Osteogenesis with coral is increased by BMP and BMC in a rat cranioplasty

Autologous bone marrow cells (BMC), bone morphogenetic protein (BMP) and na tural coral exoskeleton (CC) were used to enhance the repair of large skull bone defects in a craniotomy model. Nine millimeter calvarial defects were created in adult rats and were either left empty (control defects) or impl anted with CC alone, CC-BMC, CC-BMP, or CC-BMC-BMP. After 1 or 2 months, os teogenesis was insufficient to allow union when defects were left empty or filled with CC. Addition of BMC alone to CC had no positive influence on os teogenesis at any time and increased CC resorption at 2 months (0.1 +/- 0.1 mm(2) versus 0.5 +/- 0.3 mm(2)). In contrast addition of BMP or BMP/BMC to CC led to a significant increase in osteogenesis and allowed bone union af ter 1 month. At 2 months, the combination of CC-BMP-BMC was the most potent activator of osteogenesis. Filling a defect with CC-BMP-BMC resulted in si gnificantly increased bone surface area (11 +/- 2.7 mm(2)) in comparison to tilling a defect with CC-BMP (7.0 +/- 1.4 mm(2)), CC-BMC (3.5 +/- 1.1 mm(2 )) or CC (4.5 +/- 0.4 mm(2)). CC resorption was significantly decreased in the presence of BMP with or without BMC at both times. These data are in ac cordance with the presence of progenitor cells in bone marrow that are indu cible by BMP to the osteogenic pathway in a cranial site. The increase in m aterial resorption in defects filled with CC-BMC could suggest that cells f rom the granulocyte-macrophage lineage survived the grafting procedure and were still active after 2 months. (C) 1999 Elsevier Science Ltd. All rights reserved.