Engineering human hepatic organoids for in vitro liver modeling and implantable cell therapies

Abstract

The adult liver performs hundreds of life-sustaining functions while also exhibiting a miraculous capacity to regenerate, but methods to expand primary hepatic cells in vitro while supporting their phenotype and function remain elusive. Organoid culture has successfully grown dozens of otherwise difficult-to-culture primary cells in 3D, generating valuable biological models and offering a new source of healthy cells for regenerative medicine. Here, we describe establishment of organoid culture systems for human hepatic cells and demonstrate their utility for in vitro modeling and liver tissue engineering. We demonstrate the robustness of our adult human hepatocyte organoid culture conditions by generating organoids from eight different adult donors. Mature organoids accurately model the phenotype and morphology of hepatocytes in the adult liver, express a mature liver transcriptome distinct from fetal hepatocytes, and exhibit adult functions such as inducible cytochrome activity. To demonstrate their translational potential, we implanted human hepatocyte organoids in vivo and found that they exhibited up to 25-fold greater functionality after engraftment compared to previous adult hepatocyte models. Furthermore, organoids negate the need for inclusion of exogenous non-parenchymal cells in engineered tissues to support engraftment, an important translational milestone. Finally, we established a strategy for rapid vascularization and scale-up of engineered liver tissues to move this therapeutic idea closer to clinical reality. These results demonstrate the potential of adult human hepatocyte organoids for basic and translational applications such as pharmaceutical screening and hepatic regenerative medicine.