BMP-2 Modified Hydroxyapatite/Chitosan Composite Scaffold for Bone Engineering

To improve the osteoinductive capability of hydroxyapatite/chitosan composite(HCC), which was previously demonstrated of perfect biocompatibility, osteoconductive ability and biodegradability, recombinant human bone morphogenetic protein 2(rhBMP-2) modification was applied to HCC. The osteogenetic ability of this new complex were detected both in vitro and in vivo. Mouse bone marrow stroma cells(mMSCs) were primarily cultured and seeded on either boneBMP-2 modified HCC(BHCC) or unmodified HCC. All the cell seeded scaffolds were cultured in osteoinductive medium, alkaline phosphatase (ALP) activity and osteocalcin (ocn) gene expression were evaluated at different time, cell morphology was investigated by scanning electron microscope (SEM) at 5 days culture and in vito calcification was detected at 14 days culture. To further detect its in vivo osteogenetic capability, mMSCs seeded scaffolds were implanted into athymic mice backs subcutaneously, ectopic bone formation was verified by X-ray examination and histomorphological staining. As a result, compared with HCC, cells on BHCC showed markedly increased ALP activity and ocn gene expression thought out the experiments, more proper and functional cell morphology could been seen by SEM, larger area of calcium deposition was revealed by Alizarin red S staining. At eight weeks implantation apparent new bone formation was supported by X-ray images and H&E stained slides. The findings of this study indicate the potential of BHCC as an ideal bone tissue engineering scaffold.