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.

Effect of rhBMP-2 sustained-release nanocapsules on the ectopic osteogenesis process in Sprague-Dawley rats.

OBJECTIVE: To explore the effect of sustained-release recombinant human bone morphogenetic protein-2 (rhBMP-2) on ectopic osteogenesis in the muscle pouches of rats through preparing rhBMP-2 sustained-release capsules by wrapping morphogenesis protein bones-2 (BMP-2) using chitosan nanoparticles, and compositing collagen materials. METHODS: Twenty four Sprague-Dawley rats were randomly divided into four groups with six rats in each group, that is Group A (control group), Group B (only treated with collagen), Group C (rhBMP-2+collagen treated group) and Group D (rhBMP-2/cs+collagen treated group). The composite materials for each group were implanted in the bilateral peroneal muscle pouches in rats. The peroneal muscles were only separated without implanting any materials in control group. Rats were sacrificed 2 weeks and 4 weeks post treatment and samples were cut off for general observation, Micro CT scans and histological observation. RESULTS: General observation showed no new bone formation in Groups A and B mice, while new bones were formed in Groups C and D mice. Two weeks after treatment Micro CT scans showed that The bone volume fraction (BVF), trabecular thickness (Tb.Th), bone mineral density (BMD) in Group C mice were all higher than that in Group D (P<0.05). At the fourth week, the BVF, Tb.Th and BMD were significantly higher than that at the second week (P<0.01). CONCLUSIONS: The slow-release effect of rhBMP-2/cs sustained-release capsules can significantly promote ectopic osteogenesis. Its bone formation effect is better than that of rhBMP-2 burst-release group.

Application of ultrasonic inspection in monitoring dynamic healing of mandibular fracture in rabbit model.

OBJECTIVE: To investigate the feasibility of ultrasonic diagnosis for monitoring fracture healing. METHODS: Thirty rabbit models with fraction of mandible body were established by surgically removing partial lower jawbone. At the 1st, 2nd, 4th, 6th, 8th and 12th week after the operation, they were examined by X-ray and ultrasound, respectively. All detection results were scored according to a generally accepted standard. Spearman rank correlation analysis was conducted to explore the relationship between the results of the two inspection methods. RESULTS: In each healing stage, the results of the ultrasonic inspection were basically consistent with those of the X-ray examination, as supported by a Spearman rank correlation coefficient of 0.892 (P<0.001). CONCLUSIONS: Non-invasive ultrasonic inspection can be used instead of X-ray examination to monitor and diagnose fracture healing.

[Study on osteogenic ability of chitosan/beta-tricalcium phosphate scaffold combined with human bone morphogenetic protein].

OBJECTIVE: Using chitosan (CS)/beta-tricalcium phosphate (TCP)/recombinant human bone morphogenetic protein (rhBMP)-2 for the reconstruction of rabbits' mandible defect, to prove the feasibility of CS/beta-TCP as an injectable bone tissue engineering scaffold material. METHODS: Twenty-four New Zealand white rabbits were randomized into 4 groups on average: Experimental group 1 embedding CS/beta-TCP/rhBMP-2, experimental group 2 embedding CS/ beta-TCP, control group 1 embedding autograft bone group, control group 2 embedding nothing. At 2, 4 and 8 weeks after surgery, all rabbits were executed group by group. The new bone growth situations were observed with hematoxylin-eosin staining and immunofluorescence microscopy, the bone mineral density was detected by bone sonometers. RESULTS: After 2, 4, 8 weeks, there was significant difference among the areas of bone regeneration of all groups. The effect of experimental group 1 was better than experimental group 2. There was significant difference at different times, the areas of bone regeneration was gradually increased with time. The area of stained yellow in experimental group 1 was larger, the area of stained red was smaller. The quantities of bone density in experimental group 1 at every time after surgery were significantly higher than experimental group 1 and control group 2, but had no statistical significance with control group 1. CONCLUSION: CS/beta-TCP/rhBMP-2 has good biocompatibility, degradability and the capacity of guided and inducing osteogenesis. CS/beta-TCP as a good injection of carrier could become a promising carrier for rhBMP-2 and potential new degradable biological material for repairing bone defect in clinical application.