Objective:
Patients with low bone mass disease have an increasing clinical demand for autologous bone grafts, such as the repair of craniofacial bone defects caused by trauma and tumors, or dental implant surgery. Autologous bone grafting, which is one of most common procedures for craniofacial surgery, can provide mechanical support, fill the bone defect, and accelerate the healing process. The viability, and consequently the osteogenic capacity, of an autograft is directly impacted by the interval between harvest and transplantation, but how the temperature and the solution in which the graft is held intraoperatively affect viability is not clear.

Materials and Methods:
In this study, we conducted in vitro experiment to analyze the impact of storage temperature and storage time on osteogenic potential of bone graft. Then we conducted in vivo experiment and used rats as an animal model to simulate low bone mass phenotype. After harvesting, the autologous bone grafts were cultured under the optimal temperature and time conditions. The autologous bone grafts were implanted to the bilateral alveolar bone defects of the rats. Based on the treatment strategies, the in vivo experiment was divided into three groups: Control group (soaked autologous bone grafts in Phosphate Buffered Saline, PBS); Autologous bone grafts treated with blood; and Autologous bone grafts treated with platelet-rich plasma (PRP).

Results:
The results showed that the best in vitro handling conditions for autologous bone grafts were at a temperature of 4°C and in vitro storage time within 10 minutes, which can maintain the best osteogenic activity of autologous bone graft. The imaging and histological analysis of in vivo experiment found that the group preoperatively treated with PRP improved the alveolar bone healing more significantly than the other two groups.

Conclusions:
By optimal handling of bone graft in vitro with stimulating with PRP, the osteogenic activity of autologous bone grafts had been activated and the differentiation of osteogenic precursor cells into osteoblasts had been promoted. The results of this study demonstrated that by treatment with PRP, the strategy might increase bone formation and reduce bone resorption, contributing better craniofacial bone regeneration under compromised conditions.

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