Background Owing to the decreased bone formation/healing capability,there is a critical clinical need todevelop newbone anabolic agents that can accelerate boneformation and bone defect repairing in osteoporotic fractures．Recombinant forms of bone morphogenetic protein 2 (rhBMP2) is FDA approved to promote spinal fusion and fracture healing. It also might be possible to be used in the treatmentof osteoporosis and related fractures or bone defects. However, the optimum release pattern of rhBMP2 has not yet beenestablished, and excess dosage with rhBMP2 may be dangerous because it has other activities such as organogenesis, celldifferentiation, cell proliferation, and apoptosis.