Cell apoptosis and expression of Fas protein, PCNA, p53 and bcl-2 mRNA during hepatic ischemia/reperfusion in rats

Objective To investigate characteristics of time and areas of liver cell apoptosis and features of gene expression during ischemia/reperfusion and explore their significance. Methods Based on determination of survival rate and pathomorphological changes in 40 SD rats reperfused for 3, 6 and 24 h after hepatic ischemia for 0, 30, 45 and 60 min, we observed pattern of TUNEL cells, indices of G 0-G 1 phase, proliferated and apoptotic cells with flow cytometry, the cell morphological changes with electron microscopy, expression of p53, bcl-2 mRNA with in situ hybridization and Fas protein and PCNA with immunohistochemistry in 100 rats reperfused for 0, 0.5, 1, 3, 6, 12, 24, 48, 72 and 96 h after hepatic ischemia for 30 min. Results Apoptotic phenomenon was mainly found in the group of hepatic ischemia for 30 min. In this group, TUNEL cells appeared near the vascular system at 6 h and developed for all hepatic labor 12 h after the reperfusion. Subsequently, the increase of index of apoptotic hepatocytes was firstly seen 3 h after reperfusion. The expression pattern of Fas was the earliest and strongest. Fas protein and p53 mRNA also expressed firstly near the vascular system between 1 to 3 h and expressed widely from 3 to 72 h. The expression pattern of PCNA appeared from 3 to 96 h. The index of proliferated cells was significantly increased at the 12 h. bcl-2 mRNA also expressed from 3 to 96 h after reperfusion and but it was weaker. Three different morphological characteristics of hepatic cells were observed during the acute (0-3 h after reperfusion), subacute (3-24 h after reperfusion) and earlier repair phase (24-96 h after reperfusion) of liver responses to I/R: severe cell degeneration, cell atrophy and cell proliferation. Conclusion Apoptosis and proliferation are early events after hepatic ischemia/reperfusion and the specific features of this injury. They are probably related to regulating balances of cell death/survival, apoptosis/proliferation and cell cycle transition after hepatic ischemia/reperfusion injury.