Focus on Extracellular Vesicles: Introducing the Next Small Big Thing

Extracellular vesicles for personalized medicine: The input of physically triggered production, loading and theranostic properties

Emerging advances in extracellular vesicle (EV) research brings along new promises for tailoring clinical treatments in order to meet specific disease features of each patient in a personalized medicine concept. EVs may act as regenerative effectors conveying endogenous therapeutic factors from parent cells or constitute a bio-camouflaged delivery system for exogenous therapeutic agents. Physical stimulation may be an important tool in the field of EVs for personalized therapy by powering EV production, loading and therapeutic properties. Physically-triggered EV production is inspired by naturally occurring EV release by shear stress in blood vessels. Bioinspired physically-triggered EV production technologies may bring along high yield advantages combined to scalability assets. Physical stimulation may also provide new prospects for high-efficient EV loading. Additionally, physically-triggered EV theranostic properties brings new hopes for spatio-temporal controlled therapy combined to tracking. Technological considerations related to EV-based personalized medicine and the input of physical stimulation on EV production, loading and theranostic properties will be overviewed herein.

Advances in the diagnosis of exosomal miRNAs in ischemic stroke

Early diagnosis, early treatment, and improved prognosis in patients with ischemic stroke are vital requirements. Current clinical practices for the diagnosis of stroke include computed tomography, magnetic resonance imaging, and other traditional imaging methods to quickly check the location, volume, etc, in the hospital; however, diagnosis of the underlying cause of infarction is not effective with these practices. Owing to the coexistence of various etiologies, accurate and timely diagnosis using routine hematology and biochemical tests remains a challenge. Exosomes are membrane vesicles, approximately 30-150 nm in diameter, which fuse with cell membrane and are released into the extracellular space. As one of the research hotspots in the field of medicine in recent years, exosomes can participate in immune response, antigen presentation, cell migration, tumor invasion, and so on. Owing to the important role played by the miRNAs contained in exosomes, the latter have shown great potential in the diagnosis and treatment of ischemic stroke. This article reviews the progress made regarding the exosomal miRNAs as ischemic stroke biomarkers.

Microvesicle detection by a reduced graphene oxide field-effect transistor biosensor based on a membrane biotinylation strategy

A reduced graphene oxide field-effect transistor biosensor for the detection of microvesicles by using a membrane biotinylation strategy.

Proteomic Profiling of LPS-Induced Macrophage-Derived Exosomes Indicates Their Involvement in Acute Liver Injury

Exosomes are typically involved in cellular communication and signaling. Macrophages play a key role in lipopolysaccharide (LPS)-induced sepsis. However, the molecular comparison of exosomes derived from LPS-induced macrophage has not been well analyzed. The macrophage-exosomes are validated and the protein composition of those exosomes are investigated by isobaric tags for relative and absolute quantification (iTRAQ) mass spectrometry. A total of 5056 proteins are identified in macrophage-exosomes. We discovered 341 increased proteins and 363 reduced proteins in LPS-treated macrophage-exosomes compared with control exosomes. In addition, gene ontology analysis demonstrates that macrophage-exosomes proteins are mostly linked to cell, organelle, extracellular region, and membrane. The bioinformatics analysis also indicates that these proteins are mainly involved in cellular process, single-organism process, metabolic process, and biological regulation. Among these 341 upregulated proteins, Kyoto Encyclopedia of Genes and Genomes analysis reveals that 22 proteins are involved in the NOD-like receptor signaling pathway. Finally, hepatocytes can uptake macrophage-exosomes and subsequently NLRP3 inflammasome is activated in vitro and in vivo. These data emphasize the fundamental importance of macrophage-exosomes in sepsis-induced liver injury. Therefore, the iTRAQ proteomic strategy brings new insights into macrophage-derived exosomes. It may improve our understanding of macrophage-exosomes' functions and their possible use as therapeutic targets for sepsis.

Extracellular Vesicles Released by Leishmania (Leishmania) amazonensis Promote Disease Progression and Induce the Production of Different Cytokines in Macrophages and B-1 Cells

The extracellular vesicles (EVs) released by Leishmania can contribute to the establishment of infection and host immunomodulation. In this study, we characterized the shedding of EVs from Leishmania (Leishmania) amazonensis promastigotes. This species is the causative agent of cutaneous leishmaniasis, and its role during interactions with bone marrow-derived macrophages (BMDMs) and peritoneal B-1 cells was evaluated. Leishmania amazonensis promastigotes cultivated in vitro at different times and temperatures spontaneously released EVs. EVs were purified using size-exclusion chromatography (SEC) and quantitated by nanoparticle tracking analysis (NTA). NTA revealed that the average size of the EVs was approximately 180 nm, with concentrations ranging from 1.8 × 10⁸ to 2.4 × 10⁹ vesicles/mL. In addition, the presence of LPG and GP63 were detected in EVs obtained at different temperatures. Naïve BMDMs stimulated with EVs exhibited increased IL-10 and IL-6 expression. However, incubating B-1 cells with parasite EVs did not stimulate IL-10 expression but led to an increase in the expression of IL-6 and TNFα. After 7 weeks post-infection, animals infected with L. amazonensis promastigotes in the presence of parasite EVs had significant higher parasite load and a polarization to Th2 response, as compared to the group infected with the parasite alone. This work demonstrated that EVs isolated from L. amazonensis promastigotes were able to stimulate macrophages and B-1 cells to express different types of cytokines. Moreover, the immunomodulatory properties of EVs probably contributed to an increase in parasite burden in mice. These findings suggest that the functionality of L. amazonensis EVs on immune system favor of parasite survival and disease progression.

DNA Vectors Generating Engineered Exosomes Potential CTL Vaccine Candidates Against AIDS, Hepatitis B, and Tumors

Eukaryotic cells constitutively produce nanovesicles of 50-150 nm of diameter, referred to as exosomes, upon release of the contents of multivesicular bodies (MVBs). We recently characterized a novel, exosome-based way to induce cytotoxic T lymphocyte (CTL) immunization against full-length antigens. It is based on DNA vectors expressing products of fusion between the exosome-anchoring protein Nef mutant (Nef^mut) with the antigen of interest. The strong efficiency of Nef^mut to accumulate in MVBs results in the production of exosomes incorporating huge amounts of the desired antigen. When translated in animals, the injection of Nef^mut-based DNA vectors generates engineered exosomes whose internalization in antigen-presenting cells induces cross-priming and antigen-specific CTL immunity. Here, we describe the molecular strategies we followed to produce DNA vectors aimed at generating immunogenic exosomes potentially useful to elicit a CTL immune response against antigens expressed by the etiologic agents of major chronic viral infections, i.e., HIV-1, HBV, and the novel tumor-associated antigen HOXB7. Unique methods intended to counteract intrinsic RNA instability and nuclear localization of the antigens have been developed. The success we met with the production of these engineered exosomes opens the way towards pre-clinic experimentations devoted to the optimization of new vaccine candidates against major infectious and tumor pathologies.

