Platelet-derived microvesicles: multitalented participants in intercellular communication.

Platelets can release a heterogeneous pool of vesicles which include plasma membrane-derived microparticles (PMPs) and multivesicular body-derived exosomes. As both vesicle types are generated upon activation and their distinction is complicated due to an overlap in their molecular properties and sizes, they are best discussed as an entity, the platelet-derived microvesicles (PMVs). PMPs can be formed through several induction pathways, which determine their different molecular profiles and facilitate tailor-made participation in intercellular communication. This dynamic variability may lie behind the multifaceted and sometimes very different observations of the PMPs in physiological and pathological settings. Currently, little is known of platelet-derived exosomes. In all, PMVs not only participate in several homeostatic multicellular processes, such as hemostasis, maintenance of vascular health, and immunity, but they also play a role in thrombotic and inflammatory diseases and cancer progression. In the past few years, the number of original articles and reviews on microvesicles has dramatically increased, but the data simultaneously raise further questions, the answers to which depend on forthcoming analytical improvements. In this article, the differential activation pathways and the molecular and functional properties of PMVs are reviewed in context with their sometimes paradoxical role in health and in disease. Also, the methodological issues of PMV detection and analysis are discussed in the light of recent advances within the field. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.