Healing characteristics of polymer-coated or collagen-treated Dacron grafts: an experimental porcine study.

The healing characteristics of polymer-coated Dacron grafts with or without heparin-bonding and collagen-coated Dacron grafts are compared with standard knitted Dacron grafts by implanting eight of each graft into pig iliac arteries. The grafts were implanted at random bilaterally with end-to-side anastomoses. The grafts were explanted after 1, 2 and 4 weeks and prepared for histological evaluation by in vivo fixation. Graft segments were investigated by light microscopy, scanning electron microscopy and transmission electron microscopy. The endothelial coverage, intimal thickness and healing characteristics were subjected to one-way analysis of variance. One week after surgery endothelial-like cells appeared close to the anastomoses and after 2 weeks a clear growing endothelial edge was observed in the collagen-coated grafts. After 4 weeks' implantation all grafts were patent and endothelial cells covered the grafts to a various extent. Collagen-coated grafts had significantly greater endothelial cell coverage compared with Dacron and polymer-coated grafts without heparin bonding (P < 0.05). Evaluation by transmission electron microscopy revealed the luminal coverage of the collagen-coated grafts to consist of organized smooth muscle cells and endothelial cells containing Weibel-Palade bodies. The smooth muscle cells in the other grafts were less organized and were covered by endothelial cells to a lesser degree. No differences were noted regarding the inflammatory response of the graft materials and no further positive effects were encountered by the addition of heparin to the polymer coating. The study demonstrates that various coating procedures and surface modulation of knitted Dacron grafts produce a graft which is impervious to blood but still allows tissue incorporation.(ABSTRACT TRUNCATED AT 250 WORDS)