Circulating Platelet-Derived Extracellular Vesicles Are a Hallmark of Sars-Cov-2 Infection

The emerging roles of platelet-derived extracellular vesicles in disease

INTRODUCTION

Platelet-derived extracellular vesicles (pEVs) are nanoscale, membrane-bound vesicles released by platelets during activation or apoptosis. They contain various bioactive and non-bioactive molecules and play significant roles in numerous physiological and pathological processes through intercellular communication, thus attracting growing attention in biomedical research.

METHODS

This review comprehensively overviews the biogenesis, clearance, and molecular characteristics of pEVs. It also covers current methodologies for their isolation and characterization. The therapeutic implications of pEVs in key clinical settings like tissue regeneration, hemostasis, immune modulation, and vascular repair, with a focus on cancer progression, wound healing, and hemorrhagic shock management, are explored. Their role in cellular signal transduction is examined, and their functional properties are compared with other platelet-derived products such as platelet-rich plasma.

RESULTS

pEVs show potential as both therapeutic agents and diagnostic biomarkers. They are involved in modulating inflammatory responses, promoting angiogenesis, and enhancing cellular repair mechanisms.

CONCLUSION

Future research should concentrate on optimizing their therapeutic efficacy, refining biomarker applications, and exploring targeted delivery strategies to fully utilize their potential in regenerative medicine, oncology, and hemostasis management.

Liposome-encapsulated lambda exonuclease-based amplification system for enhanced detection of miRNA in platelet-derived microvesicles of non-small cell lung cancer

Platelet-derived microvesicles (PMVs) and their encapsulated microRNAs (miRNAs) hold immense potential as biomarkers for early non-small cell lung cancer (NSCLC) diagnosis. This study presents a pioneering liposome-based approach for enhanced miRNA detection within PMVs, employing a lambda exonuclease (λ EXO)-based amplification system encapsulated in immunoliposomes. The platform exploits the novel catalytic functionality of λ EXO, demonstrating its unprecedented capability to catalyze RNA-DNA hybrid substrates. The λ EXO-based amplification system exhibited high sensitivity and specificity in detecting miRNA-21, a key miRNA associated with NSCLC, demonstrating a limit of detection (LOD) of 33.11 fg mL-1. The system was successfully encapsulated within liposomes, which were then functionalized with CD41 antibody to facilitate targeted delivery and fusion with PMVs. The results reveal a significant difference in miRNA-21 levels between PMVs from NSCLC patients and healthy individuals, with a 2.06-fold higher abundance observed in NSCLC patients. This research presents a significant technological advancement in miRNA detection, paving the way for improved early diagnosis and personalized medicine approaches.

Blood CD45+/CD3+ lymphocyte-released extracellular vesicles and mortality in hospitalized patients with coronavirus disease 2019

BACKGROUND

The global pandemic of coronavirus disease 2019 (COVID-19) represented a major public health concern. Growing evidence shows that plasma of COVID-19 patients contains large numbers of circulating extracellular vesicles (cEVs) that correlate with disease severity and recovery. In this study, we sought to characterize the longitudinal cEV signature in critically ill COVID-19 patients during hospitalization and its relation to mortality risk.

METHODS

cEVs were quantitatively and phenotypically analysed in hospitalized non-surviving COVID-19 patients at baseline (n = 42) and before exitus (n = 40) and in 40 healthy volunteers as a reference group by high sensitivity nano flow cytometry using specific markers for parental cell sources and activation.

RESULTS

Levels of cEV subtypes differed between patients with severe COVID-19 and healthy subjects, specifically those from platelets and endothelial, inflammatory and viral infected cells, which associate to high mortality risk. In the longitudinal analysis from baseline to the time point immediately preceding death, no changes were found for platelet, pan-leukocyte, and lung epithelial cell-shed cEVs, while endothelial cell releases of EVs (eEVs) significantly differed. Vascular endothelial growth factor receptor 2-positive eEVs were significantly increased before death compared to admission whereas endoglin and E-selectin-containing eEVs did not change. Conversely, lymphocyte (ℓEV), monocyte, macrophage, pericyte and progenitor cell-derived cEVs displayed significant reductions before exitus. Noteworthy, levels of CD45+/CD3+-ℓEVs were significantly associated to the patient's survival time.

CONCLUSIONS

An evolving cEV profile able to discriminate prompt risk of death during hospitalization has been defined suggesting a role for circulating and vascular cell-derived EVs in COVID-19 pathogenesis.

A liposome-based assay for cancer biomarker detection: exploring the correlation between platelet-derived microvesicles and NSCLC-associated miRNAs

Advances in molecular biology have enabled the identification of numerous cancer biomarkers, offering the potential to improve the diagnosis and prognosis of cancer. In non-small cell lung cancer (NSCLC), the role of platelet-derived microvesicles (PMVs) in cancer progression has received limited attention. While previous studies have focused on the increase of extracellular vesicles in plasma and their interaction with cancer, the expression of microRNAs (miRNAs) delivered through PMVs following platelet activation has remained largely unexplored. This study fills this knowledge gap by investigating miRNA expression in PMVs isolated from healthy donors and NSCLC patients following calcium treatment, a known platelet activator. A significant correlation was found between PMV levels and the expression of specific miRNAs; specifically, miRNA-21 expression increased 7.89 ± 0.44-fold in NSCLC patients and 7.12 ± 0.49-fold in healthy donors after calcium treatment. These findings highlight the potential of PMVs and their miRNA cargo to serve as specific biomarkers for NSCLC, offering valuable insights into cancer diagnosis and prognosis. To facilitate the sensitive detection of these miRNAs, a novel carboxyfluorescein (CF)-loaded liposome-based assay was developed. This assay demonstrated enhanced sensitivity, achieving a detection limit of 1.03 pg mL-1, when combined with a calcium platelet-activation approach. This research has the potential to lead to the development of innovative diagnostic tools and therapeutic strategies, ultimately improving outcomes for patients with NSCLC and other cancers.

Increased circulating platelet-derived extracellular vesicles in severe COVID-19 disease

Coagulation disturbances are major contributors to COVID-19 pathogenicity, but limited data exist on the involvement of extracellular vesicles (EVs) and residual cells (RCs). Fifty hospitalized COVID-19 patients stratified by their D-dimer levels into high (>1.5 mg/L, n = 15) or low (≤1.5 mg/l, n = 35) and 10 healthy controls were assessed for medium-sized EVs (mEVs; 200-1000 nm) and large EVs/RCs (1000-4000 nm) by high sensitivity flow cytometry. EVs were analyzed for CD61, CD235a, CD45, and CD31, commonly used to detect platelets, red blood cells, leukocytes or endothelial cells, respectively, whilst phosphatidyl serine EVs/RCs were detected by lactadherin-binding implicating procoagulant catalytic surface. Small EV detection (sEVs; 50-200 nm) and CD41a (platelet integrin) colocalization with general EV markers CD9, CD63, and CD81 were performed by single particle interferometric reflectance imaging sensor. Patients with increased D-dimer exhibited the highest number of RCs and sEVs irrespective of cell origin (p < .05). Platelet activation, reflected by increased CD61+ and lactadherin+ mEV and RC levels, associated with coagulation disturbances. Patients with low D-dimer could be discriminated from controls by tetraspanin signatures of the CD41a+ sEVs, suggesting the changes in the circulating platelet sEV subpopulations may offer added prognostic value during COVID progression.

Circulating GLAST+ EVs are increased in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder, hallmarked by the gradual deterioration of motor neurons, culminating in muscle weakness and fatal paralysis. The exact etiology of ALS remains elusive, and there is a critical need for reliable biomarkers to aid in diagnosis and monitoring of disease progression. Extracellular vesicles (EVs) have emerged as promising candidates for biomarker discovery in neurodegenerative diseases such as ALS, giving access to pathologically relevant tissues otherwise typically challenging or invasive to sample. Indeed, EVs can derive by many cell types within the central nervous system, cross the blood-brain barrier and reach the blood, where they can be easily measured. One of the central mechanisms implicated in ALS pathology is glutamate excitotoxicity, which involves excessive glutamate accumulation due to impaired uptake by astrocytes and other glial cells, leading to neuronal damage. GLAST is a key glutamate transporter responsible for maintaining extracellular gluta-mate levels, and its dysregulation is thought to contribute significantly to ALS development and associated neuropathogenesis. Here, we applied a quick and validated method, to evaluate GLAST+ EVs in ALS patients' plasma and age-matched healthy controls. We found an increase in GLAST+ EVs that holds promise for uncovering novel diagnostic and therapeutic avenues in ALS research.

