Microencapsulated rBMMSCs/calcium phosphate cement for bone formation in vivo

As an injectable scaffold material for bone tissue engineering, calcium phosphate cement (CPC) has good biocompatibility, self-setting, and osteoconduction properties. Alginate-microencapsulated seed cells can pick up the degradation speed and bioactivity of CPC. The aim of this study was to explore the osteogenic ability of a composite of microencapsulated rabbit bone marrow mesenchymal stem cells (rBMMSCs) with β-tricalcium phosphate/calcium phosphate cement (β-TCP/CPC) in vivo. Cavity defects were created in both femoral condylar regions of New Zealand White rabbits. β-TCP/CPC (control group) and alginate microencapsulated rBMMSCs/β-TCP/CPC composite (composite group) were implanted separately into the bone defects of both femurs. Bone substitute degradation and new bone formation were evaluated by CBCT, and the defects were examined histologically 8, 16, and 24 weeks after implantation. In addition, fluorescent carbocyanine CM-Dil was used to track the rBMMSCs in vivo after implantation. The results showed that far more new bone and bone marrow grew into the bone defects in the composite group. Few CM-Dil labeled positive cells were observed postoperatively. However more native cells were detected in the graft areas of the composite group than those of the control group. The study indicates that a composite of microencapsulated seed cells/β-TCP/CPC might be considered as a promising injectable material for the generation of new bone tissue.