Receptor-Ligand Interaction Mediates Targeting of Endothelial Colony Forming Cell-derived Exosomes to the Kidney after Ischemic Injury

Endothelial colony forming cell (ECFC)-derived exosomes protect mice against ischemic kidney injury, via transfer of microRNA-(miR)-486-5p. Mechanisms mediating exosome recruitment to tissues are unclear. We hypothesized that ECFC exosomes target ischemic kidneys, involving interaction between exosomal CXC chemokine receptor type 4 (CXCR4) and stromal cell-derived factor (SDF)-1α. Ischemia-reperfusion was induced in mice by bilateral renal vascular clamp, with intravenous infusion of exosomes at reperfusion. Optical imaging determined exosome biodistribution, and miR-486-5p was measured by real-time PCR. Human umbilical vein endothelial cells (HUVECs) were cultured to study the CXCR4/SDF-1α interaction. Targeting of administered exosomes to ischemic kidneys was detected 30 min and 4 hrs after reperfusion. Exosomes increased miR-486-5p levels only in kidneys, within proximal tubules, glomeruli, and endothelial cells. Uptake of fluorescently-labeled exosomes into HUVECs, and exosomal transfer of miR-486-5p were enhanced by hypoxia, effects blocked by neutralizing antibody to SDF-1α or by the CXCR4 inhibitor plerixafor. Infusion of ECFC exosomes prevented ischemic kidney injury in vivo, an effect that was not observed when exosomes were pre-incubated with plerixafor. These data indicate that ECFC exosomes selectively target the kidneys after ischemic injury, with rapid cellular transfer of miR486-5p. Targeting of exosomes may involve interaction of CXCR4 with endothelial cell SDF-1α.

Molecular assessment of circulating exosomes toward liquid biopsy diagnosis of Ewing sarcoma family of tumors

Ewing sarcoma was first described in 1921 in the Proceedings of the New York Pathological Society by an eminent American pathologist from Cornell named James R. Ewing as a "diffuse endothelioma of bone." Since this initial description, more has been discovered regarding Ewing sarcoma and in the 1980's both Ewing sarcoma and peripheral primitive neuroectodermal tumors due to their similar features and shared identical genetic abnormality were grouped into a class of cancers entitled Ewing sarcoma family of tumors (ESFTs). Ewing sarcoma is the second most common pediatric osseous malignancy followed by osteosarcoma, with highest incidence among 10-20 years old. Ewing sarcoma is consistently associated with chromosomal translocation and functional fusion of the EWSR1 gene to any of several structurally related transcription factor genes of the E26 transformation-specific family. These tumor-specific molecular rearrangements are useful for primary diagnosis, may provide prognostic information, and present potential therapeutic targets. Therefore, ways to rapidly and efficiently detect these defining genomic alterations are of clinical relevance. Within the past decade, liquid biopsies including extracellular vesicles (EVs), have emerged as a promising alternative and/or complimentary approach to standard tumor biopsies. It was recently reported that fusion mRNAs from tumor-specific chromosome translocations can be detected in Ewing sarcoma cell-derived exosomes. Within this review, we overview the current advances in Ewing sarcoma and the opportunities and challenges in exploiting circulating exosomes, primarily small bioactive EVs (30-180 nm), as developing sources of biomarkers for diagnosis and therapeutic response monitoring in children and young adult patients with ESFT.

Perspectives on potentiating immunocapture-LC-MS for the bioanalysis of biotherapeutics and biomarkers

The integration of ligand-binding assay and LC-MS/MS (immunocapture-LC-MS) has unleashed the combined advantages of both powerful techniques for addressing the ever increasing bioanalytical challenges for biotherapeutics and biomarker assays. The highly specific, selective and sensitive characteristics of the immunocapture-LC-MS-based assays have enabled the determination of biotherapeutics and biomarkers in biomatrices with ease of method development, less requirements on key reagents as well as structural specificity for endogenous and engineered biomolecules. In addition, the versatile immunocapture-LC-MS technology has expanded into many challenging areas to enhance mechanistic studies of drug interactions with their targets. This paper intends to summarize our perspectives on enhancing the use of immunocapture-LC-MS in drug discovery and development for emerging new modalities.

To Protect and to Preserve: Novel Preservation Strategies for Extracellular Vesicles

Extracellular vesicles (EVs)-based therapeutics are based on the premise that EVs shed by stem cells exert similar therapeutic effects and these have been proposed as an alternative to cell therapies. EV-mediated delivery is an effective and efficient system of cell-to-cell communication which can confer therapeutic benefits to their target cells. EVs have been shown to promote tissue repair and regeneration in various animal models such as, wound healing, cardiac ischemia, diabetes, lung fibrosis, kidney injury, and many others. Given the unique attributes of EVs, considerable thought must be given to the preservation, formulation and cold chain strategies in order to effectively translate exciting preclinical observations to clinical and commercial success. This review summarizes current understanding around EV preservation, challenges in maintaining EV quality, and also bioengineering advances aimed at enhancing the long-term stability of EVs.

Rheumatoid Arthritis Patients With Circulating Extracellular Vesicles Positive for IgM Rheumatoid Factor Have Higher Disease Activity

Rheumatoid arthritis (RA) is an autoimmune inflammatory disease that mainly affects synovial joints. Validated laboratory parameters for RA diagnosis are higher blood levels of rheumatoid factor IgM (IgM-RF), anti-citrullinated protein autoantibodies (ACPA), C-reactive protein (CRP) levels and erythrocyte sedimentation rate (ESR). Clinical parameters used are the number of tender (TJC) and swollen joints (SJC) and the global patient visual analog score (VAS). To determine disease remission in patients a disease activity score (DAS28) can be calculated based on SJC, TJC, VAS, and ESR (or alternatively CRP). However, subtle and better predictive changes to follow treatment responses in individual patients cannot be measured by the above mentioned parameters nor by measuring cytokine levels in blood. As extracellular vesicles (EVs) play a role in intercellular communication and carry a multitude of signals we set out to determine their value as a biomarker for disease activity. EVs were isolated from platelet-free plasma of 41 RA patients and 24 healthy controls (HC) by size exclusion chromatography (SEC). We quantified the particle and protein concentration, using NanoSight particle tracking analysis and micro-BCA, respectively, and observed no differences between RA patients and HC. In plasma of 28 out of 41 RA patients IgM-RF was detectable by ELISA, and in 13 out of these 28 seropositive RA patients (RF⁺RA) IgM-RF was also detected on their isolated pEVs (IgM-RF⁺). In seronegative RA patients (RF^-RA) we did not find any RF present on pEVs. When comparing disease parameters we found no differences between RF⁺RA and RF^-RA patients, except for increased ESR levels in RF⁺RA patients. However, RF⁺RA patients with IgM-RF⁺ pEVs showed significantly higher levels of CRP and ESR and also VAS and DAS28 were significantly increased compared to RA⁺ patients without IgM-RF⁺ pEVs. This study shows for the first time the presence of IgM-RF on pEVs in a proportion of RF⁺RA patients with a higher disease activity.

