Figure 1.

Extracellular vesicles (EVs) circulating in blood. Different organs, tissues, and cell types secrete EVs, and they can have a local effect or enter systemic circulation and get internalized in distant tissues. The number, composition, and size of the secreted particles varies between secreting cells and, moreover, the same cell may produce different EVs depending on its status, the surrounding environment, and received stimuli. These EVs will travel in blood, migrate, and interact and/or get internalized by target cells. Therefore, circulating EVs are in constant change and they reflect diverse biological processes occurring in the organism. The characterization of EV concentration, membrane composition, and cargo could be challenging, but it is a promising source of information and biomarkers.