Isolation of multipotent progenitor cells from human fetal liver capable of differentiating into liver and mesenchymal lineages.

Little is known about the differentiation capabilities of nonhematopoietic cells of the human fetal liver. We report the isolation and characterization of a human fetal liver multipotent progenitor cell (hFLMPC) population capable of differentiating into liver and mesenchymal cell lineages. Human fetal livers (74-108 days of gestation) were dissociated and maintained in culture. We treated the colonies with geneticin and mechanically isolated hFLMPCs, which were kept in an undifferentiated state by culturing on feeder layers. We derived daughter colonies by serial dilution, verifying monoclonality using the Humara assay. hFLMPCs, which have been maintained in culture for up to 100 population doublings, have a high self-renewal capability with a doubling time of 46 h. The immunophenotype is: CD34+, CD90+, c-kit+, EPCAM+, c-met+, SSEA-4+, CK18+, CK19+, albumin-, alpha-fetoprotein-, CD44h+, and vimentin+. Passage 1 (P1) and P10 cells have identical morphology, immunophenotype, telomere length, and differentiation capacity. Placed in appropriate media, hFLMPCs differentiate into hepatocytes and bile duct cells, as well as into fat, bone, cartilage, and endothelial cells. Our results suggest that hFLMPCs are mesenchymal-epithelial transitional cells, probably derived from mesendoderm. hFLMPCs survive and differentiate into functional hepatocytes in vivo when transplanted into animal models of liver disease. hFLMPCs are a valuable tool for the study of human liver development, liver injury, and hepatic repopulation.