Hydraulic characteristics and osteoinduction capacity of calcium phosphate/BMP bioactive bone cement

Calcium phosphate (CPC)/BMP bioactive composite bone cement was prepared with ultrafine α-tricalcium phosphate (α-TCP) powders and assist agent premixed with freezed bone morphogenetic protein (BMP) powders. By means of the hydraulic characterization, the composition, cement liquid and promoting solidification agent of the bone cement were optimized. Osteogenesis of the BMP combined bone cement was investigated in the rat muscle pouch. Results show that the novel bone cement with excellent hydraulic properties can be developed with 0.95α-TCP, 0.025CaHPO4, 0.025CaO as the basic composition and 0.25 mol/L NaH2PO4/Na2HPO4 solution ([P]T = 0.5 mol/L) as the cement solution, which can satisfy with the harden strength required for clinic surgery. Initial setting time and final setting time of the bone cement are 6 min and 30 min respectively. The particle size of alpha-TCP has great influence on the characteristics of bone cement, and the suitable particle size (d50) will be 1.3 μm. The compressive strength of the bone cements reaches 33 MPa after soaking in Hank's solution for 5 days. The morphology of the bone cement becomes a network of hydroxyapatite (HA) after soaking. Ectopic osteogenesis of CPC/BMP composite bone cement is distinct, and lamellar bone can form within 4 weeks, proving the strong osteoinduction capacity of the materials. This bioactive bone cement with good hydraulic characteristics and strong osteogenesis is expected to be a promising bone grafting materials for tissue engineering.