Evaluating purified exosome product and its role in neurologic and functional recovery following spinal cord injury in female rats

Introduction: Exosomes represent extracellular vesicles that mediate intercellular interactions and have been extensively studied for their therapeutic potential. Purified exosomes product (PEP) from human plasma is reported to aid in tissue repair but has never been evaluated as a potential therapy for spinal cord injury (SCI). Objective: We aim to investigate the effects of PEP on axon myelination, reduction in cavity size, and functional improvements in rats following SCI. Methods: Following T9-T10 laminectomy and contusion to the spinal cord, female rats received either intrathecal (IT) PEP, IT ringer-lactate solution (RL), intravenous (IV) PEP, or IV RL one day post injury. Rats underwent behavioral assessments each week for 10 weeks following SCI. After 10 weeks, histological evaluations were performed to quantity axon myelination and cavity size. Results: The IT PEP group had significantly (P ≤ 0.05) more myelinated axons 1000 μm rostral to the injury, at the epicenter, and 1000 μm caudal of the injury (34.3 ± 3.1, 27.7 ± 2.1, and 32.0 ± 1.7, respectively) compared to the IT RL group (27.3 ± 2.5, 17.3 ± 2.5, and 23.3 ± 2.5, respectively). In addition, IT PEP rats had significantly reduced cavity size at the injury epicenter compared to controls (28.31%±1.74% vs. 34.39%±3.78%, respectively). Lastly, functional improvements were observed and sustained beginning at the 31 days following injury. The IV PEP group did not show sustained functional improvement compared to the IV RL rats. Conclusion: Our results suggest that IT PEP injection may yield beneficial effects following SCI. However, further studies are warranted to investigate the role of PEP following SCI and to optimize its potential for clinical translation.