Assistant Professor Gene and Cell Medicine
Assistant Professor Medicine, Liver Diseases
Mount Sinai School of Medicine
Improving liver repopulation of embryonic stem cell-derived hepatic cells
Liver diseases affect millions of people around the world. The shortage of liver donors is currently a major drawback hindering the treatment of liver diseased patients. One alternative to a whole liver transplantation protocol is the transplantation of hepatocytes. Hepatocytes derived from embryonic stem (ES) cell differentiation cultures could provide an unlimited supply for cell replacement therapy. We have recently demonstrated that BMP4, in concert with bFGF and activin-A, is required for hepatic specification of the isolated ES cell-derived definitive endoderm cells, the early progenitors for hepatic cells. Isolation of committed definitive endoderm cells was possible by using a reporter ES cell line in which hCD4 and hCD25 were targeted to the Foxa2 and Foxa3 loci. We showed that the isolated CD4-Foxa2+/CD25-Foxa3+ cells developed in our differentiation cultures generated strictly endoderm derivatives with up to 70% of hepatic cells coexpressing Foxa2, afp and albumin. Following transplantation into the liver deficient fumarylacetoacetate hydrolase Fah-/-, rag2-/-, IL2Rg -/- (FRG) mice, these hepatic cells developed only few hepatic clusters. Therefore, this proposal will evaluate in a step-wise manner the repopulation process in the FRG mice with the ES cell-derived hepatic cells compared to that from the highly regenerative hepatoblasts use as control for successful repopulation. This systematic study will define the limiting step(s) of regeneration with ES cellderived hepatic cells. In parallel, comparison of RNA profile from ES cell-derived hepatic cells and fetal hepatoblasts will be performed by deep RNA sequencing to uncover molecular pathways responsible for successful repopulation in hepatoblasts, and that are deregulated in ES cell-derived hepatic cells. This proposal is translational in nature, as it will test validation for using ES cell-derived hepatic cells as safe and efficient alternative for liver cell therapy; and will propose tools to improve the limiting steps of regeneration using pluripotent stem cell-derived hepatic cells.