THE DEGREE OF POROSITY INFLUENCES THE RELEASE OF GROWTH-FACTORS BY HEALING POLYTETRAFLUOROETHYLENE (PTFE) GRAFTS

Objectives: The aim of this study was to determine the influence of th e degree of porosity on the release of growth factors (PDGF AA, PDGF B E, bFGF) by healing PTFE grafts. Design and setting: Laboratory animal study. Materials: 1 cm long segments of non-reinforced PTFE grafts (3 0 microns fibril length, 2 mm internal diameter 0.39 mm thick) were pl aced as an abdominal aortic interposition in Lewis rats. Fifteen graft s served as control (Group A; porous grafts); in eight rats (Group B; non porous grafts) the PTFE graft was completely wrapped by a non-poro us plastic envelope. Animals were killed 4 weeks after surgery. Outcom e measures: The release of PDGF AA, PDGF BE, and bFGF was assessed by Enzyme Linked Immunosorbent Assay (ELISA). Results: The release of PDG F AA, PDGF BE and bFGF was statistically higher in porous grafts. The only histological difference between the two groups was that porous PT FE grafts were invaded by many tufts of capillaries front the surround ing tissue, whereas this phenomenon was absent in non porous PTFE graf ts. Conclusions: The degree of porosity influences the release of grow th factors by healing PTFE grafts. This fact may have implication in t he endothelisation of PTFE grafts and in myointimal hyperplasia format ion as well.