Biomimetic 3D Printing and its Applications

Abstract

The disclosed systems and methods can be used to create physiologically relevant systems and models for human and animal systems. These physiological conditions can be designed to mimic real human conditions for cell differentiation and proliferation. The disclosed systems and methods can create appropriate biomaterials to mimic those present in human or animal scaffolds. Using 3D printing technology, hydrogel scaffolds can be printed at various resolutions that closely resemble the human physiological shape. Furthermore, the structure can be optimized for the chosen application and the scaffolds can be seeded with appropriate cells before testing.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Application No. 63 / 185,298, filed May 6, 2021, the entire contents of which are incorporated herein by reference.

[0002] This application describes a novel method for studying various cells and microscaffolds at near physiological resolution, or their gas exchange and oxygen / CO between two separate complex structures within a 3D printed scaffold. 2 It relates to a method for obtaining a biomimetic 3D printed scaffold to mimic human physiological conditions for evaluating migration. [Background technology]

[0003] 3D cell culture models can be used to study physiological conditions in humans and animals. Summary of the Invention

[0004] One embodiment is to provide a 3D printed unit that can use microscopic imaging to monitor bioscaffold and cell interface studies.

[0005] Another embodiment is to evaluate various 3D cell cultures in 3D printed scaffold shapes and structures that mimic physiological environments.

[0006] Another embodiment is a 3D printed biomimetic unit to evaluate the efficacy of various chemical moieties and drugs on specific cell types with vasculature networks.

[0007] Another embodiment is to provide a complex 3D printed vasculature model for creating a vasculature system of one or several human cell types.

[0008] Another embodiment is a gas exchange unit including a vascular network configured to conduct blood and an airway section configured to hold oxygenated air, the vascular network being in contact with the airway section to allow gas exchange and increase the oxygen content of blood passing through the vascular network. Another embodiment is an artificial lung including the gas exchange unit.

[0009] Another embodiment is a method of forming a gas exchange unit comprising printing a gas exchange unit comprising a vascular network configured to conduct blood and an airway section configured to hold air containing oxygen, the vascular network being in contact with the airway section to enable gas exchange and increase the oxygen content of blood passing through the vascular network.

[0010] Another embodiment is a system-on-chip device including a vascular network configured to conduct blood and an airway section configured to hold oxygenated air, the vascular network being in contact with the airway section, and a gas exchange unit that allows gas exchange to increase the oxygen content of blood passing through the cell-seeded vascular network. [Brief description of the drawings]

