Fabrication of Bone Morphogenic Protein-2 and Icariin-Containing Sustained-Release Microcapsule and Evaluation of its Osteogenic Differentiation Capacity in MC3T3-E1 Cells

The delivery of cytokines and Chinese medicines using biodegradable microspheres may promote bone regeneration. We designed a sustained-release microcapsule containing bone morphogenetic protein-2 (BMP2) and icariin (ICA) and evaluated its effects on osteogenic differentiation in MC3T3-E1 cells. ICA was preloaded onto sodium alginate-grafted phenylboronic acid (Alg-PBA) particles. Alg-PBA-ICA was used to coat the surface of SiO₂-NH₂ colloids by electrostatic interaction, and then SiO₂ colloids were etched using HF. The Alg-PBA-ICA vesicles were immersed in a BMP2 solution, and Alg-PBA-ICA/BMP2 microcapsules were obtained. The optimal concentration of ICA and BMP2 for osteogenic differentiation induction was selected. We evaluated the microcapsules' osteogenic differentiation capacity. The microcapsules displayed intact morphology without obvious broken debris. The size of Alg-PBA-ICA@SiO₂ microcapsules was 210 ± 2 nm; the surface charge was –15.70 ± 2.12 mV. BMP2 (100 ng/mL) combined with 10 nM ICA had the strongest effect on cell behavior. The osteo-inductive effect at this concentration was stronger than that of the other combinations. The mRNA and protein expression levels of osteogenic genes increased after treatment with the microcapsules following 7 days of stimulation. This new drug delivery system has powerful osteo-inductive effects on MC3T3-E1 cells.