Characterization of physical properties of tissue factor-containing microvesicles and a comparison of ultracentrifuge-based recovery procedures

Transferrin-conjugated magnetic nanoparticles for the isolation of brain-derived blood exosomal MicroRNAs: A novel approach for Parkinson's disease diagnosis

BACKGROUND

Brain-derived exosomes circulate in the bloodstream and other bodily fluids, serving as potential indicators of neurological disease progression. These exosomes present a promising avenue for the early and precise diagnosis of neurodegenerative conditions. Notably, miRNAs found in plasma extracellular vesicles (EVs) offer distinct diagnostic benefits due to their stability, abundance, and resistance to breakdown.

RESULTS

In this study, we introduce a method using transferrin conjugated magnetic nanoparticles (TMNs) to isolate these exosomes from the plasma of patients with neurological disorders. This TMNs technique is both quick (<35 min) and cost-effective, requiring no high-priced ingredients or elaborate equipment for EV extraction. Our method successfully isolated EVs from 33 human plasma samples, including those from patients with Parkinson's disease (PD), Multiple Sclerosis (MS), and Dementia. Using quantitative polymerase chain reaction (PCR) analysis, we evaluated the potential of 8 exosomal miRNA profiles as biomarker candidates. Six exosomal miRNA biomarkers (miR-195-5p, miR-495-3p, miR-23b-3P, miR-30c-2-3p, miR-323a-3p, and miR-27a-3p) were consistently linked with all stages of PD.

SIGNIFICANCE

The TMNs method provides a practical, cost-efficient way to isolate EVs from biological samples, paving the way for non-invasive neurological diagnoses. Furthermore, the identified miRNA biomarkers in these exosomes may emerge as innovative tools for precise diagnosis in neurological disorders including PD.

Methods, Mechanisms, and Application Prospects for Enhancing Extracellular Vesicle Uptake

Extracellular vesicles (EVs) are considered to be a new generation of bioinspired nanoscale drug delivery systems due to their low immunogenicity, natural functionality, and excellent biocompatibility. However, limitations such as low uptake efficiency, insufficient production, and inhomogeneous performance undermine their potential. To address these issues, numerous researchers have put forward various methods and applications for enhancing EV uptake in recent decades. In this review, we introduce various methods for the cellular uptake of EVs and summarize recent advances on the methods and mechanisms for enhancing EV uptake. In addition, we provide further understanding regarding enhancing EV uptake and put forward prospects and challenges for the development of EV-based therapy in the future.

Characterization of extracellular vesicles in COVID-19 infection during pregnancy

Introduction: SARS-CoV-2 infection may cause a severe inflammatory response, inflicting severe morbidity and mortality. This risk is modestly increased in pregnant patients. Despite the hypercoagulability and immunosuppression associated with pregnancy, most pregnant women experience a mild COVID-19 infection. Maternal extracellular vesicles (EVs) may interact with endothelial and immune components to facilitate a favorable disease course. This pilot study aimed to explore the characteristics of EVs released during COVID-19 infection occurring during the third trimester of pregnancy. Methods: In this prospective study, blood samples were obtained from 16 healthy non-pregnant (NP), 18 healthy-pregnant (HP), and 22 COVID-19 positive pregnant subjects (CoV-P). Disease course and pregnancy outcomes were assessed and EVs were characterized. Of note, limited volumes of sample acquired from the subjects made it necessary to use smaller and different subsets of samples for each analysis. Results: The majority (91%) of the COVID-19-pregnant subjects (18 mild and 2 moderate disease) experienced good pregnancy-related outcomes. EV concentrations were higher in healthy-pregnant subjects compared to non-pregnant subjects (p = 0.0041) and lower in COVID-19-pregnant subjects compared to healthy-pregnant subjects (p = 0.0150). CD63 exosome marker expression was higher in EVs of healthy-pregnant subjects and COVID-19-pregnant subjects compared to EVs of non-pregnant subjects (p = 0.0149, p = 0.0028, respectively). Similar levels of SARS-CoV-2 entry proteins (ACE-2 and TMPRSS2) were found in all three groups. Cytokine content increased in healthy-pregnant subject-EVs compared to non-pregnant EVs, while IL-2 and IL-6 levels were decreased in COVID-19-pregnant subject-EVs compared to healthy-pregnant subject-EVs (p = 0.043, p = 0.0390, respectively). CD8+, cytotoxic T-cell marker, was lower in non-pregnant EVs compared to healthy-pregnant subject-EVs and to COVID-19-pregnant subjects (p = 0.0108, p < 0.0001, respectively). COVID-19- pregnant subject-EVs demonstrated higher levels of platelet activation marker (CD62P) than non-pregnant (p = 0.0327) and healthy-pregnant subjects (p = 0.0365). Endothelial marker EV-CD144+ was lower in healthy-pregnant subjects versus non-pregnant subjects (p = 0.0093), but similar in COVID-19-pregnant and non-pregnant subjects. Other EVs' coagulation markers/activity, D-Dimer and fibrinogen levels were similar in healthy-pregnant subjects and COVID-19 positive pregnant subjects. Conclusion: COVID-19 positive pregnant subjects' EVs demonstrated an attenuated inflammatory response, with no additional activation of the coagulation system.

Extracellular vesicles as novel drug delivery systems to target cancer and other diseases: Recent advancements and future perspectives

Extracellular vesicles (EVs) are lipid-bound vesicles produced into the extracellular space by cells. Apoptotic bodies (ApoBD), microvesicles (MVs), and exosomes are examples of EVs, which act as essential regulators in cell-cell communication in both normal and diseased conditions. Natural cargo molecules such as miRNA, messenger RNA, and proteins are carried by EVs and transferred to nearby cells or distant cells through the process of circulation. Different signalling cascades are then influenced by these functionally active molecules. The information to be delivered to the target cells depends on the substances within the EVs that also includes synthesis method. EVs have attracted interest as potential delivery vehicles for therapies due to their features such as improved circulation stability, biocompatibility, reduced immunogenicity, and toxicity. Therefore, EVs are being regarded as potent carriers of therapeutics that can be used as a therapeutic agent for diseases like cancer. This review focuses on the exosome-mediated drug delivery to cancer cells and the advantages and challenges of using exosomes as a carrier molecule.

