Multiscale Human Liver Platforms for Disease Modeling, Drug Development, and Regenerative Medicine

The liver is responsible for a wide assortment of functions (i.e., albumin synthesis, bile production, glucose and fatty acid metabolism, detoxification of drugs), which can be severely compromised by several diseases. Specifically, due to over-nutrition in the western world, non-alcoholic fatty liver disease (NAFLD) affects ~1/3 of the US population and is characterized by lipid accumulation (steatosis). Steatosis predisposes patients to develop detrimental complications, including insulin resistance, inflammation, fibrosis, cirrhosis, and hepatocellular carcinoma (HCC), which requires liver transplant. Currently, there are no therapies to reverse NAFLD and there is a severe shortage of donor organs; thus, there is a need to develop models to screen for efficacious compounds to cure NAFLD and engineer human liver tissues for transplantation. Due to significant differences between animals and humans in disease pathways, in vitro models of the human liver using primary human hepatocytes (PHHs) are most suitable for mimicking NAFLD disease profile for novel drug discovery and engineering implantable tissues for patients. Since conventional PHH monocultures display a dramatic phenotypic decline, a variety of engineering tools have been developed to modulate the PHH microenvironment in order to stabilize/enhance function; however, such models still have significant limitations for modeling NAFLD and fabricating implantable tissues. Thus, there remains a need to further develop human liver platforms for our desired applications. The goal of this dissertation is to test our novel hypothesis that in vitro human liver platforms can be developed with a focus on innovative biomaterials and microfabrication strategies, which can be used for NAFLD therapy or implantation. To test our hypothesis, we determined the utility of silk scaffolds for long-term PHH culture with varying microenvironment and NPC stimulation. Then, we utilized a multicellular micro-patterned model and developed a novel droplet microfluidic platform to generate microscale liver constructs in order to elucidate the role of key dietary/inflammatory triggers on liver dysfunctions toward developing a NAFLD drug discovery platform. Our studies and engineered in vitro human liver models will provide important advances to the scientific community for applications in discovering novel molecular targets for NAFLD and implantable human liver tissues.