[0011] [Figure 1A] 1A-1B show the 3D printed lung on a chip platform. Figure 1A shows a schematic of the alveolar gas exchange unit. Figure 1B shows the 3D printed scaffold perfused with intravascular blood and air. [Figure 1B] 1A-1B show the 3D printed lung on a chip platform. Figure 1A shows a schematic of the alveolar gas exchange unit. Figure 1B shows the 3D printed scaffold perfused with intravascular blood and air. [Diagram 2] FIG. 2 shows a schematic diagram of an inverted DLP (digital light projection) system. [Figure 3A]3A-3C show a 3D printed microfluidic component mounted on a 3D printer for 3D printing an internal lung-on-a-chip of one embodiment. [Figure 3B] 3A-3C show a 3D printed microfluidic component mounted on a 3D printer for 3D printing an internal lung-on-a-chip of one embodiment. [Figure 3C] 3A-3C show a 3D printed microfluidic component mounted on a 3D printer for 3D printing an internal lung-on-a-chip of one embodiment. [Figure 4A] Figures 4A-4D show schematic diagrams of an embodiment of a 3D printed microfluidic component. Figure 4A shows an embodiment of an inlet dispenser. Figure 4B shows an embodiment of a 3D printed hydrogel. Figure 4C shows an embodiment of a 3D printed plastic container that will hold the 3D printed gel. Figure 4D shows an embodiment of an outlet dispenser. [Figure 4B] Figures 4A-4D show schematic diagrams of an embodiment of a 3D printed microfluidic component. Figure 4A shows an embodiment of an inlet dispenser. Figure 4B shows an embodiment of a 3D printed hydrogel. Figure 4C shows an embodiment of a 3D printed plastic container that will hold the 3D printed gel. Figure 4D shows an embodiment of an outlet dispenser. [Figure 4C] Figures 4A-4D show schematic diagrams of an embodiment of a 3D printed microfluidic component. Figure 4A shows an embodiment of an inlet dispenser. Figure 4B shows an embodiment of a 3D printed hydrogel. Figure 4C shows an embodiment of a 3D printed plastic container that will hold the 3D printed gel. Figure 4D shows an embodiment of an outlet dispenser. [Figure 4D]Figures 4A-4D show schematic diagrams of an embodiment of a 3D printed microfluidic component. Figure 4A shows an embodiment of an inlet dispenser. Figure 4B shows an embodiment of a 3D printed hydrogel. Figure 4C shows an embodiment of a 3D printed plastic container that will hold the 3D printed gel. Figure 4D shows an embodiment of an outlet dispenser. [Figure 5A] Figures 5A-5D show images of fluidic components of different sized dual lumen designs according to some embodiments. Figure 5A shows three different embodiments of the fluidic part design before the hydrogel is 3D printed according to some embodiments. Figures 5B, 5C, and 5D are embodiments of assemblies including 3D printed microfluidic parts with 3D printed hydrogel perfused therein. [Figure 5B] Figures 5A-5D show images of fluidic components of different sized dual lumen designs according to some embodiments. Figure 5A shows three different embodiments of the fluidic part design before the hydrogel is 3D printed according to some embodiments. Figures 5B, 5C, and 5D are embodiments of assemblies including 3D printed microfluidic parts with 3D printed hydrogel perfused therein. [Figure 5C] Figures 5A-5D show images of fluidic components of different sized dual lumen designs according to some embodiments. Figure 5A shows three different embodiments of the fluidic part design before the hydrogel is 3D printed according to some embodiments. Figures 5B, 5C, and 5D are embodiments of assemblies including 3D printed microfluidic parts with 3D printed hydrogel perfused therein. [Figure 5D]Figures 5A-5D show images of fluidic components of different sized dual lumen designs according to some embodiments. Figure 5A shows three different embodiments of the fluidic part design before the hydrogel is 3D printed according to some embodiments. Figures 5B, 5C, and 5D are embodiments of assemblies including 3D printed microfluidic parts with 3D printed hydrogel perfused therein. [Figure 6A] Figures 6A-6D show various structural embodiments of the biomimetic unit. Figure 6A shows a capsule net structure. Figure 6B shows a giant Fischer structure. Figure 6C shows a Fischer block structure. Figure 6D shows a cubic net structure. [Figure 6B] Figures 6A-6D show various structural embodiments of the biomimetic unit. Figure 6A shows a capsule net structure. Figure 6B shows a giant Fischer structure. Figure 6C shows a Fischer block structure. Figure 6D shows a cubic net structure. [Figure 6C] Figures 6A-6D show various structural embodiments of the biomimetic unit. Figure 6A shows a capsule net structure. Figure 6B shows a giant Fischer structure. Figure 6C shows a Fischer block structure. Figure 6D shows a cubic net structure. [Figure 6D]Figures 6A-6D show various structural embodiments of the biomimetic unit. Figure 6A shows a capsule net structure. Figure 6B shows a giant Fischer structure. Figure 6C shows a Fischer block structure. Figure 6D shows a cubic net structure. [Figure 7A] Figures 7A-7D show various embodiments of the system and method of application. Figure 7A shows different fluidic part designs of 3D printed vasculature. Figure 7B shows images of the formed vasculature and cells seeded on the airways. Figure 7C is a photograph of the microscope setup for imaging. Figure 7D is an example of a test setup where blood is perfused into the formed vasculature and gas is perfused into the formed airways. [Figure 7B] Figures 7A-7D show various embodiments of the system and method of application. Figure 7A shows different fluidic part designs of 3D printed vasculature. Figure 7B shows images of the formed vasculature and cells seeded on the airways. Figure 7C is a photograph of the microscope setup for imaging. Figure 7D is an example of a test setup where blood is perfused into the formed vasculature and gas is perfused into the formed airways. [Figure 7C] Figures 7A-7D show various embodiments of the system and method of application. Figure 7A shows different fluidic part designs of 3D printed vasculature. Figure 7B shows images of the formed vasculature and cells seeded on the airways. Figure 7C is a photograph of the microscope setup for imaging. Figure 7D is an example of a test setup where blood is perfused into the formed vasculature and gas is perfused into the formed airways. [Figure 7D]Figures 7A-7D show various embodiments of the system and method of application. Figure 7A shows different fluidic part designs of 3D printed vasculature. Figure 7B shows images of the formed vasculature and cells seeded on the airways. Figure 7C is a photograph of the microscope setup for imaging. Figure 7D is an example of a test setup where blood is perfused into the formed vasculature and gas is perfused into the formed airways. [Figure 8] FIG. 8 shows several embodiment 3D printed hydrogel gas exchange unit designs with different dimensions. [Figure 9] FIG. 9 shows 3D printed lung-on-a-chip designs made with different bio-ink formulations. [Figure 10] FIG. 10 shows a 2D gas exchange membrane chip and plots of gas exchange data according to one embodiment. [Figure 11] FIG. 11 shows a whole blood perfused biomimetic model of some embodiments. [Figure 12A] 12A-12C show an embodiment of the Lung-on-a-Chip platform. FIG. 12A shows a schematic of an embodiment of an alveolar gas exchange unit. FIG. 12B shows an embodiment of a 3D printed scaffold perfused with blood and air within the vasculature. FIG. 12C shows a plot of data of gas exchange through a 3D printed hydrogel. [Figure 12B] 12A-12C show an embodiment of the Lung-on-a-Chip platform. FIG. 12A shows a schematic of an embodiment of an alveolar gas exchange unit. FIG. 12B shows an embodiment of a 3D printed scaffold perfused with blood and air within the vasculature. FIG. 12C shows a plot of data of gas exchange through a 3D printed hydrogel. [Figure 12C]12A-12C show an embodiment of the Lung-on-a-Chip platform. FIG. 12A shows a schematic of an embodiment of an alveolar gas exchange unit. FIG. 12B shows an embodiment of a 3D printed scaffold perfused with blood and air within the vasculature. FIG. 12C shows a plot of data of gas exchange through a 3D printed hydrogel. [Figure 13] FIG. 13 shows a plot of different 3D printed hydrogel gas exchange unit designs and the increase in oxygen content measured from the outlet compared to the inlet. [Figure 14A] Figures 14A-14F show an embodiment of a 2D gas exchange membrane chip. Figure 14A shows some embodiments of a membrane-based gas exchange unit. Figure 14B shows a membrane-based gas exchange unit (until) with blood perfused inside. Figures 14C-14F show plots of gas exchange data for collagen membrane and PDMS membrane. [Figure 14B] Figures 14A-14F show an embodiment of a 2D gas exchange membrane chip. Figure 14A shows some embodiments of a membrane-based gas exchange unit. Figure 14B shows a membrane-based gas exchange unit (until) with blood perfused inside. Figures 14C-14F show plots of gas exchange data for collagen membrane and PDMS membrane. [Figure 14C] Figures 14A-14F show an embodiment of a 2D gas exchange membrane chip. Figure 14A shows some embodiments of a membrane-based gas exchange unit. Figure 14B shows a membrane-based gas exchange unit (until) with blood perfused inside. Figures 14C-14F show plots of gas exchange data for collagen membrane and PDMS membrane. [Figure 14D]Figures 14A-14F show an embodiment of a 2D gas exchange membrane chip. Figure 14A shows some embodiments of a membrane-based gas exchange unit. Figure 14B shows a membrane-based gas exchange unit (until) with blood perfused inside. Figures 14C-14F show plots of gas exchange data for collagen membrane and PDMS membrane. [Figure 14E] Figures 14A-14F show an embodiment of a 2D gas exchange membrane chip. Figure 14A shows some embodiments of a membrane-based gas exchange unit. Figure 14B shows a membrane-based gas exchange unit (until) with blood perfused inside. Figures 14C-14F show plots of gas exchange data for collagen membrane and PDMS membrane. [Figure 14F] Figures 14A-14F show an embodiment of a 2D gas exchange membrane chip. Figure 14A shows some embodiments of a membrane-based gas exchange unit. Figure 14B shows a membrane-based gas exchange unit (until) with blood perfused inside. Figures 14C-14F show plots of gas exchange data for collagen membrane and PDMS membrane. [Figure 15] FIG. 15 shows endothelial cell seeding in the hydrogel using 3D printed gel matrix and different cellularization conditions. [Figure 16A] 16A-16C show cell-free and cell-based gas exchange assays of some embodiments. FIG. 16A shows a schematic of the capsule net model of some embodiments. FIG. 16B shows human whole blood perfused into the cube net model under hypoxic conditions. FIG. 16C shows the gas exchange rate achieved for the cell-free and cell-based gas exchange assays compared to the control. [Figure 16B]16A-16C show cell-free and cell-based gas exchange assays of some embodiments. FIG. 16A shows a schematic of the capsule net model of some embodiments. FIG. 16B shows human whole blood perfused into the cube net model under hypoxic conditions. FIG. 16C shows the gas exchange rate achieved for the cell-free and cell-based gas exchange assays compared to the control. [Figure 16C] 16A-16C show cell-free and cell-based gas exchange assays of some embodiments. FIG. 16A shows a schematic of the capsule net model of some embodiments. FIG. 16B shows human whole blood perfused into the cube net model under hypoxic conditions. FIG. 16C shows the gas exchange rate achieved for the cell-free and cell-based gas exchange assays compared to the control. [Figure 17] FIG. 17 is an image of the retainer designed in Example 1 of some embodiments. [Figure 18A] 18A-18B, 19A-19B, 20A-20B, 21A-21B, 22A-22B, and 23A-23B show an embodiment of Example 2 of some embodiments. [Figure 18B] 18A-18B, 19A-19B, 20A-20B, 21A-21B, 22A-22B, and 23A-23B show an embodiment of Example 2 of some embodiments. [Figure 19A] 18A-18B, 19A-19B, 20A-20B, 21A-21B, 22A-22B, and 23A-23B show an embodiment of Example 2 of some embodiments. [Figure 19B] 18A-18B, 19A-19B, 20A-20B, 21A-21B, 22A-22B, and 23A-23B show an embodiment of Example 2 of some embodiments. [Figure 20A]18A-18B, 19A-19B, 20A-20B, 21A-21B, 22A-22B, and 23A-23B show an embodiment of Example 2 of some embodiments. [Figure 20B] 18A-18B, 19A-19B, 20A-20B, 21A-21B, 22A-22B, and 23A-23B show an embodiment of Example 2 of some embodiments. [Figure 21A] 18A-18B, 19A-19B, 20A-20B, 21A-21B, 22A-22B, and 23A-23B show an embodiment of Example 2 of some embodiments. [Figure 21B] 18A-18B, 19A-19B, 20A-20B, 21A-21B, 22A-22B, and 23A-23B show an embodiment of Example 2 of some embodiments. [Figure 22A] 18A-18B, 19A-19B, 20A-20B, 21A-21B, 22A-22B, and 23A-23B show an embodiment of Example 2 of some embodiments. [Figure 22B] 18A-18B, 19A-19B, 20A-20B, 21A-21B, 22A-22B, and 23A-23B show an embodiment of Example 2 of some embodiments. [Figure 23A] 18A-18B, 19A-19B, 20A-20B, 21A-21B, 22A-22B, and 23A-23B show an embodiment of Example 2 of some embodiments. [Figure 23B] 18A-18B, 19A-19B, 20A-20B, 21A-21B, 22A-22B, and 23A-23B show an embodiment of Example 2 of some embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Like reference numbers and designations in the various drawings indicate like elements.