Subaqueous free-standing 3D cell culture system for ultrafast cell compaction, mechano-inductive immune control, and improving therapeutic angiogenesis

Conventional 3D cell culture methods require a comprehensive complement in labor-intensive and time-consuming processes along with in vivo circumstantial mimicking. Here, we describe a subaqueous free-standing 3D cell culture (FS) device that can induce the omnidirectional environment and generate ultrafast human adipose-derived stem cells (hADSCs) that efficiently aggregate with compaction using acoustic pressure. The cell culture conditions were optimized using the FS device and identified the underlying molecular mechanisms. Unique phenomena in cell aggregation have led to extraordinary cellular behavior that can upregulate cell compaction, mechanosensitive immune control, and therapeutic angiogenesis. Therefore, we designated the resulting cell aggregates as "pressuroid." Notably, external acoustic stimulation produced by the FS device affected the pressuroids. Furthermore, the pressuroids exhibited upregulation in mechanosensitive genes and proteins, PIEZO1/2. CyclinD1 and PCNA, which are strongly associated with cell adhesion and proliferation, were elevated by PIEZO1/2. In addition, we found that pressuroids significantly increase angiogenic paracrine factor secretion, promote cell adhesion molecule expression, and enhance M2 immune modulation of Thp1 cells. Altogether, we have concluded that our pressuroid would suggest a more effective therapy method for future cell therapy than the conventional one.

TOP-EVs: Technology of Protein delivery through Extracellular Vesicles is a versatile platform for intracellular protein delivery

Extracellular vesicles (EVs) have emerged as biocompatible drug delivery vehicles due to their native ability to deliver bioactive cargo to recipient cells. However, the application of EVs as a therapeutic delivery vehicle is hampered by effective methods for endogenously loading target proteins inside EVs and unloading proteins after delivery to recipient cells. Most EV-based engineered loading methods have a limited delivery efficiency owing to their inefficient endosomal escape or cargo release from the intraluminal attachment from the EV membrane. Here, we describe the 'Technology Of Protein delivery through Extracellular Vesicles' (TOP-EVs) as a tool for efficient intracellular delivery of target proteins mediated via EVs. The vesicular stomatitis virus glycoprotein and the rapamycin-heterodimerization of the FKBP12/T82L mutant FRB proteins were both important for the effective protein delivery through TOP-EVs. We showed that TOP-EVs could efficiently deliver Cre recombinase and CRISPR/Cas9 ribonucleoprotein complex in vitro. Moreover, our results demonstrated that the capacity of TOP-EVs to deliver intracellular proteins in recipient cells was not an artifact of plasmid contamination or direct plasmid loading into EVs. Finally, we showed that TOP-EVs could successfully mediate intracellular protein delivery in the liver in vivo. Taken together, TOP-EVs are a versatile platform for efficient intracellular protein delivery in vitro and in vivo, which can be applied to advance the development of protein-based therapeutics.

Magnetic transferrin nanoparticles (MTNs) assay as a novel isolation approach for exosomal biomarkers in neurological diseases

BACKGROUND

Brain-derived exosomes released into the blood are considered a liquid biopsy to investigate the pathophysiological state, reflecting the aberrant heterogeneous pathways of pathological progression of the brain in neurological diseases. Brain-derived blood exosomes provide promising prospects for the diagnosis of neurological diseases, with exciting possibilities for the early and sensitive diagnosis of such diseases. However, the capability of traditional exosome isolation assays to specifically isolate blood exosomes and to characterize the brain-derived blood exosomal proteins by high-throughput proteomics for clinical specimens from patients with neurological diseases cannot be assured. We report a magnetic transferrin nanoparticles (MTNs) assay, which combined transferrin and magnetic nanoparticles to isolate brain-derived blood exosomes from clinical samples.

METHODS

The principle of the MTNs assay is a ligand-receptor interaction through transferrin on MTNs and transferrin receptor on exosomes, and electrostatic interaction via positively charged MTNs and negatively charged exosomes to isolate brain-derived blood exosomes. In addition, the MTNs assay is simple and rapid (< 35 min) and does not require any large instrument. We confirmed that the MTNs assay accurately and efficiently isolated exosomes from serum samples of humans with neurodegenerative diseases, such as dementia, Parkinson's disease (PD), and multiple sclerosis (MS). Moreover, we isolated exosomes from serum samples of 30 patients with three distinct neurodegenerative diseases and performed unbiased proteomic analysis to explore the pilot value of brain-derived blood protein profiles as biomarkers.

RESULTS

Using comparative statistical analysis, we found 21 candidate protein biomarkers that were significantly different among three groups of neurodegenerative diseases.

CONCLUSION

The MTNs assay is a convenient approach for the specific and affordable isolation of extracellular vesicles from body fluids for minimally-invasive diagnosis of neurological diseases.

LAMP3 transfer via extracellular particles induces apoptosis in Sjögren's disease

Sjögren's disease (SjD) is an autoimmune disease that affects exocrine tissues and is characterized by increased apoptosis in salivary and lacrimal glands. Although the pathogenic mechanism triggering SjD is not well understood, overexpression of lysosome-associated membrane protein 3 (LAMP3) is associated with the disease in a subset of SjD patients and the development of SjD-like phenotype in mice. In this study, histological analysis of minor salivary glands of SjD patients suggested that LAMP3-containing material is being ejected from cells. Follow-on in vitro experiments with cells exposed to extracellular particles (EPs) derived from LAMP3-overexpressing cells showed increased apoptosis. Proteomics identified LAMP3 as a major component of EPs derived from LAMP3-overexpressing cells. Live-cell imaging visualized release and uptake of LAMP3-containing EPs from LAMP3-overexpressing cells to naïve cells. Furthermore, experiments with recombinant LAMP3 protein alone or complexed with Xfect protein transfection reagent demonstrated that internalization of LAMP3 was required for apoptosis in a caspase-dependent pathway. Taken together, we identified a new role for extracellular LAMP3 in cell-to-cell communication via EPs, which provides further support for targeting LAMP3 as a therapeutic approach in SjD.

Microfluidics facilitating the use of small extracellular vesicles in innovative approaches to male infertility

Sperm are transcriptionally and translationally quiescent and, therefore, rely on the seminal plasma microenvironment for function, survival and fertilization of the oocyte in the oviduct. The male reproductive system influences sperm function via the binding and fusion of secreted epididymal (epididymosomes) and prostatic (prostasomes) small extracellular vesicles (S-EVs) that facilitate the transfer of proteins, lipids and nucleic acids to sperm. Seminal plasma S-EVs have important roles in sperm maturation, immune and oxidative stress protection, capacitation, fertilization and endometrial implantation and receptivity. Supplementing asthenozoospermic samples with normospermic-derived S-EVs can improve sperm motility and S-EV microRNAs can be used to predict non-obstructive azoospermia. Thus, S-EV influence on sperm physiology might have both therapeutic and diagnostic potential; however, the isolation of pure populations of S-EVs from bodily fluids with current conventional methods presents a substantial hurdle. Many conventional techniques lack accuracy, effectiveness, and practicality; yet microfluidic technology has the potential to simplify and improve S-EV isolation and detection.

