Abstract

Endothelial- and leukocyte-derived circulating microvesicles (cMV) represent a majority of the cMV present in the blood. The purpose of this study was to determine if depletion of these more common cMV populations is possible, allowing for the enrichment and analysis of the remaining subpopulations of cMV. Circulating microvesicles were isolated from the plasma of breast cancer patients. Magnetic beads conjugated to antibodies specific for either CD31 or CD45 were used to deplete the isolated endothelial- and leukocyte-derived cMV. The remaining cMV population was characterized with a multiplexed immunoassay against a panel of 20 different antigens. In addition to the expected depletion of the biomarker used to remove the targeted cMV in the remaining cMV population, a concomitant depletion of associated biomarkers was observed. In the case of the cMV population in which CD31 had been used to remove endothelial-derived cMV, for instance, there was a significant concomitant depletion of DLL4, a highly associated endothelial marker. This was
not the case with general epithelial microvesicle markers, such as CD9, which were still very much present in the cMV population remaining after depletion. These findings suggest a potential method for a more complete characterization of biomarker profiles associated with cMV derived from disease-associated cells and provide the foundation for a novel cMV-based strategy for disease detection through a non-invasive blood test.