The effects of calcium and phosphate contents on bone formation activity by BMP-2 with nano-hydroxyapatite-collagen composites (nHACs) were evaluated. Nanosize crystallites with different concentrations of hydroxyapatite were successfully fabricated by changing the mixing ratio of calcium solution and phosphate-containing neutralization buffer. Composites were implanted into the subcutaneous tissue in the Wistar male rats with BMP-2 for 2 and 4 weeks. nHAC was degraded and inflammation in the surrounding area decreased with time.
Ectopic bone formation was observed around nHACs with higher contents of nano-hydroxyapatite in BMP-2 application at 2 weeks, but was not observed with lower contents at 4 weeks. These results suggest that nHAC with a higher content of nano-hydroxyapatite is suitable as a carrier for BMP-2.
Key words: nanomaterials; hydroxyapatite; BMP-2; bone formation; in vivo