Enhanced BMP-2-Mediated Bone Repair Using an Anisotropic Silk Fibroin Scaffold Coated with Bone-like Apatite

Abstract

The repair of large bone defects remains challenging and often requires graft material due to limited availability of autologous bone. In clinical settings, collagen sponges loaded with excessive amounts of bone morphogenetic protein 2 (rhBMP-2) are occasionally used for the treatment of bone non-unions, increasing the risk of adverse events. Therefore, strategies to reduce rhBMP-2 dosage are desirable. Silk scaffolds show great promise due to their favorable biocompatibility and their utility for various biofabrication methods. For this study, we generated silk scaffolds with axially aligned pores, which were subsequently treated with 10× simulated body fluid (SBF) to generate an apatitic calcium phosphate coating. Using a rat femoral critical sized defect model (CSD) we evaluated if the resulting scaffold allows the reduction of BMP-2 dosage to promote efficient bone repair by providing appropriate guidance cues. Highly porous, anisotropic silk scaffolds were produced, demonstrating good cytocompatibility in vitro and treatment with 10× SBF resulted in efficient surface coating. In vivo, the coated silk scaffolds loaded with a low dose of rhBMP-2 demonstrated significantly improved bone regeneration when compared to the unmineralized scaffold. Overall, our findings show that this simple and cost-efficient technique yields scaffolds that enhance rhBMP-2 mediated bone healing.

Silk-Based 3D Porous Scaffolds for Tissue Engineering

“…Eight weeks postimplantation, radiographic analysis revealed new bone formation on the surface of the implant, effectively bridging the defect within the scaffold. Micro-CT imaging corroborated the formation of new bone surrounding the implant, and histological examinations confirmed the presence of new bone tissue in the implanted area. , …”

“…Micro-CT imaging corroborated the formation of new bone surrounding the implant, and histological examinations confirmed the presence of new bone tissue in the implanted area. 92,93 3.1.2. Cartilage.…”

Integrating Melt Electrowriting and Fused Deposition Modeling to Fabricate Hybrid Scaffolds Supportive of Accelerated Bone Regeneration

“…[48] Other similar approaches have also demonstrated the benefits of combining low doses of BMPs with CaP containing materials for bone regeneration. [49,50] Here, we loaded 10 μg of BMP2 per scaffold, which was bound to the mineral coating to enable a sustained release profile. [25] The resulting healing outcomes were excellent, with little ectopic bone identified, verifying the efficacy of this CaP mediated delivery strategy.…”

Biomimetic gradient scaffolds for the tissue engineering and regeneration of rotator cuff enthesis

“…Despite its advantageous properties, gelatin has relatively low mechanical properties and is frequently combined with other biological substances to improve the mechanical properties of the scaffold, such as calcium phosphate ceramics, alginate and chitosan [72]. Silk proteins, on the other hand, provides tunable mechanical properties and favorable biocompatibility [73][74][75]. Nevertheless, their prolonged production cycle and high costs limit mass production [76,77].…”