Dynamic imaging of the effect of mesenchymal stem cells on osteoclast precursor cell chemotaxis for bone defects in the mouse skull

BACKGROUND/PURPOSE: Mesenchymal stem cells (MSCs) transplantation has previously been used in the field of regenerative medicine. Although bone regeneration is known to occur through the interaction between osteoblasts and osteoclasts, the effect of MSCs on osteoclasts is unknown. Therefore, the purpose of this study was to investigate the effect of MSCs on the chemotaxis of osteoclast precursor cells (RAW264 macrophage cells). MATERIALS AND METHODS: Bone defects were created in mice skulls, and MSCs and a scaffold of carbonated hydroxyapatite were transplanted into the bone defects. RAW264 cells were then transplanted into the mouse tail vein, and their dynamics were observed by an in vivo imaging system. RESULTS: The fluorescent intensity of the MSCs transplant group at the bone defect region was significantly higher on days 3, 5, and 7 compared with the MSCs non-transplant group. CONCLUSION: Increased RAW264 chemotaxis to the bone defect region occurred following the simultaneous implantation of MSCs in the skull defect.