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

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.

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.

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).

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.