Repair of cranial bone defects with bone morphogenetic protein-2/collagen/sr-HA scaffold

Abstract

Objective To investigate the osteogenetic capacticy of bone morphogenetic protein-2 ( BMP-2 )/collagen/sr-HA scafffold. Methods Preparation of collagen,collagen/HA,collagen/sr-HA,BMP-2/collagen/sr-HA scaffolds.And the scaffolds were tested by scan electron microscope.To evaluate BMP-2/collagen/sr-HA scaffolds biocompatibility,the extract of the composite material was used to carry out a cytotoxicity test and in vitro hemolytic test.Cranial defects were created on 24 Sprague-Dawley rats.The Cranial defects were implanted the 4 scaffohls. Up to the 12 weeks,the rats were scanned hy CT and the whole calvaria were scanned with 0.5 mm in thickness.The rat calvaria from four groups were observed by histological staining and Immunohistochemistry. Results The toxicity of BMP-2/collagen/sr-HA to L929 cells was one degree.Three-dimensional reconstruction of computed tomography indicated that the cranial defects of BMP-2/collagen/sr-HA group were almost repair completely. The CT scores of these gourp were (98.5±10.2),(208.4±19.5),(418.4±27.1),(476.8±30.5) hu.And the density of radiodense areas of BMP-2/collagen/sr-HA group were highest among all groups.Histological observation showed a large amount of new and mature bone had been observed in the BMP-2/collagen/sr-HA groups,but in the collagen/HA and collagen/sr-HA the number of new bone were less.Immunohistochemistry in collagen/HA and collagen/sr-HA group the β-catenin andosteopontin (OPN) signals appeared on some cells at the boundary of the formed bone,in BMP-2/collagen/sr-HA group more intense and concentrated β-catenin and OPN signals were observed on the cells surrounding the newly formed extracellular matrix.Conclsion The osteogenic capability of BMP-2/collager/sr-HA scaffold is obviously superior to col/HA and col/sr-HA.BMP-2/collagen/sr-HA scaffold biomimetic scaffold material can be a potential repairing material for bone defects. Key words: Bone morphogenetic protein-2; Strontium substituted hydroxyapatite; Cranial bone defects; Bone regeneration