Sequential releasing of VEGF and BMP-2 in hydroxyapatite collagen scaffolds for bone tissue engineering: Design and characterization.

The property of biomaterials to control the sequential release of growth factors has been widely concerned in the field of bone repair and regeneration. Double-factor sustained-release scaffolds have good biocompatibility and bioactivity. O‑Carboxymethyl chitosan microspheres (O-CMCS) has antimicrobial activity, biodegradability, biocompatibility and film formation. This study developed scaffolds materials with microspheres with a purpose of forming a controlled slow release secondary structure. O-CMCS were used as drug carrier to construct the compound sustained-release system with rhBMP-2 and VEGF double factors release. The O-CMCS were loaded with rhBMP-2 and the hydroxyapatite collagen (HC) scaffolds were loaded with VEGF to prepare the scaffolds. These were double factors composite sustained-release system scaffolds. The biocompatibility of the sustained-release system was evaluated by in vitro and in vivo experiments. HC composite scaffolds were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction detection (XRD), in vitro sustained release test, in vitro cell culture and in vivo animal experiments. The results showed that rhBMP-2/VEGF in HC composite scaffolds (HCBV) successfully achieved the sequential release of the double factors, which could benefit bone regeneration.