MV have been investigated for prognosis in coronary artery syndrome, aneurysm, thrombosis, pulmonary embolism, thrombotic thrombocytopenic purpura, paroxysmal nocturnal hemoglobinuria, heparin induced thrombocytopenia, sickle cell disease, sepsis, rheumatoid disease, multiple sclerosis, preeclampsia, myeloproliferative disorder and some types of cancer (Zwaal and Schroit, 1997, Berckmans et al., 2001, VanWijk et al., 2003, Morel et al., 2006, Zwicker et al., 2007, Toth et al., 2008a and Toth et al., 2008b). We reported that concentrations of platelet and endothelium-derived MV were

elevated in plasma samples from recently-menopausal women who were at low risk for cardiovascular disease by Framingham scores but who had unexpected coronary calcification (Jayachandran et al., 2008). Methods for isolation, identification, characterization and, especially, enumeration of circulating PS-341 in vivo MV have not been validated completely. Several reviews of the topic have emphasized the need for validation of pre-analytical

procedures, including anticoagulants and isolation methods, and for analytical procedures, including reagent compositions, instrument settings and calibration (Kim et al., 2002, Horstman et al., 2004, Jy et al., 2004, see more Michelsen et al., 2006, Enjeti et al., 2007, Lynch and Ludlam, 2007, Shet, 2008, Dey-Hazra et al., 2010, van Ierssel et al., 2010, Ayers et al., 2011 and Yuana et al., 2011). The present study was undertaken to define pre-analytical, analytical and post-analytical factors in MV analysis and to refine, standardize and validate methods for isolation, identification, quantification and characterization of MV in Etofibrate peripheral blood samples. Annexin-V and mouse anti-human CD42a, CD61 and 62E conjugated with fluorescein isothiocynate (FITC) or R-phycoerythrin (PE) and TruCOUNT™ (4.2 μm) beads were purchased from BD Biosciences, San Jose, CA. Fluorescent latex beads (1 μm

and 2 μm) were purchased from Sigma-Aldrich, Saint Louis, Missouri. Fluoresbrite® Microparticles (0.2 μm, 0.5 μm, 1 μm and 2 μm) were purchased from Polysciences, Inc., Warrington, PA. Soybean trypsin inhibitor was purchased from Sigma, St. Louis, MO, hirudin from CIBA GEIGY Ltd, Basle, Switzerland, and paraformaldehyde (16% solution, EM grade) from Electron Microscopy Sciences, Hatfield, PA. Blood collection tubes were purchased from Becton, Dickson and Company, Franklin Lakes, NJ. All studies were approved by the Mayo Clinic Institutional Review Board. Blood samples were collected from 120 male and female participants (19–85 years of age) who were either apparently healthy or diagnosed with type II diabetes, coronary artery disease (CAD) with and without diabetes, or prior stroke or venous thromboembolism. These participants were selected to provide a wide range of MV counts and properties.