Osteogenesis analysis of calcium phosphate cement/bone morphogenetic protein implanted into muscle or bone

Aim. To study the degradation rate, osteogenesis character and bone-bonding capability of calcium phosphate cement (CPC) combined with bone morphogenetic protein (BMP) implanted into bone or muscle and to investigate the clinical values of the compound artificial bone. Methods. A new type of non-ceramic hydroxyapatite cement of CPC was synthesized, and CPC/BMP composite was implanted into muscle and radius of mice for repairing 15 mm bone defect to study its biodegrade rate, osteogenesis character and bone-bonding capability. Samples were observed by scanning electron microscope (SEM) and energy dispersion analysis and X-ray (EDAX). Results. Compared with CPC, the CPC/BMP composite had the ideal degradation rate and osteogenesis character. When implanting the composite into muscle pouches of mice, new bone formation was observed with significant degradation of the material. No new bone formation and degradation of the material were found in CPC group. Implanting the CPC/BMP into 15 mm-defect in the middle of the radial diaphysis of mice, new bone formed at 4 weeks with the morphologic change of the material and the damage of crystal structure, and then new bone had bridged the gap between the proximal and distal fragments at the end of 24 weeks, and most of the CPC/BMP composite was degraded and absorbed. Only little new bone formed in the CPC group and no visible degradation was found. EDAX indicated calcification was significantly higher in the CPC/BMP group than that of CPC group, and the degree of calcification in the CPC/BMP group was close to that of the normal bone. Conclusion. CPC/BMP composite has the ideal degradation rate with the great potential in bone defect repair, and it is expected to use as grafting material in dealing with segmental bone defect in clinic.