Recent advances in the application of engineered extracellular vesicles from mesenchymal stem cells for traumatic...

Traumatic injuries to the central nervous system (CNS), including traumatic brain injury (TBI) and spinal cord injury (TSCI), are among the leading causes of disability and mortality worldwide. The valuable effect of extracellular vesicles (EVs) from mesenchymal stem cells (MSCs-EVs) in the treatment of traumatic injuries has been documented. EVs, including exosomes, are heterogeneous cell-derived particles, contributing to cell communication through exchanging biomolecules between cells. MSCs-EVs can regulate physiological processes, including synaptic plasticity, neuronal firing, development and repair of myelin sheath, neuroprotection, advancement of neuroinflammation, and extent and elimination of protein aggregates. However, natural MSCs-EVs have some limitations. Recent advancements have shown that MSCs-EVs can be engineered for effective and targeted therapy in traumatic injuries. Most experiments have focused on miRNA-engineered MSCs-EVs to boost their therapeutic effects. In TBI models, MSCs-EVs have been modified to deliver miR-124, miR-17-92, miR-124-3p, or BDNF, whereas in TSCI models, EVs have been engineered with miR-216a-5p, miR-146a-5p, miR-133b, miR-146, miR-138-5p, miR-29b, miR-181c, lncGm37494, siRNAs, or Shh. Results from in vitro and animal studies show the substantial potential of engineered MSCs-EVs for protection, neuroregeneration, and functional recovery. But challenges remain in translating these outcomes into clinical trials, including standardization, safety, and delivery efficacy. In this review, we summarize recent knowledge on MSCs-EVs, focusing on their mechanisms of action in CNS traumatic injuries, and discuss the latest developments, inherent advantages, and potential hurdles in evolving these groundbreaking therapeutic approaches.