Therapeutic Targeting Cancer-Initiating Cell Markers by Exosome miRNA: Efficacy and Functional Consequences Exemplified for claudin7 and EpCAM

AIM: Transfer of exosomes (Exo) miRNA was described interfering with tumor progression. We here explored for claudin7 (cld7) and EpCAM (EpC), cancer-initiating-cell markers in colorectal and pancreatic cancer, the efficacy of Exo loading with miRNA and miRNA transfer. METHODS: Exo were collected from nontransformed mouse (NIH3T3) and rat lung fibroblasts (rFb), which were transfected with Tspan8 cDNA (NIH3T3-Tspan8, rFb-Tspan8). Exo were loaded by electroporation with miRNA. The transfer of Exo-miRNA was evaluated in vitro and in vivo in a rat pancreatic (ASML) and a human colon (SW948) cancer line. RESULTS: NIH3T3-Tspan8- or rFb-Tspan8-Exo were efficiently loaded with cld7- or EpC-miRNA. Exo targeting in vivo was strongly improved by tailoring with Tspan8. Exo-miRNA transfer into tumor targets promoted cld7, respectively, EpC downregulation by 33%-60%. Cld7 silencing was accompanied by reduced expression of additional cancer-initiating cell markers and NOTCH. EpC silencing reduced vimentin, N-cadherin, and Nanog expression. The Exo-miRNA transfer affected anchorage-independent growth, motility, and invasion. CONCLUSIONS: Exo are efficiently loaded with miRNA, miRNA-delivery being supported by Exo tailoring. Partial cld7 and EpC silencing by Exo miRNA affects metastasis-promoting tumor cell activities. The findings suggest miRNA loading of tailored Exo as an easy approachable and efficient adjuvant therapy.

Extracellular Vesicles in Herpes Viral Spread and Immune Evasion

Extracellular vesicles (EVs) are involved in numerous processes during infections by both enveloped and non-enveloped viruses. Among them, herpes simplex virus type-1 (HSV-1) modulates secretory pathways, allowing EVs to exit infected cells. Many characteristics regarding the mechanisms of viral spread are still unidentified, and as such, secreted vesicles are promising candidates due to their role in intercellular communications during viral infection. Another relevant role for EVs is to protect virions from the action of neutralizing antibodies, thus increasing their stability within the host during hematogenous spread. Recent studies have suggested the participation of EVs in HSV-1 spread, wherein virion-containing microvesicles (MVs) released by infected cells were endocytosed by naïve cells, leading to a productive infection. This suggests that HSV-1 might use MVs to expand its tropism and evade the host immune response. In this review, we briefly describe the current knowledge about the involvement of EVs in viral infections in general, with a specific focus on recent research into their role in HSV-1 spread. Implications of the autophagic pathway in the biogenesis and secretion of EVs will also be discussed.

Exosome Biogenesis and Biological Function in Response to Viral Infections

Introduction

Exosomes are extracellular vesicles that originate as intraluminal vesicles during the process of multivescular body formation. Exosomes mediate intercellular transfer of functional proteins, lipids, and RNAs. The investigation into the formation and role of exosomes in viral infections is still being elucidated. Exosomes and several viruses share similar structural and molecular characteristics.

Explanation

It has been documented that viral hijacking exploits the exosomal pathway and mimics cellular protein trafficking. Exosomes released from virus-infected cells contain a variety of viral and host cellular factors that are able to modify recipient host cell responses. Recent studies have demonstrated that exosomes are crucial components in the pathogenesis of virus infection. Exosomes also allow the host to produce effective immunity against pathogens by activating antiviral mechanisms and transporting antiviral factors between adjacent cells.

Conclusion

Given the ever-growing roles and importance of exosomes in both host and pathogen response, this review will address the impact role of exosome biogenesis and composition after DNA, RNA virus, on Retrovirus infections. This review also will also address how exosomes can be used as therapeutic agents as well as a vaccine vehicles.

Mechanism of drug extrusion by brain endothelial cells via lysosomal drug trapping and disposal by neutrophils

Located at the apical (blood-facing) site of brain capillary endothelial cells that form the blood–brain barrier (BBB), the efflux transporter P-glycoprotein (Pgp) restricts the brain entry of various lipophilic xenobiotics, which contributes to BBB function. Pgp may become saturated if exposed to too-high drug concentrations. Here, we demonstrate a second-line defense mechanism in human brain capillary endothelial cells—that is, Pgp-mediated intracellular lysosomal drug trapping. Furthermore, we describe a mechanism of drug disposal at the BBB, which is shedding of lysosomal Pgp/substrate complexes at the apical membrane of human and porcine BBB endothelial cells and subsequent phagocytosis by neutrophils. Thus, we have discovered a fascinating mechanism of how Pgp might contribute to brain protection.

The blood–brain barrier protects the brain against a variety of potentially toxic compounds. Barrier function results from tight junctions between brain capillary endothelial cells and high expression of active efflux transporters, including P-glycoprotein (Pgp), at the apical membrane of these cells. In addition to actively transporting drugs out of the cell, Pgp mediates lysosomal sequestration of chemotherapeutic drugs in cancer cells, thus contributing to drug resistance. Here, we describe that lysosomal sequestration of Pgp substrates, including doxorubicin, also occurs in human and porcine brain endothelial cells that form the blood–brain barrier. This is followed by shedding of drug-sequestering vesicular structures, which stay attached to the apical side of the plasma membrane and form aggregates (“barrier bodies”) that ultimately undergo phagocytosis by neutrophils, thus constituting an as-yet-undescribed mechanism of drug disposal. These findings introduce a mechanism that might contribute to brain protection against potentially toxic xenobiotics, including therapeutically important chemotherapeutic drugs.

From Inflammasome to Exosome-Does Extracellular Vesicle Secretion Constitute an Inflammasome-Dependent Immune Response?

