Effect Of Biodegradable External Stent On Preventing Restenosis Of Autologous Vein Graft In Hyperlipemia Rabbit

Objective: To investigate effect of the polyglycolic acid (PGA) biodegradable external stent on preventing restenosis of autologous vein graft in hyperlipemia rabbit. Methods: (1)The rabbits were fed with high-cholesterol diet for 12 weeks. At week 0,2,4,8 and 12, jugular veins were harvested and submitted to light microscope analysis using histochemical stainings and immuno-histochemistry with specific antibodies. Griess assay was used to determine the NO production(2) Mechanical properties of PGA non-woven fabric was tested by Instron tensile testdevice.(3)Jugular vein grafts with and without biodegradable external stent were interposed into carotid arteries of hyperlipemia rabbit. The vein grafts were harvested at2, 4,8,12 and 20 weeks after implantation respectively and were examined with Oil Red "O", HE, VB and immunohistochemical stain and scanning electron microscopy. NO production was detected by the way of nitrate reductase. The flow condition in the vein grafts was checked with ultrasonography. The expression of eNOS, NO production and histomorphological variation were compared. Results: (1)Hyperlipemia rabbit model was established at 8 weeks after fed with high-cholesterol diet. The jugular veins of hyperlipemia rabbits had less expression of eNOS, NO production and elastic fiber.(2)The modulus of elasticity of PGA non-woven fabric is 11.371Mpa.(3)Restenosis was no found in sheathed grafts (with biodegradable external stent). The expression of eNOS and NO production in sheathed grafts were higher than that in unsheathed grafts. Sheathed grafts significantly reduced intimal and medial thickening and lipids deposition as compared with unsheathed grafts at 12 and 20 weeks after implantation. Conclusion: The PGA external stent can prevent restenosis of vein grafts in hyperlipemia rabbit, which persists in long term, even after degradation of stent itself. The mechanism of biodegradable external stent on preventing restenosis of vein graft may be related to improve endothelium function and inhibit the contractive vessel remodeling.