Status quo of Extracellular Vesicle isolation and detection methods for clinical utility

Extracellular vesicles (EVs) are nano-sized particles that hold tremendous potential in the clinical space, as their biomolecular profiles hold a key to non-invasive liquid biopsy for cancer diagnosis and prognosis. EVs are present in most bodily fluids, hence are easily obtainable from patients, advantageous to that of traditional, invasive tissue biopsies and imaging techniques. However, there are certain constraints that hinder clinical use of EVs. The translation of EV biomarkers from "bench-to-bedside" is encumbered by the methods of EV isolation and subsequent biomarker detection currently implemented in laboratories. Although current isolation and detection methods are effective, they lack practicality, with their requirement for high bodily fluid volumes, low equipment availability, slow turnaround times and high costs. The high demand for techniques that overcome these limitations has resulted in significant advancements in nanotechnological devices. These devices are designed to integrate EV isolation and biomarker detection into a one-step method of direct EV detection from bodily fluids. This provides promise for the acceleration of EVs into current clinical standards. This review highlights the importance of EVs as cancer biomarkers, the methodological obstacles currently faced in clinical studies and how novel nanodevices could advance clinical translation.

Tissue factor in cancer-associated thromboembolism: possible mechanisms and clinical applications

Venous and arterial thromboses, called as cancer-associated thromboembolism (CAT), are common complications in cancer patients that are associated with high mortality. The cell-surface glycoprotein tissue factor (TF) initiates the extrinsic blood coagulation cascade. TF is overexpressed in cancer cells and is a component of extracellular vesicles (EVs). Shedding of TF⁺EVs from cancer cells followed by association with coagulation factor VII (fVII) can trigger the blood coagulation cascade, followed by cancer-associated venous thromboembolism in some cancer types. Secretion of TF is controlled by multiple mechanisms of TF⁺EV biogenesis. The procoagulant function of TF is regulated via its conformational change. Thus, multiple steps participate in the elevation of plasma procoagulant activity. Whether cancer cell-derived TF is maximally active in the blood is unclear. Numerous mechanisms other than TF⁺EVs have been proposed as possible causes of CAT. In this review, we focused on a wide variety of regulatory and shedding mechanisms for TF, including the effect of SARS-CoV-2, to provide a broad overview for its role in CAT. Furthermore, we present the current technical issues in studying the relationship between CAT and TF.

The Therapeutic Potential of Milk Extracellular Vesicles on Colorectal Cancer

Colorectal cancer remains one of the leading prevalent cancers in the world and is the fourth most common cause of death from cancer. Unfortunately, the currently utilized chemotherapies fail in selectively targeting cancer cells and cause harm to healthy cells, which results in profound side effects. Researchers are focused on developing anti-cancer targeted medications, which is essential to making them safer, more effective, and more selective and to maximizing their therapeutic benefits. Milk-derived extracellular vesicles (EVs) from camels and cows have attracted much attention as a natural substitute product that effectively suppresses a wide range of tumor cells. This review sheds light on the biogenesis, methods of isolation, characterization, and molecular composition of milk EVs as well as the therapeutic potentials of milk EVs on colorectal cancer.

An emerging role of KRAS in biogenesis, cargo sorting and uptake of cancer-derived extracellular vesicles

Extracellular vesicles (EVs) are nanovesicles secreted for intercellular communication with endosomal network regulating secretion of small EVs (or exosomes) that play roles in cancer progression. As an essential oncoprotein, Kirsten rat sarcoma virus (KRAS) is tightly regulated by its endosomal trafficking for membrane attachment. However, the crosstalk between KRAS and EVs has been scarcely discussed despite its endocytic association. An overview of the oncogenic role of KRAS focusing on its correlation with cancer-associated EVs should provide important clues for disease prognosis and inspire novel therapeutic approaches for treating KRAS mutant cancers. Therefore, this review summarizes the relevant studies that provide substantial evidence linking KRAS mutation to EVs and discusses the oncogenic implication from the aspects of biogenesis, cargo sorting, and release and uptake of the EVs.

De-Palmitoylation of Tissue Factor Regulates Its Activity, Phosphorylation and Cellular Functions

In this study, the role of de-palmitoylation of tissue factor (TF) in the decryption of its activity was explored. TF-tGFP constructs were prepared by mutagenesis-substitution at Cys245 to prevent or mimic palmitolyation. Additionally, to reduce TF de-palmitoylation, the expression of palmitoyl-protein thioesterases (PPT) was suppressed. Other TF mutants were prepared with altered flexibility, hydrophobicity or length of the transmembrane domain. The outcome of these alterations on fXa-generation, fVIIa binding, Ser253 phosphorylation and TF-microvesicle release were assessed in endothelial cells, and the influence on endothelial and MCF-7 cell proliferation and apoptosis was analysed. Preventing TF palmitoylation (TF_Ser245-tGFP), increasing the hydrophobicity (TF_Phe241-tGFP) or lengthening (TF_LongTM-tGFP) of the transmembrane domain enhanced fXa-generation in resting cells compared to cells expressing TF_Wt-tGFP, but fXa-generation was not further increased following PAR2 activation. Extending the available length of the transmembrane domain enhanced the TF-tGFP release within microvesicles and Ser253 phosphorylation and increased cell proliferation. Moreover, prevention of PKCα-mediated Ser253 phosphorylation with Gö6976 did not preclude fXa-generation. Conversely, reducing the hydrophobicity (TF_Ser242-tGFP), shortening (TF_ShortTM-tGFP) or reducing the flexibility (TF_Val225-tGFP) of the transmembrane domain suppressed fXa-generation, fVIIa-HRP binding and Ser253 phosphorylation following PAR2 activation. PPT knock-down or mimicking palmitoylation (TF_Phe245-tGFP) reduced fXa-generation without affecting fVIIa binding. This study has for the first time shown that TF procoagulant activity is regulated through de-palmitoylation, which alters the orientation of its transmembrane domain and is independent of TF phosphorylation. However, Ser253 phosphorylation is facilitated by changes in the orientation of the transmembrane domain and can induce TF-cellular signalling that influences cellular proliferation/apoptosis.

The exosome journey: from biogenesis to uptake and intracellular signalling

The use of exosomes in clinical settings is progressively becoming a reality, as clinical trials testing exosomes for diagnostic and therapeutic applications are generating remarkable interest from the scientific community and investors. Exosomes are small extracellular vesicles secreted by all cell types playing intercellular communication roles in health and disease by transferring cellular cargoes such as functional proteins, metabolites and nucleic acids to recipient cells. An in-depth understanding of exosome biology is therefore essential to ensure clinical development of exosome based investigational therapeutic products. Here we summarise the most up-to-date knowkedge about the complex biological journey of exosomes from biogenesis and secretion, transport and uptake to their intracellular signalling. We delineate the major pathways and molecular players that influence each step of exosome physiology, highlighting the routes of interest, which will be of benefit to exosome manipulation and engineering. We highlight the main controversies in the field of exosome research: their adequate definition, characterisation and biogenesis at plasma membrane. We also delineate the most common identified pitfalls affecting exosome research and development. Unravelling exosome physiology is key to their ultimate progression towards clinical applications.

