Human induced pluripotent stem cell-derived hepatocytes for toxicology testing.

The need for more predictive in vitro toxicity models is a critical deficit in current preclinical pipeline safety evaluations. Current models employing tumor-derived cancer cell lines and isolated primary human hepatocytes (PHHs) afford an approximation of overt cytotoxicity but do not provide hepatotoxicity prediction owing to liabilities in metabolic activity along with phenotypic variability and instability in culture. Induced pluripotent stem cell-derived hepatocytes (iPSC-HCs) offer a long-term solution to accessing liver tissue from representative diverse as well as idiosyncratic patient populations and can be sourced indefinitely. iPSC-HCs are currently being evaluated as potential replacements for the existing cell models, but they have yet to prove superiority. It is acknowledged that iPSC-HCs are not functionally equivalent to PHHs and are somewhat mixed in terms of their gene expression profile, simultaneously displaying mature and immature markers in vitro. Combining iPSC-HCs with organotypic culture systems affords an opportunity to maximize the potential of both technologies where the cells benefit from more complex culture conditions while unlocking the potential of the culture systems by affording stability and reproducibility to provide the future of predictive in vitro toxicity models.