Expansion conditions for early hepatic progenitor cells from embryonal andneonatal rat livers

Long-term primary cultures were established from fetal or neonatal livers b y using cell suspensions depleted of red blood cells and by culturing the c ells in hormonally defined medium containing dimethyl sulfoxide. Two distin ct populations of hepatic progenitor cells were evident in the cultures, ba sed on morphology, proliferative ability, and liver-specific gene expressio n. Most colonies consisted of immature hepatic progenitors: small, blastlik e cells, weakly expressing cr-fetoprotein, albumin, and gamma-glutamyltrans peptidase, and showing evidence of proliferation as measured by bromodeoxyu ridine incorporation. At the perimeter of these colonies of immature cells and forming some colonies by themselves were more mature hepatic progenitor cells: larger cells, with increased cytoplasmic to nuclear ratios, little proliferation, and strongly expressing albumin, cr-fetoprotein, and gamma-g lutamyltranspeptidase. The latter two proteins were localized to the bile c analicular membranes of these cells. Glycogen deposits were present in the mature cells from day 14 embryos after eight days of culture. Thus, DMSO tr eatment of hepatic parenchymal progenitors provides a novel system for stud ies of liver development.