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Extracellular Vesicles (EVs)
Published in Peixuan Guo, Kirill A. Afonin, RNA Nanotechnology and Therapeutics, 2022
Alice Braga, Giulia Manferrari, Jayden A. Smith, Stefano Pluchino
According to this system, three broad categories of EV have been characterized (as depicted in Figure 40.1): (i) exosomes, which originate from multivesicular bodies (MVBs) associated with the endosomal pathway; (ii) microvesicles (MVs; also known as shedding vesicles or ectosomes), which arise from direct budding and shedding of the cellular plasma membrane; and (iii) apoptotic bodies, plasma membrane-derived vesicles arising from apoptosis-induced blebbing. Each category likely encompasses a variety of different EV types; the identification of type-specific biochemical markers reflecting their pathway of biogenesis and further elucidation of specific EV subtypes is an active and contentious area of research (Figure 40.1).
Nano-biosensors: A Custom-built Diagnosis
Published in Paula V. Messina, Luciano A. Benedini, Damián Placente, Tomorrow’s Healthcare by Nano-sized Approaches, 2020
Paula V. Messina, Luciano A. Benedini, Damián Placente
Exosomes are microvesicles found in all living cells formed when vesicles from the endosomal membranes fuse with the cell’s plasma membrane instead of fusing with a lysosome, for internal digestion. Resembling their cell of origin, they contain a sample of the cytosolic milieu including an abundance of DNA, RNA, proteins and other analytes (Sheridan 2016). In the last several years, nanoscale exosomes (30 nm-100 nm) and microvesicles (100 nm to 1 μm) have been discovered to contain a wealth of proteomic and genetic information for disease diagnostics as well as the monitoring of cancer progression, metastasis, and drug efficacy. They have their origin in tumour cells and that can be found circulating in the blood, and most bodily fluids. In addition, immunoblotting analysis revealed that Glypican-1 (GPC-1), an exosomal membrane protein, has much higher expression on the cancerous exosomes than on the noncancerous counterparts. This fact highlights its clinical value as an exosomal biomarker for the early diagnosis of pancreatic, breast and colorectal cancer (Liu et al. 2018b). In the light of the obtained results, a great evidence revealed the use of exosomes to the field of cancer diagnostics as a new and exciting platform in the area of “liquid biopsy”. However, establishing the clinical utility of exosomes and microvesicles as biomarkers to improve patient care has been limited by fundamental technical challenges that stalk from their small size and the extensive sample preparation required prior to measurement (Ko et al. 2016). These facts have motivated the research of Zheng Zhao and co-workers (Zhao et al. 2016), who developed what they have called “ExoSearch”. ExoSearch is a chip-based in a simple microfluidic technology that provides enriched preparation of blood plasma exosomes for in situ, multiplexed detection using immunomagnetic beads. It offers a robust, continuous-flow design for quantitative isolation and release of blood plasma exosomes in a wide range of preparation volumes (10 μL to 10 mL). The methodology was successfully employed to detect three exosomal tumour markers of ovarian cancer (CA-125, EpCAM, CD24) showing a significant diagnostic power comparable with the standard Bradford assay (Bradford 1976).
Latest advances in extracellular vesicles: from bench to bedside
Published in Science and Technology of Advanced Materials, 2019
Tomofumi Yamamoto, Nobuyoshi Kosaka, Takahiro Ochiya
It has been shown that almost all of the cells release various types of extracellular vesicles (EVs), including exosomes, microvesicles, and apoptotic bodies. EVs vary in size, properties, and secretion pathway depending on the originated cells, and the EVs are indeed taken up by recipient cells via a variety of mechanisms (Figure 1) [1,2]. Exosomes are small EVs (sEVs), their diameter is approximately 100 nm. Exosomes are initially formed by a process of inward budding in early endosomes to form multivesicular bodies (MVBs) and released into the extracellular microenvironment to transfer their components [3,4]. Microvesicles (MVs) are larger than exosomes, approximately 100–1000 nm, and are composed of lipid components of plasma membrane [5]. MVs are synthesized in directly shedding or budding from plasma membranes. Apoptotic bodies have various sizes (1–5 μm), and only when cells are killed by the process of programmed cell death, resulting in secretion of apoptotic bodies. These various types of EVs have similar characteristics, such as size and density. Thus, more detailed classification is required for EV research. Although the role of EVs was initially supposed to be cellular waste management, such as, throwing unwanted proteins and biomolecules [6], in 2007, Valadi et al. have shown that EVs have contained mRNA in their lumen as well as microRNAs (miRNAs), which is considered a novel cell to cell communication tools [7]. In a few years from that year, several groups demonstrated that EVs transferred their functional miRNAs to recipient cells [8–11].
