Isolation and purification of extracellular matrix vesicles from blood vessels.

Extracellular membrane-bound vesicles (called matrix vesicles) which occur in abundance in atherosclerotic blood vessels are believed to be associated with lipid accumulation and calcification. A technique has been developed to isolate them from experimental aneurysms in sheep in which they are known to be plentiful. The matrix vesicles were isolated by differential centrifugation following extraction by hypotonic salt solution. Most of the vesicles were pelleted at 30,000g and fell within the size range of matrix vesicles in situ in the aneurysmal wall. Preliminary characterization of the enzymatic activities indicates that many of these vesicles are formed from cell membranes rather than being derived from lysosomes, mitochondria or endoplasmic reticulum. Morphologically they are similar to matrix vesicles of other mineralizing tissues.