Extracellular vesicle-mediated delivery of M6a partially reverses chronic stress-induced behavioral and molecular alterations

Chronic stress is a major risk factor for neuropsychiatric disorders such as depression. Current treatments are limited by incomplete efficacy and adverse effects. We propose an alternative strategy based on extracellular vesicles (EVs), which are promising vehicles for biomolecule delivery to the brain. Our study focuses on the neuronal glycoprotein M6a, a key regulator of neuronal connectivity whose expression is reduced following chronic stress. EVs were isolated from HT22 cells by differential centrifugation and characterized by TEM and NTA. EVs were loaded with an M6a-GFP or GFP control plasmid using an exogenous loading protocol. Successful delivery was confirmed by plasmid detection and in vitro assays, where recipient cells expressed M6a-GFP and exhibited morphological changes associated with M6a overexpression. The therapeutic potential of M6a-loaded EVs was evaluated in a mouse model of chronic restraint stress. Treatment prevented weight loss. Behavioral analyses using BORIS software showed that mice receiving M6a-loaded EVs spent less time immobile in the Forced Swim Test (FST), suggesting an improved stress-coping behavior. Ongoing studies will evaluate performance in the Splash Test (ST) and quantify M6a levels in serum by ELISA and hippocampus by Western blot. Overall, these findings provide proof of concept that extracellular vesicles can serve as an effective delivery platform for M6a to mitigate the effects of chronic stress.