Repair of rabbit femoral defects with a novel BMP2-derived oligopeptide P24.

In this study, the bioactivity of a novel BMP2-derived oligopeptide P24 was investigated by using the model of rabbit femoral defect after loaded in the biodegradable poly (lactic acid / glycolic acid / asparagic acid-co-polyethylene glycol) (PLGA-[ASP-PEG]). A 1.5-cm unilateral segmental bone defect was created in the left femoral diaphysis in each of the 30 new zealand white rabbits. The defects of 18 legs filled with BMP2-derived peptide P24 combined with PLGA-[ASP-PEG] scaffold serves as the experimental group, and the defects in the rest 12 rabbits filled with (PLGA-[ASP-PEG]) without P24 as control group. The bone-repairing capability in the target region of the two group was grossly, radiologically, histopathologically and biomechanically evaluated 4, 8 and 12 weeks after the operation. Our results showed that in each group, primary healing of incision was achieved in the two groups. Radiographically, in experimental group, defects were filled with induced callus within 8 weeks, and a cortical bone-like structure was observed in some animals at the 12th week. According to the standardized stage of bone defect repair, 9 (64.28%) achieved grade-4 healing. In contrast, little bone formation was seen in the defects even 12 weeks after the operation, and 5 (62.50%) had grade 0 healing in this group. Histologically, tissue engineering material was mostly absorbed and cartilage was found around implants in the experimental group at the 4th week; 8 weeks after operation, the engineering material was completely absorbed, and formation of woven bone was observed and typical trabecular bone structure could be seen. In control group, 8 weeks after operation, the defect was filled with fibrous tissues, and no bone-like structure was observed. Statistical analysis showed very significant difference in biomechanical indicators between the two groups (P<0.05). It is concluded that new oligopeptide P24 can induce excellent bone regeneration and promote bone repair.