A Bio‐Orthogonal Engineered Chitosan Platform for Enhanced Mesenchymal Stem Cells Delivery and Function in Peripheral Nerve Repair

Chitosan-based mesenchymal stem cell (MSC) therapy strategies present a promising approach for peripheral nerves repair following injury. However, the therapeutic efficacy of MSCs is significantly hindered by low cell viability and suboptimal retention at the implantation site. Herein, a bio-orthogonal strategy that covalently integrates MSCs with chitosan for nerve regeneration is presented. In vitro analysis revealed covalent combination enhanced adhesion and survival of MSCs on chitosan scaffolds via phosphoinositide 3-kinase (PI3K) and protein kinase B (Akt) signaling pathway. Quantitative proteomics confirmed that these MSCs enhance the secretion of key neurotrophic factors for neuroregeneration. In vivo investigations utilizing a nerve crush injury model demonstrated that bio-orthogonal-mediated MSC therapy markedly improves cell retention at the lesion site. Furthermore, this innovative strategy actively modulates the immune microenvironment, accelerates Wallerian degeneration, promotes angiogenesis, and remodels the extracellular matrix, thereby expediting repair processes following peripheral nerve injury. Specifically, further evaluation utilizing a 10 mm sciatic nerve transection model demonstrated that the bio-orthogonal strategy significantly enhanced the therapeutic efficacy of MSCs. Collectively, the approach developed in this study provides a simple, efficient, and translatable strategy for augmenting MSC-mediated peripheral nerve repair. This work lays a solid theoretical foundation for the future clinical application of chitosan-MSC composite materials in neuroregenerative medicine.