Novel Cell Culture Technology to Harvest Hepatic Metabolites Accumulated in the Bile Canaliculus-like Structures between HepG2-NIAS Cells Utilizing Crosstalk with TFK-1 Cells

Abstract

It is necessary to develop an evaluating system for the biliary excretion of compounds for predicting drug-induced liver injury that is a major adverse event leading to drug halt and drug withdrawals. The sandwich-cultured hepatocytes do not reflect hepatic events in vivo due to using Ca²⁺-free buffer although they were used to estimate the biliary excretion of compounds. Here, we aimed to develop a novel culture technology that can extrapolate the excretion of drug metabolites in the liver into the bile duct using the crosstalk between HepG2-NIAS cells (a human hepatocellular carcinoma cell line) forming bile canaliculus-like structures (BCLSs) in a collagen vitrigel membrane chamber and monolayered TFK-1 cells (a human bile duct carcinoma cell line) in a plate-well. In the co-culture system of HepG2-NIAS cells and TFK-1 cells, the total excretion amount of fluorescein accumulated in BCLSs and its excretion rate towards the plate-well represented a time-dependent increase after HepG2-NIAS cells were exposed to fluorescein diacetate. In contrast, the co-culture system of HepG2-NIAS cells and monolayered cells of HUVECs (human umbilical vein endothelial cells) or HDFs (human dermal fibroblasts) did not increase the excretion rate of fluorescein towards the plate-well. The selective excretion of fluorescein towards the plate-well was observed even in a single culture system of HepG2-NIAS cells with BCLSs put on the plate-well poured a serum-free conditioned medium derived from co-culturing HepG2-NIAS cells with BCLSs and TFK-1 cells. These findings suggest that the culture technology utilizing the crosstalk between HepG2-NIAS cells and TFK-1 cells would provide a new tool for extrapolating the excretion of drug metabolites in the human liver into the bile duct.