Mesenchymal stem cell-laden double-network hydrogel nerve guidance conduits for peripheral nerve injury repair.

To enhance the repair of peripheral nerve injuries (PNIs), various nerve guidance conduits (NGCs) have been developed by integrating topological, biochemical, and cellular cues. Hydrogel-based NGCs are particularly promising owing to their unique tissue-mimicking characteristics, such as high water content, softness, and porosity. However, their weak mechanical strength and insufficient biological activity limits their application. Therefore, in this study, we aimed to develop NGCs by encapsulating human umbilical cord-derived mesenchymal stem cells (ucMSCs) in double-network (DN) hydrogel conduits for improved peripheral nerve regeneration. A DN hydrogel, fabricated via sequential photo- and ionic-crosslinking of 15 % gelatin methacrylate and 1 % alginate, exhibited excellent rheological and mechanical properties, including fatigue resistance, suture retention, and kink resistance. In a rat sciatic defect model, ucMSC-encapsulated DN NGCs demonstrated significantly improved functional and structural recovery compared to medical silicone and non-cellular hydrogel NGCs. Quantitative assessments revealed that the MSC-laden NGC group exhibited superior functional recovery, as indicated by footprint analysis, electromyography, thermal withdrawal latency, and muscle weight restoration. Moreover, histological analysis and transmission electron microscopy confirmed significantly enhanced axonal regeneration and myelination in the MSC-laden NGC group (axon diameter and myelin thickness). Overall, our results indicate that the MSC-laden hydrogel NGCs can serve as a novel platform to treat PNIs and function as effective stem cell delivery scaffolds for the regeneration of various tissues, such as the skin, tendons, and muscles.