BMP-2 and ALP gene expression induced by a BMP-2 gene–fibronectin–apatite composite layer

The bone morphogenetic protein 2 (BMP-2) gene delivery system with a gene–fibronectin (Fn)–apatite composite layer was fabricated on the surface of a hydroxyapatite ceramic scaffold. The BMP-2 gene–Fn–apatite composite layer was coated on the scaffold using a supersaturated calcium phosphate solution supplemented with BMP-2 DNA and Fn. The scaffolds were ectopically implanted into the dorsal subcutaneous tissue of rats. Four weeks after the implantation, the hydroxyapatite scaffold coated with the BMP-2 gene–Fn–apatite composite layer showed improved gene expressions of BMP-2 and alkaline phosphatase as compared with the scaffold coated with the apatite layer. Although these results suggest the possibility of ectopic bone formation induced by the present gene delivery system, further study is necessary to prove this.