The rate of re-endothelialization correlates inversely with the degree of the following intimal thickening in vein grafts - Electron microscopic and immunohistochemical studies

The distribution of re-endothelialization and the development of intimal thickening were investigated electron microscopically and immunohistochemically using saphenous vein grafts implanted into the femoral artery in dogs. Animals were divided into two groups according to a difference of preparation of the venous grafts before implantation: group 1 without storage, and group 2 with storage for 1 h in 0.9% sodium chloride solution containing papaverine and heparin. In group 2 endothelial cells were almost totally denuded at 1 day, while endothelial islands were always left on the back of valves. In group 1 small islands of surviving endothelial cells were occasionally observed away from the valves. By 1 week, the re-endothelialization of group 1 and group 2 extended to 71 ± 14.7% and 47 ± 9% (mean ± SD) of the total luminal surface area, respectively, and spread mainly from the valves but not from the adjacent artery. Immunohistochemical study using anti-dog fibrinogen IgG suggested that increased permeability of the graft wall continued for one month, in spite of the endothelial covering. Intimal thickening was most pronounced at 1 month, especially near the anastomosis, but was less in the middle of the grafts. These results indicate that intimal thickening of the venous grafts is a response to injury which intimately depends on the rate of re-endothelialization.