Long-term maintenance of functional primary human hepatocytes using small molecules.

The immediate deterioration of primary human hepatocytes (PHHs) during culture limits their utility in drug discovery studies. Here, we report that a cocktail of four small molecule signaling inhibitors, termed YPAC, is useful for maintaining various hepatic functions of PHHs, including albumin and urea productivity, glycogen storage, and cytochrome P450 (CYP) expression. Most importantly, we found that YPAC allows PHHs to retain enzymatic activities of CYP1A2, CYP2B6, and CYP3A4 even after 40 days of culture, and that inducibility of CYP3A4 activity in response to the prototypical inducers rifampicin and phenobarbital is also maintained. Our novel approach could facilitate drug discovery studies.