| Objective: Autogenous vein transplantation is an effective method of treating coronary and peripheral artery occlusive diseases, but the stenosis of vein graft after replacement is the key problem which affects the long-term results. The mechanism of vein graft stenosis remains unclear. According to recently evidence, there is smooth muscle cells (SMCs) apoptosis in the intimal hyperplasia after vascular injuty, but the role of SMCs apoptosis in vein graft is undetermined. To evaluate the effect of apoptosis during neointimal formation in autogenous vein graft, apoptosis of smooth muscle cells in vein graft and its relationship with proliferation is observed at different time after transplantation, and expression of apoptosis associated genes in SMCs were also investigated.Methods: A rat experimental model of autogenous vein graft was established by transplanting the right external carotid vein into infrarenal abdominal aorta in 100 rats. The vein grafts were harvested at different time from 1 to 8 weeks, and the plasma of vein blood was also obtained.1.ET(Endothelin) and CRGP were assayed in different time afterautogenous vein transplantation using radioimmuno-assay(RIA), andconnected with the detection of PCNA expression in vein smoothmuscle cells to investigate the relationship of ET and CGRP withproliferation of SMCs.2.In order to eveluated proliferation and apoptosis during theneointimal formation., immunohistochemical technique and TUNELwere used to detect proliferation and apoptosis in different time afterreplacement.3.Immunohistochemical technique was used to detected theexpression of apoptosis associated gene (bcl-2 and bax) afterreplacement, and their regulating effects on apoptosis of SMCs wasevaluated.Result: l.From 1 to 8 weeks after replacement, the level of plasm ET in experimental group was continuously higher than the control group.Within 2 weeks, there was a significant difference between the experimental group and the controls. The level of CGRP in 3 days after replacement reached peak. The ratio of ET and CGRP was significantly higher within 2 weeks. The increase of plasm ET coincided with the positive expression of PCNA, and had significant correlation between them (r=0.783, p<0.05).2.There were only a little positive cells in the control veins by means of TUNEL. From 1 to 8 weeks, apoptosis of SMCs in vein graft couldbe detected by means of HE and TUNEL. The positive cell percentage of apoptosis was significantly higher than the controls. The expression of PCNA after replacement was also significantly higher than the controls (p<0.05).In 1 to 2 weeks, expression of both TUNEL and PCNA reached peak, and the positive cell percentage of TUNEL was lower than that of PCNA, but in 4 to 8 weeks, the positive cell percentage of TUNEL was more than that of PCNA. From 1 to 8 weeks, the positive cell percentages of TUNEL and PCNA were correlative(r=0.813, p<0.05).3.Little expression of bcl-2 was seen in the controls. The positive expression of bcl-2 increased significantly in vein graft from 1 weeks to 2 weeks after replacement and had significant difference with controls or with vein grafts from 4 to 8 weeks(p<0.01). The positive expression decreased from 4 weeks to 8 weeks after replacement, but still significantly higher than the controls (p<0.05). In control group, endothelium and SMCs in the media near the luminal expressed bax protein, and increased obviously from 1 week to 8 weeks after replacementThe positive expression of bax from 1 week to 6 weeks was significantly higher than that of controls and vein grafts in 8 weeks(p<0.01). The expression of bax in 8 weeks had no significant difference with the controls. The ratio of bcl-2 and bax was significantly higher than the controls from 1 week to 2 weeks, and then decreased gradually, the ratio was in the normal range from 4 to8 weeks.Conclusions: 1. After autogenous vein replacement, the assay of plasma ET may be helpful to understand the pro...
|
PDF Full Text Request