Expression and its significance of telomerase in rat hepatic oval cells / 中华消化外科杂志

ABSTRACT

Objcctive To detect the telomerase activity in rat hepatic oval cells, and to explore the relationship between telomerase expression and the proliferation and differentiation of oval cells. Methods The 2-acetamidofluorene/partial bepatectomy (2-AAF/PH) rat model was used to induce the proliferation of oval cells. Oval cells were isolated by modified collagenase perfusion and gradient centrifugation. Electron microscope exami-nation and immunofluorescence were adopted to identify oval cells. Immunohistochemistry, RT-PCR and fluores-cence quantitative PCR were used to detect the expression of telomerase in oval cells. All the data collected were analyzed by t test. Results The proliferatiun of oval cells was successfully induced by 2-AAF/PH rat model. Freshly isolated oval cells showed a large and ovoid nuclei, a small proportion of cytomplasm and a cobblestone appearance. When viewed by electron microscopy, there were few and immature organelles, and the nucleus/ cytoplasm ratio was high. Immunofluorescence staining showed that oval cells expressed OV-6, alpha-fetoprotein, cytokeratin-19, albumin and c-kit. Telomerase reverse transcriptase (TERT) was located in the nuclei of oval cells which were around the portal areas. As oval cells differentiated into small hepatocytes, the number of TERT-positive cells decreased significantly. The expression level of TERT mRNA in normal rat liver tissue was 2.27 times higher than that in LE-6 oval cells; the expression level of TERT mRNA in the isolated oval cells was 1.26 times higher than that in LE-6 oval cells. The telomerase activity decreased gradually (from △A=1.05, 1.15 to △A=0.25, 0.45) as the increase of oval cells passage (from passage 24 to passage 40) (t=17.74, 12.38, P<0.05). Conclusions Oval cells have telomerase activity. Telomerase may be indispensable for maintaining the proliferative and multi-directional differentiation abilities of oval cells.