Circulating extracellular vesicles from severe COVID-19 patients induce lung inflammation

Circulating extracellular vesicles (EVs) have been associated with the development of COVID-19 due to their roles in viral infection, inflammatory response, and thrombosis. However, the direct induction of lung inflammation by circulating EVs from severe COVID-19 patients remains unknown. EVs were extracted from the plasma of severe COVID-19 patients admitted to intensive care and healthy controls. To study the effect of COVID-19 EVs on lung inflammation, mice were intratracheally instilled with EVs. To examine the proinflammatory effects of EVs in vitro, bone marrow-derived macrophages were treated with EVs. COVID-19 but not control EVs triggered lung inflammation, as assessed by total protein level, total cell count, neutrophil count, and levels of proinflammatory cytokines in the bronchoalveolar lavage. COVID-19 EVs also promoted M1 polarization of alveolar macrophages in vivo. Treatment of bone marrow-derived macrophages with COVID-19 EVs enhanced the M1 phenotype and augmented the production of IL-1β, IL-6, and TNF-α. In summary, circulating EVs from severe COVID-19 patients induce lung inflammation in mice. EVs could become a potential therapeutic target for alleviating lung injury in COVID-19.

IMPORTANCE

Extracellular vesicles (EVs) have been reported to facilitate cytokine storm, coagulation, vascular dysfunction, and the spread of the virus in COVID-19. The direct role of circulating EVs from severe COVID-19 patients in lung injury remains unrecognized. Our study demonstrated that plasma EVs obtained from severe COVID-19 patients induced lung inflammation and polarization of alveolar macrophages in vivo. In vitro experiments also revealed the proinflammatory effects of COVID-19 EVs. The present study sheds fresh insight into the mechanisms of COVID-19-induced lung injury, highlighting EVs as a potential therapeutic target in combating the disease.

Circulating Extracellular Vesicles: An Effective Biomarker for Cancer Progression

Extracellular vesicles (EVs), the ubiquitous part of human biology, represent a small heterogenous, membrane-enclosed body that contains a diverse payload including genetic materials in the form of DNA, RNAs, small non-coding RNAs, etc. mostly mirroring their source of origin. Since, a vast majority of research has been conducted on how nucleic acids, proteins, lipids, and metabolites, associated with EVs can be effectively utilized to identify disease progression and therapeutic responses in cancer patients, EVs are increasingly being touted as valuable and reliable identifiers of cancer biomarkers in liquid biopsies. However, the lack of comprehensive clinical validation and effective standardization protocols severely limits its applications beyond the laboratories. The present review focuses on understanding the role of circulating EVs in different cancers and how they could potentially be treated as cancer biomarkers, typically due to the presence of bioactive molecules such as small non-coding RNAs, RNAs, DNA, proteins, etc., and their utilization for fine-tuning therapies. Here, we provide a brief general biology of EVs including their classification and subsequently discuss the source of circulatory EVs, the role of their associated payload as biomarkers, and how different cancers affect the level of circulatory EVs population.

A narrative review on lung injury: mechanisms, biomarkers, and monitoring

Lung injury is closely associated with the heterogeneity, severity, mortality, and prognosis of various respiratory diseases. Effective monitoring of lung injury is crucial for the optimal management and improved outcomes of patients with lung diseases. This review describes acute and chronic respiratory diseases characterized by significant lung injury and current clinical tools for assessing lung health. Furthermore, we summarized the mechanisms of lung cell death observed in these diseases and highlighted recently identified biomarkers in the plasma indicative of injury to specific cell types and scaffold structure in the lung. Last, we propose an artificial intelligence-driven lung injury monitoring model to assess disease severity, and predict mortality and prognosis, aiming to achieve precision and personalized medicine.

Effect of Unfractionated Heparin Dose on Complement Activation and Selected Extracellular Vesicle Populations during Extracorporeal Membrane Oxygenation

Extracorporeal membrane oxygenation (ECMO) provides critical support for patients with severe cardiopulmonary dysfunction. Unfractionated heparin (UFH) is used for anticoagulation to maintain circuit patency and avoid thrombotic complications, but it increases the risk of bleeding. Extracellular vesicles (EVs), nano-sized subcellular spheres with potential pro-coagulant properties, are released during cellular stress and may serve as potential targets for monitoring anticoagulation, particularly in thromboinflammation. We investigated the impact of UFH dose during ECMO therapy at the coagulation-inflammation interface level, focusing on complement activation and changes in circulating large EV (lEV) subsets. In a post hoc analysis of a multicenter randomized controlled trial comparing two anticoagulation management algorithms, we examined lEV levels and complement activation in 23 veno-venous-ECMO patients stratified by UFH dose. Blood samples were collected at different time points and grouped into three phases of ECMO therapy: initiation (day 1), mid (days 3-4), and late (days 6-7). Immunoassays detected complement activation, and flow cytometry analyzed lEV populations with an emphasis on mitochondria-carrying subsets. Patients receiving <15 IU/kg/h UFH exhibited higher levels of the complement activation product C5a and soluble terminal complement complex (sC5b-9). Lower UFH doses were linked to increased endothelial-derived lEVs, while higher doses were associated with elevated RBC-derived and mitochondria-positive lEVs. Our findings suggest the potential theranostic relevance of EV detection at the coagulation-inflammation interface. Further research is needed to standardize EV detection methods and validate these findings in larger ECMO patient cohorts.

Plasma Extracellular Vesicles Derived from Pediatric COVID-19 Patients Modulate Monocyte and T Cell Immune Responses Based on Disease Severity

BACKGROUND

The COVID-19 pandemic has caused significant morbidity and mortality globally. The role of plasma-derived extracellular vesicles (EVs) in pediatric COVID-19 patients remains unclear.

METHODS

We isolated EVs from healthy controls (n = 13) and pediatric COVID-19 patients (n = 104) with varying severity during acute and convalescent phases using serial ultracentrifugation. EV effects on healthy PBMCs, naïve CD4+ T cells, and monocytes were assessed through in vitro assays, flow cytometry, and ELISA.

RESULTS

Our findings indicate that COVID-19 severity correlates with diverse immune responses. Severe acute cases exhibited increased cytokine levels, decreased IFNγ levels, and lower CD4+ T cell and monocyte counts, suggesting immunosuppression. EVs from severe acute patients stimulated healthy cells to express higher PDL1, increased Th2 and Treg cells, reduced IFNγ secretion, and altered Th1/Th17 ratios. Patient-derived EVs significantly reduced proinflammatory cytokine production by monocytes (p < .001 for mild, p = .0025 for severe cases) and decreased CD4+ T cell (p = .043) and monocyte (p = .033) populations in stimulated healthy PBMCs.

CONCLUSION

This study reveals the complex relationship between immunological responses and EV-mediated effects, emphasizing the impact of COVID-19 severity. We highlight the potential role of plasma-derived EVs in early-stage immunosuppression in severe COVID-19 patients.

Platelet and Monocyte Microvesicles as Potential Biomarkers of COVID-19 Severity: A Cross-Sectional Analysis

Background

Coronavirus disease (COVID-19) induces inflammation, coagulopathy following platelet and monocyte activation, and fibrinolysis, resulting in elevated D-dimer levels. Activated platelets and monocytes produce microvesicles (MVs). We analyzed the differences in platelet and monocyte MV counts in mild, moderate, and severe COVID-19, as well as their correlation with D-dimer levels.

Methods

In this cross-sectional study, blood specimens were collected from 90 COVID-19 patients and analyzed for D-dimers using SYSMEX CS-2500. Platelet MVs (PMVs; PMVCD42b+ and PMVCD41a+), monocyte MVs (MMVs; MMVCD14+), and phosphatidylserine-binding annexin V (PS, AnnV+) were analyzed using a BD FACSCalibur instrument.