Inflammasomes are intracellular protein complexes of pattern recognition receptors and caspase-1, with essential functions in regulating inflammatory responses of macrophages and dendritic cells. The primary role of inflammasomes is to catalyze processing and secretion of pro-inflammatory cytokines IL-1β and IL-18. Recently, intracellular non-canonical inflammasome activation by caspases-4/5, which are also regulators of pyroptosis via processing gasdermin D, has been elucidated. Caspase-1, the effector protease of inflammasome complex, is also known to modulate secretion of large number of other proteins. Thereby, besides its known role in processing pro-inflammatory cytokines, the inflammasome turns into a universal regulator of protein secretion, which allows the danger-exposed cells to release various proteins in order to alert and guide neighboring cells. Majority of these proteins are not secreted through the conventional ER-Golgi secretory pathway. Instead, they are segregated in membrane-enclosed compartment and secreted in nanosized extracellular vesicles, which protect their cargo and guide it for delivery. Growing evidence indicates that inflammasome activity correlates with enhanced secretion of extracellular vesicles and modulation of their protein cargo. This inflammasome-driven unconventional, vesicle-mediated secretion of multitude of immunoregulatory proteins may constitute a novel paradigm in inflammatory responses. In this mini review we discuss the current knowledge and highlight unsolved questions about metabolic processes, signals, and mechanisms linking inflammasome activity with regulated extracellular vesicle secretion of proteins. Further investigations on this relationship may in the future help understanding the significance of extracellular vesicle secretion in inflammatory diseases such as atherosclerosis, gouty arthritis, asthma, Alzheimer's and many others.

Emerging role of extracellular vesicles in mediating cancer cachexia

Cancer cachexia is a multifactorial metabolic syndrome characterized by the rapid loss of skeletal muscle mass with or without the loss of fat mass. Nearly 50-80% of all cancer patients' experience rapid weight loss results in ∼20% of cancer-related deaths. The levels of pro-inflammatory and pro-cachectic factors were significantly up-regulated in cachexia patients when compared with the patients who were without cachexia. It is becoming evident that these factors work synergistically to induce cancer cachexia. Extracellular vesicles (EVs) including exosomes and microvesicles are implicated in cell-cell communication, immune response, tissue repair, epigenetic regulation, and in various diseases including cancer. It has been reported that these EVs regulate cancer progression, metastasis, organotropism and chemoresistance. In recent times, the role of EVs in regulating cancer cachexia is beginning to unravel. The aim of this mini article is to review the recent knowledge gained in the field of EVs and cancer cachexia. Specifically, the role of tumour cell-derived EVs in promoting catabolism in distally located skeletal muscles and adipose tissue will be discussed.

New Insights into the Role of Exosomes in the Heart After Myocardial Infarction

Intercellular communications play a pivotal role in several cardiac pathophysiological processes. One subtype of extracellular vesicles, so-called exosomes, became known as important intercellular communication mediators in the heart. Exosomes are lipid bilayer biological nanovesicles loaded with diverse proteins, lipids, and mRNAs/microRNAs. All major cardiac cell types can modulate recipient cellular function via the release of exosomes. After myocardial infarction (MI), exosomes, especially those secreted by different cardiac stem cells, have been shown to confer cardioprotective effects, activate regenerative signals, and participate into cardiac repair. In this review, we rapidly recall the biology of exosomes at the beginning. Then we summarize the exosomes secreted by different myocardial cells and their function in cardiac intercellular communication. At last, we discuss the role of these vesicles in cardiac repair after MI.

Exosomes as possible spread factor and potential biomarkers in Alzheimer's disease: current concepts

Increasing evidence points that important factors during development/spread of Alzheimer's disease in brain tissue are small extracellular vesicles, called exosomes. Exosomes comprise disease-related biomolecules such as the amyloid protein precursor, β-amyloid peptide and tau protein. Exosomes are hypothesized to facilitate the spread of β-amyloid peptide and tau protein from their cells of origin (e.g., neurons) to the extracellular space and to recipient cells to alter their phenotype and function. The roles of exosomes carry a rich biomolecules cargo in physiology and pathology is poorly understood. In this review, we will consider new information about the role of exosomes in Alzheimer's disease spreading and progression and underline their possible usefulness as the future diagnostic antemortem biomarkers in this devastating disorder.

Nanomechanics of Extracellular Vesicles Reveals Vesiculation Pathways

Extracellular vesicles (EVs) are emerging as important mediators of cell-cell communication as well as potential disease biomarkers and drug delivery vehicles. However, the mechanical properties of these vesicles are largely unknown, and processes leading to microvesicle-shedding from the plasma membrane are not well understood. Here an in depth atomic force microscopy force spectroscopy study of the mechanical properties of natural EVs is presented. It is found that several natural vesicles of different origin have a different composition of lipids and proteins, but similar mechanical properties. However, vesicles generated by red blood cells (RBC) at different temperatures/incubation times are different mechanically. Quantifying the lipid content of EVs reveals that their stiffness decreases with the increase in their protein/lipid ratio. Further, by maintaining RBC at "extreme" nonphysiological conditions, the cells are pushed to utilize different vesicle generation pathways. It is found that RBCs can generate protein-rich soft vesicles, possibly driven by protein aggregation, and low membrane-protein content stiff vesicles, likely driven by cytoskeleton-induced buckling. Since similar cortical cytoskeleton to that of the RBC exists on the membranes of most mammalian cells, our findings help advancing the understanding of the fundamental process of vesicle generation.

Extracellular Vesicle Characteristics in β-thalassemia as Potential Biomarkers for Spleen Functional Status and Ineffective Erythropoiesis

β-thalassemia major (β-TM) is a therapeutically challenging chronic disease in which ineffective erythropoiesis is a main pathophysiological factor. Extracellular vesicles (EVs) are membrane-enclosed vesicles released by cells into biological fluids; they are involved in intercellular communication and in multiple physiological and pathological processes. The chaperone heat-shock protein 70 (HSP70), which is released from cells via EVs, aggravates ineffective erythropoiesis in β-TM. We propose that β-TM EVs may show specific signatures, reflecting disease mechanisms, stages and severity. Our study aims were to define EV profiles in β-TM patients, investigate the influence of hypersplenism and splenectomy on EV features, and explore the association of circulating EVs with ineffective erythropoiesis and iron-overload parameters. We characterized circulating EVs in 35 transfusion-dependent β-thalassemia patients and 35 controls using several techniques. Nanoparticle-tracking analysis revealed increased EV concentration in patients vs. controls (P = 0.0036), with smaller EV counts and sizes in patients with hypersplenism. Flow cytometry analysis showed lower levels of RBC and monocyte EVs in patients vs. controls. RBC-EV levels correlated with patient hematocrit, reflecting degree of anemia. The procoagulant potential of the EVs evaluated by flow cytometry revealed lower levels of endothelial protein C receptor-labeled EVs in patients vs. controls, and increased tissue factor-to-tissue factor pathway inhibitor-labeled EV ratio in splenectomized patients, suggesting a hypercoagulable state. Protein content, evaluated in EV pellets, showed increased levels of HSP70 in patients (P = 0.0018), inversely correlated with transfusion requirement and hemoglobin levels, and positively correlated with reticulocyte, erythropoietin and lactate dehydrogenase levels. This first description of EVs in patients with hypersplenism reveals the spleen’s importance in EV physiology and clearance. Circulating EV-HSP70 levels were associated with markers of ineffective erythropoiesis, hemolysis and hematological disease severity. EV analysis in β-TM—reflecting spleen status, hypercoagulability state and ineffective erythropoiesis—may serve as a biomarker of disease dynamics, supporting both anticipation of the risk of complications and optimizing treatment.

