Enhanced Small Extracellular Vesicle Uptake by Activated Interneurons Improves Stroke Recovery in Mice.

Neuronal circuitry remodelling, which comprises excitatory and inhibitory neurons, is critical for improving neurological outcomes after a stroke. Preclinical studies have shown that small extracellular vesicles (sEVs) have a therapeutic effect on stroke recovery. However, it is highly challenging to use sEVs to specifically target individual neuronal populations to enhance neuronal circuitry remodelling after stroke. In the present study, using a chemogenetic approach to specifically activate peri-infarct cortical interneurons in combination with the administration of sEVs derived from cerebral endothelial cells (CEC-sEVs), we showed that the CEC-sEVs were preferentially taken up by the activated neurons, leading to significant improvement of functional outcome after stroke, which was associated with augmentation of peri-infarct cortical axonal/dendritic outgrowth and of axonal remodelling of the corticospinal tract. The ultrastructural and Western blot analyses revealed that neurons with internalization of CEC-sEVs exhibited significantly reduced numbers of damaged mitochondria and proteins that mediate dysfunctional mitochondria, respectively. Together, these data indicate that the augmented uptake of CEC-sEVs by activated peri-infarct cortical interneurons facilitates neuronal circuitry remodelling and functional recovery after stroke, which has the potential to be a novel therapy for improving stroke recovery.