Effect of recombinant human bone morphogenetic protein-4 with carriers in rat calvarial defects.

BACKGROUND

Bone morphogenetic proteins (BMPs) are being evaluated as candidates for periodontal and bone regenerative therapy. However, the research on recombinant human bone morphogenetic protein-4 (rhBMP-4) has been insufficient to evaluate its capacity to enhance bone formation and its carrier system. The purpose of this study was to evaluate the bone regenerative effect of rhBMP-4 delivered with an absorbable collagen sponge (ACS) or beta-tricalcium phosphate (beta-TCP). We also compared the potential of beta-TCP to that of ACS as a carrier system for rhBMP-4.

METHODS

Eight-mm calvarial critical-sized defects were created in 100 male Sprague-Dawley rats. The animals were divided into 5 groups of 20 animals each. The defects were treated with rhBMP-4/ACS (rhBMP-4 at 0.05 mg/ml), rhBMP-4/beta-TCP (rhBMP-4 at 0.05 mg/ml), ACS alone, beta-TCP alone, or left untreated for surgical control. The rats were sacrificed at 2 or 8 weeks postsurgery, and the results were evaluated radiodensitometrically, histologically, and histomorphometrically.

RESULTS

The results of radiodensitometric analysis were as follows: the rhBMP-4/ACS and the rhBMP-4/beta-TCP groups were more radiopaque than other groups at both 2 and 8 weeks (P < 0.01). The histologic observations were as follows: in the rhBMP-4/ACS and the rhBMP-4/beta-TCP groups, new bone was evident at the defect sites at 2 weeks and 8 weeks. The results of histomorphometric analysis were as follows: the rhBMP-4/ACS and the rhBMP-4/beta-TCP groups had more bone (%) than other groups at both 2 and 8 weeks (P < 0.01).

CONCLUSIONS

Surgical implantation of rhBMP-4/ACS may be used to support bone regeneration in the rat calvarial critical-sized defect, and rhBMP-4/beta-TCP may be able to regenerate bone in the rat calvarial critical-sized defect without complication. In addition, both ACS and beta-TCP may be considered as available carriers for rhBMP-4.