Isolation of spontaneously‐released brain extracellular vesicles: implications for brain pathology

Abstract

AbstractBackgroundIn the era of Precision Medicine, extracellular vesicles (EVs) exhibit great potential for the theragnostic of brain disorders such as Alzheimer’s disease (AD), a complex disease with no effective treatment and poorly understood risk factors, where pathological heterogeneity and diverse clinical presentations complicate the development of precise patient‐tailored therapies. Thus, the collection and characterization of physiologically relevant EVs, as well as the study of its precipitating/risk factors, are of the utmost importance. However, standard brain EV isolation approaches rely on tissue dissociation, which can contaminate EV preparations with intracellular vesicles.MethodBased on a multiscale analysis, including cryo‐EM, label‐free proteomics, and ExoView, we hereby present a novel purification method of small EVs (sEVs) based on the spontaneous release of EVs from the brain.ResultOur advanced EVs analysis demonstrated that our method represents an efficient purification method that captures a small EV‐enriched population spontaneously released by mouse and human brain tissue. In addition, we tested the significance of the release method under conditions where biogenesis/secretion of sEVs was pharmacologically manipulated and under exposure to chronic stress, a clinically‐relevant precipitant of AD. Here we found that the released method monitors the drug‐evoked inhibition or enhancement of sEVs secretion in a very sensitive manner, while chronic stress induces the secretion of brain exosomes accompanied by memory loss and mood deficits suggesting a potential role of sEVs in the brain response to stress and related stress‐driven brain pathologies.ConclusionOverall, this method will contribute to the characterization of the biomarker profile of physiologically relevant brain‐derived sEVs in brain function and pathology.