A BMP-2 sustained-release scaffold accelerated bone regeneration in rats via the BMP-2 consistent activation maintained by a non-sulfate polysaccharide

Bone morphogenetic protein 2 (BMP-2) and a polysaccharide (SUP) were embedded in the calcium phosphate cement (CPC) scaffold, and the bone repair ability was evaluated. The new scaffolds were characterized using x-ray diffraction, Fourier transform-infrared, scanning electron microscopy, and energy dispersive spectroscopy analyses. CPC-BMP2-SUPH scaffold promoted the BMP-2 release by 1.21 folds of the CPC-BMP2 scaffold on day 3. SUP sustained the release of BMP-2 within 21 d. It enhanced alkaline phosphatase activity by 25.9% in comparison to the CPC scaffold. These results suggest that the SUP consistently activated and sustained BMP-2 releasein vitro. Furthermore, the CPC-BMP2-SUPH scaffold activated the BMP-2/Smads and runt-related transcription factor 2 (Runx-2) pathways in MC3T3-E1 cells to up-regulate the levels of osteogenic relative genes (BMP-2, bone sialoprotein, collagen 1, osteocalcin, osteopontin, and Runx-2). Thein vivoresult showed that the bone defect area in the CPC-BMP2-SUPH scaffold-treated Sprague-Dawley rats lessened significantly compared with the CPC group after 4 weeks. CPC-BNP2-SUPH scaffold also improved collagen regeneration in bone. The bone surface and bone volume in the CPC-BMP2-SUPH group improved by 3.68 and 2.17-fold compared with the CPC group, respectively. In conclusion, the CPC-BMP2-SUPH scaffold represents a novel biomaterial capable of accelerating osteoblast differentiation and promoting bone injury repair.