Extracellular Vesicles: Evolutionarily Conserved Mediators of Intercellular Communication

Extracellular vesicles (EV) are sub-micron circulating vesicles found in all bodily fluids and in all species so far tested. They have also recently been identified in seawater and it has further been shown that they are released from microorganisms and may participate in interspecies communication in the gut. EV are typically composed of a lipid bilayer formed from the plasma membrane and which encases a cargo that can include genetic material, proteins, and lipids. At least two different processes of formation and release have been described in mammalian cells. The exosome population (50 to 150nm size) are produced via a lyso-endosomal pathway, while microvesicles (100 to 1000nm) are formed by budding of the plasma membrane in a calcium dependent process. Both pathways are highly regulated and appear to be conserved amongst different species. EV release has been shown to be upregulated in a number of human chronic diseases including cardiovascular disease, metabolic disorders, obesity, and cancer; evaluation of their presence in veterinary samples may aid diagnosis in the future. This review will provide insight into the formation of EV and their detection in bodily fluids from different veterinary species and how they may provide a novel addition to the veterinary toolkit of the future.