Vascular regeneration by pinpoint delivery of growth factors using a microcatheter reservoir system in a rabbit hind-limb ischemia model

The purpose of this study was to compare the results of delivering low doses of growth factor iteratively (20 µg x5) via a reservoir system with results obtained following a single administration of 100 µg of growth factor. The delivery systems using gelatin microspheres (GMS) facilitate the controlled release of drugs. The controlled release of growth factors at specific sites is essential for vascular regeneration. An ischemic hindlimb model was established in nine rabbits. A reservoir system was implanted in each rabbit. GMS impregnated with basic fibroblast growth factor (bFGF) through an indwelling 2-Fr catheter was infused in the reservoir system. The rabbits were divided into three equal groups: group 1 received 20 µg iteratively (x5) via the reservoir, a single dose of 100 µg growth factor was administered to group 2 and group 3 was the saline control. The therapeutic effects were evaluated by measuring the thigh temperature, blood pressure and blood flow. An immunohistological analysis was also performed for CD31. No significant difference was observed between pre- and post-treatment (4 weeks following bFGF infusion) in the thigh temperature, blood pressure and blood flow results from each group. Pathological analysis revealed that the number of regenerated vessels was significantly higher in the group treated iteratively with low-dose bFGF.