Endothelium on the flow surface of human aortic Dacron vascular grafts

Abstract

The rapidity with which the specimens were fixed probably enabled identification of endothelium. These findings suggest that endothelialization of synthetic arterial grafts may occur more frequently in human beings than previously recognized.

Prosthetic vascular grafts: Wrong models, wrong questions and no healing

“…This suspicion is confirmed by descriptions of true midgraft regions in particularly long grafts in which the inner fibrin capsule appears to be both impenetrable for the ingrowing interstitial graft tissue [34,70,82,122,[137][138][139] and non-endothelialized [76,140,141]. This lack of surface healing occurs [6,7,76,131,132,140,142] although transmural tissue reaches the compacted fibrin of the blood surface within 3-4 weeks in the calf [76], the yellow baboon [70] and the dog [34,143] and 3-6 months in humans [7,76]. Very occasionally, though, even complete endothelialization of very long prostheses, [65,126] comparable to that in highly porous ePTFE grafts, is seen.…”

“…This process is quite variable in its extent and time course. In dogs it can be seen as early as 2-3 weeks after implantation [129], whereas in humans it may be observed after 5 months [58] or not at all [10,130,131]. Exceptionally, the tissue reaches the inner fibrin capsule and begins to organize the basis of the fibrin capsule in a few scanty areas of the graft [130].…”

“…In the rare event that such tissue forms, it was found to occur after 4-8 weeks in dogs [58,128] and after 18 months in humans [130]. In even fewer cases, these tissue areas replace the inner fibrin capsule in its entire thickness and form a pseudo-neointima [58,130,131]. Both the pseudo-neointima and the compacted fibrin usually reach an equilibrium at a thickness of approximately 400-500 mm [130].…”

“…Usually no endothelial cells are found at all within the first 1-2 years [58,130,131]. After prolonged implantation periods of up to 11 years-which are naturally restricted to humans-small islands of endothelial cells may occasionally appear [130,131]. These endothelial islands always rest on the compacted fibrin rather than the scanty islands of connective tissue.…”

AAA Stent–Grafts: Past Problems and Future Prospects

“…In animal models, endothelialization of the stent graft seems to occur quickly (within 3 months) and along the whole length of the graft. 59,122 Although there are occasional reports of this occurring in humans, 106 it is thought that endothelialization does not commonly take place. 87 Therefore, further work on developing methods to encourage endothelialization should be performed, so that the stent graft becomes integrated with the body.…”