The gold standard for human drug metabolism studies is primary hepatocytes. However, availability is limited by donor organ scarcity. Therefore, efforts have been made to provide alternatives, e.g., the hepatocyte-like (NeoHep) cell type, which was generated from peripheral blood monocytes. In this study, expression and activity of phase I and phase II drug-metabolizing enzymes were investigated during transdifferentiation of NeoHep cells and compared with primary human hepatocytes. Important drug-metabolizing enzymes are cytochrome P450 isoforms (CYP1A1, 1A2, 2A6, 2B6, 2C8, 2C9, 2D6, 2E1, and 3A4), microsomal epoxide hydrolase 1, glutathione S-transferase A1 and M1, N-acetyltransferase 1, NAD(P)H menadione oxidoreductase 1, sulfotransferase 1A1, and UDP-glucuronosyltransferase 1A6. Monocytes and programmable cells of monocytic origin expressed only a few of the enzymes investigated. Throughout differentiation, NeoHep cells showed a continuously increasing expression of all drug-metabolizing enzymes investigated, resulting in stable basal activity after approximately 15 days. Fluorescence-based activity assays indicated that NeoHep cells and primary hepatocytes have similar enzyme kinetics, although the basal activities were significantly lower in NeoHep cells. Stimulation with 3-methylcholanthrene and rifampicin markedly increased CYP1A1/2 or CYP3A4 activities, which could be selectively inhibited by nifedipine, verapamil, ketoconazole, and quercetin. Our data reveal similarities in expression, activity, induction, and inhibition of drug-metabolizing enzymes between NeoHep cells and primary human hepatocytes and hence suggest that NeoHep cells are useful as an alternative to human hepatocytes for measuring bioactivation of substances.     «

The gold standard for human drug metabolism studies is primary hepatocytes. However, availability is limited by donor organ scarcity. Therefore, efforts have been made to provide alternatives, e.g., the hepatocyte-like (NeoHep) cell type, which was generated from peripheral blood monocytes. In this study, expression and activity of phase I and phase II drug-metabolizing enzymes were investigated during transdifferentiation of NeoHep cells and compared with primary human hepatocytes. Important dr...     »