EXTERNAL BIODEGRADABLE SUPPORTING CONDUIT PROTECTS ENDOTHELIUM IN VEIN GRAFT IN ARTERIAL INTERPOSITION

The prevention of circumferential distension could reduce structural d amage in arteriovenous grafts. We studied the effect of an external bi odegradable supporting conduit on the endothelium and extracellular ma trix in vein graft in a pig model. Cephalic vein control grafts (Group I) and jugular veins wrapped in a vicryl mesh tube (I.D. 4mm) (Group II) were implanted into autologous carotid arteries (n=14). The grafts were explanted after 1 and 24 hours and at 1 and 3 weeks and evaluate d by ELISA for endothelial DNA synthesis and by immunohistoenzymic ass ays for cells and extracellular matrix. In group I an initial loss of endothelial and smooth muscle cells along with elastin breakdown was f ollowed by an impaired endothelial regeneration and significant graft wall thickening. The elastic tissue was replaced by collagen type I an d chondroitin sulfate accumulations, which included a disarray of alph a-smooth muscle actin positive cells. The endothelium was preserved in group II. After 3 weeks the circumferential elastin layers were densi fied, distended and separated from the endothelium by a neointimal gro wth of irregular thickness. Biodegradable perivenous conduit minimized endothelial injury and allowed the partial preservation of elastin fi bers and smooth muscle cells in the arteriovenous graft. If did not ho wever, prevent myofibroblastic cell proliferation and triggered a macr ophagic reaction.