Enhanced regeneration of critical bone defects using a biodegradable gelatin sponge and β-tricalcium phosphate with bone morphogenetic protein-2

We examine the osteogenicity of a sponge biomaterial consisting of a biodegradable mixture of gelatin and β-tricalcium phosphate (βTCP) that bound bone morphogenetic protein 2 (BMP-2) in critical-sized bone defects in rats. Gelatin-βTCP sponges containing either phosphate buffered saline or incorporating BMP-2 are implanted into 5 mm diameter bone defects created in rat mandibles. We assess the defects biweekly for 8 weeks following implantation. There is significantly higher osteoinductive activity and significantly more Gla-osteocalcin content at bone-defect healing sites treated with gelatin-βTCP sponges incorporating BMP-2 than there is in those treated with sponges that did not contain BMP-2. Histologically, new bone that contains bone marrow and that is connected to the original bone almost entirely replaces the regenerated bone. These results show that biodegradable gelatin-βTCP incorporating BMP-2 is osteogenic enough to promote healing in large bone defects.