Alternative activation of human macrophages enhances tissue factor expression and production of extracellular vesicles

Macrophages are versatile cells that can be polarized by the tissue environment to fulfill required needs. Proinflammatory polarization is associated with increased tissue degradation and propagation of inflammation whereas alternative polarization within a Th2 cytokine environment is associated with wound healing and angiogenesis. To understand whether polarization of macrophages can lead to a procoagulant macrophage subset we polarized human monocyte-derived macrophages to proinflammatory and alternative activation states. Alternative polarization with interleukin-4 and interleukin-13 led to a macrophage phenotype characterized by increased tissue factor (TF) production and release and by an increase in extracellular vesicle production. In addition, TF activity was enhanced in extracellular vesicles of alternatively polarized macrophages. This TF induction was dependent on signal transducer and activator of transcription- 6 signaling and poly ADP ribose polymerase activity. In contrast to monocytes, human macrophages did not show increased TF expression upon stimulation with lipopolysaccharide and interferon-γ. Previous polarization to either a proinflammatory or an alternative activation subset did not change the subsequent stimulation of TF. The inability of proinflammatory activated macrophages to respond to lipopolysaccharide and interferon- γ with an increase in TF production seemed to be due to an increase in TF promoter methylation and was reversible when these macrophages were treated with a demethylating agent. In conclusion, we provide evidence that proinflammatory polarization of macrophages does not lead to enhanced procoagulatory function, whereas alternative polarization of macrophages leads to an increased expression of TF and increased production of TF-bearing extracellular vesicles by these cells suggesting a procoagulatory phenotype of alternatively polarized macrophages.

Synergistic effects of extracellular vesicle phenotyping and AFP in hepatobiliary cancer differentiation

BACKGROUND

Biliary cancer, comprising cholangio- and gallbladder carcinomas, is associated with high mortality due to asymptomatic disease onset and resulting late diagnosis. Currently, no robust diagnostic biomarker is clinically available. Therefore, we explored the feasibility of extracellular vesicles (EVs) as a liquid biopsy tool for biliary cancer screening and hepatobiliary cancer differentiation.

METHODS

Serum EVs of biliary cancer, hepatocellular carcinoma, colorectal cancer and non-small cell lung cancer patients, as well as from healthy individuals, were isolated by sequential two-step centrifugation and presence of indicated EVs was evaluated by fluorescence activated cell sorting (FACS) analysis.

RESULTS

Two directly tumour-related antigen combinations (AnnV⁺ CD44v6⁺ and AnnV⁺ CD44v6⁺ CD133⁺ ) and two combinations related to progenitor cells from the tumour microenvironment (AnnV⁺ CD133⁺ gp38⁺ and AnnV⁺ EpCAM⁺ CD133⁺ gp38⁺ ) were associated with good diagnostic performances that could potentially be used for clinical assessment of biliary cancer and differentiation from other cancer entities. With 91% sensitivity and 69% specificity AnnV⁺ CD44v6⁺ EVs showed the most promising results for differentiating biliary cancers from HCC. Moreover using a combined approach of EV levels of the four populations with serum AFP values, we obtained a perfect separation of biliary cancer and HCC with sensitivity, specificity, positive and negative predictive value all reaching 100% respectively.

CONCLUSIONS

EV phenotyping, especially if combined with serum AFP, represents a minimally invasive, accurate liquid biopsy tool that could improve cancer screening and differential diagnosis of hepatobiliary malignancies.

Extracellular vesicles: Roles and applications in drug-induced liver injury

Extracellular vesicles (EV) are defined as nanosized particles, with a lipid bilayer, that are unable to replicate. There has been an exponential increase of research investigating these particles in a wide array of diseases and deleterious states (inflammation, oxidative stress, drug-induced liver injury) in large part due to increasing recognition of the functional capacity of EVs. Cells can package lipids, proteins, miRNAs, DNA, and RNA into EVs and send these discrete packages of molecular information to distant, recipient cells to alter the physiological state of that cell. EVs are innately heterogeneous as a result of the diverse molecular pathways that are used to generate them. However, this innate heterogeneity of EVs is amplified due to the diversity in isolation techniques and lack of standardized nomenclature in the literature making it unclear if one scientist's "exosome" is another scientist's "microvesicle." One goal of this chapter is to provide the contextual understanding of EV origin so one can discern between divergent nomenclature. Further, the chapter will explore the potential protective and harmful roles that EVs play in DILI, and the potential of EVs and their cargo as a biomarker. The use of EVs as a therapeutic as well as a vector for therapeutic delivery will be discussed.

Modern Techniques for the Isolation of Extracellular Vesicles and Viruses

Extracellular signaling is pivotal to maintain organismal homeostasis. A quickly emerging field of interest within extracellular signaling is the study of extracellular vesicles (EV), which act as messaging vehicles for nucleic acids, proteins, metabolites, lipids, etc. from donor cells to recipient cells. This transfer of biologically active material within a vesicular body is similar to the infection of a cell through a virus particle, which transfers genetic material from one cell to another to preserve an infection state, and viruses are known to modulate EV. Although considerable heterogeneity exists within EV and viruses, this review focuses on those that are small (< 200 nm in diameter) and of relatively low density (< 1.3 g/mL). A multitude of isolation methods for EV and virus particles exist. In this review, we present an update on methods for their isolation, purification, and phenotypic characterization. We hope that the information we provide will be of use to basic science and clinical investigators, as well as biotechnologists in this emerging field. Graphical Abstract.

Prognostic Value of Circulating Microvesicle Subpopulations in Ischemic Stroke and TIA

Platelet microvesicles (PMV) have previously been found elevated in acute ischemic stroke (IS) and could be biomarkers for risk of recurrence. PMV surface antigens such as P-selectin and phosphatidylserine (PS) reflect platelet activation and procoagulance. Tissue factor-positive microvesicles (TF⁺MV) are considered procoagulant, in particular if co-expressing PS. We enumerated MV subpopulations with these surface antigens in a cohort of 211 patients with primarily non-cardioembolic IS or transient ischemic attack (TIA) and investigated their association with long-term outcome. MV concentrations were determined by flow cytometry in the acute and convalescent phase. Primary outcome was a composite of fatal and non-fatal recurrent IS or myocardial infarction. Secondary outcomes were recurrent IS and all-cause mortality. Outcome events were obtained from Swedish registers during a follow-up of 1100 patient years. Concentrations of PS-positive and PS-negative MV populations were elevated in patients compared with healthy controls in both the acute and convalescent phase. PS⁺TF⁺PMV displayed pronounced elevations, median fold change 77 in the acute phase (p < 0.0001) but were not associated with outcome, neither were PS⁺P-selectin⁺PMV. The only subpopulation positively associated with primary outcome was PS^-TF⁺PMV, with adjusted hazard ratio of 1.86 (1.04-3.31, p = 0.036) by Cox regression. Unexpectedly, several MV subpopulations tended to be associated with reduced risk of poor long-term outcome. Our results suggest that PS⁺TF⁺PMV may be a promising marker for cerebral ischemia, and that the in vivo generation of PS^-MV after IS/TIA warrants further study. Future MV studies should ideally enumerate PS⁺ and PS^-MV subpopulations separately.

