Fabrication of bioinspired grid-crimp micropatterns by melt electrospinning writing for bone-ligament interface study.

Many strategies have been adopted to engineer bone-ligament interface, which is of great value to both the tissue regeneration and the mechanism understanding underlying interface regeneration. However, how to recapitulate the complexity and heterogeneity of the native bone-ligament interface including the structural, cellular and mechanical gradients is still challenging. In this work, a bioinspired grid-crimp micropattern fabricated by melt electrospinning writing (MEW) was proposed to mimic the native structure of bone-ligament interface. The printing strategy of crimped fiber micropattern was developed and the processing parameters were optimized, which were used to mimic the crimp structure of the collagen fibrils in ligament. The guidance effect of the crimp angle and fiber spacing on the orientation of fibroblasts was studied, and both of them showed different levels of cell alignment effect. MEW grid micropatterns with different fiber spacings were fabricated as bone region. Both the alkaline phosphatase activity and calcium mineralization results demonstrated the higher osteoinductive ability of the MEW grid structures, especially for that with smaller fiber spacing. The combined grid-crimp micropatterns were applied for the co-culture of fibroblasts and osteoblasts. The results showed that more cells were observed to migrate into the in-between interface region for the pattern with smaller fiber spacing, suggested the faster migration speed of cells. Finally, a cylindrical triphasic scaffold was successfully generated by rolling the grid-crimp micropatterns up, showing both structural and mechanical similarity to the native bone-ligament interface. In summary, the proposed strategy is reliable to fabricate grid-crimp triphasic micropatterns with controllable structural parameters to mimic the native bone-to-ligament structure, and the generated 3D scaffold shows great potential for the further bone-ligament interface tissue engineering.

Melt electrohydrodynamic 3D printed poly (ε-caprolactone)/polyethylene glycol/roxithromycin scaffold as a potential anti-infective implant in bone repair.

Implanted scaffold or bone substitute is a common method to treat bone defects. However, the possible bone infection caused by orthopaedic surgery has created a challenging clinical problem and generally invalidate bone repair and regeneration. In this study, a poly (ε-caprolactone) (PCL)/polyethylene glycol (PEG)/roxithromycin (ROX) composite scaffold was prepared via melt electrohydrodynamic (EHD) 3D printing. Fourier transform infrared spectroscopy (FTIR) spectroscopy was performed to verify the existence of PEG and ROX in the scaffolds. By water contact angle measurement, the addition of both PEG and ROX was found to improve the hydrophilicity of the scaffolds. By in vitro drug release assay, the PCL/PEG/ROX scaffolds showed an initial burst drug release and subsequent long-term sustained release behaviour, which is favourable for the prevention and treatment of bone infections. The antibacterial assays against E. coli and S. aureus demonstrated that the composite scaffold with ROX possessed effective antibacterial activity, especially for S. aureus, the main cause of bone infection. The immunostaining and MTT assay with human osteoblast-like cells (MG63) indicated that cells showed good viability and growth on the scaffolds. Therefore, the melt EHD 3D printed PCL/PEG/ROX scaffold could be a promising anti-infective implant for bone tissue engineering.