Platelet Interactions with Heparin Binding Growth Factor and Fibronectin

Abstract

A fibronectin (Fn)/heparin/heparin binding growth factor (HBGF)/heparin (FHHH) complex can be affixed to vascular grafts. This study examines the effect of HBGF, Fn, and FHHH on platelet adhesion and aggregation. Expanded polytetrafluoroethylene (PTFE) grafts (5 cm ± 4 mm) were treated with Fn (n = 9), FHHH (n = 9), or neither (n = 10) and interposed into canine aortoiliac systems, using each dog as its own control. Autogenous radiolabeled (111In oxine-650 μCi) platelets were injected IV prior to re-establishment of circulation. Blood flow was determined by electromagnetic flowmetry and perfusion maintained for 30 min. Grafts were removed with native aorta and ipsilateral iliac arteries (IIA). Specimens, excluding anastomoses, were sectioned for gamma counting and computerized planimetry. Results showed that FHHH and Fn treated grafts contained significantly more radioactivity than control segments, when normalized to their IIA. FHHH treated grafts contained 27 ± 16 times more radioactivity per mm2 than IIA, Fn treated prostheses 12 ± 8 times more, and untreated PTFE 4 ± 3 times more. FHHH was significantly more radioactive than Fn alone (p ± 0.03). Platelet aggregation in response to either Fn or HBGF was studied in vitro. Aggregation was not activated by either Fn (1–100 μg/100 μl) or HBGF (25–2,500 ng/100 μl). These data suggest that Fn and HBGF promote platelet adhesion but not aggregation.