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

Emerging additive manufacturing (AM) strategies can enable the engineering of hierarchal scaffold structures for guiding tissue regeneration. Here, we leverage and integrate the advantages of two AM approaches, melt electrowriting (MEW) and fused deposition modelling (FDM), to fabricate hybrid scaffolds for large bone defect healing. MEW was used to fabricate a microfibrous core to guide bone healing, while FDM was used to fabricate a stiff outer shell for mechanical support, with constructs being coated with pro-osteogenic calcium phosphate (CaP) nano-needles. Compared to MEW scaffolds alone, hybrid scaffolds prevented soft tissue collapse into the defect region and supported increased vascularization and higher levels of new bone formation 12 weeks post-implantation. In an additional group, hybrid scaffolds were also functionalised with BMP2 via binding to the CaP coating, which further accelerated healing and facilitated the complete bridging of defects after 12 weeks. Histological analyses demonstrated that such scaffolds supported the formation of well-defined annular bone, with an open medullary cavity, smooth periosteal surface, and no evidence of abnormal ectopic bone formation. These results demonstrate the potential of integrating different AM approaches for the development of regenerative biomaterials, and in particular, demonstrate the enhanced bone healing outcomes possible with hybrid MEW-FDM constructs. This article is protected by copyright. All rights reserved.