Ectopic Osteogenesis Induced by Coating-incorporated Depot of BMP-2 in Coral

Methods: CHA granules ( 0.25g per sample) bearing a CaP coating into which BMP-2 (20μg, 40μg or 60μg per sample) was incorporated or bearing no BMP-2 were implanted subcutaneously in rats  (n=6 per group) . Five weeks later, the implants were retrieved for a micro-CT evaluation and histomorphometric analysis. The volumes of ectopic bone and the degree of CHA degradation were estimated by volume density of bone and volume density of CHA, respectively. All data were analyzed with a one-way analysis of variance (ANOVA) and the level of significance was set at P<0.05.

Results: Newly formed bone was observed along the surface of CHA granules that bore a CaP coating-incorporated depot of BMP-2, as well as bone marrow. There was a tendency for a higher osteoinductive efficacy of BMP-2 when its amounts increased. However, no significant differences were found in the volume of bone among the three dosages of BMP-2. Although the CHA revealed certain degree of degradation in all the groups, no statistically significant differences were found.

Conclusion: These findings indicate that the CaP coating-incorporated BMP-2 confer porous CHA granules with the property of osteoinductivity and thus dually enhancing its clinical potential in the repair of bony defects.