Results

PMV and MMV counts were significantly increased in COVID-19 patients. AnnV+ PMVCD42b+ and AnnV+ PMVCD41a+ cell counts were higher in patients with severe COVID-19 than in those with moderate clinical symptoms. The median (range) of AnnV+ PMVCD42b+ (MV/μL) in mild, moderate, and severe COVID-19 was 1,118.3 (328.1-1,910.5), 937.4 (311.4-2,909.5), and 1,298.8 (458.2-9,703.5), respectively (P =0.009). The median (range) for AnnV+ PMVCD41a+ (MV/μL) in mild, moderate, and severe disease was 885.5 (346.3-1,682.7), 663.5 (233.8-2,081.5), and 1,146.3 (333.3-10,296.6), respectively (P =0.007). D-dimer levels (ng/mL) weak correlated with AnnV+ PMVCD41a+ (P =0.047, r=0.258).

Conclusions

PMV PMVCD42b+ and PMVCD41a+ counts were significantly increased in patients with severe clinical symptoms, and PMVCD41a+ counts correlated with D-dimer levels. Therefore, MV counts can be used as a potential biomarker of COVID-19 severity.

CD66b+/CD68+ circulating extracellular vesicles, lactate dehydrogenase and neutrophil-to-lymphocyte ratio can differentiate coronavirus disease 2019 severity during and after infection

Coronavirus disease 2019 (COVID-19) has been a major public health burden. We hypothesised that circulating extracellular vesicles (cEVs), key players in health and disease, could trace the cell changes during COVID-19 infection and recovery. Therefore, we studied the temporal trend of cEV and inflammatory marker levels in plasma samples of COVID-19 patients that were collected within 24 h of patient admission (baseline, n = 80) and after hospital discharge at day-90 post-admission (n = 59). Inflammatory markers were measured by standard biochemical methods. cEVs were quantitatively and phenotypically characterized by high-sensitivity nano flow cytometry. In patients recovered from COVID-19 lower levels of inflammatory markers were detected. cEVs from vascular (endothelial cells) and blood (platelets, distinct immune subsets) cells were significantly reduced at day-90 compared to admission levels, a pattern also observed for cEVs from progenitor, perivascular and epithelial cells. The best discriminatory power for COVID-19 severity was found for inflammatory markers lactate dehydrogenase and neutrophil-to-lymphocyte ratio and for granulocyte/macrophage-released CD66b+/CD68+-cEVs. Albeit inflammatory markers were good indicators of systemic inflammatory response and discriminators of COVID-19 remission, they do not completely reveal cell stress and organ damage states. cEVs reaching baseline pre-infection levels at 90 days post-infection in recovered patients discriminate parental cells affected by disease.

Efficient and highly reproducible production of red blood cell-derived extracellular vesicle mimetics for the loading and delivery of RNA molecules

Extracellular vesicles (EVs) are promising natural nanocarriers for the delivery of therapeutic agents. As with any other kind of cell, red blood cells (RBCs) produce a limited number of EVs under physiological and pathological conditions. Thus, RBC-derived extracellular vesicles (RBCEVs) have been recently suggested as next-generation delivery systems for therapeutic purposes. In this paper, we show that thanks to their unique biological and physicochemical features, RBCs can be efficiently pre-loaded with several kinds of molecules and further used to generate RBCEVs. A physical vesiculation method, based on "soft extrusion", was developed, producing an extremely high yield of cargo-loaded RBCEV mimetics. The RBCEVs population has been deeply characterized according to the new guidelines MISEV2023, showing great homogeneity in terms of size, biological features, membrane architecture and cargo. In vitro preliminary results demonstrated that RBCEVs are abundantly internalized by cells and exert peculiar biological effects. Indeed, efficient loading and delivery of miR-210 by RBCEVs to HUVEC has been proven, as well as the inhibition of a known mRNA target. Of note, the bench-scale process can be scaled-up and translated into clinics. In conclusion, this investigation could open the way to a new biomimetic platform for RNA-based therapies and/or other therapeutic cargoes useful in several diseases.

Exploring platelet-derived microvesicles in vascular regeneration: unraveling the intricate mechanisms and molecular mediators

Microvesicles (MVs) serve as biomarkers and transmitters for cell communication and also act as essential contributors to diseases. Platelets release microvesicles when activated voluntarily, making them a significant source. Platelet-derived microvesicles possess a range of characteristics similar to their parent cells and were shown to exert regulatory impacts on vascular and immunological cells. MVs can alter the activity of recipient cells by transferring their internal components. Furthermore, it has been identified that microvesicles derived from platelets possess the ability to exert immunomodulatory effects on different kinds of cells. Recent research has shown that microvesicles have a bidirectional influence of harming and preventing the receptor cells. Nevertheless, the specific characteristics of the active molecules responsible for this phenomenon are still unknown. The primary focus of this review was to explore the mechanism of vascular tissue regeneration and the specific molecules that play a role in mediating various biological effects throughout this process. These molecules exert their effects by influencing autophagy, apoptosis, and inflammatory pathways.

Nutrition, Immunity and Aging: Current Scenario and Future Perspectives in Neurodegenerative Diseases

Aging is a gradual decline of physiological function and tissue homeostasis and, in many instances, is related to increased (neuro)-degeneration, together with inflammation, becoming one of the most important risks for developing neurodegenerative diseases. Certain individual nutrients or foods in combination may counteract aging and associated neurodegenerative diseases by promoting a balance between the pro- and anti-inflammatory responses. Thus, nutrition could represent a powerful modulator of this fine balance, other than a modifiable risk factor to contrast inflammaging. This narrative review explores from a broad perspective the impact of nutrition on the hallmarks of aging and inflammation in Alzheimer's disease (AD), Parkinson's disease (PD) and Amyotrophic Lateral Sclerosis Syndrome (ALS), starting from nutrients up to single foods and complex dietary patterns.

Extracellular vesicle features are associated with COVID-19 severity

COVID-19 is heterogeneous; therefore, it is crucial to identify early biomarkers for adverse outcomes. Extracellular vesicles (EV) are involved in the pathophysiology of COVID-19 and have both negative and positive effects. The objective of this study was to identify the potential role of EV in the prognostic stratification of COVID-19 patients. A total of 146 patients with severe or critical COVID-19 were enrolled. Demographic and comorbidity characteristics were collected, together with routine haematology, blood chemistry and lymphocyte subpopulation data. Flow cytometric characterization of the dimensional and antigenic properties of COVID-19 patients' plasma EVs was conducted. Elastic net logistic regression with cross-validation was employed to identify the best model for classifying critically ill patients. Features of smaller EVs (i.e. the fraction of EVs smaller than 200 nm expressing either cluster of differentiation [CD] 31, CD 140b or CD 42b), albuminemia and the percentage of monocytes expressing human leukocyte antigen DR (HLA-DR) were associated with a better outcome. Conversely, the proportion of larger EVs expressing N-cadherin, CD 34, CD 56, CD31 or CD 45, interleukin 6, red cell width distribution (RDW), N-terminal pro-brain natriuretic peptide (NT-proBNP), age, procalcitonin, Charlson Comorbidity Index and pro-adrenomedullin were associated with disease severity. Therefore, the simultaneous assessment of EV dimensions and their antigenic properties complements laboratory workup and helps in patient stratification.

