Vascular Calcification Regulation by Exosomes in the Vascular Wall.

Vascular calcification is a tightly regulated process that increases during ageing and occurs mainly in patients with diabetes and chronic renal failure. Exosomes are small membrane vesicles that are synthesized in a particular population of endosomes, also called multivesicular bodies, by inside budding into the lumen of the compartment. After fusion of exosome with the plasma membrane, these internal vesicles are secreted. Exosomes have a defined set of membrane and cytosolic proteins. The physiological function of exosomes is still a matter of debate. Investigators implicated microvesicles/exosomes as a specific signaling mechanism to induce vascular mineralization during vascular smooth muscle cells phenotypic transition. Vascular wall from healthy individual exhibit exosomes loaded with calcification inhibitors such as Fetuin A and MGP. Conversely, calcifying conditions induce secretion of exosomes, characterized by decreased calcifying inhibitors and increased phosphatidyl serine and Annexin A6 content, which serves as a nidus for vascular calcification.