Mesenchymal Stem Cell-Derived Exosomes: A Promising Therapeutic Strategy for Spinal Cord Injury.

Spinal cord injury (SCI) is a central nervous system injury caused by external forces or pathological factors, and traumatic SCI is the most common. If not treated promptly, traumatic SCI can cause secondary injury and neuroinflammation, leading to the proliferation of glial cells and formation of glial scars. Clinically, SCI is usually treated with surgical intervention, pharmacological therapy, or rehabilitation. However, good outcomes cannot be guaranteed. Therefore, SCI repair remains a central focus in neurotraumatic injury research. With an in-depth study of stem cells in nerve injury repair, stem cells and exosomes secreted by them have brought new hope for SCI treatment. Exosomes secreted by stem cells are small nano-sized vesicles, approximately 30-150 nm in diameter, that contain lipids, proteins, and nucleic acids. They can cross the blood-brain barrier (BBB) or blood-spinal cord barrier (BSCB) through the blood system, and the proteins or nucleic acid molecules they carry promote nerve repair. Existing studies have demonstrated that exosomes exert therapeutic effects on SCI through multiple mechanisms: miRNA-mediated modulation of inflammatory responses, promotion of axonal regeneration and angiogenesis, inhibition of glial scar formation and apoptosis, as well as regulation of target cell gene expression via signal transduction pathways mediated by their carried signaling molecules. Although exosome research has yielded promising results in animal models of SCI, significant challenges remain in their clinical translation. Future research should focus on optimizing exosome production, improving purity, elucidating their precise mechanisms of action, and advancing their clinical translational applications.