Effects of neural stem cell‐derived extracellular vesicles on neuronal protection and functional recovery in the rat model of middle cerebral artery occlusion

Stroke imposes a long‐term neurological disability with limited effective treatments available for neuronal recovery. Transplantation of neural stem cells (NSCs) is reported to improve functional outcomes in the animal models of brain ischemia. However, the use of cell therapy is accompanied by adverse effects, so research is growing to use cell‐free extracts such as extracellular vesicles (EVs) for targeting brain diseases. In the current study, male Wistar albino rats (20 months old) were subjected to middle cerebral artery occlusion (MCAO). Then, EVs (30 μg) were injected at 2 hours after stroke onset via an intracerebroventricular (ICV) route. Measurements were done at day 7 post‐MCAO. EVs administration reduced lesion volume and steadily improved spontaneous locomotor activity. EVs administration also reduced microgliosis (ionized calcium‐binding adaptor molecule 1 (Iba1) + cells) and apoptotic (terminal‐deoxynucleotidyl transferase mediated nick end labelling [TUNEL]) positive cells and increased neuronal survival (neuronal nuclear (NeuN) + cells) in the ischemic boundary zone (IBZ). However, it had no effect on neurogenesis within the sub‐ventricular zone (SVZ) but decreased cellular migration toward the IBZ (doublecortin (DCX) + cells). The results of this study showed neuroprotective and restorative mechanisms of NSC‐EVs administration, which may offer new avenues for therapeutic intervention of brain ischemia. Significance of the study Based on our results, EVs administration can effectively reduce microglial density and neuronal apoptosis, thereby steadily improves functional recovery after MCAO. These findings provide the beneficial effect of NSC‐EVs as a new biological treatment for stroke.