Effects of cold preservation and reperfusion injury on the regeneration of donor liver and associated mechanisms.

Abstract

Objective To investigate the effects of cold preservation and reperfusion injury on the regen-eration of donor liver and to study the mechanisms. Methods Male SD rats were divided in to sham group (6 rats), UW 1 h group (48 rats) and UW 12 h group (48 rats). Liver tissue specimens were collected at different time points after orthotopic liver transplantation or sham operation. The morphology of liver tissue was observed via light microscope and transmission electron microscope. Proliferation of hepatocytes and sinusoidal endothelial cells (SECs) were assessed by a double immunostaining technique using antibodies against rat endothelial cell antigen-1 and bromodeoxyuridine (BrdU). Expression of vascular endothelial growth factor (VEGF) and its receptors, fins-like tyrosine kinase-1 (flt-1) and fetal liver kinase-1 (flk-1) was evaluated by immunohistochemistry. The mRNA expression of flt-1 was detected by a RT-PCR method. Mean comparison in groups was conducted by one-way ANOVA or t test. Results BrdU labeling indexes of hepatocytes and SECs in UW 12 h group was significantly higher than those in UW 1 h group (F = 61.45,41.4, P < 0.05). The proliferation of hepatocytes peaked at 48 h after operation in both UW 1 h group and UW 12 h group. However, the proliferation of SECs was fallen behind compared to hepatocytes, with a peak appeared at 72 h in UW 1 h group and at 96 h in UW 12 h group, respec-tively. The expression of VEGF was up-regulated in both UW 1 h group and UW 12 h group compared to sham group. Furthermore, expression of flt-1 and flk-1 was found to be mainly limited in SECs, with a peak in expres-sion occurring between 72 h and 96 h, coinciding with the peak in SECs proliferation in UW 1 h group. Conversely, flt-1 was found to be reduced significantly on mRNA level at any time throughout the experiment in UW 12 h group compared to sham group (F = 141.67, P < 0.05). Conclusion Reduced expression of flt-1 results in a retarded regeneration of SECs, and then the recovery of rat donor liver function is delayed after cold-preserved transplantation. Key words: Liver transplantation; Sinusoidal endothelial cells; Liver regeneration