Cellular fluctuations, alpha-fetoprotein expression, and the question of stem cells in experimental liver regeneration and hepatocarcinogenesis

Animal studies have shown stem-like properties of adult hepatocytes and stem-like properties of biliary epithelial cells with the latter originating from the canaliculi of HERING. In partial hepatectomy and after carbon tetrachloride injury, adult hepatocytes are the main source for liver restitution. In these cases, special stem cells are not required. Increase of serum AFP concentration is associated with the proliferative activity of hepatocytes. The extent of AFP synthesis depended largely on animal species and their respective strains. Hepatocyteproliferationmaybe blocked owingto the nature of the damage. Then, liver repair follows pathways which involve the proliferation of biliary epithelial cells(oval cells). Oval cells and their progenies are descendants from the canaliculi of HERINGand small interlobular bile ducts. They act as stem-like cells,andthey reach levels with fetal gene activationduring proliferative stages with AFP synthesis signalling reversal ontogeny.In hepatocarcinogenesis,cancer cells may derive from oval cells or from mature hepatocytes. AFP resurgence in liver cancerreflects traits of retro-differentiationorstages of maturation arrest duringcell differentiation.AFP re-expression is not confined to malignancy because such molecules can also resurge during non-malignant growth. The broader term “transitory cellantigens” is anappropriate naming.