可降解外套管减轻自体移植静脉内膜增生的动物模型建立

Establishment of experimental animal model for reducing the thickness of intima in vein grafts with a biodegradable external stent

目的 建立可降解外套管束缚自体移植静脉减轻静脉内膜增生的动物模型 ,探讨可降解材料做外套管对防止或延缓桥静脉再狭窄的可行性。方法 以“no touch”方法取犬股静脉 ,调转后移植到同侧股动脉 ,其中一侧加用聚乳酸 聚乙醇酸 (PLGA)做成的圆柱形外套管 (外套管组 ) ,另一侧单纯静脉移植 (对照组 )。超声多普勒观察移植静脉是否通畅。术后 4周和 2 4周再次手术取移植静脉段。病理切片行苏木素 伊红 (HE)染色测量移植静脉中段内膜、中层厚度 ;维多利亚蓝(VB)染色观察胶原纤维、弹力纤维 ;免疫组织化学平滑肌α actin抗体染色鉴定静脉平滑肌。结果(1)所有动静脉吻合口无狭窄 ,术后早期 ,外套管组 2条静脉血栓形成、闭塞 ,对照组 1条静脉血栓形成、闭塞 ;(2 )外套管变化 :术后 4周内外套管无变形 ,6周开始变形 ,2 4周完全降解 ;(3 )静脉内膜和中层厚度 :外套管组静脉内膜增生轻 ,厚度均匀 ,对照组静脉内膜不均匀增厚 ,术后 4周和 2 4周外套管组静脉中段的内膜及中层厚度均显著小于对照组 ,差异有非常显著性 (P <0 .0 1) ;(4 )移植静脉新生内膜主要由平滑肌细胞 (SMCs)和胶原纤维构成 ,术后 4周和 2 4周对照组两者含量丰富 ,而外套管组含量少于对照组且排列整齐。结论 该动物模型设计合理 ,PLGA可以做?

Objective To establish an animal model of reducing neointima hyperplasia of autologous vein graft with a biodegradable external stent made by poly (lactic acid/glycolic acid)(PLGA).Methods The both sides of femoral veins of 12 dogs were implanted into the same side femoral artery with the “no touch” technique.One side of the vein graft was supported by a biodegradable external stent.Veins were examined under a light microscope to observe α-actin in SMCs and to assay the thickness of vessel intima and media quantitatively.Results No dogs died and all anastomoses had no stenosis.The external stent had no distortion within 4 weeks and completely substituted by fiber tissue at 24 weeks after operation.The mean thickness of intimal and medial wall in sheathed group were much less than those in control group at 4 weeks and 24 weeks after implantation,respectively (P< 0.05 or P< 0.01).The mean area of intimal and medial wall in sheathedveins was also less than those in control group at 4 weeks and 24 weeks after implantation respectively (P< 0.01).There were more smooth muscle cells and more collagen in control group vein grafts than that in sheathed veins.Conclusion The model was developed scientifically with a high successful rate.The supporting,biodegradable external sent can function as a protective scaffold for vein grafts not only before but also after the stent biodegraded.