The promotion effect of small intestinal submucous layer on the endothelial regeneration of percutaneously-inserted stent surface: An experimental study in swine

Objective: To explore the promotion effect of small intestinal submucosa (SIS) on the endothelial regeneration of vascular stent surface that was percutaneously-inserted in experimental swine, and to discuss its clinical value in preventing restenosis of the stent. Methods: Fourteen domestic swine were used for this study. Via the carotid access the bilateral iliac arterial catheterization was performed in all animals. After excessive balloon dilatation of bilateral iliac arteries, bare stent (BS) was implanted in randomly-selected one iliac artery, while SIS-eluting stent was placed in the iliac artery on the opposite side. The animals were separately re-examined with angiography at 4 weeks (n = 4), 8 weeks (n = 5) and 12 weeks (n = 5) after the treatment. After the angiography the animals were sacrificed. The specimens carrying stent were collected and sent for histopathological and electron-microscopic studies. The results were analyzed and compared between the SIS-eluting stent group and the BS group. Results: Implantation of 14 SIS-eluting stents and 14 BS stents was successfully accomplished in 28 iliac arteries of the 14 pigs. Follow-up angiography showed that one iliac artery was occluded in both SIS-eluting stent group and BS group at 8 weeks after the treatment, and all the remaining 26 stents were patent. At 4, 8 and 12 weeks after the treatment, no statistically significant difference in restenosis rate existed between the SIS-eluting stent group and the BS group (P > 0.05). Immunohistochemistry study revealed that mean percentage of the cells with positive proliferating cell nuclear antigen (PCNA) of the SIS-eluting stent group at 4, 8 and 12 weeks after the treatment was significantly lower than that of the BS group (P < 0.05). Electron-microscopic study revealed that the number of intimal endothelial cells of the SIS-eluting stent group was significantly larger than that of the BS group (P < 0.05). Conclusion: SIS does have the function of promoting the regeneration of endothelium as well as speeding up the endothelialization of stent surface. It can indirectly inhibit the proliferation of vessel smooth muscle cells and promote the transformation of synthetic smooth muscle cells to contractive ones.