[0013] Unless otherwise specified, "a" or "an" means "one or more."

[0014] The disclosed systems and methods can be used to create physiologically relevant systems and models for human and animal systems, including disease state models. These physiological conditions can be designed to mimic actual human conditions for cell differentiation and proliferation. The disclosed systems and methods allow the formation of biological scaffolds, such as scaffolds that mimic the extracellular matrix (ECM) of human lungs, using materials such as hydrogels or other polymers. Using 3D printing technology, polymer scaffolds can be printed at various resolutions, including resolutions that approximate the physiological shape of humans. The structure can be optimized for the chosen application, and the scaffolds can be seeded with appropriate cells prior to testing.

[0015] A biomimetic modela can be used as an alternative to animal or human testing, for example, making testing more efficient, less expensive, and / or faster. The systems and methods described herein can be used to study various physiological processes, such as the effects of therapeutic candidates, as well as cell proliferation and differentiation. For example, the systems described herein can be used to model normal or abnormal conditions, such as diseased or injured conditions. These models can be used to evaluate therapeutic candidates, or cellular or other physiological responses in these conditions. Furthermore, biomimetic model design can enable the creation of synthetic organs for disease treatment. Unfortunately, there are challenges in designing biomimetic models to mimic natural physiological dimensions, due in part to manufacturing obstacles.

[0016] The disclosed systems and methods allow for the creation of many variations of biomimetic model designs. In some embodiments, these biomimetic models may be lung-on-a-chip designs. The disclosed systems and methods allow for the manufacture of technically challenging yet physiologically relevant aspect ratios. Various configurations of the lung-on-a-chip once formed may be considered and these configurations may be subjected to testing to optimize their use. Although various configurations and embodiments are described herein, these should not be considered limiting, as they are merely examples of configurations that have been designed and tested for specific use cases chosen for the particular embodiment.

[0017] Furthermore, 3D cell culture models have attracted interest because they can provide physiologically relevant conditions for research and applications. These physiological conditions can be designed to mimic real human conditions for cell differentiation and proliferation. Unfortunately, these current modeling platforms utilize synthetic polymers such as poly dimethyl siloxane (PDMS), which are different from the natural conditions.

[0018] In contrast, the disclosed system and method allows suitable biomaterials to be formed to mimic those present in human or animal scaffolds. Using 3D printing technology, hydrogel scaffolds can be printed at various resolutions, including near or at the human physiological shape. The scaffolds may be formed using natural polymers such as type I collagen or gelatin. Using such biomaterials, the scaffolds achieve material properties very close to those of natural human scaffolds, allowing the growth of various cell types.

[0019] The present disclosure addresses systems and methods for making and using 3D printed hydrogels that can mimic human scaffolds. The scaffolds may be made of natural hydrogels. These systems and methods may be used as a testing platform to evaluate various bioinks and hydrogel scaffolds for proliferation of various cell types, drug screening in a 3D culture environment, drug screening, efficacy on various cell types, pharmacokinetics, and pharmacodynamics studies. Additionally, these systems and methods may be used to 3D print scaffolds that may be used for tissue repair.

[0020] The biomimetic system also provides gas exchange, as described in more detail below. The gas exchange unit may include an airway segment and a vascular network. Various parameters of the airway segment and vascular network may be customized for the application: airway volume, airway surface area, vasculature volume, vasculature area, vascular lumen diameter, airway-vascular interface thickness, and airway vessel arrangement. The airway segment and vascular network may be made from biomaterials such as hydrogels or other polymers, with or without additional components. The airway segment and vascular network may be 3D printed with any printable bioink to form a hydrogel. Cells may be seeded, cultured, and perfused as part of the airway segment and vascular network. Various configurations and adaptations of the gas exchange unit are described in more detail below.

[0021] The gas exchange unit may include a vascular network configured to conduct a fluid, such as blood or a blood substitute (e.g., a perfluorocarbon blood substitute). The gas unit may include an airway section configured to hold a gas. The gas may be a combination of several gases, such as air, and may include oxygen. The vascular network may be in contact with the airway section to allow gas exchange between the fluid in the vascular network and the gas in the airway section. In some embodiments, the gas exchange increases the oxygen content of the fluid. In some embodiments, the fluid may release carbon dioxide into the airway section. The gas exchange unit may be seeded with any suitable cell type, including pulmonary artery endothelial cells. The gas exchange unit composition may include a hydrogel. The gas exchange unit composition may include one or more compounds, such as polyethylene glycol, polyethylene glycol diacrylate, polyethylene glycol methacrylate, polyethylene glycol methyl ether, N,N'-methylenebiasacrylamide, and methacrylated collagen.

[0022] The gas exchange unit may have an interface between the vascular network and the airway segment. In some embodiments, the diameter of the interface between the vascular network and the airway segment is between 250 μm and 350 μm. The vascular network may include a lumen. In some embodiments, the lumen of the vascular network may be between 350 μm and 450 μm. In some embodiments, the lumen of the vascular network may be between 150 μm and 250 μm. The lumen of the vascular network may be larger than the diameter of the interface between the vascular network and the airway segment.

[0023] Biomimetic units that provide gas exchange may be constructed to have any of a variety of structures. These structures may be modeled after biological organs such as the lungs, kidneys, heart, intestines, or other organs. These structures may be modeled on the basic principle of maximizing the surface area to volume ratio of structures that include vasculature and airway networks.

[0024] The gas exchange unit may be fabricated using materials such as biomaterials that mimic human or animal scaffolds. The gas exchange unit may include a biomaterial hydrogel scaffold. The biomaterial hydrogel scaffold may include a natural polymer. The natural polymer may be one or more of collagen and gelatin. The natural polymer may be gelatin.