Circulating endothelial extracellular vesicle signatures correspond with ICU requirement: an exploratory study in COVID-19 patients

Extracellular vesicles (EVs) represent nanometer-sized, subcellular spheres, that are released from almost any cell type and carry a wide variety of biologically relevant cargo. In severe cases of coronavirus disease 2019 (COVID-19) and other states of systemic pro-inflammatory activation, EVs, and their cargo can serve as conveyors and indicators for disease severity and progression. This information may help distinguish individuals with a less severe manifestation of the disease from patients who exhibit severe acute respiratory distress syndrome (ARDS) and require intensive care measures. Here, we investigated the potential of EVs and associated miRNAs to distinguish normal ward patients from intensive care unit (ICU) patients (N = 10/group), with 10 healthy donors serving as the control group. Blood samples from which plasma and subsequently EVs were harvested by differential ultracentrifugation (UC) were obtained at several points in time throughout treatment. EV-enriched fractions were characterized by flow cytometry (FC), nanoparticle tracking analysis (NTA), and qPCR to determine the presence of selected miRNAs. Circulating EVs showed specific protein signatures associated with endothelial and platelet origin over the course of the treatment. Additionally, significantly higher overall EV quantities corresponded with increased COVID-19 severity. MiR-223-3p, miR-191-5p, and miR-126-3p exhibited higher relative expression in the ICU group. Furthermore, EVs presenting endothelial-like protein signatures and the associated miR-126-3p showed the highest area under the curve in terms of receiver operating characteristics regarding the requirement for ICU treatment. In this exploratory investigation, we report that specific circulating EVs and miRNAs appear at higher levels in COVID-19 patients, especially when critical care measures are indicated. Our data suggest that endothelial-like EVs and associated miRNAs likely represent targets for future laboratory assays and may aid in clinical decision-making in COVID-19.

Expression of Tissue Factor and Platelet/Leukocyte Markers on Extracellular Vesicles Reflect Platelet-Leukocyte Interaction in Severe COVID-19

Severe COVID-19 is frequently associated with thromboembolic complications. Increased platelet activation and platelet-leukocyte aggregate formation can amplify thrombotic responses by inducing tissue factor (TF) expression on leukocytes. Here, we characterized TF-positive extracellular vesicles (EVs) and their cellular origin in 12 patients suffering from severe COVID-19 (time course, 134 samples overall) and 25 healthy controls. EVs exposing phosphatidylserine (PS) were characterized by flow cytometry. Their cellular origin was determined by staining with anti-CD41, anti-CD45, anti-CD235a, and anti-CD105 as platelet, leukocyte, red blood cell, and endothelial markers. We further investigated the association of EVs with TF, platelet factor 4 (PF4), C-reactive protein (CRP), and high mobility group box-1 protein (HMGB-1). COVID-19 patients showed higher levels of PS-exposing EVs compared to controls. The majority of these EVs originated from platelets. A higher amount of EVs in patient samples was associated with CRP, HMGB-1, PF4, and TF as compared to EVs from healthy donors. In COVID-19 samples, 16.5% of all CD41+ EVs displayed the leukocyte marker CD45, and 55.5% of all EV aggregates (CD41+CD45+) co-expressed TF, which reflects the interaction of platelets and leukocytes in COVID-19 on an EV level.

Genomic communication via circulating extracellular vesicles and long-term health consequences of COVID-19

COVID-19 continues to affect an unprecedented number of people with the emergence of new variants posing a serious challenge to global health. There is an expansion of knowledge in understanding the pathogenesis of Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and the impact of the acute disease on multiple organs. In addition, growing evidence reports that the impact of COVID-19 on different organs persists long after the recovery phase of the disease, leading to long-term consequences of COVID-19. These long-term consequences involve pulmonary as well as extra-pulmonary sequelae of the disease. Noteably, recent research has shown a potential association between COVID-19 and change in the molecular cargo of extracellular vesicles (EVs). EVs are vesicles released by cells and play an important role in cell communication by transfer of bioactive molecules between cells. Emerging evidence shows a strong link between EVs and their molecular cargo, and regulation of metabolism in health and disease. This review focuses on current knowledge about EVs and their potential role in COVID-19 pathogenesis, their current and future implications as tools for biomarker and therapeutic development and their possible effects on long-term impact of COVID-19.

Advanced extracellular vesicle bioinformatic nanomaterials: from enrichment, decoding to clinical diagnostics

Extracellular vesicles (EVs) are membrane nanoarchitectures generated by cells that carry a variety of biomolecules, including DNA, RNA, proteins and metabolites. These characteristics make them attractive as circulating bioinformatic nanocabinets for liquid biopsy. Recent advances on EV biology and biogenesis demonstrate that EVs serve as highly important cellular surrogates involved in a wide range of diseases, opening up new frontiers for modern diagnostics. However, inefficient methods for EV enrichment, as well as low sensitivity of EV bioinformatic decoding technologies, hinder the use of EV nanocabinet for clinical diagnosis. To overcome these challenges, new EV nanotechnology is being actively developed to promote the clinical translation of EV diagnostics. This article aims to present the emerging enrichment strategies and bioinformatic decoding platforms for EV analysis, and their applications as bioinformatic nanomaterials in clinical settings.

Extracellular Vesicles as a Translational Approach for the Treatment of COVID-19 Disease: An Updated Overview

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused a global pandemic in the years 2020-2022. With a high prevalence, an easy route of transmission, and a long incubation time, SARS-CoV-2 spread quickly and affected public health and socioeconomic conditions. Several points need to be elucidated about its mechanisms of infection, in particular, its capability to evade the immune system and escape from neutralizing antibodies. Extracellular vesicles (EVs) are phospholipid bilayer-delimited particles that are involved in cell-to-cell communication; they contain biological information such as miRNAs, proteins, nucleic acids, and viral components. Abundantly released from biological fluids, their dimensions are highly variable, which are used to divide them into exosomes (40 to 150 nm), microvesicles (40 to 10,000 nm), and apoptotic bodies (100-5000 nm). EVs are involved in many physiological and pathological processes. In this article, we report the latest evidence about EVs' roles in viral infections, focusing on the dual role of exosomes in promoting and inhibiting SARS-CoV-2 infection. The involvement of mesenchymal stromal/stem cells (MSCs) and MSC-derived EVs in COVID-19 treatment, such as the use of translational exosomes as a diagnostical/therapeutic approach, is also investigated. These elucidations could be useful to better direct the discovery of future diagnostical tools and new exosome-derived COVID-19 biomarkers, which can help achieve optimal therapeutic interventions and implement future vaccine strategies.

Platelet-derived extracellular vesicles for drug delivery

Platelet-derived extracellular vesicles (PEVs) are a subset of EVs that are released from platelets, which are small nuclear cell fragments that play a critical role in hemostasis and thrombosis. PEVs have been shown to have important roles in a variety of physiological and pathological processes, including inflammation, angiogenesis, and cancer. Recently, researchers, including our group have utilized PEVs as drug delivery platforms as PEVs could target inflammatory sites both passively and actively. This review summarizes the biological function of PEVs, introduces recent applications of PEVs in targeted drug delivery, and provides an outlook for the further development of utilizing PEVs for drug delivery.

Diagnosis of genitourinary tuberculosis: detection of mycobacterial lipoarabinomannan and MPT-64 biomarkers within urine extracellular vesicles by nano-based immuno-PCR assay

We detected a cocktail of Mycobacterium tuberculosis lipoarabinomannan (LAM) and MPT-64 biomarkers within urine extracellular vesicles (EVs) of genitourinary TB (GUTB) patients by nano-based immuno-PCR (I-PCR) assay, i.e., magnetic bead-coupled gold nanoparticle-based I-PCR (MB-AuNP-I-PCR) and compared the results with I-PCR and Magneto-ELISA. The size (s) of urine EVs ranged between 52.6 and 220.4 nm as analyzed by transmission electron microscopy (TEM) and nanoparticle tracking analysis. Functionalized AuNPs (coupled with detection antibodies/oligonucleotides) were characterized by UV-vis spectroscopy, TEM, ELISA, PCR, Atomic Force Microscopy and Fourier Transform Infrared spectroscopy, while conjugation of capture antibodies with MBs was validated by UV-vis spectroscopy and Magneto-ELISA. Our MB-AuNP-I-PCR exhibited sensitivities of 85% and 87.2% in clinically suspected (n = 40) and total (n = 47) GUTB cases, respectively, with 97.1% specificity in non-TB controls (n = 35). These results were further authenticated by the quantitative SYBR Green MB-AuNP-real-time I-PCR (MB-AuNP-RT-I-PCR). Concurrently, I-PCR and Magneto-ELISA showed sensitivities of 68.1% and 61.7%, respectively in total GUTB cases, which were significantly lower (p < 0.05-0.01) than MB-AuNP-I-PCR. Markedly, a wide range (400 fg/mL-11 ng/mL) of LAM+MPT-64 was quantified within urine EVs of GUTB cases by SYBR Green MB-AuNP-RT-I-PCR, which can assess the disease dynamics. This study will certainly improve the current algorithms used in GUTB diagnostics.

