Integration of photo-reactive hydrogels for spatially organized 3D cultures housed in a microfluidic chip

The research presented in this thesis was conceived as a result of the recent focus on the development of organ-on-chip technologies; platforms that aim to emulate at least part of human biology under a controlled environment. These platforms have the long-term goal to serve as a complementary tool to study organ function, model disease, test novel drugs, and personalized medicine. While models of various organs have been developed, the lymph node (LN) remains unexplored. Given the important role that the LN plays in immunity, it is vital that a robust model is included amongst all other organs. When considering factors that would create a biomimetic model of the LN both (1) spatial organization and (2) fluid flow control were deemed critical; however, techniques to spatially arrange 3D cultures of primary cells inside microfluidic devices had been limited. This dissertation provides the foundation on how to establish a robust method of micropatterning cell-laden hydrogels on-chip and further, it explores ways in which different biomaterials behave under culture conditions. The work will be discussed in two main chapters, followed by a discussion of the necessary next steps to achieve immune function on-chip and the vision for subsequent experiments. Chapter 2 discusses the importance of a multi-assay approach for quality control gelatin-based photo-patternable materials, in order to achieve reproducible results without extensive troubleshooting with every new batch of hydrogel produced. Chapter 3 provides a detailed account of all necessary components that were optimized to establish a robust photo-patterning set-up, how it was used to assess the performance of gelatin-methacryloyl and gelatin-thiol hydrogels, and investigates how spatial configurations impact the viability of CD4 T cells. Finally, Chapter 4 will establish the need and approaches to enhance immune cell function within the micropatterned cultures and describes the plans to use spatial organization as a means to establish and test T-B cell interactions. The work that has been developed and presented in this dissertation will also be useful for the refinement of organ-on-chip platforms to achieve simultaneous control over cellular distribution, local matrix composition, and fluid flow during studies of organized cell-cell interactions in 3D culture.