Hepatic epithelial stem-like cells.

The liver is composed of long-lived hepatocytes and biliary epithelial cells whose replacement ordinarily occurs from the proliferation of residual differentiated cells of each type, obviating the need for stem cells to renew hepatocytic and biliary epithelial lineages. Nevertheless, small epithelial cells that are phenotypically distinct from either hepatocytes or biliary epithelial cells can be isolated from normal and pathological livers and established as cultured cell lines. When transplanted into the livers of syngeneic rats, cells of some cultured hepatic epithelial lines migrate into hepatic plates and differentiate into hepatocytes. The strong differentiation-inducing potency of the liver microenvironment is indicated by intrahepatic hepatocytic differentiation and coordinate suppression of tumorigenicity of some aneuploid, neoplastic hepatic epithelial cells that are highly tumorigenic when transplanted into subcutaneous sites. The liver appears to contain cells that have stem-like potential to differentiate into hepatocytes and biliary epithelial cells.