Modern Techniques for the Isolation of Extracellular Vesicles and Viruses

Extracellular signaling is pivotal to maintain organismal homeostasis. A quickly emerging field of interest within extracellular signaling is the study of extracellular vesicles (EV), which act as messaging vehicles for nucleic acids, proteins, metabolites, lipids, etc. from donor cells to recipient cells. This transfer of biologically active material within a vesicular body is similar to the infection of a cell through a virus particle, which transfers genetic material from one cell to another to preserve an infection state, and viruses are known to modulate EV. Although considerable heterogeneity exists within EV and viruses, this review focuses on those that are small (< 200 nm in diameter) and of relatively low density (< 1.3 g/mL). A multitude of isolation methods for EV and virus particles exist. In this review, we present an update on methods for their isolation, purification, and phenotypic characterization. We hope that the information we provide will be of use to basic science and clinical investigators, as well as biotechnologists in this emerging field. Graphical Abstract.

Extracellular vesicles in diagnostics and therapy of the ischaemic heart: Position Paper from the Working Group on Cellular Biology of the Heart of the European Society of Cardiology

Extracellular vesicles (EVs)—particularly exosomes and microvesicles (MVs)—are attracting considerable interest in the cardiovascular field as the wide range of their functions is recognized. These capabilities include transporting regulatory molecules including different RNA species, lipids, and proteins through the extracellular space including blood and delivering these cargos to recipient cells to modify cellular activity. EVs powerfully stimulate angiogenesis, and can protect the heart against myocardial infarction. They also appear to mediate some of the paracrine effects of cells, and have therefore been proposed as a potential alternative to cell-based regenerative therapies. Moreover, EVs of different sources may be useful biomarkers of cardiovascular disease identities. However, the methods used for the detection and isolation of EVs have several limitations and vary widely between studies, leading to uncertainties regarding the exact population of EVs studied and how to interpret the data. The number of publications in the exosome and MV field has been increasing exponentially in recent years and, therefore, in this ESC Working Group Position Paper, the overall objective is to provide a set of recommendations for the analysis and translational application of EVs focussing on the diagnosis and therapy of the ischaemic heart. This should help to ensure that the data from emerging studies are robust and repeatable, and optimize the pathway towards the diagnostic and therapeutic use of EVs in clinical studies for patient benefit.

The Ratio of Factor VIIa:Tissue Factor Content within Microvesicles Determines the Differential Influence on Endothelial Cells

Tissue factor (TF)-positive microvesicles from various sources can promote cellular proliferation or alternatively induce apoptosis, but the determining factors are unknown. In this study the hypothesis that the ratio of fVIIa:TF within microvesicles determines this outcome was examined. Microvesicles were isolated from HepG2, BxPC-3, 786-O, MDA-MB-231, and MCF-7 cell lines and microvesicle-associated fVIIa and TF antigen and activity levels were measured. Human coronary artery endothelial cells (HCAECs) were incubated with these purified microvesicles, or with combinations of fVIIa-recombinant TF, and cell proliferation/apoptosis was measured. Additionally, by expressing mCherry-PAR2 on HCAEC surface, PAR2 activation was quantified. Finally, the activation of PAR2 on HCAEC or the activities of TF and fVIIa in microvesicles were blocked prior to addition of microvesicles to cells. The purified microvesicles exhibited a range of fVIIa:TF ratios with HepG2 and 786-O cells having the highest (54:1) and lowest (10:1) ratios, respectively. The reversal from proapoptotic to proliferative was estimated to occur at a fVIIa:TF molar ratio of 15:1, but HCAEC could not be rescued at higher TF concentrations. The purified microvesicles induced HCAEC proliferation or apoptosis according to this ruling. Blocking PAR2 activation on HCAEC, or inhibiting fVIIa or TF-procoagulant function on microvesicles prevented the influence on HCAEC. Finally, incubation of HCAEC with recombinant TF resulted in increased surface exposure of fVII. The induction of cell proliferation or apoptosis by TF-positive microvesicles is dependent on the ratio of fVIIa:TF and involves the activation of PAR2. At lower TF concentrations, fVIIa can counteract the proapoptotic stimulus and induce proliferation.

Advances in Technologies for Purification and Enrichment of Extracellular Vesicles

Extracellular vesicles (EVs) are lipid bilayer-bound vesicles secreted by cells. Subtypes of EVs such as microvesicles and exosomes are further categorized mainly by their different biogenesis mechanisms. EVs have been revealed to play an important role in disease diagnosis and intercellular communication. Despite the wide interest in EVs, the technologies for the purification and enrichment of EVs are still in their infancy. The isolation of EVs, especially exosomes, is inherently challenging due to their small size and heterogeneity. In this review, we mainly introduce the advances of techniques in isolating microvesicles and exosomes according to their approaches. Also, we discuss the limitations of currently reported technologies in terms of their specificity and efficiency, and provide our thoughts about future developments of EV purification and enrichment technology.

Alteration in endothelial permeability occurs in response to the activation of PAR2 by factor Xa but not directly by the TF-factor VIIa complex

Alterations in the endothelial permeability occur in response to the activation of coagulation mechanisms in order to control clot formation. The activation of the protease activated receptors (PAR) can induce signals that regulate such cellular responses. PAR2 is a target for the coagulation factor Xa (fXa) and tissue factor-factor VIIa (TF-fVIIa) complex. By measuring the permeability of dextran blue across endothelial monolayer, we examined the mechanisms linking coagulation and endothelial permeability. Activation of PAR2 using the agonist peptide (PAR2-AP) resulted in increased permeability across the monolayer and was comparable to that obtained with VEGF at 60 min. Incubation of cells with activated factor Xa (fXa) resulted in an initial decrease in permeability by 30 min, but then significantly increased at 60 min. These responses required fXa activity, and were abrogated by incubation of the cells with a PAR2-blocking antibody (SAM11). Activation of PAR2 alone, or inhibition of PAR1, abrogated the initial reduction in permeability. Additionally, inclusion of Rivaroxaban (0.6 μg/ml) significantly inhibited the response to fXa. Finally, incubation of the endothelial monolayers up to 2 h with TF-containing microvesicles derived from MDA-MB-231 cells, in the presence or absence of fVIIa, did not influence the permeability across the monolayers. In conclusion, fXa but not TF-fVIIa is a noteworthy mediator of endothelial permeability. The rapid initial decrease in permeability requires PAR2 and PAR1 which may act to constrain bleeding. The longer-term response is mediated by PAR2 with increased permeability, presumably to enhance clot formation at the site of damage.

