Hypoxia induces changes in the secretion of extracellular vesicles (EVs) in several non-neuronal cells and pathological conditions. EVs are packed with biomolecules, such as microRNA(miR)-21-5p, which respond to hypoxia. However, the true EV association of miR-21-5p, and its functional or biomarker relevance, are inadequately characterised. Neurons are extremely sensitive cells, and it is not known whether the secretion of neuronal EVs and miR-21-5p are altered upon hypoxia. Here, we characterised the temporal EV secretion profile and cell viability of neurons under hypoxia. Hypoxia induced a rapid increase of miR-21a-5p secretion in the EVs, which preceded the elevation of hypoxia-induced tissue or cellular miR-21a-5p. Prolonged hypoxia induced cell death and the release of morphologically distinct EVs. The EVs protected miR-21a-5p from enzymatic degradation but a remarkable fraction of miR-21a-5p remained fragile and non-EV associated. The increase in miR-21a-5p secretion may have biomarker potential, as high blood levels of miR-21-5p in stroke patients were associated with significant disability at hospital discharge. Our data provides an understanding of the dynamic regulation of EV secretion from neurons under hypoxia and provides a candidate for the prediction of recovery from ischemic stroke.

BioVendor laboratorni medicina a s Brno Czech Republic

Department of Biochemistry and Chemistry School of Agriculture Biomedicine and Environment La Trobe University Melbourne Victoria Australia

Department of Computer Science University of Verona Verona Veneto Italy

Department of Human Genetics KU Leuven Leuven Flanders Belgium

Department of Immunology University of Arizona Tucson Arizona USA

Department of Pathology Erasmus University Medical Center Rotterdam The Netherlands

Department of Urology Erasmus University Medical Center Rotterdam The Netherlands

Institute de Biomedicine of Seville IBiS Hospital Universitario Virgen del Rocío CSIC University of Seville and Department of Neurology Hospital Universitario Virgen Macarena Seville Andalucía Spain

Institute for Health and Sport Victoria University Melbourne Victoria Australia

International Clinical Research Center Neurological Department St Anne's University Hospital and Masaryk University Brno Czech Republic

La Trobe Institute for Molecular Science La Trobe University Bundoora Victoria Australia

Neurovascular Research Laboratory Vall d'Hebron Institute of Research Universitat Autònoma de Barcelona Barcelona Spain

University of Eastern Finland A 1 Virtanen Institute for Molecular Sciences Kuopio Finland

University of Eastern Finland School of Medicine Kuopio Finland

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