| BackgroundHepatic stem cells possessed multi-direction differentiation potential and ability of self-renewing. In recent years, with the progress of study on the function of hepatic stem cell in the liver injury and plerosis, oval cells as the present of hepatic stem cells had been paid more and more attention. During the process of embryogenesis, hepatic stem cells presented as small hepatocytes and as oval cells in the liver tissue in adult mammal. The characters of oval cell are small and oval-shaped, big nucleus and rare plasm. We previously observed that the oval cells firstly appeared on the bile duct epithelium in portal area and had immediate relationship with formation and development of hepatocellular carcinoma. On the basis of these, we took 3'-methyl dimethylamino azobenzene as inducing drug to construct rat hepatocellular carcinoma model and the migration and the change of ultrastructure of oval cell were observed by microscop electron microscope and immunohistochemistry, and the variation of the expression of p21ras was also analysed during the process of hepatocarcinoma, and the methods of density gradient centrifugation separation were usded to separate oval cells, Epidermal growth factor(EGF) was used to intervene the cultured oval cells and the biological characteristics of oval cells and the dynamic evolvement of p21ras protein were observed. From these, the regulation mechanism of oval cell abnormally differentiate towards carcinoma cell was primary observed. ObjectivesTo study the law of migration and the alteration of ultrastructure of oval cell and the alteration of p21ras expression on the process of development of rat hepatocellular carcinoma,and to explore the effective methods of separating and culturing oval cells from rats' liver and the law of regulation on the growth of oval cell.of epidermal growth factor. Methods and Results1 .DAB was used as inducing drug to successfully construct the model ofliver oval cell differentiation and hepatocellular carcinoma and the results showed that DAB was a kind of simple, economic, effective hepatocellular carcinoma inducing drug.2.Collegen type IV was used to infuse rat's liver and the high density oval cells could be acquired by the methods of density gradient centrifugation, which could be the basis of study of oval cell in vitro3.The pathological alteration of rat liver tissue was observed during the hepatocarcinogenesis induced by DAB. The development of HCC including three stages: inflammation stage, hyperplasia and sclerosis stage and carcinomatous change stage. Migration and the alteration of ultrastructure of oval cell were observed by microscope, electronic microscope and immunohistochemistry in the each stage of hepatocarcinogenesis and the results showed that in the early stage of hepatocarcinogenesis, oval cells occurred firstly in the portal area then migrated into hepatic lobules in the metaphase of hepatocarcinogenesis and then scattered among and gathered around carcinoma nods during the telophase of hepatocarcinogenesis. The electron microscopy observed that during the hepatocarcinogenesis of rats, the nucleus of oval cells gradually enlarged and lossed the normal formation and chromatin gathered to the nuclear membrane, and the intercellular space gradually enlarged. The results of immunohistochemistry showed that the CK18, CK19 positive oval cells firstly occurred in the portal area then gathered around the sclerosis nodes and in the end stage of inducing carcinoma, positive cells scattered among the carcinoma nodes.4. Density gradient centrifugation could successfully separate high desity oval cells which express both CK18 and CK19.5.The oval cells' biological behavior and the expression of p21ras protein of oval cells regulated by EGF were detected. The results showed that in the condition of EGF intervene, the expression of p21 ras protein increased gradually and meanwhile the vigor of oval cell was enhanced as well. There also had significant correlation between the expression of p21 ras protein inova...
|
PDF Full Text Request