Expansion of hepatic and hematopoietic stem cells utilizing mouse embryonic liver explants

Ex vivo embryonic liver explant culture is a novel and attractive approach to obtain abundant hepatic and hematopoietic stem cells. Gene therapy of au tologous hepatic and hematopoietic stem cells represents an alternative the rapeutic approach to liver transplantation for genetic and metabolic disord ers. In this study we characterize the growth and differentiation of hepati c stem cells utilizing embryonic liver cultures. Day 9.5 liver buds are mic rodissected and cultured under specific conditions. Modulation of growth co nditions by addition of hepatocyte growth factor, Flt-3 ligand, and stem ce ll factor leads to enrichment of hepatic progenitor cells in embryonic live r explants. Under these conditions, we also demonstrate the role of a novel marker PRAJA-1 to identify hepatic stem cells and transitional hepatocytes . Utilization of dexamethasone enhanced pseudolobule formation with increas ed hepatocytic and biliary differentiation. Transforming growth factor-beta leads to enrichment of biliary cells in the culture, Gut formation is enha nced in the presence of interleukin-3 and blood formation by increasing the mesodermal tissue in these cultures. We also show increased retroviral-med iated expression of the green fluorescent protein expression in the expande d hepatic and hematopoietic stem cells under different culture conditions. Thus, the embryonic liver explant culture is an attractive source for hepat ic progenitors and is a possible step towards generating nontumorigenic imm ortalized hepatocytes with possible transplantation applications.