The last decade has seen a sharp increase in the number of scientific publications describing physiological and pathological functions of extracellular vesicles (EVs), a collective term covering various subtypes of cell-released, membranous structures, called exosomes, microvesicles, microparticles, ectosomes, oncosomes, apoptotic bodies, and many other names. However, specific issues arise when working with these entities, whose size and amount often make them difficult to obtain as relatively pure preparations, and to characterize properly. The International Society for Extracellular Vesicles (ISEV) proposed Minimal Information for Studies of Extracellular Vesicles (“MISEV”) guidelines for the field in 2014. We now update these “MISEV2014” guidelines based on evolution of the collective knowledge in the last four years. An important point to consider is that ascribing a specific function to EVs in general, or to subtypes of EVs, requires reporting of specific information beyond mere description of function in a crude, potentially contaminated, and heterogeneous preparation. For example, claims that exosomes are endowed with exquisite and specific activities remain difficult to support experimentally, given our still limited knowledge of their specific molecular machineries of biogenesis and release, as compared with other biophysically similar EVs. The MISEV2018 guidelines include tables and outlines of suggested protocols and steps to follow to document specific EV-associated functional activities. Finally, a checklist is provided with summaries of key points.

Poly (ADP-ribose) polymerase-1 is a nuclear DNAbinding protein that participates in the DNA base excision repair pathway in response to genotoxic stress in mammalian cells. Here we show that PARP-1-deficient cells are defective in NF-κB-dependent transcription activation, but not in its nuclear translocation, in response to TNF-α. Treating mice with lipopolysaccharide (LPS) resulted in the rapid activation of NF-κB in macrophages from PARP-1 ⍣/⍣ but not from PARP-1 -/-mice. PARP-1-deficient mice were extremely resistant to LPS-induced endotoxic shock. The molecular basis for this resistance relies on an almost complete abrogation of NF-κB-dependent accumulation of TNF-α in the serum and a downregulation of inducible nitric oxide synthase (iNOS), leading to decreased NO synthesis, which is the main source of free radical generation during inflammation. These results demonstrate a functional association in vivo between PARP-1 and NF-κB, with consequences for the transcriptional activation of NF-κB and a systemic inflammatory process.

Inflammation has a pivotal role in the development of atherosclerosis and acute activation of the vascular wall with consecutive local thrombosis and altered vasomotion. This process is orchestrated by the interactions between inflammatory cells, such as platelets and T and B lymphocytes, and vascular cells, endothelial cells, and smooth muscle cells. When they are activated by an agonist, shear stress, or apoptosis, these cells release vesicles shed from the blebbing plasma membrane called microparticles. Microparticles harbor cell surface proteins and contain cytoplasmic components of the original cell. They exhibit negatively charged phospholipids, chiefly phosphatidylserine, at their surface, which accounts for their procoagulant character and proinflammatory properties, including alteration of vascular function. Elevated levels of circulating microparticles have been detected in pathological states associated with vascular dysfunction, including attenuation of endothelium-dependent vasodilatation and/or alteration of responsiveness of vascular smooth muscle to vasoconstrictor stimuli in conductance and resistance arteries. This review points out the characteristics of microparticles as well as the biological messages they can mediate. In particular, it summarizes the signaling cascades involved in microparticle-induced vascular dysfunction with special attention to the cellular origin of these vesicles (platelet, endothelial, and leukocytic), which may explain their differential consequences on vascular remodeling. The available information provides a rationale for the paracrine role of microparticles as vectors of transcellular exchange of message between circulating cells and cells from the vascular wall.

Extracellular vesicles (EVs) are biological vectors that can modulate the metabolism of target cells by conveying signalling proteins and genomic material. The level of EVs in plasma is significantly increased in cardiometabolic diseases associated with obesity, suggesting their possible participation in the development of metabolic dysfunction. With regard to the poor definition of adipocyte-derived EVs, the purpose of this study was to characterise both qualitatively and quantitatively EVs subpopulations secreted by fat cells. Adipocyte-derived EVs were isolated by differential centrifugation of conditioned media collected from 3T3-L1 adipocytes cultured for 24 h in serum-free conditions. Based on morphological and biochemical properties, as well as quantification of secreted EVs, we distinguished two subpopulations of adipocyte-derived EVs, namely small extracellular vesicles (sEVs) and large extracellular vesicles (lEVs). Proteomic analyses revealed that lEVs and sEVs exhibit specific protein signatures, allowing us not only to define novel markers of each population, but also to predict their biological functions. Despite similar phospholipid patterns, the comparative lipidomic analysis performed on these EV subclasses revealed a specific cholesterol enrichment of the sEV population, whereas lEVs were characterised by high amounts of externalised phosphatidylserine. Enhanced secretion of lEVs and sEVs is achievable following exposure to different biological stimuli related to the chronic low-grade inflammation state associated with obesity. Finally, we demonstrate the ability of primary murine adipocytes to secrete sEVs and lEVs, which display physical and biological characteristics similar to those described for 3T3-L1. Our study provides additional information and elements to define EV subtypes based on the characterisation of adipocyte-derived EV populations. It also underscores the need to distinguish EV subpopulations, through a combination of multiple approaches and markers, since their specific composition may cause distinct metabolic responses in recipient cells and tissues.