The replicative potential of hepatocytes and liver stem cells

The cellular basis of liver growth is reviewed from overall recent and previous data. According to the present-day ideas, the adult mammalian liver contains at least two cellular populations with many properties similar to the stem cells of renewing tissues that provide for the liver postnatal growth and parenchyma regeneration under various conditions. According to the present nomenclature, the differentiated parenchyma cells-hepatocytes-are a unipotent committed population of stem cells. In addition, there is a system of nonparenchymal multipotent stem cells or oval cells in the liver. Certain key models of liver growth, regeneration, and repopulation that contributed to development of these notions are considered. The recent data are discussed in the context of yet unclear cellular mechanisms providing for the tremendous replicative potential of hepatocytes, the role of polyploidy in the growth effects, and the sources of malignant transformation in the liver.