Nutrient environment improves drug metabolic activity in human iPSC-derived hepatocytes and HepG2

Abstract

Induced pluripotent stem cells (iPSCs) have emerged as a transformative tool in regenerative medicine, in liver research. The perspective of a stable and functional source of hepatocytes has led to developing protocols for human iPSC-derived hepatocytes-like cells (HLCs). Yet, hepatic models remain one of most challenging systems to functionally reproduce with iPSCs, due to its resulting limited metabolic function. Using an adapted nutrient regimen, two human hepatocyte models were characterized: HLCs (derived from iPSCs) and metabolically active HepG2 (mHepG2, derived from the cell line HepG2), for their drug metabolism activity. In these cell systems, the transcriptome, proteome, and metabolome of 11 drug-relevant cytochrome P450 (CYP) isoenzymes were studied. A liquid chromatography-mass spectrometry (LC-MS)-based metabolomics approach, using model drugs as isoenzyme reporters, was applied, achieving a comprehensive overview of mHepG2 and HLCs drug metabolism. Drugs used in this study to characterize xenobiotic machinery were: bupropion (25 µM), phenacetin (30 µM), rosiglitazone (10 µM), diclofenac (75 µM), dextromethorphan (15 µM), chlorzoxazone (60 µM), midazolam (15 µM), benzydamine (15 µM), coumarin (250 µM) and 7-ethoxycoumarin (60 µM). Being HepG2 notorious for its limited metabolic capacity, our study raises mHepG2 as a highly performant cell model, with activity on 8 drug-metabolizing CYPs. Modulation by nutrient environment in improving metabolic function of in vitro models is here proven as a key determinant. Likewise, HLCs hold the widest CYP coverage at the transcript level and were able to cope with a wide variety of chemical insults, making them a promising model for personalized metabolic studies.

Keywords: Cytochrome P450 (CYP); Drug metabolism; Induced pluripotent stem cells (iPSCs); LC–MS; Liver; Metabolomics.