Purpose: To determine if a complete intra-arterial environment affects endothelialization rate and basement membrane organization in polytetrafluoroethylene (PTFE) grafts.
Method: Thirty dogs underwent either infrarenal abdominal aorta PTFE interposition (12) or intraluminal stented (18) grafting. Grafts were explanted at 4 and 8 weeks and rate of endothelial ingrowth calculated. Endothelial cells were identified and basement membrane organization assessed using antibodies against endothelial cell-specific surface antigen CD31, type IV collagen, and laminin.
Results: Endothelialization rates, expressed as percent graft surface area coverage per week, were 3.7% +/- 0.62% (4-week control), 12.9% +/- 0.58% (4-week stented), 4.2% +/- 0.62% (8-week control), and 10.0% +/- 0.54% per week (8-week stented grafts). Endothelial repaving rates were constant for control and increased in all stented grafts (P <0.01). At 4 weeks, laminin was identified in all control (6 of 6) and no stented grafts. Staining was confined to the 20% of the hyperplastic intimal area immediately below the endothelium. At 4 weeks, type IV collagen was present throughout the entire hyperplastic intima in control specimens but was confined to a discrete subendothelial zone in stented grafts. By 8 weeks, type IV collagen became concentrated in the luminal one third of the intima in control grafts.
Conclusion: Intra-arterial graft location is associated with early formation of an organized basement membrane and accelerated endothelialization in PTFE grafts.