[0025] The gas exchange unit may be seeded with cells. In some embodiments, the cells may be endothelial cells. The gas exchange unit may be seeded with small airway epithelial cells (SAECs) on one side of the biomaterial hydrogel scaffold. The gas exchange unit may be seeded with endothelial cells on the other side of the biomaterial hydrogel scaffold.

[0026] The method may include measuring gas exchange between the vascular network and the airway compartment. Measurement of gas exchange between the vascular network and the airway compartment may be used as a criterion in monitoring cell growth, proliferation, or differentiation. In some embodiments, oxygen exchanged between the airway compartment and fluid in the vascular network may be monitored. In some embodiments, carbon dioxide exchange between fluid in the vascular network and the airway compartment may be monitored.

[0027] Another aspect of the present disclosure is directed to an artificial lung including a gas exchange unit. The artificial lung may include multiple gas exchange units arranged in any suitable shape. For example, a single vascular network may be in contact with multiple airway segments. The gas exchange units may be arranged in series or parallel. The gas exchange units may be seeded with one or more cell types to mimic one or more physiological conditions.

[0028] Another aspect of the present disclosure is directed to a method of forming a gas exchange unit. The method may include printing the gas exchange unit, for example, using one or more 3D printing techniques. The gas exchange unit may include a vascular network configured to conduct blood and an airway section configured to hold a gas or a mixture of gases including oxygen, for example air. The vascular network may be in contact with the airway section to enable gas exchange and increase the oxygen content of blood passing through the vascular network. The gas exchange unit may be printed using a 3D printer. The gas exchange unit may be printed using a bio-ink. The gas exchange unit may be printed using an ink including one or more compounds selected from the group: polyethylene glycol, polyethylene glycol diacrylate, polyethylene glycol methacrylate, polyethylene glycol methyl ether, N,N'-Methylenebiasacrylamide, and methacrylated collagen. The gas exchange unit may be printed with an ink including one or more compounds including methacrylated collagen, polyethylene glycol diacrylate, lithium phenyl-2,4,6-trimethylbenzophosphinate, UV386A dye, and 3-hydroxypropyl acrylate. The bio-ink may be one or more of the bio-inks described in the co-pending application entitled "USE OF FUNCTIONALIZED AND NON-FUNCTIONALIZED ECMS, ECM FRAGMENTS, PEPTIDES AND BIOACTIVE COMPONENTS TO CREATE CELL ADHESIVE 3D PRINTED OBJECTS," filed May 6, 2021, which is incorporated by reference in its entirety for the bio-ink disclosure.

[0029] The method may include seeding the gas exchange unit or vascular network with any suitable cells in one or more steps. In embodiments, such as pulmonary bio, the cells may include one or more of pulmonary smooth muscle cells, pulmonary fibroblasts, pulmonary mesenchymal stem cells, pluripotent stem cells, and cell-derived cell types. In some embodiments, progenitor cells, such as stem cells, are differentiated into a suitable cell type after the cells are seeded into the gas exchange unit. Gas may be provided to the gas exchange unit to promote cell seeding, proliferation, differentiation, or to mimic various physiological conditions. Similarly, a fluid, such as whole blood, may be perfused into the vascular network to promote cell seeding, proliferation, differentiation, or to mimic various physiological conditions. In some embodiments, the method includes seeding the cells onto the gas exchange unit and the vascular network scaffold simultaneously. In other embodiments, the cells may be seeded in stages, for example, the airway compartment is seeded before the vascular network. The methods may include providing growth factors, cytokines, or other components to promote cell seeding, proliferation, differentiation, or to mimic various physiological conditions. These components may be provided using gas in the airway compartment, using fluid in the vascular network, or by other means.

[0030] Another aspect of the present disclosure is directed to a method utilizing a system-on-chip device to provide physiologically relevant conditions for an ex vivo model. The system-on-chip device may be used to screen pharmaceutical compositions. The system-on-chip device may be used to model lung disorders such as any form of pulmonary hypertension, e.g., pulmonary arterial hypertension. The system-on-chip device may be used to perform pulmonary toxicity testing.

[0031] Those skilled in the art will appreciate that this summary is for illustrative purposes only and is not intended to be in any way limiting. Other aspects, inventive features, and advantages of the devices and / or methods described herein will become apparent in the detailed description, as defined solely by the claims, set forth herein and taken in conjunction with the accompanying drawings.

[0032] The details of one or more implementations of the inventive subject matter described herein are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages of the inventive subject matter will become apparent from the description, drawings, and claims.

[0033] 1A-1B show an embodiment of a printed lung-on-a-chip platform. The printed lung-on-a-chip platform may include one or more alveolar-type gas exchange units. FIG. 1A shows a schematic diagram of an embodiment of an alveolar-type gas exchange unit 100. The alveolar-type gas exchange unit 100 may include an airway compartment and a vascular compartment. The gas exchange unit 100 may have the following customizable parameters: airway volume, airway surface area, vasculature volume, vasculature area, vascular lumen diameter, airway-vascular interface thickness, and airway-vascular geometry. The gas exchange unit 100 may be 3D printed with any printable ink ranging from plastic resins to bioinks to hydrogels.

[0034] Once formed, cells may be seeded, cultured, and perfused into the gas exchange unit 100. Whole blood may be perfused into the gas exchange unit 100 and gas exchange may be measured. This gas exchange unit 100 may enable evaluation of relevant cell types in lung tissue engineering, airway vascular designs in lung tissue engineering, and materials that meet mechanical, bioactivity, and oxygen diffusion requirements in lung tissue engineering.

[0035] The alveolar gas exchange unit 100 may include a scaffold 110. The alveolar gas exchange unit 100 may include a vascular network 112. The alveolar gas exchange unit 100 may include a ventilating section 114. The lung-on-a-chip platform and the alveolar gas exchange unit 100 may be formed by 3D printing. The structure of the biomimetic platform and the alveolar gas exchange unit 100 may vary depending on the embodiment. FIG. 1B shows a scaffold 110 with blood perfusion inside the vascular network 112 and air perfusion inside the ventilating section 114. The scaffold may be formed by 3D printing. The scaffold may be a hydrogel. The hydrogel scaffold may be printed at various resolutions that closely resemble the human physiological shape in some embodiments. The scaffold may be made of natural polymers. These natural polymers may be biomaterials such as collagen, gelatin, or other known biomaterials. By using such biomaterials, the scaffold may have material properties that are very close to those of natural human scaffolds.

[0036] FIG. 2 shows a schematic diagram of an inverted DLP (digital light projection) system 500. As an alternative to using a solid film with an inverted DLP 3D printer. The system for forming a three-dimensional object may include a platform (e.g., a print platform) on which the three-dimensional object is formed. The three-dimensional object may include an artificial organ (e.g., an artificial lung, an artificial heart, an artificial kidney, an artificial liver, etc.). The build surface and the platform may define a build area (e.g., a build window) therebetween. The system may include a controller configured to move the platform away from the build surface. For example, the controller may raise and lower the platform. The system may include a radiation source (e.g., a DLP projector, a projector, an illumination source, etc.) configured to illuminate the build area. The radiation source may be configured to illuminate the build area through a light-transmissive component to form a solid polymer from a light-sensitive liquid (e.g., a light-sensitive resin, ink, etc.). Embodiments of the system and method used are discussed in U.S. Patent Application Publication No. 63 / 069317, filed Aug. 24, 2020, which is incorporated by reference herein.