Nanovesicle-mediated delivery of anticancer agents effectively induced cell death and regressed intrahepatic tumors in athymic mice

Hepatocellular carcinoma is highly resistant to chemotherapy. Here we evaluated the use and efficacy of milk-derived nanovesicles (MNV) as an approach to improve delivery of anticancer agents into HCC cells and intrahepatic tumors. We developed a protocol for isolation of MNVs from skim milk using ultracentrifugation, and characterized using nanoparticle tracking analysis (NTA) and electron microscopy. MNVs were loaded with doxorubicin (dox-MNV) or miR221 antisense oligonucleotides (anti-miR221-MNV), and further evaluated using spectrophotometry, NTA, and zeta potential measurements. HepG2, Hep3B, and PLC/PRF/5 HCC cells in culture were treated with dox-MNV and anti-miR221-MNV and evaluated with drug delivery and anticancer activity. The efficacy of dox-MNV and anti-miR221-MNV to arrest tumor growth in vivo was assessed on intrahepatic tumors induced in nude mice. Cellular uptake studies showed plain and dox-MNV attained saturation within 4 h of treatment. Cytotoxicity studies on HepG2, Hep3B, and PLC/PRF/5 HCC cells with dox-MNV at 1 µM resulted in 20% cell death at 24 h, 50% at 48 h, and 80% at 72 h. HepG2 cells treated with dox-MNV and anti-miR221-MNV exhibited nuclear disintegration, and apoptosis within 24 h. Combination treatment of intrahepatic tumors with dox-MNV and anti-miR221-MNV resulted in marked reduction of tumor size and increased survival rate in nude mice. Our studies demonstrated that MNVs can be effectively used for successful delivery of anticancer agents into HCC cells and intrahepatic tumors. MNV-mediated targeted delivery of anticancer agents could be an efficient modality for the treatment of malignant HCC and might produce a great impact on anticancer therapy.

Fibroblast growth factor-6 enhances CDK2 and MATK expression in microvesicles derived from human stem cells extracted from exfoliated deciduous teeth

Background: Stem cells from human exfoliated deciduous teeth (SHEDs) are considered one of the most convenient sources of adult stem cells. This study aimed to examine the effect of fibroblast growth factor 6 (FGF-6) on SHEDs and evaluate CDK2 and MATK gene expression in SHED-derived microvesicles (MVs). SHEDs were cultured from deciduous teeth pulp.

Methods: SHEDs were divided into two groups: the control group and test groups, with and without FGF-6 supplementation, respectively. After the third passage, SHED proliferation was assessed by MTT assay. MVs were purified and CDK2 and MATK gene expression was assessed by real-time polymerase chain reaction. SHEDs were identified by their positivity for CD90 and CD73, and negativity for CD45 and CD34.

Results: SHEDs proliferation in the test group was significantly higher than in the control group (P<0.001). mRNA from SHED-derived MVs from the test group exhibited a markedly elevated expression of CDK2 and MATK, (P<0.002 and P<0.005, respectively) in comparison with those of the control group. FGF-6 enhanced the proliferation of SHEDs. Proliferation enhancement is favorable for the production of a large number of stem cells, which will then be beneficial for cell-based therapies.

Conclusions:CDK2 and MATK genes in SHED-derived MVs can be used as molecular biomarkers for SHED proliferation.

Hepatitis C virus: Morphogenesis, infection and therapy

Hepatitis C virus (HCV) is a major cause of liver diseases including liver cirrhosis and hepatocellular carcinoma. Approximately 3% of the world population is infected with HCV. Thus, HCV infection is considered a public healthy challenge. It is worth mentioning, that the HCV prevalence is dependent on the countries with infection rates around 20% in high endemic countries. The review summarizes recent data on HCV molecular biology, the physiopathology of infection (immune-mediated liver damage, liver fibrosis and lipid metabolism), virus diagnostic and treatment. In addition, currently available in vitro, ex vivo and animal models to study the virus life cycle, virus pathogenesis and therapy are described. Understanding of both host and viral factors may in the future lead to creation of new approaches in generation of an efficient therapeutic vaccine.

Accumulation of tissue factor in endothelial cells induces cell apoptosis, mediated through p38 and p53 activation

We previously reported that high levels of tissue factor (TF) can induce cellular apoptosis in endothelial cells. In this study, TF-mediated mechanisms of induction of apoptosis were explored. Endothelial cells were transfected to express wild-type TF. Additionally, cells were transfected to express Asp253-substituted, or Ala253-substitued TF to enhance or prevent TF release, respectively. Alternatively, cells were pre-incubated with TF-rich and TF-poor microvesicles. Cell proliferation, apoptosis and the expression of cyclin D1, p53, bax and p21 were measured following activation of cells with PAR2-agonist peptide. Greatest levels of cell proliferation and cyclin D1 expression were observed in cells expressing wild-type or Asp253-substituted TF. In contrast, increased cellular apoptosis was observed in cells expressing Ala253-substituted TF, or cells pre-incubated with TF-rich microvesicles. The level of p53 protein, p53-phosphorylation at ser33, p53 nuclear localisation and transcriptional activity, but not p53 mRNA, were increased in cells expressing wild-type and Ala253-substituted TF, or in cells pre-incubated with TF-rich microvesicles. However, the expression of bax and p21 mRNA, and Bax protein were only increased in cells pre-incubated with TF-rich microvesicle and in cells expressing Ala253-substituted TF. Inhibition of the transcriptional activity of p53 using pifithrin-α suppressed the expression of Bax. Finally, siRNA- mediated suppression of p38α, or inhibition using SB202190 significantly reduced the p53 protein levels, p53 nuclear localisation and transcriptional activity, suppressed Bax expression and prevented cellular apoptosis. In conclusion, accumulation of TF within endothelial cells, or sequestered from the surrounding can induce cellular apoptosis through mechanisms mediated by p38, and involves the stabilisation of p53.

