Biological Activity of an Injectable Biphasic Calcium Phosphate/PMMA Bone Cement for Induced Osteogensis in Rabbit Model

Polymethylmethacrylate (PMMA) bone cement is widely used in repair of vertebral fracture because of its good biomechanical properties and fast curing. However, the bioinertness of PMMA cement may cause interfacial loosening, fatigue, fracture, and ultimate failure. In this study, biphasic calcium phosphate (BCP) is introduced into PMMA cement to prepare an injectable composite bone cement (BCPx/PMMA) and the content of BCP is optimized to achieve appropriate rate of absorption that matches the bone regeneration. The compressive strength of BCPx/PMMA bone cement is found to comply with the International Standardization Organization standard 5833, and can promote biomineralization as well as adhesion, proliferation, and osteogenic differentiation of Sprague-Dawley rat bone marrow mesenchymal stem cells in vitro. Furthermore, in vivo test performed on a rabbit radius defect model demonstrates that the presence of BCP can significantly improve the osteogenic efficacy of PMMA cement. Therefore, it is anticipated that BCPx/PMMA bone cement, as a promising injectable biomaterial, is of great potential in bone tissue regeneration.