32 P局部照射对移植静脉内膜平滑肌细胞增殖与凋亡的影响

目的 研究β射线局部照射对自体移植静脉内膜平滑肌细胞（VSMC）增生与凋亡的影响及可能机制。方法 建立80只大鼠自体静脉移植模型,随机分成^32P局部照射组、对照组,每组按3、7、14、28d随机分成4个亚组、每亚组10只。取材固定,弹力纤维染色,增殖细胞核抗原、p53、bcl-2、bax免疫组化测定,TUNEL法检测静脉平滑肌细胞的凋亡,计算机图象分析仪测量移植血管内膜厚度,计算细胞增殖及凋亡百分化。结果 术后2组移植静脉段的内膜平均厚度：7、14、28d,照射组明显 于对照组（t＝15．694,P＜0．05）;7、14d照射组VSMC增殖较对照组受到明显抑制（t＝60．157,P＜0．01）。凋亡指数14d照射组高于对照组（t＝56．176,P＜0．01）。p53的表达,2组间差异无显著性意义（t＝0．473,P＞0．05）,bax与bcl－2的表达,14d照射组高于对照组（t＝9．783,P＜0．05）。结论 ^32P局部照射可以抑制自体移植静脉的内膜增生及VSMC的增殖,促进VSMC的凋亡,可能是通过bax、bcl－2基因的表达实现的。

The role of beta irradiation on neointimal formation and apoptosis in vein grafts model

Objective To evaluate the effect of beta irradiation on intimal proliferation and apoptosis in vein grafts. Methods Autogenous vein graft model was established in 80 rats by transplanting the internal branch of the jugular vein to the carotid artery by end to end anastomosis.The veins were irradiated by 32 P solution before anastomosis. Two dose schedules were studied: control group (graft, nonirradiated) and radiation group (20 Gy).The grafted veins were harvested at 3?7?14?28 d respectively after the operation. Intimal hyperplasia(IH), smooth muscle cell (SMC), proliferation, p53, bcl 2 and bax were observed pathologically and immunohistochemically. They were analyzed by a computerized system. The presence of apoptotic VSMC was demonstrated by TUNEL method. Results There was a significant decrease in the average intimal thickness at 7, 14 and 28 d( t =15 694, P <0 05) in the radiation group. Immunohistochemical analysis of PCNA indicated decreased positive cells in the radiation group compared with the controls at 1 and 2 weeks ( t =60 157, P <0 01). Apoptosis of VSMC was highter in the radiation group than in the control group at 2 weeks ( t =56 176, P <0 01). There was no significant difference in expression of p53 between the two groups , and there was a significant increase in bax and bcl 2 in the radiation group at 2 weeks ( t =9 783, P <0.05). Conclusion These preliminary results demonstrated that low dose of beta irradiation in the vein graft inhibits SMC proliferation and induces the apoptosis of VSMC in rats.