Magnetically induced anisotropic conductive in situ hydrogel for skeletal muscle regeneration by promoting cell alignment and myogenic differentiation

For volumetric muscle loss regeneration, tissue engineering scaffolds with anisotropic characteristics could mimic the structure of natural skeletal muscle and guide the growth of myoblasts in a specific direction. In addition, scaffolds with conductivity and biodegradability that can provide a suitable microenvironment to facilitate cell growth and myogenic differentiation are also critical for skeletal muscle repair. In this study, a series of anisotropic conductive in situ hydrogels, based on hyaluronic acid methacrylate (HAMA (HM)) and methacrylamide-modified gelatin (GelMA (GM)), induced by magnetic fields are prepared for promoting skeletal muscle regeneration. Polydopamine (PDA)-chelated carbon nanotube (CNT)-Fe3O4 (PFeCNT (PFeC)) nanohybrids are used as magnetic nanohybrids for magnetic field induction and conductive components. These hydrogels (HM/GM/PFeC) show clear anisotropic structure, electrical conductivity and interconnected porous morphology. These cytocompatible anisotropic hydrogels could effectively promote cell oriented alignment. After tryptophan (Trp) loaded, hydrogel (HM/GM/PFeC/Trp) further enhanced myogenic differentiation of mouse myoblasts (C2C12) cells. Regeneration results in SD rat tibialis anterior muscle defect model indicated that HM/GM/PFeC/Trp hydrogels promoted skeletal muscle regeneration, reduced inflammatory response and enhanced the myogenic differentiation factors expression. Therefore, this hydrogel could serve as a promising scaffold for promoting skeletal muscle regeneration by inducing cell alignment and promoting myogenic differentiation.