Injectable Conductive Hydrogels as Multifunctional Bioactive Soft Interfaces for Skeletal Muscle Regeneration

The skeletal muscle is an essential organ in exercise and energy metabolism and it significantly contributes to maintaining body posture, facilitating movement, and supporting overall health. The skeletal muscle has an intrinsic capacity for self-repair and functional restoration following minor injury. However, this reparative ability is limited, and in cases of volumetric muscle loss (VML) caused by traumatic injury or tumor resection, substantial muscle loss and functional impairments may occur. Injectable conductive hydrogels (ICHs) have received increasing attention in the repair and regeneration of VML due to their controlled conductivity and minimally invasive application. In ICHs, conductive mediums are introduced into a hydrogel to improve the electrical integration between hydrogel and host tissue, promoting skeletal muscle repair. Furthermore, shear-thinning ICHs that undergo in situ gelation can reduce the injury size and inflammation, thus approaching the clinical transformation target of conductive biomaterials. Notably, ICHs can also serve as carriers of bioactive molecules or cells to improve the cellular microenvironment in the injured region and induce skeletal muscle regeneration. This review focuses on exploring different conductive mediums integrated into ICHs, including their formation principles, key performance metrics, immunoregulatory activity, and potential applications in skeletal muscle regeneration. Additionally, this review emphasizes the future development and optimization of ICHs to enhance skeletal muscle repair and regeneration.