Direct 3D printing of tough hydrogel incorporated with carbon nanotubes for bone regeneration
The emerging three-dimensional (3D) printing technique has shown prominent advantages to fabricate hydrogel‐based tissue scaffolds for the regeneration of bone defects. Here, a tough polyion complex (PIC) hydrogel was synthesized, and multiwalled carbon nanotubes (MWCNTs) was incorporated into PIC matrix to form PIC/MWCNT biohybrid hydrogel, which was manufactured into 3D scaffolds by extrusion-based 3D printing for bone defect repair. To the best of our knowledge this is the first study to combine CNTs with PIC hydrogels as the biohybrid scaffolds for bone repair. The results of in vitro cell culture demonstrated that the PIC/MWCNT scaﬀolds exhibited good biocompatibility to rat bone marrow-derived mesenchymal stem cells (rBMSCs) and facilitates the osteogenic differentiation of rBMSCs. Moreover, rBMSCs cultured on the PIC/MWCNT scaffolds exhibited a higher degree of osteogenic diﬀerentiation than those cultured on PIC scaffolds, in terms of mineralized matrix formation and osteogenesis-related gene upregulated. The in vivo experiments in a calvarial defect model of Sprague−Dawley (SD) rats revealed that PIC/MWCNT scaﬀolds significantly promoted regeneration of calvarial defect healing. These ﬁndings suggest that PIC hydrogel is the potential scaffold material for bone regeneration, and the addition of MWCNTs provides further enhancement of bone repair efficiency by PIC/MWCNT scaﬀolds.