Utility of human hepatocyte spheroids for evaluation of hepatotoxicity

抄録

Drug-induced hepatotoxicity is a common reason for discontinuing the development of candidate clinical drugs. In the present study, we investigated the utility of three-dimensionally cultured human hepatocytes (spheroids) for prediction of hepatotoxicity, using a panel of model drugs: acetaminophen, benzbromarone, chlorpromazine, cyclosporin A, diclofenac, fialuridine, flutamide, imipramine, isoniazid, ticlopidine and troglitazone. Cultured spheroids showed a significant increase of albumin secretion from 2 to 7 days; the secretion started to decrease at 14 days, but continued from 14 days to 21 days. The morphology of the spheroids was well maintained for 21 days. Long-term exposure of spheroids to hepatotoxic drugs resulted in concentration-dependent depression of albumin secretion and elevation of aspartate aminotransferase (AST) leakage. The estimated 50% effective concentration (IC ₅₀ ) values for decrease of albumin secretion changed from 7 days to 14 days, but similar values were obtained at 14 and 21 days, except for diclofenac. Since the IC₅₀ values and the values of drug concentration inducing 1.2-fold elevation of AST leakage (F1.2) were similar at 14 and 21 days, an incubation period of 14 days was considered sufficient. The coefficient of determination (R²) between IC₅₀ values and F1.2 values of all drugs was 0.335. When cyclosporine A and fialuridine were excluded, the value of R² became 0.887. The results indicate that the proposed human hepatocyte spheroid assay should be helpful in the evaluation of hepatotoxicity during the early development stage of clinical drug candidates.