Design of Engineered Substrates to Modulate Human Liver Cell Phenotype for Disease Modeling

Suitable cell sources and mimicking in vivo environmental cues are two main factors to generate engineered human liver models that can be used to investigate liver pathologies and systematically screen drugs. Therefore, we seek to use three main cell sources (primary cells, cell lines, and induced pluripotent stem cell [iPSC]-derived cells) to develop functional human liver models for drug screening and disease modeling. To begin, we aim to use one popular cell line, HepaRG, for drug screening. HepaRG monocultures are not suitable for drug screening due to their low hepatic functions and lower sensitivity for hepatotoxicity relative to primary human hepatocytes (PHHs). A culture platform that can stabilize and improve HepaRG functions is needed. Micropatterned cocultures (MPCCs), with hepatocytes on patterned collagen islands surrounded by supportive 3T3-J2 murine fibroblasts, have been shown to maintain high and stable hepatic functions for several weeks and have been used for disease modeling and hepatotoxic drug prediction. Thus, we plan to adapt HepaRG into the MPCC platform to improve functions long-term for drug screening. In addition, iPSC-derived cells can provide a diverse genetic background but are similarly limited by low functions, and thus, we aim to establish a functional human liver model using MPCC with three main liver cell types (hepatocyte, endothelial cell, and macrophage) derived from iPSCs that can be used to evaluate different responses from cell types for drug development. In addition, to reproduce complex cell-ECM interactions found in vivo, we used natural ECM-based electrospun nanofibers to create functional liver models with PHHs and/or 3T3-J2 fibroblasts. Finally, as an application of our liver models, we explored the effects of liver cancer secretions on PHHs. Tumor cells can affect non-cancerous cells’ phenotypes. However, the effect of liver cancer secretions on non-cancerous hepatocytes in drug metabolism is unclear. Therefore, we aim to investigate the effect of liver cancer secretion by using PHH MPCC as a non-cancerous hepatocyte model. Ultimately, the three main cell sources explored here can be useful for drug screening and/or disease modeling within the MPCC platform. Moreover, electrospun nanofibers can be used to create functional liver models with a more physiologically relevant ECM topography. Overall, this thesis will lead to the engineering of functionally improved human liver models for different stages of the drug development pipeline and basic science investigations.