[0037] 3A-3C show an embodiment of a 3D printed microfluidic component. FIG. 3A shows an embodiment of an inlet dispenser. The inlet dispenser may be used to perfuse liquid or gas into the gas exchange unit 100 for testing or use. FIG. 3B shows an embodiment of the gas exchange unit 100. The gas exchange unit may be printed with hydrogel, polymer, or biomaterial into the microfluidic component. FIG. 3C shows a plastic container. The plastic container may be 3D printed. The plastic container may hold the gas exchange unit or hydrogel of some embodiments, which may be 3D printed into the plastic container. FIG. 3D shows an embodiment of an outlet dispenser. In some embodiments, the outlet dispenser may be used to remove liquid or gas perfused into the gas exchange unit 100. In some embodiments, the bottom and top of the microfluidic component may be coated with PDMS. This may prevent leakage of the printed hydrogel and allow it to dry. Optionally, the bottom and top surfaces will be coated with 134um PDMS. The platform may include a flexible membrane, which may include a polytetrafluoroethylene membrane. The membrane 702 may have a build surface upon which a 3D printed hydrogel may be placed. The build surface and the platform may have a build area therebetween.

[0038] The platform may include an ink (e.g., a photosensitive ink). The photosensitive liquid may be disposed on an oxygen permeable membrane. The platform may include a radiation source. The radiation source may be configured to illuminate the build area 504 through the light permeable membrane and the oxygen permeable membrane to form a solid polymer from the photosensitive liquid.

[0039] The biomimetic units may be 3D printed with photosensitive inks using DLP or SLA technology, and may be removed from the 3D printer and placed into a holder for further seeding with cells and evaluation of gas exchange between the vasculature network and the airways.

[0040] Figures 4A-4D show images of fluidic components and embodiments of two lumen designs with different microfluidic component dimensions ranging from millimeter sized channels to 10 um channels. Figure 4A shows three different embodiments of the fluidic component design before the hydrogel is 3D printed according to some embodiments. Figures 4B, 4C, and 4D are embodiments of assemblies including 3D printed microfluidic components with 3D printed hydrogel perfused therein. Microfluidic component dimensions may be optimized for the intended application.

[0041] 5A-5D show several embodiment gas exchange unit designs with different dimensions. The gas unit dimensions may be selected based on the intended application or biomimetic dimensions. The dimensions may be selected to mimic physiologically relevant aspect ratios. Various configurations of the formed gas exchange unit are possible and may be tested to optimize use.

[0042] The gas exchange unit may include a vascular network configured to conduct blood. The gas unit may include an airway section configured to hold oxygenated air. The vascular network may be in contact with the airway section to allow gas exchange and increase the oxygen content of blood passing through the vascular network. The gas exchange unit may have an interface between the vascular network and the airway section. The interface between the vascular network and the airway section has a diameter of 250 μm to 350 μm. The vascular network may include a lumen. The lumen of the vascular network may have a diameter of 350 μm to 450 μm. The lumen of the vascular network may have a diameter of 150 μm to 250 μm. The lumen of the vascular network may have a diameter larger than the diameter of the interface between the vascular network and the airway section. These dimensions are intended to be merely examples of the myriad possible dimensions for the gas exchange unit, and one of ordinary skill in the art will recognize that many alternatives may be used.

[0043] The biomimetic units may be formed in a variety of structures. Figures 6A-6D show examples of some of these structures. Figure 6A shows an embodiment where the structure is a capsule net. A capsule net may be defined as a complex vasculature network surrounding a capsule-like cavity that mimics an enlarged alveolar structure. Figure 6B shows an embodiment where the structure is a giant fisher. A giant fisher may be defined as a complex fisher shape with dense and complex vasculature inside. Figure 6A shows an embodiment where the structure is a fisher block. A fisher block may be defined as a denser vasculature of a fisher foam. Figure 6D shows an embodiment where the gas exchange unit has a cubic net structure. A cubic net may be defined as a small cubic cavity with a vasculature network around it. These structures are intended to be merely examples of a myriad of possible structures for evaluating cell seeding in complex structures, studying the interaction of 3D printed scaffolds with various cell types, and evaluating gas exchange.

[0044] The biomimetic unit may include a vascular network. The vascular network may be seeded with endothelial cells. The vascular unit may be configured to conduct blood. The biomimetic unit may include an airway compartment. The airway compartment may be seeded with cells, such as epithelial cells, e.g., small airway epithelial cells (SAECs). The airway compartment may be configured to hold air containing oxygen. The vascular network may be in contact with the airway compartment to enable gas exchange to increase the oxygen content of blood passing through the cell-seeded vascular network.

[0045] Figures 7A-7D show various embodiments of the system and method of application. Figure 7A shows the fluidic design of 3D printed vasculature with different structures. Figure 7B shows images of the formed vasculature and cells seeded on the airways. Figure 7C is a photograph of the microscope setup for imaging. Figure 7D is an example of a test setup where blood is perfused into the formed vasculature and gas is perfused into the formed airways.

[0046] Figure 8 shows a lung chip gas exchange unit design where the blood-air interface is fabricated with membranes made from different formulations, and Figure 9 shows a 3D printed lung chip design made with different bioink formulations.

[0047] The gas exchange unit may be 3D printed using the methods disclosed above. The gas exchange unit may be printed using a bio-ink. The gas exchange unit may be printed using an ink including one or more compounds selected from the group: polyethylene glycol, polyethylene glycol diacrylate, polyethylene glycol methacrylate, polyethylene glycol methyl ether, N,N'-Methylenebisacrylamide, and methacrylated collagen. The gas exchange unit may be printed using an ink including one or more compounds including methacrylated collagen, polyethylene glycol diacrylate, lithium phenyl-2,4,6-trimethylbenzophosphinate, UV386A dye, and 3-hydroxypropyl acrylate. This list is intended to be representative, and one of skill in the art will recognize that a variety of inks suitable for use in 3D printing are available now and in the future.

[0048] FIG. 10 shows a 2D gas exchange membrane chip and plots of gas exchange data, according to one embodiment. Once the gas exchange unit is formed, it may be subjected to testing to determine the amount of gas exchanged through the membrane. In this embodiment, a 325um PDMS and bioink spin-coated membrane was used. The vasculature gas exchange unit was perfused with blood. In this example, the change in oxygen concentration in the blood measured from the inlet of the gas exchange unit to the outlet of the gas exchange unit is compared using a 325um membrane and nitrogen as the inert gas. The results were compared to air at 37°C. The gas exchange results in FIG. 7B show that the gas exchange data is different using N2 and air.

