Culture methods focusing on bile canalicular formation using primary human hepatocytes in a short time

The development of models for predicting hepatotoxicity is warranted, as the hepatotoxicity risk of 38–51% of compounds is undetectable in nonclinical studies. Cholestatic drug-induced liver injury (DILI) is a condition in which bile acids are abnormally excreted into the capillary bile canaliculi and are accumulated in hepatocytes, caused by the inhibition of bile salt export pump (BSEP), a transporter that is mainly associated with excretion of bile acids. Although laboratory animals are used as models, the use of human-derived cells is required owing to species differences. Unfortunately, primary human hepatocytes (PHHs) show rapid loss of function in culture and difficulties in forming bile canaliculi. Therefore, we aimed to develop an in vitro culture method for the efficient formation of bile canaliculi and for assessing the function of BSEP in PHHs. Here, PHHs were cultured from 1 h after thawing to day 2 with Z-VAD-FMK, a total caspase inhibitor, and RevitaCell™ supplement, an irreversible Rho-associated coiled-coil forming kinase (ROCK) inhibitor, in combination with RM-101. The PHHs formed bile canaliculi and showed BSEP function on day 6 of culture. Our findings suggest that cultured PHHs may improve the prediction accuracy of the risks of cholestatic DILI-contained toxicity on bile canaliculi.