Prevention of microvesiculation by adhesion of buds to the mother cell membrane--a possible anticoagulant effect of healthy donor plasma.

Microvesicles (MVs) found in peripheral blood are derived from the budding of cell membranes and are associated with a higher risk of thrombosis. Recently, a hypothesis has been suggested that certain plasma proteins could suppress microvesiculation by mediating adhesion of the buds to the mother cell membrane. In a pilot study, we have tested this hypothesis by considering the relation between the amount of MVs in peripheral blood and the ability of plasma to induce adhesion between giant phospholipid vesicles (GPVs). MVs were isolated from human plasma and counted by flow cytometry. The adhesion between GPVs was measured by assessing the average angle of contact between the adhered vesicles. It was found that greater ability of plasma to induce adhesion relates to smaller concentration of MVs in plasma. The ratio between the concentration of MVs and the concentration of platelets proved the most efficient parameter to predict the propensity of the membrane to shed vesicles. Our results indicate that a stronger attractive interaction between GPVs mediated by plasma is associated with a smaller amount of MVs per platelets. Plasma that mediates stronger attractive interaction between GPVs might potentially be associated with a smaller risk of thrombosis.