[0049] FIG. 11 shows a biomimetic model perfused with whole blood of some embodiments. The biomimetic model may be formed using 3D printing. The biomimetic model may include a vascular compartment and an airway compartment. The vascular compartment and the airway compartment may be separated by a hydrogel wall. The lung-on-a-chip model may be perfused with whole blood. Deoxygenated blood may be perfused into the inlet of the vascular compartment, and air may be perfused into the airway compartment. Whole blood may be flowed into the vascular compartment. As the whole blood passes through the vascular compartment, it may absorb oxygen through gas exchange across the membrane wall separating the airway compartment. The amount of oxygen absorbed by the blood flowing through the vascular compartment may be measured by comparing the concentration of oxygen in the blood between the inlet and the outlet. This may be compared to the change in the amount of oxygen in the blood when nitrogen is flowed into the airway compartment. Four sets of measurements on a model component with a cube net structure and 200um lumen showed an average difference in measurements between the air test example and the nitrogen control.

[0050] 12A-12C show an embodiment of a printed lung-on-a-chip platform. FIG. 12A shows a schematic of an embodiment of an alveolar gas exchange unit. The schematic shows an embodiment of an airway compartment, blue region, surrounded by a vascular compartment, red region. The schematic shows an embodiment of a cubic net structure on top and a capsule net structure on bottom printed with 5-15% (w / w) PEGDA3400, 6-9% (w / w) PEG575, 1-3% (w / w) lithium phenyl-2,4,6-trimethylbenzoylphosphinate, and 0.13% (w / w) UV386A. FIG. 12B shows an embodiment of a 3D printed scaffold with blood and air perfusion in the vasculature. On top is an image of an embodiment of a cubic net structure with 5mm vessel diameter and 200um interface perfused with blood. At the bottom is an image of an embodiment of a capsule net structure with a blood perfusion vessel diameter of 15 mm and an interface of 200 um. The 3D printed scaffold was formed in the following manner: 5-15 (w / w)% PEGDA3400, 6-9 (w / w)% PEG575, 1-3 (w / w)% lithium phenyl-2,4,6-trimethylbenzoylphosphinate, and 0.13 (w / w)% UV386A. Figure 12C shows a plot of data of gas exchange across the 3D printed hydrogel obtained from the gas exchange unit imaged in Figure 8B. As can be seen, the structure and dimensions affect the amount of oxygen absorbed by the blood as it flows through the biomimetic device.

[0051] Figure 13 shows various biomimetic unit designs and a plot of the increase in blood oxygen content measured at the outlet of the unit compared to the oxygen content of blood measured at the inlet side of the unit. A physiological 100% oxygen transfer capacity is a 15% to 20% increase in oxygen, or 5 mL of O2 per dL of blood. 2The diameter and interface of the biomimetic models are defined as the change in the gas exchange rate. The Capsule Net, Giant Fisher, and Fisher Block represent biomimetic designs with different oxygen transfer capacity and gas exchange capacity levels. The lumen diameter of the biomimetic units varied from 200um to 500um in the vasculature. The interface between the vasculature and the airway was 400um. The bioink used in this study was 5% PEGDA6000, 10% 4-HBA (4-hydroxybutyl acrylate) 1.5% lithium phenyl-2,4,6-trimethylbenzoylphosphinate, and 0.1% UV386A. Changing the diameter and interface of these biomimetic models is expected to result in different amounts of gas exchange rates. As expected, the Fisher Block with the highest surface area will result in the highest amount of oxygen transfer capacity compared to the other scaffolds.

[0052] 14A-14F show 2D lung chips made of different materials and measured at multiple temperatures according to one embodiment. FIG. 14A shows a membrane-based gas exchange unit according to some embodiments. The unit is set up so that air can be infued into the vent compartment and blood can be infused into the vascular compartment. The oxygen content of this blood may be measured at the inlet and outlet of the vascular contents. Testing is completed with a multi-temperature water bath. FIG. 14B shows a membrane-based gas exchange unit with blood perfused inside. FIG. 14C shows a plot of gas exchange data for the collagen membrane at 25° C. FIG. 14D shows a plot of gas exchange data for the collagen membrane at 37° C. FIG. 14E shows a plot of gas exchange data for the PDMS membrane at 25° C. FIG. 14F shows a plot of gas exchange data for the PDMS membrane at 37° C. These results show that the gas exchange rate is significantly lower at 37° C. compared to 25° C. This is consistent with physiological predictions that hemoglobin tends to release oxygen at higher temperatures, resulting in a lower rate of gas exchange.

[0053] Figure 15 shows endothelial cell seeding in the biomimetic system under various cellularization conditions. Biomimetic scaffolds were 3D printed using the method described above. The materials were 8% PEGDA3400, 10% 3-hydroxypicolinic acid (3-HPA), 1% lithium phenyl-2,4,6-trimethylbenzoylphosphinate, and 0.1% UV386A. Using this platform, various cellularization conditions with different flow rates and cell densities seeded in different geometries were imaged. This illustration shows that the biomimetic system can be used to monitor the process of endothelization and the interaction of endothelial cells on 3D printed hydrogels.

[0054] 16A-16C show cell-free and cell-based gas exchange assays of some embodiments. FIG. 16A shows a schematic diagram of a capsule net model of some embodiments. The capsule net was fabricated from 5-15 (w / w)% PEGDA3400, 6-9 (w / w)% PEG575, 1-3 (w / w)% lithium phenyl-2,4,6-trimethylbenzoylphosphinate, and 0.13 (w / w)% UV386A. FIG. 16B shows human whole blood perfused into a cube net model under hypoxic conditions. The materials were 8% PEGDA2400, 10% 3-HPA, 1% lithium phenyl-2,4,6-trimethylbenzoylphosphinate, and 0.1% UV386A. FIG. 16C shows the gas exchange rates achieved in the cell-free and cell-based gas exchange assays compared to the control. The materials were 8% PEGDA2400, 10% 3-HPA, 1% Lithium Phenyl-2,4,6-trimethylbenzoylphosphinate, 0.1% UV386A. The structures had a 200 μm lumen. Endothelial cells were seeded at a flow rate of 100 μl min. The acellularized average was 0.0004 ml O2 / min ml tissue. The cellularized average was 0.00038 ml O2 / min ml tissue. As can be seen above, the addition of cells to the gas exchange assay resulted in differences in gas exchange between the cell-free and cell-based assays.

[0055] The gas exchange unit may be seeded with different types of cells. The gas exchange unit may be seeded on a membrane. The seeded cells may be pulmonary artery endothelial cells. The cells may be endothelial cells. The cells may be epithelial cells. The cells may be small airway epithelial cells.

[0056] Different cells may be seeded on different sides of the gas exchange unit membrane. For example, small airway epithelial cells (SAECs) may be seeded on one side of a biomaterial hydrogel scaffold and endothelial cells may be seeded on the other side of the biomaterial hydrogel scaffold. For example, SAECs may be seeded on the airway side of the biomaterial scaffold and endothelial cells may be seeded on the vascular side of the membrane.

[0057] The biomimetic units may be used in multiple applications as physiologically relevant models. For example, if the biomimetic unit is a synthetic lung, pharmaceutical compositions may be screened for efficacy of drugs against lung disorders. In other embodiments, lung toxicity testing may be performed on the system-on-chip device. The biomimetic units may be alternate organs such as kidney, liver, lung, colon, heart, or other organs. This list is intended to be illustrative and not exhaustive. These synthetic organs may be used in screening the toxicity or efficacy of drugs or other substances on the associated system-on-chip device. One of skill in the art will recognize that many synthetic organs may be generated in this manner and similar efficacy and toxicity testing may be performed using the techniques described herein.

