可降解外套管抑制自体移植静脉内膜增生的研究

目的:研究可降解的外套管束缚自体移植静脉对减轻桥静脉内膜、中层增厚的作用,探讨其防止或延缓桥静脉再狭窄的机制。方法:建立犬自体股静脉至股动脉的端-端静脉移植模型,其中一侧桥静脉外加聚乳酸-聚乙醇酸(PLGA)做成的圆柱形外套管(外套管组),对侧单纯静脉移植作为对照组。超声多普勒观察在体移植血管的通畅性。术后2、4、6、8、24周再次手术取桥静脉。光镜观察移植静脉中段内膜、中层厚度,胶原、弹力纤维变化;透射电镜观察静脉壁基底膜、细胞排列、细胞增殖、凋亡,细胞骨架结构,细胞外基质(ECM)变化等;免疫组化观察静脉壁细胞增殖、凋亡及分布。结果:术后40条静脉均通畅,吻合口无狭窄。对照组术后2周见内膜、中层增厚;随时间延长,增厚更加明显。外套管组术后2周内膜、中层稍增厚;4~24周持续增厚,但各时间点均明显小于对照组(P<0.05,P<0.01);对照组术后2周见中层平滑肌、外膜弹力纤维断裂严重,而外套管组无明显断裂。新生静脉内膜由平滑肌细胞(SMCs)和大量ECM构成,中层主要为SMCs和ECM;术后2周,静脉壁细胞增殖和凋亡率都较高,主要分布在内膜和中层,外套管组明显低于对照组(P<0.01),4周以后两者显著下降,凋亡率高于增殖率(P<0.05)。结论:可降解外套管在术后早期可保持静脉结构的完整性,减轻管壁结构破

Biodegradable external stent inhibits intimal hypertrophy of autologous vein graft

Objective: To study the inhibition effects of biodegradable stent made of poly (lactic acid/glycolic acid) (PL-GA) on the intimal hyperplasia of autologous vein graft. Methods: Femoral vein grafts of 20 dogs were implanted into their femoral arteries. The vein graft on one side was supported by the PLGA external stent. The untreated vein graft on the other side was taken as control. The vein grafts were harvested at 2, 4, 6, 8, 24 weeks after implantation. The intimal and medial thickness of vein grafts were examined with light microscopy. The transmission electron microscopy was used to evaluate the intimal elastic membrane, cellular structure and extracellular matrix. Proliferating cell nuclaious antigen (PCNA) were marked with PCNA antibody and cell apoptosis was examined with TUNEL method. Results: The biodegradable PLGA external stent supported the vein graft for 4 weeks and began to biodegrade 6 weeks later. There were more broken smooth muscle layers and elastic fibers in control groups than those in stent groups during week 2. The intimal hyperplasia was seen during week 2 and became more significant after 4 weeks. The mean intimal thickness in external stent vein grafts was significantly less than that in control group on 2, 4, 6, 8, 24 weeks after implantation(P<0. 05, P<0. 01). The ratios of PCNA and TUNEL positive cells in external stent group were much less than those in control group(P<0. 05,P<.0. 01). Transmission electronic microscope examination revealed that there were many smooth muscle cells and collagen in intima. Conclusion: The external stent can reduce intimal and medial layer thickness and cell proliferation in vein grafts transplanted into the arterial position, and the effects remains after stent having degraded.