Roles for Exosomes from Various Cellular Sources in Spinal Cord Injury

Spinal cord injury (SCI) is a severe disorder characterized by regeneration challenges in the central nervous system (CNS), resulting in permanent paralysis, loss of sensation, and abnormal autonomic functions. The complex pathophysiology of SCI poses challenges to traditional treatments, highlighting the urgent need for novel treatment approaches. Exosomes have emerged as promising candidates for SCI therapy because of their ability to deliver a wide range of bioactive molecules, such as RNAs, proteins, and lipids, to target cells with minimal immunogenicity, which contribute to anti-inflammatory, anti-apoptotic, autophagic, angiogenic, neurogenic, and axon remodeling activities. In this study, we classified exosomes from different sources into four categories based on the characteristics of the donor cells (mesenchymal stem cells, neurogenic cells, immune cells, vascular-associated cells) and provided a detailed summary and discussion of the current research progress and future directions for each source. We also conducted an in-depth investigation into the applications of engineered exosomes in SCI therapy, focusing on their roles in drug delivery and combination with surface engineering technologies and tissue engineering strategies. Finally, the challenges and prospects of exosomal clinical applications in SCI repair are described.