Xenograft seeding of Dacron grafts in dogs

The benefit of autologous endothelial cell seeding in dogs has been widely accepted. This experiment seeks to determine if a similar effect accompanies the use of xenograft (porcine) endothelial cells in dogs. Thirty-two mongrel dogs underwent thoracoabdominal aortic bypass with 25- to 30-cm segments of double velour Dacron 8-mm grafts. Endothelial cell seeding was performed with whole blood suspensions of either autologous endothelial cells (Group I) or heterologous endothelial cells from pigs (Group II). Cell-free culture medium was added to whole blood for preclotting in unseeded control animals (Group III). Ten animals in each group were sacrificed at 30 days and all grafts were patent. Thrombus-free surface areas were Group I = 61.7 (+/- 6.4%, SEM); Group II = 53.2 (+/- 6.8%, SEM); and Group III 42.2 (+/- 8.0%, SEM). There was a significant difference between autologous-seeded and unseeded grafts (P less than 0.04). Endothelialization was confirmed by scanning and transmission electron microscopy in all groups but was better in both seeded groups: Group I-9/10 grafts, Group II-8/10 grafts, and Group III-4/10 grafts. Factor VIII immunofluorescent staining confirmed the presence of endothelium on selected grafts in each group. These results raise questions concerning the proposed mechanism of endothelial seeding since xenograft cells seem to facilitate healing in the canine model. If heterograft cells can be effective, it may not be necessary to harvest cells from the recipient in order to achieve the benefits of seeding.