Host response to autologous endothelial seeding☆☆☆★

Abstract 

Dacron and expanded polytetrafluoroethylene grafts, seeded with autologous venous endothelial cells at the time of implantation, subsequently develop endothelial linings. However, it has not been shown whether the endothelial cells in these linings are derived from the seeded cells, or whether the seeding process itself stimulates host endothelial cells to proliferate and cover the grafts. As a first step in testing this hypothesis, bilateral end-to-side aortoiliac expanded polytetrafluoroethylene grafts with an internal diameter of 6 mm, an internodal distance of 22 μm, and an average length of 9.2 cm were placed in 10 adult mongrel dogs weighing 20 to 25 kg; the aorta was ligated just distal to the origin of the grafts. The graft on one side, chosen at random, was seeded with autologous endothelium that was harvested by enzyme single-stage technique from external jugular veins; the other side was not seeded. After 4 weeks the animals were anesthetized and heparinized, and the grafts were fixed by perfusion in vivo with 2.5% glutaraldehyde solution before they were removed. Both grafts occluded in two animals, and both grafts were patent in five animals. In two animals the seeded grafts were open and the unseeded grafts were occluded. In one the seeded graft was occluded and the unseeded graft was patent. There was no significant difference in clot-free surface area between seeded (29% ± 18%) and unseeded (31% ± 11%) grafts. Scanning electron microscopy showed the presence of an endothelial monolayer that averaged 39% ± 20% and 36% ± 26% coverage, respectively, in the clot-free midgraft portions of all seeded and unseeded patent grafts. In addition, transmission electron microscopy revealed endothelial cells under a thin adherent layer of fibrin and red cells, seen by light microscopy over an average of 35% of the surface area. The lack of differences between seeded and unseeded grafts in patency and clot-free surface, and the extent and distribution of the endothelial coverage in unseeded grafts after only 4 weeks implantation, provide supportive, although inconclusive, evidence that the seeding process may be more important as a stimulus for growth of host endothelium than as a vehicle providing cells to line grafts. (J Vasc Surg 1989:9:656–64.)