Preparation of gelatin microspheres encapsulated with bFGF for therapeutic angiogenesis in a canine ischemic hind limb.

There is urgent need for the treatment of limb ischemia. In order to avoid the risk of genetic materials or injury in collection of implanted cells, a basic fibroblast growth factor (bFGF) sustained release system using cross-linked gelatin microspheres was developed for therapeutic angiogenesis. In this study, gelatin microspheres (MSs) and the complex of MSs and bFGF (MSs-bFGF) were prepared. MSs and MSs-bFGF were analyzed for morphology, particle size, in vitro bFGF release and the bioactivity of the released medium. MSs-bFGF was intramuscularly implanted into the ischemic hind limb of a dog and free bFGF, empty MSs and untreated animals were used as controls. Histological examination was performed for angiogenesis evaluation. After immersion in an aqueous solution, the un-cross-linked MSs became deformed and adhered together. The cross-linked MSs showed a more stable character both in vivo and in vitro. The bFGF released from MSs remained bioactive. The histological examination indicated that the densities of micro-vessels in the MSs-bFGF-treated hind limb muscle were significantly greater than that in the untreated control, free bFGF and empty MSs groups. The MSs-bFGF sustained release system was a simple, safe and effective way to achieve therapeutic angiogenesis in an ischemic limb.