Single-Vesicle Assays Using Liposomes and Cell-Derived Vesicles: From Modeling Complex Membrane Processes to Synthetic Biology and Biomedical Applications

The plasma membrane is of central importance for defining the closed volume of cells in contradistinction to the extracellular environment. The plasma membrane not only serves as a boundary, but it also mediates the exchange of physical and chemical information between the cell and its environment in order to maintain intra- and intercellular functions. Artificial lipid- and cell-derived membrane vesicles have been used as closed-volume containers, representing the simplest cell model systems to study transmembrane processes and intracellular biochemistry. Classical examples are studies of membrane translocation processes in plasma membrane vesicles and proteoliposomes mediated by transport proteins and ion channels. Liposomes and native membrane vesicles are widely used as model membranes for investigating the binding and bilayer insertion of proteins, the structure and function of membrane proteins, the intramembrane composition and distribution of lipids and proteins, and the intermembrane interactions during exo- and endocytosis. In addition, natural cell-released microvesicles have gained importance for early detection of diseases and for their use as nanoreactors and minimal protocells. Yet, in most studies, ensembles of vesicles have been employed. More recently, new micro- and nanotechnological tools as well as novel developments in both optical and electron microscopy have allowed the isolation and investigation of individual (sub)micrometer-sized vesicles. Such single-vesicle experiments have revealed large heterogeneities in the structure and function of membrane components of single vesicles, which were hidden in ensemble studies. These results have opened enormous possibilities for bioanalysis and biotechnological applications involving unprecedented miniaturization at the nanometer and attoliter range. This review will cover important developments toward single-vesicle analysis and the central discoveries made in this exciting field of research.

Stabilization of the CD81 Large Extracellular Loop with De Novo Disulfide Bonds Improves Its Amenability for Peptide Grafting

Tetraspan proteins are significantly enriched in the membranes of exosomal vesicles (EVs) and their extracellular domains are attractive targets for engineering towards specific antigen recognition units. To enhance the tolerance of a tetraspanin fold to modification, we achieved significant thermal stabilization of the human CD81 large extracellular loop (hCD81 LEL) via de novo disulfide bonds. The best mutants were shown to exhibit a positive shift in the melting temperature (Tm) of up to 25 °C. The combination of two most potent disulfide bonds connecting different strands of the protein resulted in a mutant with a Tm of 109 °C, 43 °C over the Tm of the wild-type hCD81 LEL. A peptide sequence binding to the human transferrin receptor (hTfr) was engrafted into the D-segment of the hCD81 LEL, resulting in a mutant that still exhibited a compact fold. Grafting of the same peptide sequence between helices A and B resulted in a molecule with an aberrant profile in size exclusion chromatography (SEC), which could be improved by a de novo cysteine bond connecting both helices. Both peptide-grafted proteins showed an enhanced internalization into the cell line SK-BR3, which strongly overexpresses hTfr. In summary, the tetraspan LEL fold could be stabilized to enhance its amenability for engineering into a more versatile protein scaffold.

Nanoplasmonic pillars engineered for single exosome detection

Exosomes are secreted nanovesicles which incorporate proteins and nucleic acids, thereby enabling multifunctional pathways for intercellular communication. There is an increasing appreciation of the critical role they play in fundamental processes such as development, wound healing and disease progression, yet because of their heterogeneous molecular content and low concentrations in vivo, their detection and characterization remains a challenge. In this work we combine nano- and microfabrication techniques for the creation of nanosensing arrays tailored toward single exosome detection. Elliptically–shaped nanoplasmonic sensors are fabricated to accommodate at most one exosome and individually imaged in real time, enabling the label-free recording of digital responses in a highly multiplexed geometry. This approach results in a three orders of magnitude sensitivity improvement over previously reported real-time, multiplexed platforms. Each nanosensor is elevated atop a quartz nanopillar, minimizing unwanted nonspecific substrate binding contributions. The approach is validated with the detection of exosomes secreted by MCF7 breast adenocarcinoma cells. We demonstrate the increasingly digital and stochastic nature of the response as the number of subsampled nanosensors is reduced from four hundred to one.

Revascularization and endothelial progenitor cells in stroke

Stroke is one of the leading causes of death and disability worldwide. Tremendous improvements have been achieved in the acute care of stroke patients with the implementation of stroke units, thrombolytic drugs, and endovascular trombectomies. However, stroke survivors with neurological deficits require long periods of neurorehabilitation, which is the only approved therapy for poststroke recovery. With this scenario, more treatments are urgently needed, and only the understanding of the mechanisms of brain recovery might contribute to identify new therapeutic agents. Fortunately, brain injury after stroke is counteracted by the birth and migration of several populations of progenitor cells towards the injured areas, where angiogenesis and vascular remodeling play a key role providing trophic support and guidance during neurorepair. Endothelial progenitor cells (EPCs) constitute a pool of circulating bone-marrow derived cells that mobilize after an ischemic injury with the potential to incorporate into the damaged endothelium, to form new vessels, or to secrete trophic factors stimulating vessel remodeling. The circulating levels of EPCs are altered after stroke, and several subpopulations have proved to boost brain neurorepair in preclinical models of cerebral ischemia. The goal of this review is to discuss the current state of the neuroreparative actions of EPCs, focusing on their paracrine signaling mechanisms thorough their secretome and released extracellular vesicles.

Mass-Spectrometric Analysis of Proteome of Microvesicles Produced by NK-92 Natural Killer Cells

Membrane extracellular microvesicles serve as carriers of a wide range of molecules, the most important among these are proteins, lipids, and nucleic acids. Cytotoxic proteins of natural killer cells play a key role in the realization of their cytolytic functions. An important stage in understanding of the distant communication of cells and mechanisms of its regulation is analysis of the proteome composition of microvesicles. We studied the proteomic composition of microvesicles produced by NK-92 natural killer cells. Granzyme A, a specific protein of cytotoxic cells, has been identified in the microvesicles by QTOF-mass spectrometry. It was shown that heat shock proteins, components of the ubiquitin-proteasome system, enzymes of protein biosynthesis and energy metabolism, nuclear and serum proteins, as well as cytoskeleton proteins are associated with the microvesicles.

