Circulating microvesicles (cMVs) are small membrane bound fragments of between 50 and 1,000 nanometers (nm) in diameter, found in many types of body fluids as well as the interstitial space between cells. Though initially dismissed as cellular debris, cMVs have a role in cell signaling and the process of molecular communication between cells, and are released by a number of cell types. Although a consistent and precise definition is lacking, cMVs are generally considered to be a heterogeneous population of exosomes (<100 nm) and shed microvesicles (100-1000 nm), which are similar but have distinct mechanisms of formation. Through these mechanisms, cMVs are released into the extracellular space and interact with specific target cells, delivering bioactive molecules. Changes in cMV levels ar