Wnt5a‐Induced Exosomes From Bone Marrow Mesenchymal Stem Cells Promote Spinal Cord Injury Repair by Modulating Immune Cell Phenotypes and Alleviating Neuroinflammation via the <scp>NF</scp> ‐ <scp>κB</scp> Pathway

OBJECTIVE: Spinal cord injury is a devastating neurological disorder. The transplantation of mesenchymal stem cell-derived exosomes has shown great promise. Wnt5a has been reported to promote neuronal differentiation and spinal cord regeneration. However, its mechanistic role when delivered via exosomes remains unclear. In the present study, the function and underlying mechanism of Wnt5a in promoting neuronal differentiation and spinal cord repair were investigated using bone marrow mesenchymal stem cell-derived exosomes. METHODS: This study initially constructed Wnt5a-overexpressing BMSCs and isolated and characterized their exosomes. Subsequently, in vitro experiments were conducted to detect markers of neurons, astrocytes, and microglia. This was followed by high-throughput sequencing to analyze related pathways. Finally, in vivo experiments were performed, in which rats were divided into the Sham group, the SCI group, the Exo group, and the pLV-Exo-Wnt5a group. The effects of exosomes in vivo were analyzed through histological, behavioral, electrophysiological, western blot, PCR, and immunofluorescence assays. RESULTS: Our results demonstrated that Wnt5a-enriched BMSC-Exos significantly enhanced the proliferation and neuronal differentiation of neural stem cells, while suppressing astrocyte formation. High-throughput RNA sequencing revealed an association between Wnt5a and the NF-κB signaling pathway. Intervention with lipopolysaccharide confirmed that Wnt5a exerts a suppressive effect on this pathway. In vivo, the transplantation of Wnt5a-modified BMSC-Exos facilitated the polarization of microglia towards an anti-inflammatory M2 phenotype, promoted neurogenesis, reduced astrocyte accumulation, improved spinal cord tissue architecture, and led to better motor function recovery. CONCLUSION: Collectively, these findings indicate that Wnt5a enhances the neuroregenerative potential of BMSC-Exos by modulating immune responses and suppressing neuroinflammation, likely through inhibiting the NF-κB signaling pathway.