Figure 4.

Interposition isolation models for studying endothelialisation without the interference of trans-anastomotic endothelial out- and over-growth. (A) Rat infra-renal loop graft model. A high porosity polyurethane graft was welded into the mid-segment of an up to 100 mm long low-density ePTFE graft. The confluent mid-graft endothelium reached onto the otherwise endothelial-free ePTFE sections. Transmural ingrowth from the adventitial side was confirmed with corrosion casting. The origin of the surface endothelium was sometimes traceable to capillary openings on the blood surface. (B) Senescent baboon femoro-femoral isolation graft model. Experimental grafts were equally welded into the mid-section of low-porosity ePTFE. The experimental ePTFE graft shown possessed a dense middle layer which made it impenetrable for cells. After 6 weeks, cellularity was almost exclusively on the adventitial side, highlighting that trans-mural ingrowth from the adventitia overwhelmingly accounts for the cell population of the graft wall unless actively recruited by transanastomotic endothelium (see Figure 6). From (113) and (102) with permission.