Optimisation of the HepaRG cell line model for drug toxicity studies using two different cultivation conditions: advantages and limitations.

The HepaRG cell line represents a successful model for hepatotoxicity studies. These cells are of human origin and are differentiated in vitro into mature and functional hepatocyte-like cells. The objective of this research was to compare two different culture protocols, Sison-Young et al. 2017 (hereinafter referred as Sison) and Gripon et al. 2002 (hereinafter referred as Biopredic) for HepaRG cells in order to optimise this model for drug metabolism and toxicity testing studies. HepaRG cells obtained from the same batch were cultured according to the described protocols. Using both protocols, differentiated HepaRG cells retained their drug metabolic capacity (major phase I/II enzymes) and transporters, as well as their morphological characteristics. Morphologically, HepaRG cells cultured after the Biopredic protocol formed more apical membranes and small ductular-like structures, than those cultivated using the Sison protocol. Also, the efflux activity of multidrug resistance protein 1 (MDR1) and multidrug resistance-associated protein 1 (MRP1) as well as the activity of uridine-glucuronosyltransferase (UGT) and glutathione S-transferase (GST) were significantly reduced in HepaRG cultured using the Sison protocol. Applying well-established drug cocktails to measure cytochrome P450 (CYPs) activity, we found that production of the corresponding metabolites was hampered in Sison-cultured HepaRG cells, indicating that the activity of CYP1A2, CYP2C9, CYP3A4, CYP2B6 and CYP2C19 was significantly reduced. Moreover, HepaRG sensitivity to well-known drugs, namely diclofenac, amiodarone, imipramine and paracetamol, revealed some differences between the two culture protocols. Furthermore, the HepaRG cells can be maintained with higher viability and sufficient CYPs activity and expression (i.e. CYP3A4, CYP1A2 and CYP2B6) as well as liver-specific functions, using Biopredic compared with the Sison culture protocol. These maintained liver-specific functions might be dependent on the prolongation of the culture conditions in the case of the Biopredic protocol. In conclusion, based on the metabolic activity of HepaRG cells using the standard protocol from Biopredic, we believe that this protocol is optimal for investigating drug metabolism and pharmacokinetic screening studies.