[Exosomes in the life cycle of viruses and the pathogenesis of viral infections]

Exosomes are extracellular vesicles of endosomal origin, with a bilayer membrane, 30160 nm in diameter. Exosomes are released from cells of different origins and are detected in various body fluids. They contain nucleic acids, proteins, lipids, metabolites and can transfer the contents to recipient cells. Exosome biogenesis involves cellular proteins of the Rab GTPase family and the ESCRT system, which regulate budding, vesicle transport, molecule sorting, membrane fusion, formation of multivesicular bodies and exosome secretion. Exosomes are released from cells infected with viruses and may contain viral DNA and RNA, as well as mRNA, microRNA, other types of RNA, proteins and virions. Exosomes are capable of transferring viral components into uninfected cells of various organs and tissues. This review analyzes the impact of exosomes on the life cycle of widespread viruses that cause serious human diseases: human immunodeficiency virus (HIV-1), hepatitis B virus, hepatitis C virus, SARS-CoV-2. Viruses are able to enter cells by endocytosis, use molecular and cellular pathways involving Rab and ESCRT proteins to release exosomes and spread viral infections. It has been shown that exosomes can have multidirectional effects on the pathogenesis of viral infections, suppressing or enhancing the course of diseases. Exosomes can potentially be used in noninvasive diagnostics as biomarkers of the stage of infection, and exosomes loaded with biomolecules and drugs - as therapeutic agents. Genetically modified exosomes are promising candidates for new antiviral vaccines.

The Long Journey of Extracellular Vesicles towards Global Scientific Acclamation

Extracellular vesicles (EVs) are a heterogeneous class of cell-derived vesicles that are responsible for eliciting a wide array of biological processes. After decades of intense investigation, the therapeutic potential of EVs will be finally explored in a series of upcoming clinical trials. EVs are rapidly changing the understanding of human physiology and will undoubtedly transform the field of medicine. The applicability of EVs as diagnostic biomarkers and treatment vectors has captured the attention of the scientific community and investors, facilitating the rapid progression of numerous EVs-based platforms. This mini-review provides an outline of the pioneering discoveries, and their respective significances, on progressing EVs toward clinical use. We focus the attention of the readers on several promising classes of EVs that hold major opportunities to translate in clinical practice. Market analysis and future challenges facing EVs-based therapies are also discussed.

Long-term hypercoagulability, endotheliopathy and inflammation following acute SARS-CoV-2 infection

INTRODUCTION

both symptomatic and asymptomatic SARS-CoV-2 infections - coined Coronavirus disease 2019 (COVID-19) - have been linked to a higher risk of cardiovascular events after recovery.

AREAS COVERED

our review aims to summarize the latest evidence on the increased thrombotic and cardiovascular risk in recovered COVID-19 patients and to examine the pathophysiological mechanisms underlying the interplay among endothelial dysfunction, inflammatory response and coagulation in long-COVID. We performed a systematic search of studies on hypercoagulability, endothelial dysfunction and inflammation after SARS-CoV-2 infection.

EXPERT OPINION

endothelial dysfunction is a major pathophysiological mechanism responsible for most clinical manifestations in COVID-19. The pathological activation of endothelial cells by a virus infection results in a pro-adhesive and chemokine-secreting phenotype, which in turn promotes the recruitment of circulating leukocytes. Cardiovascular events after COVID-19 appear to be related to persistent immune dysregulation. Patients with long-lasting symptoms display higher amounts of proinflammatory molecules such as tumor necrosis factor-α, interferon γ and interleukins 2 and 6. Immune dysregulation can trigger the activation of the coagulation pathway. The formation of extensive microclots in vivo, both during acute COVID-19 and in long-COVID-19, appears to be a relevant mechanism responsible for persistent symptoms and cardiovascular events.

Shedding Light on the Cell Biology of Platelet-Derived Extracellular Vesicles and Their Biomedical Applications

EVs are membranous subcellular structures originating from various cells, including platelets which consist of biomolecules that can modify the target cell's pathophysiological functions including inflammation, cell communication, coagulation, and metastasis. EVs, which are known to allow the transmission of a wide range of molecules between cells, are gaining popularity in the fields of subcellular treatment, regenerative medicine, and drug delivery. PEVs are the most abundant EVs in circulation, being produced by platelet activation, and are considered to have a significant role in coagulation. PEV cargo is extremely diverse, containing lipids, proteins, nucleic acids, and organelles depending on the condition that induced their release and can regulate a wide range of biological activities. PEVs, unlike platelets, can overcome tissue barriers, allowing platelet-derived contents to be transferred to target cells and organs that platelets cannot reach. Their isolation, characterization, and therapeutic efficacy, on the other hand, are poorly understood. This review summarizes the technical elements of PEV isolation and characterization methods as well as the pathophysiological role of PEVs, including therapeutic potential and translational possibility in diverse disciplines.

Uncoupling of platelet granule release and integrin activation suggests GPIIb/IIIa as a therapeutic target in COVID-19

Thromboembolic events are frequent and life-threating complications of COVID-19 but are also observed in patients with sepsis. Disseminated thrombosis can occur despite anticoagulation, suggesting that platelets play a direct but incompletely understood role. Several studies demonstrated altered platelet function in COVID-19 with some controversial findings, while underlying disease-specific mechanisms remain ill defined. We performed a comprehensive cohort study with 111 patients, comprising 37 with COVID-19, 46 with sepsis, and 28 with infection, compared with control participants. Platelet phenotype and function were assessed under static and flow conditions, revealing unexpected disease-specific differences. From hospital admission onward, platelets in COVID-19 failed to activate the integrin glycoprotein IIb/IIa (GPIIb/IIIa) in response to multiple agonists. Dense granule release was markedly impaired due to virtually missing granules, also demonstrated by whole-mount electron microscopy. By contrast, α-granule marker CD62P exposure was only mildly affected, revealing a subpopulation of PAC-1-/CD62P+ platelets, independently confirmed by automated clustering. This uncoupling of α-granule release was not observed in patients with sepsis, despite a similar disease severity. We found overall unaltered thrombus formation in COVID-19 and sepsis samples under venous shear rates, which was dependent on the presence of tissue factor. Unexpectedly, under arterial shear rates, thrombus formation was virtually abrogated in sepsis, whereas we detected overall normal-sized and stable thrombi in blood from patients with COVID-19. These thrombi were susceptible to subthreshold levels of GPIIb/IIIa blockers, eptifibatide, or tirofiban that had only a minor effect in control participants' blood. We provide evidence that low-dose GPIIb/IIIa blockade could be a therapeutic approach in COVID-19.

Annexin-V positive extracellular vesicles level is increased in severe COVID-19 disease

Objectives

To evaluate extracellular vesicles levels in a cohort of SARS-CoV-2's patients hospitalized in an intensive care unit with and without COVID-19 associated thromboembolic events.

Methods

In this study, we aim to assess endothelial and platelet membrane-derived extracellular vesicles levels in a cohort of SARS-CoV-2 patients with and without COVID-19-associated thromboembolic events who were hospitalized in an intensive care unit. Annexin-V positive extracellular vesicles levels were prospectively assessed by flow cytometry in one hundred twenty-three critically ill adults diagnosed with acute respiratory distress syndrome associated with a SARS-CoV-2 infection, ten adults diagnosed for moderate SARS-CoV-2 infection and 25 healthy volunteers.

Results

On our critically ill patients, thirty-four patients (27.6%) had a thromboembolic event, Fifty-three (43%) died. Endothelial and platelet membrane-derived extracellular vesicles were drastically increased in SARS-CoV-2 patients hospitalized in the ICU compared to healthy volunteers. Moreover a slighty higher small/large ratio for platelets membrane-derived extracellular vesicles in patients was linked to thrombo-embolic events.

