From blood to biomarker Exploring extracellular vesicles for stroke diagnosis

To minimize irreversible brain injury, fast identification and classification of patients presenting with stroke symptoms is essential. Current diagnosis depends on clinical assessment and CT scans, which are time-consuming, especially when patients need to be transferred to specialized stroke centers. A blood-based test that can be used in pre-hospital settings may accelerate diagnosis and improve patient outcomes.
In this thesis, we investigated whether analysis of extracellular vesicles (EVs), small membrane-enclosed particles released by cells into blood and containing information about their cells of origin, offers potential biomarkers.
First, we established a clinically applicable blood collection protocol that preserves the in vivo concentrations of blood EVs. Furthermore, we developed a practical approach to enable accurate EV concentration measurements by flow cytometry.
Secondly, a biobank was established containing plasma samples from patients presenting with acute stroke symptoms. Analysis of a subset of these samples showed that concentrations of leukocyte-derived EVs are reduced in patients with ischemic stroke compared to all other patients presenting with stroke symptoms. Combining leukocyte-EV concentration with diastolic blood pressure further improved identification of ischemic stroke.
Overall, this thesis investigated the potential diagnostic potential of measuring blood EVs in an acute clinical setting. By improving the reproducibility of EV research and indicates that EVs hold potential as biomarkers for acute stroke diagnosis. These findings may support the development of an EV-based point-of-care test, enabling earlier recognition and treatment of ischemic stroke.