Tissue Factor-Expressing Tumor-Derived Extracellular Vesicles Activate Quiescent Endothelial Cells via Protease-Activated Receptor-1

Tissue factor (TF)-expressing tumor-derived extracellular vesicles (EVs) can promote metastasis and pre-metastatic niche formation, but the mechanisms by which this occurs remain largely unknown. We hypothesized that generation of activated factor X (FXa) by TF expressed on tumor-derived EV could activate protease-activated receptors (PARs) on non-activated endothelial cells to induce a pro-adhesive and pro-inflammatory phenotype. We obtained EV from TF-expressing breast (MDA-MB-231) and pancreatic (BxPC3 and Capan-1) tumor cell lines. We measured expression of E-selectin and secretion of interleukin-8 (IL-8) in human umbilical vein endothelial cells after exposure to EV and various immunologic and chemical inhibitors of TF, FXa, PAR-1, and PAR-2. After 6 h of exposure to tumor-derived EV (pretreated with factor VIIa and FX) in vitro, endothelial cells upregulated E-selectin expression and secreted IL-8. These changes were decreased with an anti-TF antibody, FXa inhibitors (FPRCK and EGRCK), and PAR-1 antagonist (E5555), demonstrating that FXa generated by TF-expressing tumor-derived EV was signaling through endothelial PAR-1. Due to weak constitutive PAR-2 expression, these endothelial responses were not induced by a PAR-2 agonist peptide (SLIGKV) and were not inhibited by a PAR-2 antagonist (FSLLRY) after exposure to tumor-derived EV. In conclusion, we found that TF-expressing cancer-derived EVs activate quiescent endothelial cells, upregulating E-selectin and inducing IL-8 secretion through generation of FXa and cleavage of PAR-1. Conversion of resting endothelial cells to an activated phenotype by TF-expressing cancer-derived EV could promote cancer metastases.

Peptidyl-prolyl isomerase 1 (Pin1) preserves the phosphorylation state of tissue factor and prolongs its release within microvesicles

The exposure and release of TF is regulated by post-translational modifications of its cytoplasmic domain. Here, the potential of Pin1 to interact with the cytoplasmic domain of TF, and the outcome on TF function was examined. MDA-MB-231 and transfected-primary endothelial cells were incubated with either Pin1 deactivator Juglone, or its control Plumbagin, as well as transfected with Pin1-specific or control siRNA. TF release into microvesicles following activation, and also phosphorylation and ubiquitination states of cellular-TF were then assessed. Furthermore, the ability of Pin1 to bind wild-type and mutant forms of overexpressed TF-tGFP was investigated by co-immunoprecipitation. Additionally, the ability of recombinant or cellular Pin1 to bind to peptides of the C-terminus of TF, synthesised in different phosphorylation states was examined by binding assays and spectroscopically. Finally, the influence of recombinant Pin1 on the ubiquitination and dephosphorylation of the TF-peptides was examined. Pre-incubation of Pin1 with Juglone but not Plumbagin, reduced TF release as microvesicles and was also achievable following transfection with Pin1-siRNA. This was concurrent with early ubiquitination and dephosphorylation of cellular TF at Ser253. Pin1 co-immunoprecipitated with overexpressed wild-type TF-tGFP but not Ser258→Ala or Pro259→Ala substituted mutants. Pin1 did interact with Ser258-phosphorylated and double-phosphorylated TF-peptides, with the former having higher affinity. Finally, recombinant Pin1 was capable of interfering with the ubiquitination and dephosphorylation of TF-derived peptides. In conclusion, Pin1 is a fast-acting enzyme which may be utilised by cells to protect the phosphorylation state of TF in activated cells prolonging TF activity and release, and therefore ensuring adequate haemostasis.

Interplay between alternatively spliced Tissue Factor and full length Tissue Factor in modulating coagulant activity of endothelial cells

BACKGROUND

Full length Tissue factor (flTF) is a key player in hemostasis and also likely contributes to venous thromboembolism (VTE), the third most common cardiovascular disease. flTF and its minimally coagulant isoform, alternatively spliced TF (asTF), have been detected in thrombi, suggesting participation of both isoforms in thrombogenesis, but data on participation of asTF in hemostasis is lacking. Therefore, we assessed the role of asTF in flTF cofactor activity modulation, using a co-expression system.

OBJECTIVE

To investigate the interplay between flTF and asTF in hemostasis on endothelial cell surface.

METHODS

Immortalized endothelial (ECRF) cells were adenovirally transduced to express asTF and flTF, after which flTF cofactor activity was measured on cells and microvesicles (MVs). To study co-localization of flTF/asTF proteins, confocal microscopy was performed. Finally, intracellular distribution of flTF was studied in the presence or absence of heightened asTF levels.

RESULTS

Levels of flTF antigen and cofactor activity were not affected by asTF co-expression. asTF and flTF were found to localize in distinct subcellular compartments. Only upon heightened overexpression of asTF, lower flTF protein levels and cofactor activity were observed. Heightened asTF levels also induced a shift of flTF from non-raft to lipid raft plasma membrane fractions, and triggered the expression of ER stress marker BiP. Proteasome inhibition resulted in increased asTF - but not flTF - protein expression.

CONCLUSION

At moderate levels, asTF appears to have negligible impact on flTF cofactor activity on endothelial cells and MVs; however, at supra-physiological levels, asTF is able to reduce the levels of flTF protein and cofactor activity.

Oligoubiquitination of tissue factor on Lys255 promotes Ser253-dephosphorylation and terminates TF release

Restriction of tissue factor (TF) activity at the cell surface and TF release are critical for prevention of excessive coagulation. This study examined the regulation of TF dephosphorylation and its release through ubiquitination. A plasmid containing the sequence to express the tandem protein TF-tGFP was mutated to include an arginine-substitution at Lys255 within TF. MDA-MB-231 cell line, and HCAEC endothelial cells were transfected and subsequently activated with PAR2-agonist peptide. The wild-type and mutant TF-tGFP were immunoprecipitated from the cell lysates and the ubiquitination and phosphorylation state of TF examined. Analysis of the proteins showed that arginine-substitution of Lys255 within TF prevented its ubiquitination while the wild-type TF-tGFP was oligoubiquitinated. The TF-associated oligoubiquitin chain was estimated to contain up to 4 ubiquitin units, with the linkage formed between Lys63 of one ubiquitin unit, and the C-terminus of the next unit. The Lys255→Arg substitution of TF-tGFP prolonged the phosphorylation of Ser253 within TF, compared to the wild-type TF-tGFP, lengthened the presence of TF-tGFP at the cell surface and extended the duration of TF-tGFP release from cells following PAR2 activation. A biotinylated 19-mer peptide corresponding to the C-terminus of TF (TFc) was used as substrate to show that the ubiquitination of TF was mediated by the Ube2D family of E2-enzymes and involved Mdm2. Moreover, double-phosphorylation of TFc was prerequisite for ubiquitination, with subsequent dephosphorylation of Ser253 by phosphatase PP2A. In conclusion, oligoubiquitination of Lys255 within TF permits PP2A to bind and dephosphorylate Ser253 and occurs to terminate TF release and contain its activity.

