Influence of fibril length upon ePTFE graft healing and host modification of the implant.

Influence of fibril length (porosity) upon synthetic vascular graft healing has not been investigated in detail. The purpose of this study was to determine the dependence of neoendothelial healing, cellular response, and biocompatibility on the fibril length of expanded polytetrafluoroethylene (ePTFE) grafts with an internal diameter of 1.5 mm. ePTFE grafts of different fibril length, 20, 40, 60, and 90 microns, were implanted into the abdominal aorta of rats (n = 5 for each group). After 5 weeks, the implants were harvested and examined for neointimal and pseudointimal coverage by light microscopy and SEM. The hydroxyproline content of the implants was measured, and the distribution of collagen types was examined. The neointimal and pseudointimal coverage was related to the fibril length, and the neoendothelial healing was better on 60-microns and 90-microns grafts than on 20-microns and 40-microns grafts. The amount of hydroxyproline was also related to the fibril length, however, no significant difference could be observed between 60-microns and 90-microns grafts. Collagen types I and III were almost identically located in the middle portion of the implants. Our results demonstrate that the fibril length of ePTFE grafts affected neoendothelial healing and its affinity to collagen.