Role of Exosomes as a Treatment and Potential Biomarker for Stroke

Approximately, 16 million strokes occur worldwide each year, causing 6 million deaths and considerable disability, implying an enormous social, individual health, and economic burden. Due to this high incidence, strategies to promote stroke recovery are urgently needed. Research into new therapeutic approaches for stroke has determined that intravenous administration of mesenchymal stem cells (MSCs) is a good strategy to improve recovery by amplifying mechanisms implicated in brain plasticity. Recent studies have demonstrated the efficacy of MSCs in stroke, with no need for them to reach the area of brain injury. Although the mechanisms by which they mediate restorative effects are still unknown, the evidence suggests that MSCs might use specialised communication by sending and receiving biological information included in elements called exosomes. Exosomes are nanosized extracellular vesicles released into physical environments, and they have recently been suggested to mediate restorative stem cell effects. Moreover, after stroke, exosomes can also be synthesised and released from brain cells, passing through the blood-brain barrier (BBB), and can be detected in peripheral blood or in cerebrospinal fluid. Thus, exosomes could possibly be biomarkers that reflect pathological progress and promote stroke recovery. This review discusses the translational aspects of MSC-derived exosomes and their various roles in brain repair and as circulating biomarkers in stroke.

Detailed analysis of the plasma extracellular vesicle proteome after separation from lipoproteins

The isolation of extracellular vesicles (EVs) from blood is of great importance to understand the biological role of circulating EVs and to develop EVs as biomarkers of disease. Due to the concurrent presence of lipoprotein particles, however, blood is one of the most difficult body fluids to isolate EVs from. The aim of this study was to develop a robust method to isolate and characterise EVs from blood with minimal contamination by plasma proteins and lipoprotein particles. Plasma and serum were collected from healthy subjects, and EVs were isolated by size-exclusion chromatography (SEC), with most particles being present in fractions 8-12, while the bulk of the plasma proteins was present in fractions 11-28. Vesicle markers peaked in fractions 7-11; however, the same fractions also contained lipoprotein particles. The purity of EVs was improved by combining a density cushion with SEC to further separate lipoprotein particles from the vesicles, which reduced the contamination of lipoprotein particles by 100-fold. Using this novel isolation procedure, a total of 1187 proteins were identified in plasma EVs by mass spectrometry, of which several proteins are known as EV-associated proteins but have hitherto not been identified in the previous proteomic studies of plasma EVs. This study shows that SEC alone is unable to completely separate plasma EVs from lipoprotein particles. However, combining SEC with a density cushion significantly improved the separation of EVs from lipoproteins and allowed for a detailed analysis of the proteome of plasma EVs, thus making blood a viable source for EV biomarker discovery.

Extracellular vesicles characteristics and emerging roles in atherosclerotic cardiovascular disease

The term extracellular vesicles (EVs) describes membrane vesicles released into the extracellular space by most cell types. EVs have been recognized to play an important role in cell-to-cell communication. They are known to contain various bioactive molecules, including proteins, lipids, and nucleic acids. Although the nomenclature of EVs is not entirely standardized, they are considered to include exosomes, microparticles or microvesicles and apoptotic bodies. EVs are believed to play important roles in a wide range of biological processes. Although the pathogenic roles of EVs are largely documented, their protective roles are not as well established. Cardiovascular disease represents one of the most relevant and rapidly growing areas of the EV research. Circulating EVs released from platelets, erythrocytes, leukocytes, and endothelial cells may contain potentially valuable biological information for biomarker development in cardiovascular disease and could serve as a vehicle for therapeutic use. Herein, we provide an overview of the current knowledge in EV in cardiovascular disease, including a discussion on challenges in EV research, EV properties in various cell types, and their importance in atherosclerotic disease.

Development of a Highly Sensitive Device for Counting the Number of Disease-Specific Exosomes in Human Sera

BACKGROUND

Although circulating exosomes in blood play crucial roles in cancer development and progression, difficulties in quantifying exosomes hamper their application for reliable clinical testing. By combining the properties of nanobeads with optical disc technology, we have developed a novel device named the ExoCounter to determine the exact number of exosomes in the sera of patients with various types of cancer.

METHOD

In this system, individual exosomes were captured in the groove of an optical disc coated with antibodies against exosome surface antigens. The captured exosomes were labeled with antibody-conjugated magnetic nanobeads, and the number of the labeled exosomes was counted with an optical disc drive.

RESULTS

We showed that the ExoCounter could detect specific exosomes derived from cells or human serum without any enrichment procedures. The detection sensitivity and linearity with this system were higher than those with conventional detection methods such as ELISA or flow cytometry. In addition to the ubiquitous exosome markers CD9 and CD63, the cancer-related antigens CD147, carcinoembryonic antigen, and human epidermal growth factor receptor 2 (HER2) were also used to quantify cancer cell line-derived exosomes. Furthermore, analyses of a cross-sectional cohort of sera samples revealed that HER2-positive exosomes were significantly increased in patients with breast cancer or ovarian cancer compared with healthy individuals and those with noncancer diseases.

CONCLUSIONS

The ExoCounter system exhibits high performance in the direct detection of exosomes in cell culture and human sera. This method may enable reliable analysis of liquid biopsies.

Proteomic Profiling of Exosomes Secreted by Breast Cancer Cells with Varying Metastatic Potential

Cancer cells actively release extracellular vesicles, including exosomes, into the surrounding microenvironment. Exosomes play pleiotropic roles in cancer progression and metastasis, including invasion, angiogenesis, and immune modulation. However, the proteome profile of exosomes isolated from cells with different metastatic potential and the role of these exosomes in driving metastasis remains unclear. Here, we conduct a comparative proteomic analysis of exosomes isolated from several genetically related mouse breast tumor lines with different metastatic propensity. The amount of exosomes produced and the extent of cancer-associated protein cargo vary significantly between nonmetastatic and metastatic cell-derived exosomes. Metastatic cell-derived exosomes contain proteins that promote migration, proliferation, invasion, and angiogenesis while the nonmetastatic cell-derived exosomes contain proteins involved in cell-cell/cell-matrix adhesion and polarity maintenance. The metastatic exosomes contain a distinct set of membrane proteins including Ceruloplasmin and Metadherin which could presumably aid in targeting the primary cancer cells to specific metastatic sites. Hence, it can be concluded that the exosomes contain different protein cargo based on the host cells metastatic properties and can facilitate in the dissemination of the primary tumors to distant sites.

An update of knowledge on cortactin as a metastatic driver and potential therapeutic target in oral squamous cell carcinoma

Cortactin is a protein encoded by the CTTN gene, localized on chromosome band 11q13. As a result of the amplification of this band, an important event in oral carcinogenesis, CTTN is also usually amplified, promoting the frequent overexpression of cortactin. Cortactin enhances cell migration in oral cancer, playing a key role in the regulation of filamentous actin and of protrusive structures (invadopodia and lamellipodia) on the cell membrane that are necessary for the acquisition of a migratory phenotype. We also analyze a series of emerging functions that cortactin may exert in oral cancer (cell proliferation, angiogenesis, regulation of exosomes, and interactions with the tumor microenvironment). We review its molecular structure, its most important interactions (with Src, Arp2/3 complex, and SH3-binding partners), the regulation of its functions, and its specific oncogenic role in oral cancer. We explore the mechanisms of its overexpression in cancer, mainly related to genetic amplification. We analyze the prognostic implications of the oncogenic activation of cortactin in potentially malignant disorders and in head and neck cancer, where it appears to be relevant in the development of lymph node metastasis. Finally, we discuss its usefulness as a therapeutic target and suggest future research lines.

