Generation of liver organoids from human induced pluripotent stem cells as liver fibrosis and steatosis models

Background & Aims: Liver cirrhosis is a major cause of death worldwide, and its prevalence is growing rapidly due to the growth of obesity and diabetes population with non-alcoholic fatty liver disease (NAFLD). Yet, no effective therapeutics have been developed to treat NAFLD or its more advanced stage, non-alcoholic steatohepatitis (NASH). This has raised great concern for a representative liver model to be developed so that novel drugs could be screened, identified and developed. Presently, we aim to develop a liver organoid entirely from human induced pluripotent stem cells (hiPSC) to model liver fibrogenesis and NAFLD. Methods: Hepatoblasts (HBs), mesenchymal stem cells (MSCs), hepatic stellate cell (HSCs) and endothelial cells (ECs) were derived from hiPSCs, allowed to self-organized and differentiated into liver organoids. Liver functions, transcriptomic and protein expression of liver organoids were characterized and validated. Liver organoids were exposed to thioacetamide (TAA) and free fatty acids (FFA) to be induced into liver disease model. Results: The liver organoids we fabricated were highly vascularized, exhibited liver-specific functions and hepatic cellular spatial organization. The presence of liver specific ECs, macrophages and cholangiocytes were found within our organoids. TAA induced fibrosis in our liver organoids that exhibited diminished liver functions, elevated pro-inflammatory cytokines and fibrosis-related gene expression, as well as extensive collagen deposit. Organoids treated with FFA developed steatosis, inflammation and fibrosis. Conclusions: We generated a novel method, that is Matrigel-independent and size-controllable, for making human liver organoids. These organoids can potentially be utilized as tissue-mimetic in vitro model for high throughput screening to identify drugs that can be used to treat liver fibrosis and NAFLD.