Hepatotoxicity assessment system using in vitro liver model with bile canaliculi formation and high metabolic functions.

Abstract

Drug-induced-liver-injury (DILI) is one of the most significant reasons for the discontinuation of drug development or sales. Although many researchers have addressed this problem using in vitro liver models, it remains a challenge to present models that comprehensively have the required features such as the functional structure like bile canaliculi and long-term maintenance of metabolic functions. In the present study, we constructed a hepatic model with bile canaliculi and highly-maintained metabolic functions by using a unique tissue-engineering method. Briefly, we created a viscous body from human hepatocytes (PXB cell) by suspending cells with heparin and collagen, then embedded the viscous body into a hydrogel in which cells can accumulate spontaneously to construct a liver-like functional structure. The model was evaluated for liver function and its potentiality as a toxicity assessment tool. The transcriptome analysis among 3 culture models (sandwich, spheroid, and our model) indicated that our model showed higher expressions of metabolism-related genes than other conventional models. Our model was also more similar to the expression pattern in the real liver. In addition, bile canaliculi structures were formed in our model. The hepatotoxicity of cyclosporine A, which is known to induce cholestasis, could be predicted with 20 times higher sensitivity in our model than the spheroid. The predictability comparison for 49 toxic/non-toxic compounds between our model and the spheroid showed the tendency that our model was more consistent with the clinical DILI risk.