Therapeutic Prospects of Extracellular Vesicles in Cancer Treatment

Extracellular vesicles (EVs) are released by all cells within the tumor microenvironment, such as endothelial cells, tumor-associated fibroblasts, pericytes, and immune system cells. The EVs carry the cargo of parental cells formed of proteins and nucleic acids, which can convey cell-to-cell communication influencing the maintenance and spread of the malignant neoplasm, for example, promoting angiogenesis, tumor cell invasion, and immune escape. However, EVs can also suppress tumor progression, either by the direct influence of the protein and nucleic acid cargo of the EVs or via antigen presentation to immune cells as tumor-derived EVs carry on their surface some of the same antigens as the donor cells. Moreover, dendritic cell-derived EVs carry major histocompatibility complex class I and class II/peptide complexes and are able to prime other immune system cell types and activate an antitumor immune response. Given the relative longevity of vesicles within the circulation and their ability to cross blood–brain barriers, modification of these unique organelles offers the potential to create new biological-tools for cancer therapy. This review examines how modification of the EV cargo has the potential to target specific tumor mechanisms responsible for tumor formation and progression to develop new therapeutic strategies and to increase the efficacy of antitumor therapies.

Extracellular vesicles: mediators and biomarkers of pathology along CNS barriers

Extracellular vesicles (EVs) are heterogeneous, nano-sized vesicles that are shed into the blood and other body fluids, which disperse a variety of bioactive molecules (e.g., protein, mRNA, miRNA, DNA and lipids) to cellular targets over long and short distances. EVs are thought to be produced by nearly every cell type, however this review will focus specifically on EVs that originate from cells at the interface of CNS barriers. Highlighted topics include, EV biogenesis, the production of EVs in response to neuroinflammation, role in intercellular communication and their utility as a therapeutic platform. In this review, novel concepts regarding the use of EVs as biomarkers for BBB status and as facilitators for immune neuroinvasion are also discussed. Future directions and prospective are covered along with important unanswered questions in the field of CNS endothelial EV biology.

Nano-sized CA125 antigen glycocamouflage: Mucin - Extracellular vesicles alliance to watch?

Mucin 16 (MUC16) is a transmembrane type mucin and its released extracellular portion is designated as CA125 antigen. It is considered to be part of a supramolecular glycoprotein complex having a complicated epitope map and extreme structural heterogeneity. Starting from the initial transmembrane localization of MUC16/CA125 antigen and its alternative routes of release by shedding or putative secretion, CA125 antigen from human amniotic fluid soluble and extracellular vesicles (EVs)-containing fractions were characterized aiming at the possible glycosylation-associated mode of distribution as a factor contributing to the reported conflicting structural data. Ultracentrifugation, sucrose density gradient centrifugation, ion-exchange chromatography and TEM were used for analysis. The results indicated that the smeared abundantly glycosylated high molecular mass CA125-immunoreactive species, which follow the wheat germ agglutinin-binding pattern, were shared across amniotic fluid soluble and particulate fractions. A lower molecular mass glycoprotein-like CA125-immunoreactive species which follows the peanut agglutinin-binding pattern and was specifically associated with the EVs-enriched fraction was observed. CA125 presentation in the particulate amniotic fluid fraction was found to be shaped by a complex interactome partially involving lactose-sensitive galectin-3 binding. The MUC16 - EVs alliance as well as heterogeneous mucin/macromolecular complexes, at membranes or extracellularly, may represent cryptic pools of distinct CA125 species.

Extracellular Vesicles in Chagas Disease: A New Passenger for an Old Disease

Extracellular vesicles (EVs) are small lipid vesicles released by prokaryotic and eukaryotic cells containing nucleic acids, proteins, and small metabolites essential for cellular communication. Depending on the targeted cell, EVs can act either locally or in distant tissues in a paracrine or endocrine cell signaling manner. Released EVs from virus-infected cells, bacteria, fungi, or parasites have been demonstrated to perform a pivotal role in a myriad of biochemical changes occurring in the host and pathogen, including the modulation the immune system. In the past few years, the biology of Trypanosoma cruzi EVs, as well as their role in innate immunity evasion, has been started to be unveiled. This review article will present findings on and provide a coherent understanding of the currently known mechanisms of action of T. cruzi-EVs and hypothesize the implication of these parasite components during the acute and chronic phases of Chagas disease.

A low voltage nanopipette dielectrophoretic device for rapid entrapment of nanoparticles and exosomes extracted from plasma of healthy donors

An insulator-based dielectrophoresis (iDEP) is a label-free method that has been extensively utilized for manipulation of nanoparticles, cells, and biomolecules. Here, we present a new iDEP approach that can rapidly trap nanoparticles at the close proximity of a glass nanopipette’s tip by applying 10 V/cm direct current (DC) across the pipette’s length. The trapping mechanism was systemically studied using both numerical modeling and experimental observations. The results showed that the particle trapping was determined to be controlled by three dominant electrokinetic forces including dielectrophoretic, electrophoretic and electroosmotic force. Furthermore, the effect of the ionic strength, the pipette’s geometry, and the applied electric field on the entrapment efficiency was investigated. To show the application of our device in biomedical sciences, we demonstrated the successful entrapment of fluorescently tagged liposomes and unlabeled plasma-driven exosomes from the PBS solution. Also, to illustrate the selective entrapment capability of our device, 100 nm liposomes were extracted from the PBS solution containing 500 nm polystyrene particles at the tip of the pipette as the voltage polarity was reversed.

Extracellular Vesicles as Conveyors of Membrane-Derived Bioactive Lipids in Immune System

Over the last 20 years, extracellular vesicles (EVs) have been established as an additional way to transmit signals outside the cell. They are membrane-surrounded structures of nanometric size that can either originate from the membrane invagination of multivesicular bodies of the late endosomal compartment (exosomes) or bud from the plasma membrane (microvesicles). They contain proteins, lipids, and nucleic acids—namely miRNA, but also mRNA and lncRNA—which are derived from the parental cell, and have been retrieved in every fluid of the body. As carriers of antigens, either alone or in association with major histocompatibility complex (MHC) class II and class I molecules, their immunomodulatory properties have been extensively investigated. Moreover, recent studies have shown that EVs may carry and deliver membrane-derived bioactive lipids that play an important function in the immune system and related pathologies, such as prostaglandins, leukotrienes, specialized pro-resolving mediators, and lysophospholipids. EVs protect bioactive lipids from degradation and play a role in the transcellular synthesis of prostaglandins and leukotrienes. Here, we summarized the role of EVs in the regulation of immune response, specifically focusing our attention on the emerging role of EVs as carriers of bioactive lipids, which is important for immune system function.

