Accelerated endothelialization model for the study of Dacron graft healing.

Accelerated endothelialization was studied by creating a vascular tissue environment around porous Dacron grafts. Three study groups, each containing 10 dogs, were divided equally into 2- and 4-week implant periods, with 8 mm x 6 cm knitted Dacron grafts implanted in the abdominal aorta. Grafts in group 1, the control group, were implanted conventionally. In group 2 each implanted graft was completely wrapped in a resected segment of the autogenous inferior vena cava, with its intima against the wall. In group 3 the adventitial side of the vein was wrapped against the wall. The vein wrap produced accelerated endothelialization as follows: endothelial-like cell coverage scores at 2 and 4 weeks were, respectively, 78% and 98% for group 2 and 80% and 95% for group 3, compared to only 14% and 50% for group 1 (p < 0.05). The neointima, which contained smooth muscle cells, was formed as early as 2 weeks in the vein-wrapped grafts. There were no differences in the speed of healing or in healing patterns according to whether the intimal or the adventitial side of the inferior vena cava was placed against the graft. Histologic findings did not support the hypothesis that accelerated flow surface endothelialization results in direct migration of endothelial cells from the intima of the vein wrap, and there was no clear correlation between the surface endothelial-like cell coverage and microostia. To gain further insight into why accelerated healing occurs in this model, earlier observations accompanied by molecular biology analysis are needed, and vein wrap studies provide a method of comparison for this work.