[0058] Any reference herein to system and method implementations or elements or acts in the singular can include implementations that include a plurality of those elements, and any reference herein to implementations or elements or acts in the plural can include implementations that include only a single element. References in the singular or plural are not intended to limit the disclosed systems or methods, their components, acts, or elements to a single or multiple configuration. When an act or element is said to be based on information, acts, or elements, this may include implementations in which the act or element is based at least in part on the information, acts, or elements.

[0059] As used herein, the terms "approximately," "about," "substantially," and similar terms are intended to have a broad meaning consistent with common and accepted usage by those of ordinary skill in the art to which the subject matter of the present disclosure pertains. Those of ordinary skill in the art who review this disclosure should understand that these terms are intended to enable the description of certain features as described and claimed without limiting the scope of these features to the precise numerical ranges provided. These terms should therefore be interpreted as indicating that insubstantial or insignificant modifications or variations of the subject matter of the invention as described and claimed are considered to be within the scope of the present disclosure as set forth in the appended claims.

[0060] As used herein, the term "biomaterial" is intended to have a broad meaning consistent with common and accepted usage by those of ordinary skill in the art to which the subject matter of this disclosure pertains. Biomaterials may be natural and / or synthetic polymers. Biomaterials encompass other naturally occurring biological materials, as well as materials that are synthetically engineered to mimic biological materials. Such materials may include polymers, hydrogels, peptides, proteins, cellulose, sugars, and a variety of other materials known to those of ordinary skill in the art, whether derived from biological materials or synthetically formed.

[0061] It should be noted that the use of the word "exemplary" and variations thereof in describing various embodiments herein is intended to indicate that such embodiments are possible examples, representations, or illustrations of possible embodiments (nor is such wording intended to imply that such embodiments are necessarily particular or best examples).

[0062] As used herein, the term "coupled" and variations thereof mean that two components are directly or indirectly connected to each other. Such connection may be permanent (e.g., permanent or fixed) or movable (e.g., removable or releasable). Such connection may be achieved by two components being directly connected to each other, two components being connected to each other with a separate intervening component and any additional intermediate components that are connected to each other, or two components being connected to each other with an intervening component that is integral with one of the two components to form a single body. When "coupled" or variations thereof are modified by an additional word (e.g., directly coupled), the inclusive definition of "coupled" provided above is modified by the plain language meaning of the additional word (e.g., "directly coupled" means that two components are connected without a separate intervening component), resulting in a definition narrower than the inclusive definition of "coupled" provided above. Such coupling may be mechanical, electrical, or fluid.

[0063] This application incorporates by reference in its entirety: (a) U.S. Provisional Application No. 63 / 185,300, entitled “CONTROLLING THE SIZE OF 3D PRINTING HYDROGEL OBJECTS USING HDROPHILIC MONOMERS, HYDROPHOBIC MONOMERS, AND CROSSLINKERS,” filed on May 6, 2021, and U.S. non-provisional and / or PCT applications of the same title, filed on May 6, 2022; (b) U.S. Provisional Application No. 63 / 185,302, entitled “MODIFIED 3D-PRINTED OBJECTS AND THEIR USES,” filed on May 6, 2021, and U.S. non-provisional and / or PCT applications of the same title, filed on May 6, 2022; (c) U.S. Provisional Application No. 63 / 185,302, entitled “PHOTOCURABLE REINFORCEMENT OF 3D No. 63 / 185,305, entitled “ADDITIVE MANUFACTURING OF HYDROGEL OBJECTS” and U.S. non-provisional and / or PCT applications of the same title, filed on May 6, 2022; (d) U.S. Provisional Application No. 63 / 185,299, entitled “ADDITIVE MANUFACTURING OF HYDROGEL TUBE FOR BIOMEDICAL APPLICATIONS” and U.S. non-provisional and / or PCT applications of the same title, filed on May 6, 2021; (e) U.S. Provisional Application No. 63 / 185,299, entitled “USE OF FUNCTIONALIZED AND NON-FUNCTIONALIZED ECMS, ECM FRAGMENTS, PEPTIDES AND BIOACTIVE COMPONENTS TO CREATE CELL ADHESIVE 3D PRINTED No. 63 / 185,293, entitled "PROCESS FOR THE USE OF SUCH PRODUCTS IN AN IMPROVED MODEL AND SYSTEM FOR USE ...

[0064] Any implementation disclosed herein may be combined with any other implementation, and references to "an implementation," "several implementations," "alternate implementations," "various implementations," "an implementation," or the like are not necessarily mutually exclusive and are intended to indicate that a particular feature, structure, or characteristic described in connection with an implementation may be included in at least one implementation. Such terms, when used herein, do not necessarily all refer to the same implementation. Any implementation may be combined with any other implementation, inclusively or exclusively, in any manner consistent with the aspects and implementations disclosed herein.

[0065] The term "or" may be construed as inclusive, such that any group of words listed with "or" may refer to any one, more than one, or all of the listed words. At least one of a linked list of words may be construed as an inclusive or, referring to any one, more than one, or all of the listed words. For example, "at least one of 'A' and 'B'" may include only 'A', only 'B', and both 'A' and 'B'. Components other than 'A' and 'B' may also be included.

[0066] References herein to the location of components (e.g., "top," "bottom," "upper," "lower") are merely used to describe the placement of the various components in the figures. It should be noted that the placement of the various components may differ in other preferred embodiments, and that such variations are intended to be encompassed by the present disclosure.

[0067] Although the figures and description may illustrate a particular order of method steps, the order of such steps may differ from that shown and described unless otherwise specified above. Also, two or more steps may be performed simultaneously or with partial concurrence unless otherwise specified above. Such variations may depend, for example, on the software and hardware systems selected, and on the designer's choice. All such variations are within the scope of this disclosure. Similarly, software implementations of the described methods may be accomplished with standard programming techniques, with logic such as rule-based logic to accomplish the various connection, processing, comparison, and decision steps.

[0068] The systems and methods described herein may be embodied in other specific forms without departing from the spirit and scope of the invention, and the above implementations are intended to be illustrative and are not intended to be limiting of the systems and methods described.

[0069] When a reference sign follows a technical feature in a drawing, the detailed description, or any claim, the reference sign is included to enhance the clarity of the drawing, the detailed description, and the claims, and thus the presence or absence of a reference sign has no limiting effect on the scope of the claim element.

[0070] The systems and methods described herein may be implemented in other specific forms without departing from the characteristics thereof. The above implementation forms are for illustrative purposes only and do not limit the described systems and methods. Therefore, the scope of the systems and methods described herein is indicated by the appended claims, not the above description, and changes within the meaning and equivalent range of the claims are also encompassed by the invention.

[0071] Below are examples of the systems and methods disclosed herein. The following are merely examples, and one of ordinary skill in the art will readily recognize the myriad parameters that can be adapted with the disclosed systems and methods to optimize them for various applications. EXAMPLES

[0072] Example 1:

[0073] Bioink was formed by combining 5-15% (w / w) PEGDA3400, 6-9% (w / w) PEGDMA575, 1-3% (w / w) lithium phenyl-2,4,6-trimethylbenzoylphosphinate, and 0.13% (w / w) UV386A by slowly mixing PEGDA3400 in deionized water and adding PEGDMA575. 1.5% (w / w) lithium phenyl-2,4,6-trimethylbenzoylphosphinate was added to the solution and mixed thoroughly. UV386A dye was added to the solution and mixed. The bioink was placed in the vat of a custom 3D printer from 3DSYSTEMS Corp.

