Characterization of EPC-derived MVs. (A) Representative FACS analysis of MVs (dark) and of 1-, 2-, 4-, and 6-μm beads used as internal size standards. (B,C) Representative micrographs of scanning electron microscopy of EPC-derived MV showing a spheroid shape. Images were obtained by secondary electron at a working distance of 15 to 25 mm and an accelerating voltage of 20 and 30 kV (original magnification B, ×1500; C, ×3500). Digital acquisition and analysis were performed using the JEOL Semafore system. (D) Representative FACS analysis of MVs showing expression (thick lines) of ICAM-1, α4 integrin, CD44, CD29, αvβ3 integrin, and α6 integrin. Thin lines indicate the isotypic controls. Five MV preparations were analyzed with similar results. In each experiment the Kolmogorov-Smirnov statistical analysis between relevant antibodies and the isotypic control was significant (P < .001).