Transmural communication at a subcellular level may play a critical role in the fallout based‐endothelialization of dacron vascular prostheses in canine

Abstract

A microporous and permeable wall is important for the healing of vascular prostheses, however, the significance of its permeability to soluble substances at subcellular level has not been demonstrated. Polyester arterial prostheses were prepared in such a way that each of them contained three segments, of which at least one segment was impervious and another segment was permeable to water but impermeable to cells. Twenty graft segments were implanted in 7 dogs as a thoraco-abdominal bypass for 2 months. The prostheses were then harvested, photographed, and treated for histological and morphological studies. The low porosity graft capped by two thrombogenic segments was fully endothelialized, proving the fallout mechanism. The striking contrast with its impermeable counterpart demonstrated that a wall permeable to small substances of subcellular level was critical for the endothelial healing. A wide range of water permeabilities did not reveal advantages of high water permeable segments over low water permeable ones. Endothelial ingrowth from anastomoses was also jeopardized in the absence of wall permeability. In conclusion, transmural communication at a subcellular level may have played a critical role in the fallout based-endothelialization of arterial prostheses in canine. This highlights the potential function of perigraft cytokines and growth factors in endothelial healing.

Tissue Responses to Endovascular Stent Grafts for Saccular Abdominal Aortic Aneurysms in a Canine Model

“…Successful endovascular grafting can be expected, when early endothelialization of graft prevents thrombosis. Zhang et al (10) reported the possibility of permeable prosthetic graft to help organization of thrombosis. Subcellular substances such as cytokines and growth factors generated in perigraft tissues could reach thrombi in the lumen and recruit endothelial progenitor cells.…”

“…Successful endovascular grafting requires endothelialization covering graft as soon as possible, which prevents grafts from subsequent thrombosis or excessive tissue formation. Theoretically, endothelial cells were believed to come from artery stems at anastomoses, perigraft capillaries or circulating cells (10). Migration of endothelial cells from anastomoses to graft was commonly observed in animal models, but its role has not shown a meaningful role in humans (11, 12).…”

The in vivo performance of small-caliber nanofibrous polyurethane vascular grafts

“…After grafting, the surface of vascular graft is initially covered with a thin layer of thrombi, which then gradually transforms into a fibrous membrane. Endothelial cells colonize this membrane, differentiate, and finally completely cover the internal surface of the graft, completing the endothelialization [20,21]. …”

New biodegradable small‐diameter artificial vascular prosthesis: A feasibility study

“…The sections were stained with hematoxylin‐eosin for the identification of cells. Sections were analyzed using routine bright field light microscopy, and images were acquired using a digital color camera 17…”

“…The total period of implantation lasted 9 months. After 9 months, the animals were anaesthetized and heparin was administrated at 0.5 mg/kg intravenously to minimize the postmortem thrombotic deposits over the lumen of the prostheses 17. NIH guidelines for the care and use of laboratory animals have been observed.…”