Generation of high-density human induced pluripotent stem cell derived-liver organoid by enabling growth factors accumulation in a simple dialysis medium refinement culture platform

Abstract: The human pluripotent stem cells-derived liver organoid (HLOs) has recently become a promising alternative source for liver regenerative therapy. To realize this application, a large number of the hiPSCs derived-liver cells are required for partial liver replacement in transplantation. This method requires a stepwise induction by using costly growth factors to direct the hiPSCs into the hepatic lineage. Therefore, we developed a simple dialysis culture system to fully utilize the growth factors accumulation with continuous medium refinement. The results showed that the dialysis culture system was able to accumulate the four essential growth factors required in each differentiation stage, such as Activin A, BMP4, HGF, and OSM. As a result, this culture system allowed a very high-density bipotential hepatic differentiation in approximately 4.5×10⁷ cells/mL of human liver organoids (HLOs), mainly consisting of hiPSCs derived-hepatocytes (HLCs) and cholangiocytes (CLCs). Moreover, the differentiated liver organoids showed a better or comparable hepatic marker and physiological activity with the organoids differentiated in suspension culture with conventional daily medium replacement in a lower cell density. This simple miniaturized dialysis culture system demonstrated the feasibility of cost-effective hepatic differentiation in high density.