Extracellular vesicles in neurodegenerative disorders

Extracellular vesicles (EVs) are important modulators of physiological functions in the central nervous system (CNS). These cell-derived lipid-bilayer encapsulated nanovesicles contain a wide array of cargoes such as proteins, RNA and bioactive lipids—all of which can take part in different functional roles in cell to cell communication. Furthermore, emerging evidence highlights that secreted EVs are highly heterogeneous, differing in their hydrodynamic size as well as EV surface composition. In neurodegenerative disorders EV secretion is dysfunctional in a sense that EVs secreted from diseased cells in the CNS take on additional roles in spreading the disease pathology. This alters the balance of the entire cell communication network. Understanding these pathological mechanisms helps not only to shed light to novel aspects of biological mechanisms of neurodegenerative diseases, it also helps to devise innovative therapeutic strategies, and to develop biomarkers for monitoring disease progression and response to treatments. In this chapter we discuss the role of EVs in normal CNS physiology and in neurodegenerative diseases, by focusing on Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, amyotrophic lateral sclerosis and prion diseases as examples.