Targeting CYP4A attenuates hepatic steatosis in a novel multicellular organotypic liver model

Background Non-alcoholic fatty liver disease (NAFLD) begins as simple hepatic steatosis, but further progress to chronic liver diseases results in severe liver damage and hepatic failure. However, therapeutic options are scarce due to the lack of reliable human in vitro liver models for understanding disease progression mechanisms and developing therapies. Results We describe here a novel method for generating 3D hepatic spheroids using HepaRG cells, vascular endothelial cells, and mesenchymal stem cells cultured on a thick layer of soft matrix in a narrow conical tube; this method improved self-organization efficiency and functional competence. We further developed a 3D hepatic steatosis model with excess glucose and palmitate, accurately recapitulating steatosis phenotypes such as neutral lipid accumulation, enhanced expression of lipogenesis and gluconeogenesis markers, increased intracellular triglyceride content, and reduced glucose uptake. The expression and activity of cytochrome P450 4A (CYP4A), a hepatic glucose and lipid homeostasis enzyme, that is highly expressed in liver tissues from NAFLD patients, was induced in our in vitro steatosis model, and inhibiting CYP4A with the selective inhibitor HET0016 or a specific siRNA ameliorated steatosis-related pathology through reduced ER stress and improved insulin signaling. Conclusions We provide here a novel 3D human cell-based hepatic model that can be easily generated and reliably simulate hepatic steatosis pathology. We have experimentally validated its potential for target validation and drug evaluation by focusing on CYP4A, which may serve as a translational platform for drug development.