Postprandial Increase in Blood Plasma Levels of Tissue Factor-Bearing (and Other) Microvesicles Measured by Flow Cytometry: Fact or Artifact?

Tissue factor (TF)–bearing microvesicles (MVs) and exosomes may play a role in hemostasis and thrombosis. MVs may be quantified by flow cytometry (FC)–based detection of phosphatidylserine (PS)-positive submicron particles carrying specific antigens, although interference from lipoproteins complicates this approach. In this study, we evaluated the effect of food intake on blood levels of TF-bearing particles measured by FC and small extracellular vesicles (EVs) measured by a protein microarray–based test termed EV Array. Platelet-free plasma (PFP) was obtained from 20 healthy persons in the fasting state and 75 minutes after consumption of a meal. Postprandial changes in the concentration of PS-positive particles, including subgroups binding labeled antibodies against TF, CD41, CD146, and CD62E, respectively (FC), small EVs (EV Array), and TF antigen and procoagulant phospholipids (PPLs) were measured. Furthermore, we tested the effect on FC results of in vitro addition of lipoproteins to fasting PFP. We found significantly increased plasma concentrations of PS-positive particles and all examined subgroups postprandially, while no changes in small EVs, PPL, or TF antigen levels were found. Levels of all types of particles measured by FC were also elevated by lipoprotein spiking. In conclusion, meal consumption as well as in vitro addition of lipoproteins to fasting plasma induces increased levels of PS-positive particles as measured by FC, including TF-positive subtypes and subtypes exposing other antigens. While the observed postprandial increase may to some extent reflect elevated MV levels, our results indicate a substantial interference from lipoproteins.

Role of Extracellular Vesicles in Viral and Bacterial Infections: Pathogenesis, Diagnostics, and Therapeutics

Extracellular vesicles (EVs), or exosomes, are nanovesicles of endocytic origin that carry host and pathogen-derived protein, nucleic acid, and lipid cargos. They are secreted by most cell types and play important roles in normal cell-to-cell communications but can also spread pathogen- and host-derived molecules during infections to alter immune responses and pathophysiological processes. New research is beginning to decipher how EVs influence viral and bacterial pathogenesis. In this review, we will describe how EVs influence viral and bacterial pathogenesis by spreading pathogen-derived factors and how they can promote and inhibit the immune response to these pathogens. We will also discuss the emerging potential of EVs as diagnostic and therapeutic tools.

Extracellular vesicles as modulators of wound healing

Impaired healing of cutaneous wounds and ulcers continues to have a major impact on the quality of life of millions of people. In recent years, the capacity for stem and progenitor cells to promote wound repair has been investigated with evidence that secreted factors are responsible for the observed therapeutic benefits. This review addresses current evidence in support of stem/progenitor cell-derived extracellular vesicles (EVs) as a regenerative therapy for acceleration of wound healing. Encouraging results for local or systemic administration of EVs have been reported in a range of clinically-relevant animal models of cutaneous wounds. Furthermore, a number of plausible mechanisms involving EV-mediated transfer of proteins and RNAs that trigger pro-repair pathways in target cells have been demonstrated experimentally. However, for successful clinical translation in the coming years, further emphasis on standardized experimental protocols, detailed methodological reporting and clear definition of EV-based therapeutic products will be required.

Extracellular Vesicle Subtypes Released From Activated or Apoptotic T-Lymphocytes Carry a Specific and Stimulus-Dependent Protein Cargo

Extracellular vesicles (EVs) are released from nearly all mammalian cells and different EV populations have been described. Microvesicles represent large EVs (LEVs) released from the cellular surface, while exosomes are small EVs (SEVs) released from an intracellular compartment. As it is likely that different stimuli promote the release of distinct EV populations, we analyzed EVs from human lymphocytes considering the respective release stimuli (activation Vs. apoptosis induction). We could clearly separate two EV populations, namely SEVs (average diameter <200 nm) and LEVs (diameter range between 200 and 1000 nm). Morphology and size were analyzed by electron microscopy and nanoparticle tracking analysis. Apoptosis induction caused a massive release of LEVs, while activated T-cells released SEVs and LEVs in considerably lower amounts. The release of SEVs from apoptotic T-cells was comparable with LEV release from activated ones. LEVs contained signaling proteins and proteins of the actin-myosin cytoskeleton. SEVs carried cytoplasmic/endosomal proteins like the 70-kDa heat shock protein 70 (HSP70) or tumor susceptibility 101 (TSG101), microtubule-associated proteins, and ubiquitinated proteins. The protein expression profile of SEVs and LEVs changed substantially after the induction of apoptosis. After apoptosis induction, HSP70 and TSG101 (often used as exosome markers) were highly expressed within LEVs. Interestingly, in contrast to HSP70 and TSG101, gelsolin and eps15 homology domain-containing protein 3 (EHD3) turned out to be specific for SEVs irrespective of the stimulus causing the EV release. Finally, we detected several subunits of the proteasome (PSMB9, PSMB10) as well as the danger signal HMGB1 exclusively within apoptotic cell-released LEVs. Thus, we were able to identify new marker proteins that can be useful to discriminate between distinct LEV subpopulations. The mass spectrometry proteomics data are available via ProteomeXchange with identifier PXD009074.

Immune-related proteins detected through iTRAQ-based proteomics analysis of intestines from Apostichopus japonicus in response to tussah immunoreactive substances

Apostichopus japonicus is a species of sea cucumber that is extensively bred as a marine delicacy because of its high nutritive and medicinal value. Immunostimulants are usually used to enhance the immunity of sea cucumber against diseases, but the physiological function of immunostimulants is poorly understood. In this study, we fed A. japonicus individuals with a diet supplemented with different concentrations of tussah immunoreactive substances (TIS), and then subjected their intestines to iTRAQ-based proteomic analysis. A total of 51 differentially expressed proteins were detected in response to TIS, 13 proteins were upregulated, while 38 proteins were reduced. These proteins are involved in phagocytosis, tissue protection, cell apoptosis and energy metabolism. Among these 51 proteins, 7 proteins (GLO2, ACOX, CTTN, MARK, FADD, CSTA and CASP6) related to immunity with functional annotation in sea cucumber were further analyzed. In addition, the upregulated expression of 4 immune-related proteins (GLO2, ACOX, CTTN and MARK) was validated by qRT-PCR. The findings of this study gave further insight into the mechanism by which TIS might enhance the immunity of A. japonicus.