Development of Gelatin and Graphene-Based Nerve Regeneration Conduits Using Three-Dimensional (3D) Printing Strategies for Electrical Transdifferentiation of Mesenchymal Stem Cells

In this study, gelatin and graphene-based nerve regeneration conduits/scaffolds possessing tailored three-dimensional (3D) microstructures and mechanical properties were fabricated using 3D printing. The effect of 3D conduit microstructure and mechanical properties, along with the applied electrical stimuli on mesenchymal stem cell (MSCs) behavior and transdifferentiation into Schwann cell (SC)-like phenotypes, were investigated. The results indicated that the gelatin conduits/scaffolds had favorable 3D microstructural and mechanical properties for MSC attachment and growth. Immunocytochemistry results demonstrated that the application of electrical stimuli through the conductive graphene within the gelatin-based 3D microstructure had a profound effect on the differentiation of MSCs to SC -like phenotypes and their paracrine activity. 80% of the cells exhibited SC marker staining, and the cells showed significantly enhanced nerve growth factor (NGF) secretion. These results suggest that the electrical stimuli applied within the 3D gelatin matrix enables enhanced differentiation and paracrine activity, compared to transdifferentiation procedures involving electrical stimuli applied on two-dimensional (2D) substrates and chemical stimuli applied in 3D gelatin scaffolds, leading to promising nerve regeneration strategies.