Proliferation and hepatic differentiation of adult-derived progenitor cells

Hepatic progenitor cells, capable of maturing into hepatocytes and biliary cells, are hypothesized to be involved in all forms of liver regeneration and may prove clinically useful at reconstituting damaged livers. A murine hepatic progenitor cell population from young adult liver tissue has been isolated and characterized to establish a model for the development of liver cell therapies and for analysis of immune responses after transplantation. Hepatic progenitor cells were isolated from 3- to 6-week-old C57BL/6 mice using modifications of a two-stage liver perfusion technique followed by low speed centrifugation. Cellular analysis by phase contrast, fluorescent and confocal microscopy demonstrated that the hepatic progenitors (1) formed ex vivo colonies with a morphological appearance similar to committed hepatocytic progenitors isolated from embryonic mice and rats; (2) they are smaller than mature hepatocytes; (3) in culture they demonstrated peak expression of an oval cell marker at day 14, whereas albumin expression continued to increase beyond day 21 of culture, and (4) a subset of the progenitors phenotypically differentiated into mature hepatocytes or biliary cells. The unique antigenic profile of these hepatic progenitor cells and their ability to differentiate suggests that purification of the cells should allow for their potential use in transplantation.