Sustainable Delivery of Bone Morphological Protein 2 using Gelatin Microspheres-Silk Fibroin Composite Scaffolds for Bone Regeneration

摘要

Silk fibroin is a good natural biomaterial for tissue engineering due to the high biocompatibility and low degradation rate. It was already reported of osteogenic differentiation of the bone marrow stem cell in vitro using the 3D silk fibroin scaffold , however the vivo bone regeneration would much rely on the delivery of the effective dosage of BMP2 . And the direct loading of the BMP2 into the silk fibroin scaffold faces the problem of retention of the growth factor inside the scaffold for a long term . Therefore, the gelatin microspheres embedded silk fibroin composites scaffold was fabricated to enhance the delivery of the BMP2 for bone regeneration since the gelatin microspheres are also biocompatible natural biomaterial and itself showed the sustainable release of the BMP2 within one month . In this project, the loading efficiency of the BMP2 and release kinetics was studied, the results shows high loading efficiency in the gelatin microspheres as compared direct loading into the silk fibroin scaffold. The release kinetics also showed minimal burst release as well as a linear release profile up to one month. The composite silk fibroin scaffold was characterized in terms of surface morphology, porosity.The SEM images shows the embedding of the gelatin microspheres in the openings of the silk fibroin scaffold, while the porosity of composite silk scaffold is comparable to the homogenous silk fibroin due to the introducing of the NaCl salt as porogen. The cytotoxicty and cellular behavior of the composite scaffold was also characterized using the C2C12 cell line. Both alamar blue assay and confocal imaging indicated the low cytotoxicity of the scaffold as well as good cell attachment. Last but not least, the BMP2 bioactivity was tested using the alkaline phophatase assay and it showed the bioactivity of loaded BMP2 in the scaffold can be well maintained. To sum up, this gelatin microspheres-silk fibroin scaffold has great potential for bone regeneration due to the high biocompability and effective delivery of BMP2.