OBJECTIVETo observe the evolution and differentiation of hepatic oval cells after transplanted into the spleens of homogenous rats, providing experimental data for treating hepatic failure with hepatic stem cells.

METHODSA two-step perfusion procedure was used to separate hepatic parenchymal cells from nonparenchymal cells. Then the suspension of nonparenchymal cells was centrifuged in Percoll gradients. The isolated cells were cultured, identified, and then transplanted into the spleens of homogenous rats undergone 2/3 hepatectomy.

RESULTSThe obtained cells were various in size with ovoid nuclei and inadequate cytoplasm. After 12 hours' culture, they revealed the characteristics of epithelial cells. Both the freshly isolated and cultured cells showed positive staining for cytokeratin 19 (CK19), OV6, alpha fetal protein (AFP), but negative for leucocyte common antigen (LCA). After intraspleenic transplantation into homogenous rats undergone partial hepatectomy, hepatic oval cells were differentiated into liver tissue-like structure including hepatocyte cords and bile ducts, and formed hepaticized spleen. But this kind of structure was not observed in the controls.

CONCLUSIONThe isolated rat hepatic oval cells show the biological characteristics of hepatic stem cells and can differentiate into hepatocytes and biliary epithelial cells under appropriate circumstances.