[0074] A custom designed 3D printed microfluidic component holder was used, as shown in FIG. 17. The microfluidic component holder was printed using a commercially available plastic resin and a Formlab printer. A hydrogel microfluidic component was printed on a custom 3D Systems bioprinter and placed into the microfluidic component holder. Each embodiment of the 3D printed microfluidic component was formed using various developed inks. As an example, in one embodiment, the ink was composed of 5-15 (w / w)% PEGDA3400, 6-9 (w / w)% PEGDMA575, 1-3 (w / w)% lithium phenyl-2,4,6-trimethylbenzoylphosphinate, and 0.13 (w / w)% UV386A, mixed in a SpeedMixer at 200 rpm for 3 minutes.

[0075] The ink was poured into a vat of a 3D printer, which was specifically manufactured and designed for hydrogel 3D printing. An embodiment of the system and method used is discussed in U.S. Patent Application Publication No. 63 / 069317, filed August 24, 2020, which is incorporated by reference. The microfluidic components were printed with photopolymerization ink. The bioink was printed by a multilayer photopolymerization method. The structure of the printed scaffold was a capsule net with dimensions of 4 mm x 3 mm x 14 mm.

[0076] The scaffolds were seeded with various cells (ATCC cell lines, Manassas, VA, USA), including pulmonary artery endothelial cells (PAEC) on the vasculature side and alveolar epithelial cells on the airway side. These cells were seeded at a flow rate of 30ul / min for 6 hours, followed by perfusion with buffer for 4 days.

[0077] The scaffold was tested by perfusing blood from one side and air from the other. 2 Deoxygenated blood with a value of 50% was perfused from one side, and the amount of oxygenation was recorded from the other side. The blood flow rate was set at 200ul / min, and blood was collected before and after passing through the biomimetic system. The levels of each gas in the blood were measured using a Radiometer blood analyzer.

[0078] Example 2:

[0079] The gas exchange unit was fabricated using the 3D printing technique described herein. The capsule net structure was made of 602N material with a diameter of 20um and 385nm. The fabricated chip was placed in a 37C incubator. 100mL of horse blood was obtained and oxygenated / deoxygenated to approximately 100μm. 2 The vasculature of the chip was then infused with horse blood, and nitrogen or air was flushed through the airways of the chip.

[0080] FIG. 18A shows the capsule net structure design of the gas exchange unit used in the samples of Example 2.

[0081] FIG. 18B shows an image of the setup of a temperature-regulated gas exchange unit with blood inlets and outlets for chips 1-5.

[0082] Figure 19A shows an image of the chip 1 setup. The air / nitrogen inlet was attached at 0.5 psi pressure and the chip was perfused using a gas flow rate of 200 ul / min. Figure 19B shows a comparison of blood oxygen content measurements of blood at the outlet of the chip when air was flushed through the airways and when nitrogen was flushed through the airways. As can be seen, gas transfer was significant in both the air and nitrogen cases.

[0083] Figure 20A shows an image of chip 2 setup, printed and set up similarly to chip 1. Figure 20B shows a comparison of blood oxygen content measurements of blood at the outlet of the chip when air is flushed through the airway and when nitrogen is flushed through the airway. As can be seen, gas transfer was significant in both the air and nitrogen cases. There were some batch differences between chip 1 and chip 2.

[0084] Figure 21A shows an image of chip 3, set up similarly to chip 1. Figure 21B shows a comparison of blood oxygen content measurements of blood at the outlet of the chip when air is flushed through the airways and when nitrogen is flushed through the airways. The gas exchange results were striking in both the air and nitrogen cases. The air results are in very good agreement with chip no. 1 under similar conditions.

[0085] Figure 22A shows an image of chip 4, set up similarly to chip 1. Figure 22B shows a comparison of blood oxygen content measurements of blood at the outlet of the chip when air and nitrogen are flowing through the airways. As can be seen, gas transport was again significant in both the air and nitrogen cases.

[0086] FIG. 23A shows an image of the chip 5 setup. Chip 5 was set up similarly to chip 1, but a higher flow rate of 400 ul / min was used to perfuse the chip. FIG. 23B shows a comparison of blood oxygen content measurements of blood at the outlet of the chip when air was flowing through the airways and when nitrogen was flowing through the airways. The higher flow rate of 400 uL / min did not result in significant oxygen and nitrogen gas transfer compared to the no ventilation case, and was significantly worse than the 200 uL / min sample. This is likely due to the blood not having enough time for diffusional transfer.

[0087] While preferred embodiments have been illustrated and described, it will be understood that variations and modifications can be made therein, in accordance with ordinary skill in the art, without departing from the invention in its broader aspects as defined herein.

[0088] All references disclosed herein are specifically incorporated by reference.

Claims

1. (a) a vascular network configured to conduct a fluid; and (b) an airway section configured to retain a gas; A biomimetic unit comprising: the vascular network is in contact with the airway segment to allow gas exchange between the gas and the fluid, and each of the vascular network and the airway segment comprises a polymeric scaffold; a diameter of the interface between the vascular network and the airway segment of between 250 μm and 350 μm; The diameter of the lumen of the vascular network is 350 μm to 450 μm, and The biomimetic unit, wherein the polymer scaffold comprises polyethylene glycol diacrylate having a molecular weight of 3400 Da and polyethylene glycol methacrylate having a molecular weight of 575 Da.

2. The biomimetic unit of claim 1 , wherein the fluid is blood.

3. The biomimetic unit of claim 1 , wherein the gas comprises oxygen.

4. The biomimetic unit of claim 1 , wherein the polymeric scaffold of the vascular network is seeded with pulmonary artery endothelial cells.

5. The biomimetic unit described in claim 1, wherein each of the polymeric scaffolds of the vascular network and the airway compartment is a hydrogel scaffold.

6. The biomimetic unit of claim 1 , wherein the diameter of the lumen of the vascular network is equal to or greater than the diameter of the interface between the vascular network and the airway segment.

7. An artificial lung comprising a cellular or acellular gas exchange unit which is a biomimetic unit as described in claim 1.

8. A method for forming a gas exchange unit, the method comprising printing a gas exchange unit including a vascular network configured to conduct a fluid and an airway compartment configured to hold a gas, wherein the vascular network contacts the airway compartment to enable gas exchange between the fluid and the gas.

9. The biomimetic unit of claim 1 , wherein the polymer scaffold comprises one of collagen and gelatin.

10. The biomimetic unit of claim 1, wherein the polymer scaffold is seeded with cells.

11. The biomimetic unit of claim 10 , wherein the cells are endothelial cells, epithelial cells, fibroblasts, or smooth muscle cells.

12. 2. The biomimetic unit of claim 1, wherein small airway epithelial cells (SAECs) are seeded on one side of the biomaterial hydrogel scaffold and endothelial cells are seeded on the other side of the biomaterial hydrogel scaffold.

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