Morphological and Functional Characterization and Assessment of iPSC-Derived Hepatocytes for<i>In Vitro</i>Toxicity Testing

Drug-induced liver injury (DILI) remains a great challenge and a major concern during late-stage drug development. Induced pluripotent stem cells (iPSC) represent an exciting alternative in vitro model system to explore the role of genetic diversity in DILI, especially when derived from patients who have experienced drug-induced hepatotoxicity. The development and validation of the iPSC-derived hepatocytes as an in vitro cell-based model of DILI is an essential first step in creating more predictive tools for understanding patient-specific hepatotoxic responses to drug treatment. In this study, we performed extensive morphological and functional analyses on iPSC-derived hepatocytes from a commercial source. iPSC-derived hepatocytes exhibit many of the key morphological and functional features of primary hepatocytes, including membrane polarity and production of glycogen, lipids, and key hepatic proteins, such as albumin, asialoglycoprotein receptor and α1-antitrypsin. They maintain functional activity for many drug-metabolizing enzyme pathways and possess active efflux capacity of marker substrates into bile canalicular compartments. Whole genome-wide array analysis of multiple batches of iPSC-derived cells showed that their transcriptional profiles are more similar to those from neonatal and adult hepatocytes than those from fetal liver. Results from experiments using prototype DILI compounds, such as acetaminophen and trovafloxacin, indicate that these cells are able to reproduce key characteristic metabolic and adaptive responses attributed to the drug-induced hepatotoxic effects in vivo. Overall, this novel system represents a promising new tool for understanding the underlying mechanisms of idiosyncratic DILI and for screening new compounds for DILI-related liabilities.