Evaluation of a novel collagen-gelatin scaffold for achieving the sustained release of basic fibroblast growth factor in a diabetic mouse model

The objective of this study was to evaluate the ability of a scaffold, collagen-gelatin sponge (CGS), to release basic fibroblast growth factor (bFGF) in a sustained manner, using a pressure-induced decubitus ulcer model involving genetically diabetic mice. We confirmed that CGSs impregnated with a bFGF concentration of up to 50 µg/cm(2) were able to sustain the release of bFGF throughout their biodegradation. We prepared decubitus ulcers on diabetic mice. After debriding the ulcers, we implanted CGSs (diameter 8 mm) impregnated with normal saline solution (NSS) or bFGF solution (7, 14, 28 or 50 µg/cm(2)). At 1 and 2 weeks after implantation, the mice were sacrificed and tissue specimens were obtained. The wound area, neoepithelium length and numbers and total area of newly formed capillaries were evaluated. The CGSs impregnated with NSS became infected and degraded, whereas the CGSs impregnated with 7 or 14 µg/cm(2) bFGF displayed accelerated dermis-like tissue formation and the CGSs impregnated with 14 µg/cm(2) bFGF produced significant improvements in the remaining wound area, neoepithelium length and numbers and total area of newly formed capillaries compared with the NSS group. No significant difference was observed between the NSS and 50 µg/cm(2) bFGF groups. CGSs impregnated with 7-14 µg/cm(2) bFGF accelerated wound healing, and an excess amount of bFGF did not increase the wound-healing efficacy of the CGSs. Our CGS is a scaffold that can release positively charged growth factors such as bFGF in a sustained manner and shows promise as a scaffold for skin regeneration.