Human hepatic HepaRG cells maintain an organotypic phenotype with high intrinsic CYP450 activity/metabolism and significantly outperform standard HepG2/C3A cells for pharmaceutical and therapeutic applications

Conventional in vitro human hepatic models for drug testing are based on the use of standard cell lines derived from hepatomas or primary human hepatocytes (PHHs). Limited availability, inter-donor functional variability and early phenotypic alterations of PHHs restrict their use; whilst standard cell lines such as HepG2 lack a substantial and variable set of liver-specific functions such as CYP450 activity. Alternatives include the HepG2-derivative C3A cells selected as a more differentiated and metabolically active hepatic phenotype. Human HepaRG cells are an alternative organotypic co-culture model of hepatocytes and cholangiocytes reported to maintain in vivo-like liver-specific functions, including intact Phase 1-3 drug metabolism. In this study, we compared C3A and human HepaRG cells using phenotypic profiling, CYP450 activity and drug metabolism parameters to assess their value as hepatic models for pre-clinical drug testing or therapeutics. Compared with C3As, HepaRG co-cultures, exhibit a more organotypic phenotype, including evidence of hepatic polarity with strong expression of CYP3A4, the major isoform involved in the metabolism of over 60% of marketed drugs. Significantly greater CYP450 activity and expression of CYP1A2, CYP2E1 and CYP3A4 genes in HepaRG cells (comparable with that of human liver tissue) was demonstrated. Moreover, HepaRG cells also preferentially expressed the hepatic integrin α5β1 – an important modulator of cell behaviour including growth and survival, differentiation and polarity. Drug metabolite profiling of phenacetin (CYP1A2) and testosterone (CYP3A4) using LC-MS/MS and HPLC, respectively, revealed HepaRGs had more intact (Phase 1-2) metabolism profile. Thus, HepaRG cells significantly outperform C3A cells for potential pharmaceutical and therapeutic applications.