Three major barriers inhibit current research in human drug screening: experimental in vivo interventions in people have unacceptable risks; in vitro models of human tissue are primitive; and, non- human animal models are not directly comparable to humans. However, currently there is no in vitro platform that recapitulates physiological microenvironments using human induced pluripotent stem cells (hiPSC). Here we demonstrated hiPSC-derived hepatocytes (hiPSC-HPs)-based organs on chip, consisting of three functional components: a cell culture pocket, an endothelium-like perfusion barrier, and a nutrient transport channel acting as a capillary. A high fluidic resistance-based microfluidic endothelium-like barrier physically separates the cell culture and nutrient transport compartments. Our design allows continuous perfusion, high-throughput formation of microtissue amenable to continuous monitoring and sampling by determining a set of device parameters and cell seeding options. Cell loading was optimized to achieve high cell density and viability (>95%) right after seeding into microdevices. We also found that a high cell concentration (~10 million cells/mL) was critical for high loading quality. We validated and tested the hiPSC- HPs- based liver-on-a-chip platform for long-term functionality of the liver tissue (4 weeks), by measuring hepatocytes Albumin secretion, in the absence of coculturing with non-parenchymal cells. Also hiPSC-HPs are co-cultured with fibroblasts, T3T-J2 cells, to enhance the longevity of hepatocytes to more than 4 weeks. It was confirmed that the model is suitable for drug toxicity screening and validates the liver tissue model’s response by investigating Cytochromes P450 (CYPs) enzymes activities, specifically CYP 3A4 and 1A2, the most active drug metabolizing CYPs, using Promega P450-Glo™ Assays. Our liver-on-a-chip platform addresses the need of having a suitable in vitro liver model recapitulating the physiological functions and drug responsiveness of the liver for drug development, and disease modeling applications.
Project end date: 08/26/15