ABSTRACT
BACKGROUND: Liver cells are regulated by proliferation and apoptosis following ischemia/reperfusion injury, and the liver regeneration is obvious inhabited after ischemia/reperfusion injury, which can be relieved by ischemic preconditioning. However, the mechanism is still poorly understood.OBJECTIVE: To explore the effects of ischemic preconditioning on remained liver cell apoptosis and proliferation following autologous liver transplantation.DESIGN, TIME AND SETTING: The randomized controlled animal experiment was performed at the experimental animal center of Xiangya Medical College of Central South University from September 2006 to July 2007.MATERIALS: Totally 144 male Sprague Daweley rats were randomly divided into hepatic resection, auto-transplantation, ischemic preconditioning groups, with 48 animals in each group.METHODS: Rats in the hepatic resection group were underwent left hepatic lobe and median lobe resection without blocking blood current at the right hepatic lobe and caudal lobe. In the auto-transplantation group Venous traffic branches of rats were broke, with liberating caudate lobe, first porta hepatis, and inferior vena cava, followed by blocking and continuous hypothermical perfusion preservative fluid via porta hepatic, simultaneously, anemia hepatectomy was performed (left hepatic lobe and median lobe was resected). The liver was washed and preserved in cold preservation solution for 15 minutes. At the end, portal triad clamping was removed and underwent abdominal closure. The procedure of rats in the ischemic preconditioning group was identical to auto-transplantation group except 10 minutes blocking and 10 minutes recover the blood flow at right hepatic lobe and caudal lobe prior to portal vein perfusion. Liver tissues were harvested at hours 0, 1, 3, 6, 12, 24, 48 and 72 after hepatic resection in 3 groups. MAIN OUTCOME MEASURES: Contents of aspartate aminotransferase and alanine aminotransferase were calculated by biochemical analyzer. The index of cell apoptosis was detected by flow cytometry. In addition, proliferation of liver cells was measured by Ki-67 expression. RESULTS: Compared to the auto-transplantation group, the levels of alanine aminotransferase and aspartate aminotransferase were dramatically decreased in hepatic resection and ischemic preconditioning groups at each time point exception with 0 hour after operation (P < 0.05). Few apoptosis cells existed in each group at 0 hour after operation. The index of cell apoptosis increased slightly after resection in the hepatic resection group, which was sharp increased in the auto-transplantation group after reperfusion, reached a peak at 12 hour, and then gradually decreased. Compared auto-transplantation group, the index of cell apoptosis in ischemic preconditioning group was significantly decreased (P < 0.05). The expression of Ki-67 in 3 groups increased after hepatic resection, peaked at 24 hour after hepatic resection, then decreased lower and lower. Compared to the hepatic resection group, the expression of Ki-67 in auto-transplantation group was significantly lower after hepatic resection (P < 0.05). Compared to the auto-transplantation group, the expression of Ki-67 in ischemic preconditioning group was significantly increased after hepatic resection (P < 0.05).CONCLUSION: Ischemic preconditioning can decrease cell apoptosis and promote cell proliferation after rat's liver auto-transplantation, which may be one mechanisms of ischemic preconditioning in promoting liver regeneration.