Osteoinductive Observation for BMP-2 Gene Modification of Mesenchymal Stem Cells Combined with Plasma-sprayed Hydroxyapatite Coating

Success in bone implant depends greatly on the composition and surface features of the implant. The surface-modification measures not only favor implant's osteoconductivity, but promote both bone anchoring and biomechanical stability. This paper reports an approach to combine a hydroxyapatite(HA) coated substrate with a cellular vehicle for delivery of bone morphogenetic protein-2 (BMP-2) so that synergistically enhancing the osteoconductivity of implant surfaces. First, we examined the in vitro attachment growth and osteoinductive activity of transfected BMP-producing bone marrow mesenchymal stem cells(BMSCs) on a plasma sprayed HA coated substrate. Second, the osteointegrate efficacy of the combined method of BMP-2 gene delivery and HA coated scaffold in vivo was evaluated using a rat model. It was found that the HA coated substrate could allow the attachment and growth of BMP-2 transfected BMSCs, and this combined application synergistically augmented osteoinductive ability of the substrate surface . In vivo, the HA coated substrates successfully functioned as a surface enhancement plate for bioactive BMP-2 release, as they both elevated bone anchoring and biomechanical stability in a rat model.