Abstract
In a small-caliber vascular graft, neoarterial regeneration is essential to improve patency. The histological process of regeneration iscomplexly controlled by many structural and biological factors such asgrowth factors. Our designed segmented polyuiethane graft (innerdiameter, 1.5 mm;wall thickness, 100μm; length, 20mm), in which micropores (pore size, 100μm) were produced by excimer laser ablation technique. These grafts were coated with a mixed solution of photoreactive gelatin (20 mg/ml) and heparin (1mg/ml) with or without growth factors [vascular endothelial growth factor (VEGF), basic fibroblast growth factor(bFGF)], and were irradiated by ultraviolet light. Five grouped-grafts were implanted in aortas of rats for 4 weeks;the VEGF group (VEGF: 5μg/ml), the bFGF group (bFGF: 1μg/ml), the VEGF5/bFGF group (VEGF: 5μg/ml, bR3F: 1μg/ml), the VEGF50/bFGF group; (VEGF: 50μg/ml, bRIF: 1μg/ml) and the control group. Control grafts were treated without growth factors. The endothelial coverages were much greater for the growth factors-immobilized groups (around 50-60%) than that for the control group (around 30 %). At the midpoition of the three VEGF-immobilized groups, many capillaries were seen in the neoarterial intima as well as in the micropore, whereas such capillaries were scarcely observed in the bFGF group and control group. These results indicate that the impregnation of VEGF in the gelatinous layer of grafts enhanced transanastomotictissue ingrowth aswell astransmural capillaryingrowth.
