The utility of cold-preserved human hepatocytes in studies on cytochrome P450 induction and hepatic drug transport

Cold Preservation of Human Hepatocytes with High Viability

Freshly isolated human hepatocytes are an important model for translational research, validation of experiments done in animals, and preclinical studies. Human hepatocyte isolation often cannot be carried out easily on demand in common research laboratories, and researchers often collaborate to share hepatocytes or outsource hepatocyte isolations. As a prerequisite for such a strategy, hepatocytes have to maintain their phenotypes after transport. Therefore, this study aimed to determine if overnight storage or shipment of hepatocytes affects their quality when viability, adherence, and cytochrome P450 (CYP) activities are considered. Hepatocytes were stored overnight or shipped to a collaborator in a cold storage solution on wet ice. On the next day, viability of hepatocytes was assessed before plating the cells to determine adherence. Hepatocytes were also cultured in a sandwich culture to determine CYP activities and inducibility. The results showed that although viability (79% ± 0.7% on isolation) was significantly decreased by overnight storage or shipment by 11% (p < 0.001) or 15% (p < 0.001), respectively, the viability of hepatocytes the next day at above 64% ± 2.2% remained sufficiently high for further experiments. In addition, hepatocytes stored for 18 or 24 hours were adherent the next day, and a high confluence of 81% ± 10% to 91% ± 4% was achieved after 48 hours in culture when hepatocytes were adhered on collagen-coated plates. Furthermore, CYP enzyme activities were inducible and not affected by variables such as fibrosis, age, type of operation, steatosis, and body mass index. However, our data would suggest that the type of cancer (primary/secondary), sex (male/female), hypertension, glutamic oxaloacetic transaminase activity, partial thromboplastin time, and size of perfused liver had significant effects (p < 0.05) on induction of some CYP enzymes. In conclusion, human hepatocyte isolation can be carried out at a centralized site and shared between multiple researchers, increasing flexibility and access to a representative human liver in vitro model.