Figure 3.

General features of circulating platelet microparticles (PMPs). PMPs are phospholipid microvesicles of 0.1–1 micron in size, sheded from parental cell fragments after stimulation with physiological agonists such as thrombin or collagen or exposure to shear stress (i.e., in severe stenosis). PMPs express functional adhesion receptors, including GPIIb/IIIa (CD41), P-selectin (CD62P), CXCR4, and PAR-1 and contain different proteins and coagulation factors, thus exerting a role in the hemostatic response and in the interplay between coagulation and inflammation. PMPs also simulate cytokine release and adhesion molecule expression in endothelial cells and contraction of VSMC. Elevated levels of circulating PMPs have been described in patients with arteriosclerosis, acute vascular syndromes, diabetes mellitus, as well as central obesity. GPIIb/IIIa, glycoprotein IIb/IIIa; GP Ib, glycoprotein Ib; CXCR4, chemokine (C-X-C motif) receptor 4; PAR-1, protease-activated receptor-1; RANTES, regulated on activation, normal T-cell expressed and secreted.