It is advantageous to incorporate controlled growth factor delivery into tissue engineering strategies. The aim of this study was to develop a 3-D construct carrying an inherent sequential growth factor delivery system. BMP-2 was encapsulated in silk chitosan particles that were produced by a simple and very mild processing method. The dose–response of BMP- 2-loaded chitosan particles was examined in C2C12 cells after 5 days of culture. The BMP-2 retained most of its activity as observed by the increase in alkaline phosphatase activity, which was much higher when BMP-2 was encapsulated into the particles rather than just surface adsorbed. After 2 weeks of culture, increased mineralization was observed with BMP-2- loaded particles in comparison to soluble added growth factor. No significant cytotoxicity was detected. When implanted in a rat ectopic model, bone formation was observed by in vivo micro-computed tomography after 2 and 4 weeks post-implantation with particles loaded with 5 mg BMP-2. An increase in bone density was observed over time. Our findings show that chitosan microparticles may present an interesting option for future clinical applications in the bone tissue engineering field.