Extracellular vesicles released in response to respiratory exposures: implications for chronic disease
Published in Journal of Toxicology and Environmental Health, Part B, 2018
Birke J. Benedikter, Emiel F. M. Wouters, Paul H. M. Savelkoul, Gernot G. U. Rohde, Frank R. M. Stassen
Due to their endosomal origin, exosomes (50–150 nm) are smaller than microvesicles (100–1000 nm). Further, exosomes are enriched in members of the endosomal sorting complexes required for transport (ESCRT, e.g. Alix, TSG101) and in tetraspanins such as CD9, CD63, and CD81. As exosomes are generally smaller than the resolution limit of conventional optical techniques (light microscopy, flow cytometry scatter) (Van Der Pol et al. 2010), highly dedicated technology is required for their detection, including electron microscopy, nanoparticle tracking analysis (NTA) (Sokolova et al. 2011), tunable resistive pulse sensing (TRPS) (Maas, De Vrij, and Broekman 2014), and fluorescence-triggered high-resolution flow cytometry (Nolte-’T Hoen et al. 2012). Alternatively, exosomes may be characterized by bulk analysis techniques, such as Western blotting or bead-based flow cytometry, a technique in which EV are linked to large beads and subsequently stained for exosome marker proteins (Suarez et al. 2017; Volgers et al. 2017). The most common method for isolation of exosomes is ultracentrifugation at 100,000 × g (Gardiner et al. 2016).
Advances of engineered extracellular vesicles-based therapeutics strategy
Published in Science and Technology of Advanced Materials, 2022
Hiroaki Komuro, Shakhlo Aminova, Katherine Lauro, Masako Harada
Since all types of cells secrete EVs, their recovery has been reported in all bodily fluids [20], including blood [21], urine [22], saliva [23], breast milk [24], semen [25], bronchoalveolar lavage fluid [26], synovial fluid [27], cerebrospinal fluid [28], and amniotic fluid [29]. EVs are broadly classified into three types: exosomes, microvesicles, and apoptotic bodies (Figure 1). The classification of EV can be associated with their biogenesis. Exosomes (50–150 nm) derive from the inward budding of the endosomal compartment, multivesicular bodies (MVBs). Upon fusion with the cell membrane, exosomes are released to the extracellular space and mediate intercellular communication by transferring bioactive molecules such as RNAs, proteins, and lipids between cells in living organisms [30]. Tetraspanins belong to a cell surface protein family with four transmembrane domains required for intraluminal vesicle formation [31]. CD9, CD63, and CD81 are tetraspanin proteins found enriched in exosomes and often used as EV surface markers [12]. Microvesicles (100–1000 nm), on the other hand, are secreted directly from the plasma membrane. Microvesicles are not as well studied or defined as the other EV types, resulting in more broad characteristics. Apoptotic bodies (100–5000 nm) are produced from apoptotic cells when they undergo programmed cell death. Numerous studies illustrate the heterogeneity of these EVs and missing pieces of information left uncovered, implicating the change in descriptions in the future [12]. For example, there is no defined method or unique maker to separate one EV type from another. A report suggested that 100,000 g ultracentrifugation (UC) co-isolates two EV subtypes defined by specific proteins [32], proposing the importance of considering heterogeneity and diversity among EV types in the study design. Furthermore, some EV subtypes are named after the cell from which they are secreted, such as cardiosome (cardiovascular-origin) and oncosome (oncology-origin) [33–36], though ISEV strongly suggests that the generic term EV be widely adopted [37]. Moreover, the guidelines published by ISEV in 2018 recommend referring to small EVs (sEVs) (<100 nm or <200 nm) or >200 nm as medium/large EVs (m/lEVs) EVs based on their physical characteristic, size and density [12]. This article will adhere to the term ‘EV’ in place of exosome or the names used in the original literature to avoid terminology ambiguity.