Bone formation in a rat calvarial defect model after transplanting autogenous bone marrow with beta-tricalcium phosphate

In the present study, we evaluated the osteogenic potential of an autogenous bone marrow graft combined with beta-tricalcium phosphate (beta-TCP) in a rat calvarial bone defect model. The bone marrow harvested from the tibia of 7-week-old rats was grafted autogenously in a calvarial defect together with beta-TCP (=BTG group, n=16) or without beta-TCP (=BG group, n=16). Groups of animals were also treated with beta-TCP alone (=TG group, n=16) and control animals (n=8) received no graft implanted into the defect. We then observed the process of bone formation by histology, enzyme histochemistry and immunohistochemistry. Five days after grafting, in the BTG and BG groups, cell proliferation and osteogenic differentiation were observed. From 5 to 10 days after surgery, active Runx2, osteopontin (OPN), and TRAP- positive cells appeared in the BTG and BG groups. New bone formation started in the defect in both the BTG and BG groups. At 30 days after grafting, the BTG group showed new bone development and replacement of beta-TCP to fill the bone defect. New bone formation in the BTG group was significantly greater than in the BG group (P<0.01). The TG group showed no marked bone formation in the defect. The combination graft of bone marrow with beta-TCP showed marked bone formation in rat calvarial defects. Our results indicate that the combination grafts of bone marrow with beta-TCP may be an effective technique for repairing bone defects Beta-TCPgraft (TG) group.