3D Printed Gelatin Scaffold with Improved Shape Fidelity and Cytocompatibility by Using Antheraea pernyi Silk Fibroin Nanofibers

Gelatin(G)is a commonly used natural biomaterial owing to its good biocompatibility and easy availability.However,using pure gelatin as a bioink can barely achieve an ideal shape fidelity in 3D printing.In this study,Antheraea pernyi silk fibroin nanofibers(ASFNFs)with arginine-glycine-aspartic acid(RGD)peptide and partial natural silk structure are extracted and combined with pure gelatin bioink to simultaneously improve the shape fidelity and cytocompatibility of corresponding 3D printed scaffold.Results show that the optimum printing temperature is 30℃ for these bioinks.The printed filaments using 16G/4ASFNFs bioink(16wt%gelatin and 4wt%ASFNFs)demonstrate better morphology and larger pore size than those printed by pure gelatin bioink(20G,20wt%gelatin),thus successfully improve the shape fidelity and porosity of the 3D printed scaffold.The 16G/4ASFNFs scaffold also demonstrate higher swelling ratio and faster degradation rate than the pure gelatin scaffold.Moreover,the cell viability and proliferation ability of Schwann cells cultured on the 16G/4ASFNFs scaffold are significantly superior than those cultured on the pure 20G scaffold.The ASFNFs enhanced 16G/4ASFNFs scaffold reported here are expected to be a candidate with excellent potential for biomedical applications.

Nanofiber-induced hierarchically-porous magnesium phosphate bone cements accelerate bone regeneration by inhibiting Notch signaling

Magnesium phosphate bone cements(MPC)have been recognized as a viable alternative for bone defect repair due to their high mechanical strength and biodegradability.However,their poor porosity and permeability limit osteogenic cell ingrowth and vascularization,which is critical for bone regeneration.In the current study,we constructed a novel hierarchically-porous magnesium phosphate bone cement by incorporating extracellular matrix(ECM)-mimicking electrospun silk fibroin(SF)nanofibers.The SF-embedded MPC(SM)exhibited a heterogeneous and hierarchical structure,which effectively facilitated the rapid infiltration of oxygen and nutrients as well as cell ingrowth.Besides,the SF fibers improved the mechanical properties of MPC and neutralized the highly alkaline environment caused by excess magnesium oxide.Bone marrow stem cells(BMSCs)adhered excellently on SM,as illustrated by formation of more pseudopodia.CCK8 assay showed that SM promoted early proliferation of BMSCs.Our study also verified that SM increased the expression of OPN,RUNX2 and BMP2,suggesting enhanced osteogenic differentiation of BMSCs.We screened for osteogenesis-related pathways,including FAK signaing,Wnt signaling and Notch signaling,and found that SM aided in the process of bone regeneration by suppressing the Notch signaling pathway,proved by the downregulation of NICD1,Hes1 and Hey2.In addition,using a bone defect model of rat calvaria,the study revealed that SM exhibited enhanced osteogenesis,bone ingrowth and vascularization compared with MPC alone.No adverse effect was found after implantation of SM in vivo.Overall,our novel SM exhibited promising prospects for the treatment of critical-sized bone defects.