非限制性外支架对兔移植静脉血小板源性生长因子表达的影响

目的 探讨非限制性外支架防治移植静脉再狭窄的可能作用机制. 方法新西兰白兔随机分为支架组和对照组,每组18只.均实施颈外静脉-颈总动脉移植术,支架组在移植静脉外套以外支架(直径6 mm的人造涤纶血管),对照组无外支架.术后7、14、28 d每组各6只兔手术取出移植静脉,分别进行血小板源性生长因子B链(PDGF-B)免疫组织化学染色,计算PDGF-B阳性率;以RT-PCR方法检测PDGF-B mRNA的表达量. 结果支架组移植静脉内膜PDGF-B阳性率术后14、28 d均明显低于对照组(15.2%±3.6%vs 21.6%±4.6%,6.5%±2.6%vs 12.5%±4.4%,均P＜0.05);中膜阳性率术后7、14、28 d均明显低于对照组(13.8%±4.6%vs 25.4%±6.2%,21.3%±4.4%vs 35.7%±7.3%,7.2%±3.2%vs 19.2%±5.4%,均P＜0.01);外膜阳性率术后28 d达高峰,而对照组在术后14 d达高峰,28 d时支架组阳性率明显高于对照组.RT-PCR检测显示术后7、14、28 d 2组移植静脉均可见PDGF-B特异条带(457 bp),各时间点支架组PDGF-B mRNA的表达均明显低于对照组(31.2%±6.5%vs 45.4%±8.4%,P＜0.05;42.3%±6.2%vs 65.2%±11.5%,P＜0.01;21.3%±5.6%vs 36.2%±9.4%,P＜0.01). 结论抑制移植静脉PDGF合成、改变PDGF分布规律可能是非限制性外支架防治移植静脉再狭窄的作用机制之一.

Effect of non-restrictive external stent on the expression of platelet-derived growth factor in vein grafts of rabbits

Objective To investigate the potencial mechanism of non-restrictive external stent in preventing re-stenosis of vein grafts.Methods Thirty-six rabbits underwent reversed bypass grafting of autologous external iugular vein into common carotid artery and then were randomly divided into two equal groups,stenting group(Group S),with an external stent 6 mm in diameter(Dacron vascular prosthesis)surrounding the vein graft,and control group(Group NS),without stenting.The vein grafts were harvested 7.14.and 28 days after the operation respectively.Immunocytochemistry was used to detect the plateletderived growth factor B(PDGF-B)positive cells.The mRNA expression of PDGF-B was detected with RTPCR.Results The PDGF-B positive cell percentages in the intima of Group S7 and 14 days later were both significantly lower than those of Group NS(15.2%±3.6%vs 21.6%±4.6%.and 6.5%±2.6%vs12.5%±4.4%,both P＜0.05).The PDGF-B positive cell percentages in media 7,14 and 28 days later of Group S were all significantly lower than those of Group NS(13.8%±4.6%vs 25.4%±6.2%,21.3%±4.4%vs 35.7%±7.3%,and 7.2%±3.2%vs 19.2%±5.4%,all P＜0.01).The PDGF-B positive cell percentage in adventitia peaked 28 days later in Group S and 14 days later in Group NS,and the PDGF-B positive cell percentage in adventitia 28 days later of Group S was significantly higher than that of Group NS(42.5%±8.6%vs 31.9%±4.6%%,P＜0.01).RT-PCR analysis revealed that PDGF-B amplification products(457 bp)appeared in both group S and NS from 7 to 28 days,and the PDGF-B mRNA expression levels 7,14,and 28 days later of Group S were all significantly lower than those of Group NS(31.2%±6.5%vs 45.4%±8.4%,P＜0.05:42.3%±6.2%vs 65.2%±11.5%,P＜0.01:and 21.3%±5.6%vs 36.2%±9.4%,P＜0.01).Conclusion Non-restrictive external stenting can inhibit the synthesis of PDGF and change its distribution,which may be one of the mechanisms of external stent in preventing re-stenosis of vein grafts.