Recombinant human bone morphogenetic protein-7 and bone marrow as a substitute for bone graft in reconstruction defect of rabbit mandible

OBJECTIVE: To obtain information on the feasibility of employing recombinant human bone morphogenetic protein-7 (rhBMP-7), mixed with bone marrow as a substitute for autologous bone graft.

METHODS: We carried out the study in the University Clinic Center, Sarajevo, Bosnia and Herzegovina, from February 2002 to January 2004. Six New Zealand rabbits underwent hemiresection of the mandible. We placed rhBMP-7 in a concentration of 100 micrograms and collagen (ACS) as carrier mixed with bone marrow in the defects in 3 animals. In another group of 3, we restored the defect by placement of autologous bone graft harvested from the iliac crest. We evaluated the results by the activity of the alkaline phosphatase enzyme (ALP), CT assessment with bone mineral density (BMD) analysis, and clinical and histologic examinations.

RESULTS: The ALP activity was significantly higher after 14 days, in the rhBMP7/ACS sites than the bone graft sites (30th day). Mean BMD of tissue induced by rhBMP-7/ACS on the 30th day was 510 mg/cm3 in caudal, and 553 mg/cm3 in sagittal plane, and bone graft tissue was 510 mg/cm3 in caudal and 530 mg/cm3 in sagittal plane. Clinical inspection and histologic examination on the 60th day showed complete bridged defects with abundant woven bone in 2 of 3 rhBMP-7/ACS sites (67%), and no incorporation of the autologous bone graft into the other groups treated sites.

CONCLUSION: The rhBMP-7/ACS mixed with bone marrow was very effective in establishing complete bone regeneration into the defects, indicating that it could be an adequate alternative for autologous bone transplantation.