Conclusion

A comparison between total annexin-V positive extracellular vesicles levels in severe and moderate SARS-CoV-2 infection and healthy controls showed a significant increase in patients with severe infection and their sizes could be considered as biomarkers of SARS-CoV-2 associated thrombo-embolic events.

Severe Acute Respiratory Syndrome Coronavirus 2 Vasculopathy in a Syrian Golden Hamster Model

Clinical evidence of vascular dysfunction and hypercoagulability as well as pulmonary vascular damage and microthrombosis are frequently reported in severe cases of human coronavirus disease 2019 (COVID-19). Syrian golden hamsters recapitulate histopathologic pulmonary vascular lesions reported in patients with COVID-19. Herein, special staining techniques and transmission electron microscopy further define vascular pathologies in a Syrian golden hamster model of human COVID-19. The results show that regions of active pulmonary inflammation in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection are characterized by ultrastructural evidence of endothelial damage with platelet marginalization and both perivascular and subendothelial macrophage infiltration. SARS-CoV-2 antigen/RNA was not detectable within affected blood vessels. Taken together, these findings suggest that the prominent microscopic vascular lesions in SARS-CoV-2-inoculated hamsters likely occur due to endothelial damage followed by platelet and macrophage infiltration.

Circulating Extracellular Vesicle Levels in Patients with Coronavirus Disease 2019 Coagulopathy: A Prospective Cohort Study

Coronavirus disease 2019 (COVID-19) is associated with coagulopathy. However, the underlying mechanisms are not completely understood. We evaluated the association between COVID-19 coagulopathy and extracellular vesicle (EV) levels. We hypothesized that several EV levels would be higher in COVID-19 coagulopathy patients than in non-coagulopathy patients. This prospective observational study was conducted in four tertiary care faculties in Japan. We enrolled 99 COVID-19 patients (48 with coagulopathy and 51 without coagulopathy) aged ≥20 years who required hospitalization, and 10 healthy volunteers; we divided the patients into coagulopathy and non-coagulopathy groups according to the D-dimer levels (≥1 μg/mL and <1 μg/mL, respectively). We used flow cytometry to measure the tissue-factor-bearing, endothelium-derived, platelet-derived, monocyte-derived, and neutrophil-derived EV levels in platelet-free plasma. The EV levels were compared between the two COVID-19 groups as well as among the coagulopathy patients, non-coagulopathy patients, and healthy volunteers. No significant difference was found in EV levels between the two groups. Meanwhile, the cluster of differentiation (CD) 41 + EV levels were significantly higher in COVID-19 coagulopathy patients than in healthy volunteers (549.90 [255.05-984.65] vs. 184.3 [150.1-254.1] counts/µL, p = 0.011). Therefore, CD41+ EVs might play an essential role in COVID-19 coagulopathy development.

Effect of Genetic Factors, Age and Sex on Levels of Circulating Extracellular Vesicles and Platelets

Extracellular vesicles (EVs) mediate cell interactions in biological processes, such as receptor activation or molecule transfer. Estimates of variation by age and sex have been limited by small sample size, and no report has assessed the contribution of genetic factors to levels of EVs. Here, we evaluated blood levels of 25 EV and 3 platelet traits in 974 individuals (933 genotyped) and reported the first genome-wide association study (GWAS) on levels of these traits. EV levels all decreased with age, whereas the trend for their surface markers was more heterogeneous. Platelets and CD31dim platelet EVs significantly increased in females compared to males, although CD31 expression on both platelets and platelet EVs decreased in females. Levels of the other EV subsets were similar between sexes. GWAS revealed three statistically significant genetic signals associated with EV levels in the F10 and GBP1 genes and in the intergenic region between LRIG1 and KBTBD8. These add to a signal in the 3'UTR of RHOF associated with CD31 expression on platelets that was previously found to be associated with other platelet traits. These findings suggest that EV formation is not a simple, constant adjunct of metabolism but is under both age-related and genetic control that can be independent of the regulation of the levels of the cells from which the EVs derive.

Extracellular vesicles in COVID-19 prognosis, treatment, and vaccination: an update

The lethality of the COVID 19 pandemic became the trigger for one of the most meteoric races on record in the search for strategies of disease control. Those include development of rapid and sensitive diagnostic methods, therapies to treat severe cases, and development of anti-SARS-CoV-2 vaccines, the latter responsible for the current relative control of the disease. However, the commercially available vaccines are still far from conferring protection against acquiring the infection, so the development of more efficient vaccines that can cut the transmission of the variants of concerns that currently predominate and those that will emerge is a prevailing need. On the other hand, considering that COVID 19 is here to stay, the development of new diagnosis and treatment strategies is also desirable. In this sense, there has recently been a great interest in taking advantage of the benefits offered by extracellular vesicles (EVs), membrane structures of nanoscale size that carry information between cells participating in this manner in many physiological homeostatic and pathological processes. The interest has been focused on the fact that EVs are relatively easy to obtain and manipulate, allowing the design of natural nanocarriers that deliver molecules of interest, as well as the information about the pathogens, which can be exploited for the aforementioned purposes. Studies have shown that infection with SARS-CoV-2 induces the release of EVs from different sources, including platelets, and that their increase in blood, as well as some of their markers, could be used as a prognosis of disease severity. Likewise, EVs from different sources are being used as the ideal carriers for delivering active molecules and drugs to treat the disease, as well as vaccine antigens. In this review, we describe the progress that has been made in these three years of pandemic regarding the use of EVs for diagnosis, treatment, and vaccination against SARS-CoV-2 infection. KEY POINTS: • Covid-19 still requires more effective and specific treatments and vaccines. • The use of extracellular vesicles is emerging as an option with multiple advantages. • Association of EVs with COVID 19 and engineered EVs for its control are presented.

Platelets, Protean Cells with All-Around Functions and Multifaceted Pharmacological Applications

Platelets, traditionally known for their roles in hemostasis and coagulation, are the most prevalent blood component after erythrocytes (150,000-400,000 platelets/μL in healthy humans). However, only 10,000 platelets/μL are needed for vessel wall repair and wound healing. Increased knowledge of the platelet's role in hemostasis has led to many advances in understanding that they are crucial mediators in many other physiological processes, such as innate and adaptive immunity. Due to their multiple functions, platelet dysfunction is involved not only in thrombosis, mediating myocardial infarction, stroke, and venous thromboembolism, but also in several other disorders, such as tumors, autoimmune diseases, and neurodegenerative diseases. On the other hand, thanks to their multiple functions, nowadays platelets are therapeutic targets in different pathologies, in addition to atherothrombotic diseases; they can be used as an innovative drug delivery system, and their derivatives, such as platelet lysates and platelet extracellular vesicles (pEVs), can be useful in regenerative medicine and many other fields. The protean role of platelets, from the name of Proteus, a Greek mythological divinity who could take on different shapes or aspects, is precisely the focus of this review.

In-Depth Proteomic Analysis of Blood Circulating Small Extracellular Vesicles

Circulating small extracellular vesicles (sEVs), also called exosomes, are key players in the investigation of cell-cell communication mechanisms and in the identification of new potential biomarkers. These particles can carry proteins, DNA, mRNA, miRNA, lipids and metabolites that are transported all over the human body, potentially reaching all the cells. In particular, proteins, which are well-known biological actors in cell signalling, will be discussed in this context. In this article, we present a mass spectrometry approach for the in-depth characterization of the sEVs proteome. The protocols include strategies for the isolation and purification of sEVs, for the extraction of proteins and the purification of sEVs proteins by the immunodepletion of the most abundant plasmatic proteins. Finally, bioinformatic analysis for the extraction of the most important biological features associated with the proteomic content of sEVs is reported.

