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Neovascularization by bFGF releasing hyaluronic acid–gelatin microspheres: in vitro and in vivo studies

Therapeutic angiogenesis with angiogenic growth factors has been described as a promising approach for tissue engineering, wound healing, and for treating ischemic tissues. Here, we assessed the merit of heparin-entrapped hyaluronic acid–gelatin (HA–G) microspheres for the sustained release of recombinant basic fibroblast growth factor (rbFGF) to promote localized neovascularization. HA–G microspheres were prepared by a water-in-oil emulsion method, and the in vitro release kinetics were first examined using three model proteins. Then, bFGF was incorporated into microspheres, and the bioactivity of the in vitro-released rbFGF was tested on human umbilical vein endothelial cell cultures. The ability to promote microvessel growth was assessed in vivo, at the subcutaneous groin fascia of Wistar rats after 3, 7, 14, and 21 days. Histological and morphometrical analysis indicated that heparin-entrapped HA–G microspheres have the capacity to release bioactive rbFGF, leading to localized neovascularization in the rat subcutaneous tissue.