Silk fibroin microparticles as carriers for delivery of human recombinant BMPs. Physical characterization and drug release

Bone morphogenetic proteins (BMPs) are cytokines with strong ability to promote new bone formation. Herein, we report the use of silk fibroin microparticles as carriers for the delivery of BMP-2, BMP-9 or BMP-14. BMP-containing fibroin microparticles were prepared by a mild methodology using dropwise addition of ethanol, exhibiting mean diameters of 2.7 +/- 0.3 microm. Encapsulation efficiencies varied between 67.9 +/- 6.1 % and 97.7 +/- 2.0 % depending on the type and the amount of BMP loaded. Release kinetics showed that BMP-2, BMP-9 and BMP-14 were released in two phases profile, with a burst release in the first two days followed by a slower release, for a period of 14 days. The release data were best explained by Korsmeyer's model and the Fickian model of drug diffusion. Silk fibroin microparticles can offer a promising approach for the sustained delivery of different BMPs in tissue engineering applications.