Conventional and Novel Diagnostic Tools for the Diagnosis of Emerging SARS-CoV-2 Variants

Accurate identification at an early stage of infection is critical for effective care of any infectious disease. The "coronavirus disease 2019 (COVID-19)" outbreak, caused by the virus "Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2)", corresponds to the current and global pandemic, characterized by several developing variants, many of which are classified as variants of concern (VOCs) by the "World Health Organization (WHO, Geneva, Switzerland)". The primary diagnosis of infection is made using either the molecular technique of RT-PCR, which detects parts of the viral genome's RNA, or immunodiagnostic procedures, which identify viral proteins or antibodies generated by the host. As the demand for the RT-PCR test grew fast, several inexperienced producers joined the market with innovative kits, and an increasing number of laboratories joined the diagnostic field, rendering the test results increasingly prone to mistakes. It is difficult to determine how the outcomes of one unnoticed result could influence decisions about patient quarantine and social isolation, particularly when the patients themselves are health care providers. The development of point-of-care testing helps in the rapid in-field diagnosis of the disease, and such testing can also be used as a bedside monitor for mapping the progression of the disease in critical patients. In this review, we have provided the readers with available molecular diagnostic techniques and their pitfalls in detecting emerging VOCs of SARS-CoV-2, and lastly, we have discussed AI-ML- and nanotechnology-based smart diagnostic techniques for SARS-CoV-2 detection.

Dissecting Platelet's Role in Viral Infection: A Double-Edged Effector of the Immune System

Platelets play a major role in the processes of primary hemostasis and pathological inflammation-induced thrombosis. In the mid-2000s, several studies expanded the role of these particular cells, placing them in the "immune continuum" and thus changing the understanding of their function in both innate and adaptive immune responses. Among the many receptors they express on their surface, platelets express Toll-Like Receptors (TLRs), key receptors in the inflammatory cell-cell reaction and in the interaction between innate and adaptive immunity. In response to an infectious stimulus, platelets will become differentially activated. Platelet activation is variable depending on whether platelets are activated by a hemostatic or pathogen stimulus. This review highlights the role that platelets play in platelet modulation count and adaptative immune response during viral infection.

Extracellular Vesicles: New Players in the Mechanisms of Sepsis- and COVID-19-Related Thromboinflammation

Sepsis and COVID-19 patients often manifest an imbalance in inflammation and coagulation, a complex pathological mechanism also named thromboinflammation, which strongly affects patient prognosis. Extracellular vesicles (EVs) are nanoparticles released by cells into extracellular space that have a relevant role in cell-to-cell communication. Recently, EVs have been shown to act as important players in a variety of pathologies, including cancer and cardiovascular disease. The biological properties of EVs in the mechanisms of thromboinflammation during sepsis and COVID-19 are still only partially known. Herein, we summarize the current experimental evidence on the role of EVs in thromboinflammation, both in bacterial sepsis and in COVID-19. A better understanding of EV involvement in these processes could be useful in describing novel diagnostic and therapeutic applications of EVs in these diseases.

Extracellular vesicles from human plasma for biomarkers discovery: Impact of anticoagulants and isolation techniques

Extracellular vesicles (EVs) isolated from plasma are increasingly recognized as promising circulating biomarkers for disease discovery and progression, as well as for therapeutic drug delivery. The scientific community underlined the necessity of standard operative procedures for the isolation and storage of the EVs to ensure robust results. The understanding of the impact of the pre-analytical variables is still limited and some considerations about plasma anticoagulants and isolation methods are necessary. Therefore, we performed a comparison study between EVs isolated by ultracentrifugation and by affinity substrate separation from plasma EDTA and sodium citrate. The EVs were characterized by Nano Tracking Analysis, Western Blot, cytofluorimetric analysis of surface markers, and lipidomic analysis. While anticoagulants did not significantly alter any of the analyzed parameters, the isolation methods influenced EVs size, purity, surface markers expression and lipidomic profile. Compared to ultracentrifugation, affinity substrate separation yielded bigger particles highly enriched in tetraspanins (CD9, CD63, CD81), fatty acids and glycerolipids, with a predominant LDL- and vLDL-like contamination. Herein, we highlighted that the isolation method should be carefully evaluated prior to study design and the need of standardized operative procedures for EVs isolation and application to biomarkers discovery.

Flow Cytometry Analysis of IL-1 Receptors and Toll-Like Receptors on Platelets and Platelet-Derived Extracellular Vesicles

Flow cytometry is largely used for the immunophenotyping and quantification of several cell types or related components including platelets and extracellular vesicles. Platelets and platelet-derived extracellular vesicles (PEVs) are receiving increased interest in inflammatory diseases including sepsis. Thus, in this chapter, we will describe protocols for the flow cytometry analysis of platelets, platelet/neutrophils hetero aggregates, and PEVs mainly focusing on the evaluation of the surface expression of some IL-1 receptor (ILR) and Toll-like receptor (TLR) family members.

Circulating extracellular particles from severe COVID-19 patients show altered profiling and innate lymphoid cell-modulating ability

Introduction

Extracellular vesicles (EVs) and particles (EPs) represent reliable biomarkers for disease detection. Their role in the inflammatory microenvironment of severe COVID-19 patients is not well determined. Here, we characterized the immunophenotype, the lipidomic cargo and the functional activity of circulating EPs from severe COVID-19 patients (Co-19-EPs) and healthy controls (HC-EPs) correlating the data with the clinical parameters including the partial pressure of oxygen to fraction of inspired oxygen ratio (PaO2/FiO2) and the sequential organ failure assessment (SOFA) score.

Methods

Peripheral blood (PB) was collected from COVID-19 patients (n=10) and HC (n=10). EPs were purified from platelet-poor plasma by size exclusion chromatography (SEC) and ultrafiltration. Plasma cytokines and EPs were characterized by multiplex bead-based assay. Quantitative lipidomic profiling of EPs was performed by liquid chromatography/mass spectrometry combined with quadrupole time-of-flight (LC/MS Q-TOF). Innate lymphoid cells (ILC) were characterized by flow cytometry after co-cultures with HC-EPs or Co-19-EPs.

Results

We observed that EPs from severe COVID-19 patients: 1) display an altered surface signature as assessed by multiplex protein analysis; 2) are characterized by distinct lipidomic profiling; 3) show correlations between lipidomic profiling and disease aggressiveness scores; 4) fail to dampen type 2 innate lymphoid cells (ILC2) cytokine secretion. As a consequence, ILC2 from severe COVID-19 patients show a more activated phenotype due to the presence of Co-19-EPs.

Discussion

In summary, these data highlight that abnormal circulating EPs promote ILC2-driven inflammatory signals in severe COVID-19 patients and support further exploration to unravel the role of EPs (and EVs) in COVID-19 pathogenesis.

Coagulation potential and the integrated omics of extracellular vesicles from COVID-19 positive patient plasma

Extracellular vesicles (EVs) participate in cell-to-cell communication and contribute toward homeostasis under physiological conditions. But EVs can also contribute toward a wide array of pathophysiology like cancer, sepsis, sickle cell disease, and thrombotic disorders. COVID-19 infected patients are at an increased risk of aberrant coagulation, consistent with elevated circulating levels of ultra-high molecular weight VWF multimers, D-dimer and procoagulant EVs. The role of EVs in COVID-19 related hemostasis may depend on cells of origin, vesicular cargo and size, however this is not well defined. We hypothesized that the procoagulant potential of EV isolates from COVID-19 (+) patient plasmas could be defined by thrombin generation assays. Here we isolated small EVs (SEVs) and large EVs (LEVs) from hospitalized COVID-19 (+) patient (n = 21) and healthy donor (n = 20) plasmas. EVs were characterized by flow cytometry, Transmission electron microscopy, nanoparticle tracking analysis, plasma thrombin generation and a multi-omics approach to define coagulation potential. These data were consistent with differences in EV metabolite, lipid, and protein content when compared to healthy donor plasma isolated SEVs and LEVs. Taken together, the effect of EVs on plasma procoagulant potential as defined by thrombin generation and supported by multi-omics is enhanced in COVID-19. Further, we observe that this effect is driven both by EV size and phosphatidyl serine.

