Therapeutic Potential of Mesenchymal Stem Cell-Derived Exosomes in Spinal Cord Injury

Spinal cord injury (SCI) can lead to severe motor and sensory dysfunction, with a high rate of disability and mortality. Due to the complicated pathological process of SCI, there is no effective clinical treatment strategy at present. Although mesenchymal stem cells (MSCs) are effective in the treatment of SCI, their application is limited by factors such as low survival rate, cell dedifferentiation, tumorigenesis, blood-brain barrier, and immune rejection. Fortunately, there is growing evidence that most of the biological and therapeutic effects of MSCs may be mediated by the release of paracrine factors, which are extracellular vesicles called exosomes. Exosomes are small endosomal vesicles with bilaminar membranes that have recently been recognized as key mediators for communication between cells and tissues through the transfer of proteins, lipids, nucleic acids, cytokines, and growth factors. Mesenchymal stem cell-derived exosomes (MSC-exos) play a critical role in SCI repair by promoting angiogenesis and axonal growth, regulating inflammation and immune response, inhibiting apoptosis, and maintaining the integrity of the blood-spinal cord barrier. Furthermore, they can be used to transport genetic material or drugs to target cells, and their relatively small size allows them to permeate the blood-brain barrier. Studies have demonstrated that some exosomal miRNAs derived from MSCs play a significant role in the treatment of SCI. In this review, we summarize recent research advances in MSC-exos and exosomal miRNAs in SCI therapy to better understand this emerging cell-free therapeutic strategy and discuss the advantages and challenges of MSC-exos in future clinical applications.