Emerging roles for vascular smooth muscle cell exosomes in calcification and coagulation

Vascular smooth muscle cell (VSMC) phenotypic conversion from a contractile to 'synthetic' state contributes to vascular pathologies including restenosis, atherosclerosis and vascular calcification. We have recently found that the secretion of exosomes is a feature of 'synthetic' VSMCs and that exosomes are novel players in vascular repair processes as well as pathological vascular thrombosis and calcification. Pro-inflammatory cytokines and growth factors as well as mineral imbalance stimulate exosome secretion by VSMCs, most likely by the activation of sphingomyelin phosphodiesterase 3 (SMPD3) and cytoskeletal remodelling. Calcium stress induces dramatic changes in VSMC exosome composition and accumulation of phosphatidylserine (PS), annexin A6 and matrix metalloproteinase-2, which converts exosomes into a nidus for calcification. In addition, by presenting PS, VSMC exosomes can also provide the catalytic surface for the activation of coagulation factors. Recent data showing that VSMC exosomes are loaded with proteins and miRNA regulating cell adhesion and migration highlight VSMC exosomes as potentially important communication messengers in vascular repair. Thus, the identification of signalling pathways regulating VSMC exosome secretion, including activation of SMPD3 and cytoskeletal rearrangements, opens up novel avenues for a deeper understanding of vascular remodelling processes.

Analysis of the potential of cancer cell lines to release tissue factor-containing microvesicles: correlation with tissue factor and PAR2 expression

BACKGROUND

Despite the association of cancer-derived circulating tissue factor (TF)-containing microvesicles and hypercoagulable state, correlations with the incidence of thrombosis remain unclear.

METHODS

In this study the upregulation of TF release upon activation of various cancer cell lines, and the correlation with TF and PAR2 expression and/or activity was examined. Microvesicle release was induced by PAR2 activation in seventeen cell lines and released microvesicle density, microvesicle-associated TF activity, and phoshpatidylserine-mediated activity were measured. The time-course for TF release was monitored over 90 min in each cell line. In addition, TF mRNA expression, cellular TF protein and cell-surface TF activities were quantified. Moreover, the relative expression of PAR2 mRNA and cellular protein were analysed. Any correlations between the above parameters were examined by determining the Pearson's correlation coefficients.

RESULTS

TF release as microvesicles peaked between 30-60 min post-activation in the majority of cell lines tested. The magnitude of the maximal TF release positively correlated with TF mRNA (c = 0.717; p < 0.001) and PAR2 mRNA (c = 0.770; p < 0.001) expressions while the percentage increase correlated with PAR2 mRNA (c = 0.601; p = 0.011) and protein (c = 0.714; p < 0.001). There was only a weak correlation between resting TF release, and microvesicle release. However, TF release in resting cells did not significantly correlate with any of the parameters examined. Furthermore, TF mRNA expression correlated with PAR2 mRNA expression (c = 0.745; p < 0.001).

DISCUSSION AND CONCLUSIONS

In conclusion, our data suggest that TF and PAR2 mRNA, and PAR2 protein are better indicators of the ability of cancer cells to release TF and may constitute more accurate predictors of risk of thrombosis.

Antibody-Based Assays for Phenotyping of Extracellular Vesicles

Extracellular vesicles (EVs) are a heterogeneous population of membrane-enclosed vesicles. EVs are recognized as important players in cell-to-cell communication and are described to be involved in numerous biological and pathological processes. The fact that EVs are involved in the development and progression of several diseases has formed the basis for the use of EV analysis in a clinical setting. As the interest in EVs has increased immensely, multiple techniques have been developed aiming at characterizing these vesicles. These techniques characterize different features of EVs, like the size distribution, enumeration, protein composition, and the intravesicular cargo (e.g., RNA). This review focuses on techniques that exploit the specificity and sensitivity associated with antibody-based assays to characterize the protein phenotype of EVs. The protein phenotype of EVs can provide information on the functionality of the vesicles and may be used for identification of disease-related biomarkers. Thus, protein profiling of EVs holds great diagnostic and prognostic potential.

Breast Cancer-Derived Extracellular Vesicles: Characterization and Contribution to the Metastatic Phenotype

The study of extracellular vesicles (EVs) in cancer progression is a complex and rapidly evolving field. Whole categories of cellular interactions in cancer which were originally presumed to be due solely to soluble secreted molecules have now evolved to include membrane-enclosed extracellular vesicles (EVs), which include both exosomes and shed microvesicles (MVs), and can contain many of the same molecules as those secreted in soluble form but many different molecules as well. EVs released by cancer cells can transfer mRNA, miRNA, and proteins to different recipient cells within the tumor microenvironment, in both an autocrine and paracrine manner, causing a significant impact on signaling pathways, mRNA transcription, and protein expression. The transfer of EVs to target cells, in turn, supports cancer growth, immunosuppression, and metastasis formation. This review focuses exclusively on breast cancer EVs with an emphasis on breast cancer-derived exosomes, keeping in mind that breast cancer-derived EVs share some common physical properties with EVs of other cancers.

"Soluble Tissue Factor" in the 21st Century: Definitions, Biochemistry, and Pathophysiological Role in Thrombus Formation

Tissue factor (TF), the main trigger of blood coagulation, is essential for normal hemostasis. Over the past 20 years, heightened intravascular levels and activity of TF have been increasingly perceived as an entity that significantly contributes to venous as well as arterial thrombosis. Various forms of the TF protein in the circulation have been described and proposed to be thrombogenic. Aside from cell and vessel wall-associated TF, several forms of non-cell-associated TF circulate in plasma and may serve as a causative factor in thrombosis. At the present time, no firm consensus exists regarding the extent, the vascular setting(s), and/or the mechanisms by which such TF forms contribute to thrombus initiation and propagation. Here, we summarize the existing paradigms and recent, sometimes paradigm-shifting findings elucidating the structural, mechanistic, and pathophysiological characteristics of plasma-borne TF.

Neutrophil elastase promotes interleukin-1β secretion from human coronary endothelium

The endothelium is critically involved in the pathogenesis of atherosclerosis by producing pro-inflammatory mediators, including IL-1β. Coronary arteries from patients with ischemic heart disease express large amounts of IL-1β in the endothelium. However, the mechanism by which endothelial cells (ECs) release IL-1β remains to be elucidated. We investigated neutrophil elastase (NE), a potent serine protease detected in vulnerable areas of human carotid plaques, as a potential "trigger" for IL-1β processing and release. This study tested the hypothesis that NE potentiates the processing and release of IL-1β from human coronary endothelium. We found that NE cleaves the pro-isoform of IL-1β in ECs and causes significant secretion of bioactive IL-1β via extracellular vesicles. This release was attenuated significantly by inhibition of neutrophil elastase but not caspase-1. Transient increases in intracellular Ca(2+) levels were observed prior to secretion. Inside ECs, and after NE treatment only, IL-1β was detected within LAMP-1-positive multivesicular bodies. The released vesicles contained bioactive IL-1β. In vivo, in experimental atherosclerosis, NE was detected in mature atherosclerotic plaques, predominantly in the endothelium, alongside IL-1β. This study reveals a novel mechanistic link between NE expression in atherosclerotic plaques and concomitant pro-inflammatory bioactive IL-1β secretion from ECs. This could reveal additional potential anti-IL-1β therapeutic targets and provide further insights into the inflammatory process by which vascular disease develops.