Incorporation of fibronectin-impregnated vascular prostheses in the pig. Microscope study

An interface near the endothelial extracellular matrix is necessary to augment and maintain endothelial cell attachment. The use of plasma lectins constitutes one of the present lines of research designed to improve this interface. We studied the incorporation of 2 series of arterial prostheses with a diameter of 4 mm and a mean length of 9 cm. They were implanted in the carotid arteries of adult Europig minipigs. Prostheses were of two types: polytetrafluoro-ethylene (PTFE) and knitted Dacron. Two series of 12 pigs each were used. One was explanted at 3 months and the other at six. Each pig was grafted with one prosthesis impregnated with the plasma components of diluted Fibrogel and one non-impregnated prosthesis which served as control. The explanted prostheses and adjacent parts of the carotid were prepared for light or scanning electron microscopy. Proximal, median and distal segments were cut and embedded in resin. Collagen distribution was revealed by Milligan's trichrome stain, and fibrin distribution by Picro-Mallory staining. Macroscopic examination showed discrete periprosthetic adhesion for impregnated prostheses and complete adhesion for non-impregnated prostheses. Scanning electron microscopy revealed a median endothelial cell coating on impregnated grafts whereas the only endothelial cells on non-impregnated grafts, were perianastomotic. On impregnated grafts, Milligan's trichrome staining revealed an even collagen distribution. The walls of non-impregnated grafts exhibited capillary cell infiltrations with breaches in the outer structures. In impregnated prostheses, the absence of such breaches enabled us to postulate that their incorporation was better than that of the non-impregnated grafts. The minipig model was hard to handle because of the aggressiveness engendered by restricted feeding designed to limit weight increases. In general, however, we may justifiably conclude that in this model, the use of plasma lectins improved prosthetic incorporation.