Two-dimensional cell culture and animal models inadequately represent human pharmacokinetics and diseases like inflammatory bowel disease and colorectal cancer. This means missed diagnostic and therapeutic opportunities, high drug attrition rates, and a portfolio of approved drugs that underdeliver the desired benefits to patient outcomes. This encourages the development of a more physiologically relevant intestine model. The objective of this work was to develop a 384-well plate organ-on-a-chip platform, IFlowPlateTM, that can accommodate up to 128 human intestine models with accessible lumens and perfusable branched vasculature in an ECM environment. Fibrin-Matrigel® was used a structurally supportive and biologically instructive substrate that enabled: (1) prolonged cell culture (at least 15 days) with routine refreshment of aprotinin-supplemented medium, (2) formation of a confluent Caco-2 monolayer with barrier function, and (3) de novo assembly of a vascular network with barrier function. A fluorescent dextran permeability assay was used for in situ real-time measurements of epithelial barrier function in a high-throughput manner. Mixed co-culture of endothelial cells and fibroblasts in fibrin-Matrigel® resulted in the formation of an interconnected network of patent vessels that retained an albumin surrogate tracer within the luminal space indicating endothelial barrier function. To improve the success rate of anastomoses between living vessels and fluidic channels, the modification of inherently hydrophobic PDMS and polystyrene culture surfaces with ECM protein was explored. To address the limitations of a cancer cell line-derived intestine model, the replacement of Caco-2 cells with biopsied-derived colon organoid cells was investigated. Different gel formulations were assessed for their ability to induce colon organoid fragments to form monolayers. Finally, the incorporation of multiscale intestinal topography and luminal flow was considered through a modified approach to plate fabrication, whereby moulded alginate is embedded in ECM and sacrificed to generate a scaffold. Work to make the moulded alginate more robust is presented. / Thesis / Master of Applied Science (MASc) / Two-dimensional cell culture and animal models inadequately represent human drug metabolism and diseases like inflammatory bowel disease and colorectal cancer. The objective of this work is to develop a more physiologically relevant human intestine model. Using fabrication techniques pioneered by the semiconductor industry, a custom organ-on- a-chip platform in the format of a 384-well plate was developed. This platform is compatible with standard laboratory equipment and practices and can accommodate up to 128 human intestine models comprised of the intestinal epithelium and associated network of blood vessels. In this platform, the cells of the intestinal epithelium and vasculature are supported by a network of natural proteins. This allows processes like vessel growth to be modelled in this platform. Vessel growth plays a key role in the progression of inflammatory bowel disease and cancer, and this model could help scientists better understand these diseases.

This thesis presents a microfluidic strategy for the in-flow definition of a 3D soft material with a tunable and perfusable microstructure. The strategy was enabled by a microfluidic device containing up to fifteen layers that were individually patterned in polydimethylsiloxane (PDMS). Each layer contained an array of ten to thirty equidistantly spaced microchannels. Two miscible fluids (aqueous solutions of alginate and CaCl2) were used as working fluids and were introduced into the device via separate inlets and distributed on chip to form a complex fluid at the exit. The fluid microstructure was tuned by altering the flow rates of the working fluids. Upon solidification of alginate in the presence of calcium chloride, the created microstructure was retained and a soft material with a tunable microstructure was formed. The produced material was subsequently perfused using the same microfluidic architecture. The demonstrated strategy potentially offers applications in materials science and regenerative medicine.

This thesis presents a microfluidic strategy for the in-flow definition of a 3D soft material with a tunable and perfusable microstructure. The strategy was enabled by a microfluidic device containing up to fifteen layers that were individually patterned in polydimethylsiloxane (PDMS). Each layer contained an array of ten to thirty equidistantly spaced microchannels. Two miscible fluids (aqueous solutions of alginate and CaCl2) were used as working fluids and were introduced into the device via separate inlets and distributed on chip to form a complex fluid at the exit. The fluid microstructure was tuned by altering the flow rates of the working fluids. Upon solidification of alginate in the presence of calcium chloride, the created microstructure was retained and a soft material with a tunable microstructure was formed. The produced material was subsequently perfused using the same microfluidic architecture. The demonstrated strategy potentially offers applications in materials science and regenerative medicine.

Les maladies cardiovasculaires sont une des causes de mortalités les plus élevées mondialement. Parmi celles-ci, on retrouve l’infarctus du myocarde, qui n’a pour traitement que la transplantation cardiaque. Or, dû à la faible quantité de donneur, une solution alternative est recherchée. De ce fait, l’ingénierie tissulaire permet le développement de tissus et d’implants thérapeutiques tels les patchs cardiaques, qui peuvent être bioimprimés. Or, une des limitations actuelles de l’utilisation d’une telle stratégie est la vascularisation de tissu bioimprimés. Dans cette étude, la bioimpression 3D a été utilisée afin de bioimprimer des patchs perfusables de gélatine méthacrylate (GelMA) à utiliser potentiellement pour le tissu cardiaque. Il a été possible de développer une bioencre pouvant être utilisée pour une application dans le tissu cardiaque, d’évaluer l’imprimabilité de l’encre et de bioimprimer de patchs standards et perfusables. Pour ce faire, GelMA a été synthétisé et les propriétés mécaniques ont été évaluées pour finalement sélectionner une encre de 10 % GelMA, ayant un module de Young approprié pour le tissu cardiaque, de 23,7±5,1 kPa. Par la suite, les processus d’impression, standard et coaxial, de patchs standards et perfusables ont pu être optimisés. Finalement, des patchs perfusables de GelMA 10% et gélatine 2% ont pu être imprimés avec une viabilité cellulaire élevée, jusqu’à 79,7±8,7 % et 83,5±5,7 % obtenue aux jours 1 et 7 de culture respectivement, avec des fibroblastes 3T3. La présence de canaux vides et la perfusabilité des patchs démontrent le potentiel de cette méthode pour éventuellement bioimprimer des patchs cardiaques vascularisés épais. / Cardiovascular diseases are a leading cause of death worldwide. Myocardial infarction captures a significant segment of this population, and the end-stage myocardial infarction can only be treated by heart transplantation. However, due to the scarcity donors, tissue engineering has been considered as an alternative solution. Tissue engineering allows the development of tissues and therapeutic implants such as cardiac patches. However, one of the main hurdles in the use of such a strategy is the vascularization of bioprinted tissue. In this study, 3D bioprinting was used to bioprint perfusable gelatin methacrylate (GelMA) patches for a potential use in cardiac tissue. This work consists in the development of a bioink that can be used for the cardiac tissue, the evaluation of the printability of the ink, and the final bioprinting of standard and perfusable patches. For this purpose, GelMA was synthesized and a final concentration of 10 % was selected as it showed an appropriate Young's modulus for cardiac tissue, of 23.7±5.1 kPa, while maintaining high biocompatibility. Subsequently, the printing process of standard and perfusable patches could be optimized with the use of GelMA and gelatin inks. Finally, 10% GelMA and 2% gelatin vascularized patches could be printed with high cell viability, of up to 79,7±8,7 % and 83,5±5,7 % on days 1 and 7 of culture respectively for 3T3 fibroblasts. Additionally, the presence of hollow channels of the perfusable patches demonstrates the potential of this method to be eventually applied to the bioprinting of thick vascularized cardiac patches.