Circulating Extracellular Vesicles Are Increased in Newly Diagnosed Celiac Disease Patients

Extracellular vesicles (EVs) are a class of circulating entities that are involved in intercellular crosstalk mechanisms, participating in homeostasis maintenance, and diseases. Celiac disease is a gluten-triggered immune-mediated disorder, characterized by the inflammatory insult of the enteric mucosa following local lymphocytic infiltration, resulting in villous atrophy. The goal of this research was the assessment and characterization of circulating EVs in celiac disease patients, as well as in patients already on an adequate gluten-free regimen (GFD). For this purpose, a novel and validated technique based on polychromatic flow cytometry that allowed the identification and enumeration of different EV sub-phenotypes was applied. The analysis evidenced that the total, annexin V+, leukocyte (CD45+), and platelet (CD41a+) EV counts were significantly higher in both newly diagnosed celiac disease patients and patients under GFD compared with the healthy controls. Endothelial-derived (CD31+) and epithelial-derived (EpCAM+) EV counts were significantly lower in subjects under gluten exclusion than in celiac disease patients, although EpCAM+ EVs maintained higher counts than healthy subjects. The numbers of EpCAM+ EVs were a statistically significant predictor of intraepithelial leukocytes (IEL). These data demonstrate that EVs could represent novel and potentially powerful disease-specific biomarkers in the context of celiac disease.

Meet changes with constancy: Defence, antagonism, recovery, and immunity roles of extracellular vesicles in confronting SARS-CoV-2

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has wrought havoc on the world economy and people's daily lives. The inability to comprehensively control COVID-19 is due to the difficulty of early and timely diagnosis, the lack of effective therapeutic drugs, and the limited effectiveness of vaccines. The body contains billions of extracellular vesicles (EVs), which have shown remarkable potential in disease diagnosis, drug development, and vaccine carriers. Recently, increasing evidence has indicated that EVs may participate or assist the body in defence, antagonism, recovery and acquired immunity against SARS-CoV-2. On the one hand, intercepting and decrypting the general intelligence carried in circulating EVs from COVID-19 patients will provide an important hint for diagnosis and treatment; on the other hand, engineered EVs modified by gene editing in the laboratory will amplify the effectiveness of inhibiting infection, replication and destruction of ever-mutating SARS-CoV-2, facilitating tissue repair and making a better vaccine. To comprehensively understand the interaction between EVs and SARS-CoV-2, providing new insights to overcome some difficulties in the diagnosis, prevention and treatment of COVID-19, we conducted a rounded review in this area. We also explain numerous critical challenges that these tactics face before they enter the clinic, and this work will provide previous 'meet change with constancy' lessons for responding to future similar public health disasters. Extracellular vesicles (EVs) provide a 'meet changes with constancy' strategy to combat SARS-CoV-2 that spans defence, antagonism, recovery, and acquired immunity. Targets for COVID-19 diagnosis, therapy, and prevention of progression may be found by capture of the message decoding in circulating EVs. Engineered and biomimetic EVs can boost effects of the natural EVs, especially anti-SARS-CoV-2, targeted repair of damaged tissue, and improvement of vaccine efficacy.

Pathophysiological mechanisms of thrombosis in acute and long COVID-19

COVID-19 patients have a high incidence of thrombosis, and thromboembolic complications are associated with severe COVID-19 and high mortality. COVID-19 disease is associated with a hyper-inflammatory response (cytokine storm) mediated by the immune system. However, the role of the inflammatory response in thrombosis remains incompletely understood. In this review, we investigate the crosstalk between inflammation and thrombosis in the context of COVID-19, focusing on the contributions of inflammation to the pathogenesis of thrombosis, and propose combined use of anti-inflammatory and anticoagulant therapeutics. Under inflammatory conditions, the interactions between neutrophils and platelets, platelet activation, monocyte tissue factor expression, microparticle release, and phosphatidylserine (PS) externalization as well as complement activation are collectively involved in immune-thrombosis. Inflammation results in the activation and apoptosis of blood cells, leading to microparticle release and PS externalization on blood cells and microparticles, which significantly enhances the catalytic efficiency of the tenase and prothrombinase complexes, and promotes thrombin-mediated fibrin generation and local blood clot formation. Given the risk of thrombosis in the COVID-19, the importance of antithrombotic therapies has been generally recognized, but certain deficiencies and treatment gaps in remain. Antiplatelet drugs are not in combination with anticoagulant treatments, thus fail to dampen platelet procoagulant activity. Current treatments also do not propose an optimal time for anticoagulation. The efficacy of anticoagulant treatments depends on the time of therapy initiation. The best time for antithrombotic therapy is as early as possible after diagnosis, ideally in the early stage of the disease. We also elaborate on the possible mechanisms of long COVID thromboembolic complications, including persistent inflammation, endothelial injury and dysfunction, and coagulation abnormalities. The above-mentioned contents provide therapeutic strategies for COVID-19 patients and further improve patient outcomes.

Understanding Molecular Actors of SARS-CoV-2 Virulence to Tackle COVID-19 Outbreak

COVID-19 (coronavirus disease 2019) is a threatening disease caused by the novel enveloped, positive-sense, single-stranded RNA beta-coronavirus, denoted as SARS-CoV-2 [...].

Thrombotic storm in coronavirus disease 2019: from underlying mechanisms to its management

Introduction. Coronavirus disease 2019 (COVID-19) identified in December 2019 in Wuhan, China, is associated with high mortality rates worldwide.Hypothesis/Gap Statement. Thrombotic problems, such as coagulopathy, are common in COVID-19 patients. Despite anticoagulation, thrombosis is more common in patients in the intensive care unit and patients with more severe disease. Although the exact mechanisms of coagulopathy in COVID-19 patients are still unclear, studies showed that overactivation of the renin-angiotensin system (RAS), cytokine storm, endothelial damage, formation of neutrophil extracellular traps (NETs), and also extracellular vesicles (EVs) in response to COVID-19 induced inflammation can lead to systemic coagulation and thrombosis.Aim. The management of COVID-19 patients requires the use of basic and readily available laboratory markers, both on admission and during hospitalization. Because it is critical to understand the pathophysiology of COVID-19 induced coagulopathy and treatment strategies, in this review we attempt to explain the underlying mechanism of COVID-19 coagulopathy, its diagnosis, and the associated successful treatment strategies.Conclusion. The exact mechanisms behind COVID-19-related coagulopathy are still unclear, but several studies revealed some mechanisms. More research is needed to determine the best anticoagulant regimen and to study other therapeutic options.

EV-ADD, a database for EV-associated DNA in human liquid biopsy samples

Extracellular vesicles (EVs) play a key role in cellular communication both in physiological conditions and in pathologies such as cancer. Emerging evidence has shown that EVs are active carriers of molecular cargo (e.g. protein and nucleic acids) and a powerful source of biomarkers and targets. While recent studies on EV‐associated DNA (EV‐DNA) in human biofluids have generated a large amount of data, there is currently no database that catalogues information on EV‐DNA. To fill this gap, we have manually curated a database of EV‐DNA data derived from human biofluids (liquid biopsy) and in‐vitro studies, called the Extracellular Vesicle‐Associated DNA Database (EV‐ADD). This database contains validated experimental details and data extracted from peer‐reviewed published literature. It can be easily queried to search for EV isolation methods and characterization, EV‐DNA isolation techniques, quality validation, DNA fragment size, volume of starting material, gene names and disease context. Currently, our database contains samples representing 23 diseases, with 13 different types of EV isolation techniques applied on eight different human biofluids (e.g. blood, saliva). In addition, EV‐ADD encompasses EV‐DNA data both representing the whole genome and specifically including oncogenes, such as KRAS, EGFR, BRAF, MYC, and mitochondrial DNA (mtDNA). An EV‐ADD data metric system was also integrated to assign a compliancy score to the MISEV guidelines based on experimental parameters reported in each study. While currently available databases document the presence of proteins, lipids, RNA and metabolites in EVs (e.g. Vesiclepedia, ExoCarta, ExoBCD, EVpedia, and EV‐TRACK), to the best of our knowledge, EV‐ADD is the first of its kind to compile all available EV‐DNA datasets derived from human biofluid samples. We believe that this database provides an important reference resource on EV‐DNA‐based liquid biopsy research, serving as a learning tool and to showcase the latest developments in the EV‐DNA field. EV‐ADD will be updated yearly as newly published EV‐DNA data becomes available and it is freely available at www.evdnadatabase.com.