Department of Thoracic Surgery, General Hospital of Chinese People's Liberation Army, Beijing 100853, China.
Chin Med J (Engl). 2010 Sep;123(17):2400-4.
Among various treatments preventing vein graft restenosis, external stent is receiving more and more attention. This study aimed to investigate the effect of non-restrictive external stent on the prevention of vein graft restenosis and the potential mechanisms of platelet-derived growth factor (PDGF) in the process of restenosis.
Thirty-six "New Zealand white rabbits" were randomly divided into two groups, stented group (group S) and control group (non-stented group, group NS). Each rabbit underwent a reversed autologous external jugular vein into common carotid artery bypass grafting. In group S, the vein grafts were surrounded by a non restrictive stent which was 6 mm in diameter (a kind of Dacron vascular prosthesis); and in group NS, there was no stent to support the vein grafts. The grafts were harvested at the first week (1W), second week (2W) and fourth week (4W) after surgery respectively. The dimensions (including the thickness and area of the intima and media, luminal area) were measured by computer-aided image analysis system, and the intimal hyperplasia ratio was defined as the percentage of the area enclosed by the internal elastic lamina occupied by the intima.
At 1W, the difference of the thickness and area of the intima between groups S and NS was not significant (P > 0.05); at 2W and 4W, the thickness and area of the intima and the intimal hyperplasia ratio in group S were less significant than those in group NS (P < 0.05); from 1W to 4W, the thickness and area of the media in group S were smaller than those in group NS (P < 0.05). Immunocytochemistry staining of PDGF-B showed that the percentage of positive cells of intima in both two groups was peaked at 2W, and a significantly smaller percentage was detected in group S compared with that in group NS at 2W and 4W (P < 0.05); the percentage of PDGF-B positive cells of media in both two groups was also peaked at 2W, and that in group S was smaller than that in group NS from 1W to 4W (P < 0.05); and the percentage of PDGF-B positive cells of adventitia in group S was peaked at 4W, whereas the percentage of adventitia in group NS peaked at 2W, and the percentage of adventitia in group S was greater than in group NS at 4W (P < 0.05).
Non-restrictive external stenting inhibits the hyperplasia of the intima and media of the vein grafts and reduces the thickness and area of the intima and media; Non-restrictive external stenting inhibits the synthesis of PDGF and changes its distribution, and then inhibits the hyperplasia of the intima.
在预防静脉移植物再狭窄的各种治疗方法中，外部支架越来越受到关注。本研究旨在探讨非限制性外部支架对预防静脉移植物再狭窄的作用，以及血小板衍生生长因子（PDGF）在再狭窄过程中的潜在机制。
36 只“新西兰白兔”随机分为两组，支架组（S 组）和对照组（非支架组，NS 组）。每组兔均进行逆行自体颈外静脉至颈总动脉旁路移植术。S 组静脉移植物用 6 毫米直径的非限制性支架（一种涤纶血管假体）包裹；NS 组无支架支撑静脉移植物。术后第 1 周（1W）、第 2 周（2W）和第 4 周（4W）分别取移植物。通过计算机辅助图像分析系统测量血管内膜（包括内弹力膜内的厚度和面积、管腔面积）的厚度和面积，并定义内膜增生率为内膜占据的内弹力膜面积的百分比。
1W 时，S 组和 NS 组的内膜厚度和面积差异无统计学意义（P>0.05）；2W 和 4W 时，S 组的内膜厚度和面积以及内膜增生率明显低于 NS 组（P<0.05）；从 1W 到 4W，S 组的中膜厚度小于 NS 组（P<0.05）。PDGF-B 的免疫细胞化学染色显示，两组内膜的阳性细胞百分比均在 2W 时达到峰值，S 组在 2W 和 4W 时明显低于 NS 组（P<0.05）；两组中膜的 PDGF-B 阳性细胞百分比也在 2W 时达到峰值，从 1W 到 4W，S 组小于 NS 组（P<0.05）；S 组的外膜 PDGF-B 阳性细胞百分比在 4W 时达到峰值，而 NS 组在 2W 时达到峰值，S 组在 4W 时大于 NS 组（P<0.05）。
非限制性外支架抑制静脉移植物内膜和中膜的增生，减少内膜和中膜的厚度和面积；非限制性外支架抑制 PDGF 的合成并改变其分布，从而抑制内膜增生。
