Antigen-extracted xenogeneic cancellous bone graft with recombinant human bone morphogenetic protein-2 enhances bone regeneration in repair of mandibular defect in rabbits

The effects of a large-piece of xenogeneic bone that was separated from healthy pigs as a scaffold for the repair of a mandibular defect was investigated, and the applicability of antigen-extracted xenogeneic cancellous bone (AXCB) soaked with recombinant human bone morphogenetic protein-2 (rhBMP-2) in bone defect repair was assessed. Mandibular defects were created in 48 New Zealand rabbits, and the animals were randomly divided into four groups, in which the mandibular defects were grafted with AXCB, AXCB soaked with rhBMP-2, and autograft bone, or left blank. An equal number of animals from each group were classified into three time points (4, 8, and 12 weeks) after surgery for gross pathological observation, hematoxylin and eosin (H and E) staining, radiographic examination, and bone density measurement. H and E staining revealed that the area percentage of bone regeneration in the group of the AXCB/rhBMP-2 graft was 27.72 ± 4.68, 53.90 ± 21.92, and 77.35 ± 9.83 at 4 weeks, 8 weeks, and 12 weeks, respectively. These results were better than those of the autogenous bone graft, suggesting that the group of the AXCB/rhBMP-2 graft achieved a good osteogenic effect. With regard to the AXCB graft without rhBMP-2, the area percentage of bone regeneration was only 14.03 ± 5.02, 28.49 ± 11.35, and 53.90 ± 21.92. Therefore, the osteogenic effect of the AXCB/rhBMP-2 graft was demonstrated to have the best effect. In the group of the AXCB/rhBMP-2 graft, the area percentage of bone regeneration increased, and the implanted materials were gradually degraded and replaced by autogenous bone regeneration over time. We conclude that the AXCB graft soaked with rhBMP-2 showed good osteogenic effect in the repair of bone defects and good biocompatibility. AXCB serves as a good carrier of rhBMP-2, which promotes bone formation.