluripotent stem cell according to any one of the preceding claims, wherein the inducible promoter includes a Tet Responsive Element (TRE).11 . The pluripotent stem cell according to any one of the preceding claims, wherein the inducible promotor is a tetON promotor.

12. The pluripotent stem cell according to any one of the preceding claims, wherein said first and further genomic safe harbour sites are selected from any two of the hROSA26 locus, the AAVS1 locus, the CLYBL gene or the CCR5 gene, preferably wherein the genetic safe harbour site are hROSA26 locus and the AAVS1 locus.

13. A method for the production of adipocytes, preferably white adipocytes, comprising a ) culturing the pluripotent stem cell according to any one of the preceding claims in a proliferation medium: followed by b) inducing adipocyte differentiation by adding the exogenous substance according to claim 8, preferably the proliferation and / or differentiation medium does not comprise insulin and / or dexamethasone.

14. The method according to claim 13, wherein the differentiation phase is at most 10 days, at most 9 days, 8 days, 7 days, 6 days, 5 days, 4 days or 3 days.

15. The method according to claims 13 or 14 wherein the produced adipocytes are for human and non-human dietary consumption.

16. Use of a pluripotent stem cell according to any one of claims 1-12 or use of the method for producing a adipocyte according to any one of claims 13-15 fortissue engineering, optionally for the production of cultured meat.

17. A food product comprising the pluripotent stem cell according to any one of claims 1 -12 or the adipocytes obtained by the method according to any one of claims 13-15.

18. The food product according to claim 17, wherein the food product is cultured meat.

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