The Expression And Significance Of Skp2, P27kip1 In Autologous Vein Grafts In Rabbits

Objective: To establish a rabbit model of carotid arterial venous bridge bypass graft and observe the pathological change of the vein bridge at different phase,to study the expression of skp2 and p27^kip1 in vascular smooth cell in autologous vein graft and its relation with proliferation of smooth muscle cell and to investigate the mechanism of vein graft restenosis.Materials and methods: A total of 36 New Zealand rabbits were randomly divided into six groups with six rabbits in every group.External jugular vein was interposed between ipsilateral common cadotid arteries.The vein grafts were harvested after 2days,4days,7days,10days,14days,28day.The jugular vein of opposite side were harvested as the control group.The specimens were embedded in paraffin, made into paraffin section(4um),stained by the methods of HE and Verhoeff.Morphology of tissue was observed in optics microscope.Intimal and medial thicknesses of perfusion fixed vein grafts was measured with a computer digitized system.Then staining with antibody of Skp2,p27^kip1 and PCNA, using technique of immunohistoch-emistry (SABC method).The slide was observed in 400 optics microscope and calculated the positive cells of Skp2,p27^kip1 and PCNA respectively.Results: 1.Intimal and medial thicking peaked at 7 days and were significantly thicker (P﹤0.01) than the same region at 2 days after graft implantation and control group .While intimal and medial thickness at 28 days had no difference compared with 14 days(P﹥0.05).2.Expression of Skp2 and PCNA increased in 2 days and reached to topmost in 10 days after opraratio(nP﹤0.01).Staining for Skp2,PCNA were significantly higher(P﹤0.01) at 10 days compared with that at 2,4 days.Subsequently Skp2 and PCNA staining progressively decreased,with a significant peak at 10 days(P﹤0.01).P27kip1 protein expressed in normal vein,2 days after operation,P27kip1 didn,t express.The expression of P27kip1 was lower between 4 days to 10 days after operation,and then was significant higher (P﹤0.01)at 14 days compared with that at 10 days ,reached to topmost at 28 days .3.The expression level of PCNA in the vein graft was temporally associated with expression of skp2(r=0.96,P﹤0.01);the expression of p27^kip1 was correlated negatively with that of skp2 ,PCNA(r=﹣0.63,r=﹣0.67,P﹤0.05).Conclusion: Hyperplasia of autologous vein graft in rabbits happened as soon as after operation.After four days inimal hyperplasia is more obviously than tunica media,intimal hyperplasia reached to pinnacle in 7 days and 14 days.The intimal hyperplasia might be induced mainly by the proliferation and migration of media smooth muscle cells.The significantly negative correlation between P27kip1 and skp2 in aotologous vein graft ,which indicated that a high level of skp2 can induce degradation of P27kip1,which was a crucial step of VSMC proliferation and subsequent neointimal thickening.Skp2 may emerge as a promising target of therapy for restenosis.