Elevated urinary podocyte-derived extracellular microvesicles in renovascular hypertensive patients

BACKGROUND

An increased number of podocyte-derived extracellular vesicles (pEVs) may reflect podocyte injury in renal disease. Elevated glomerular pressure and other insults may injure podocytes, yet it remains unclear whether the numbers of pEVs are altered in hypertensive patients. We tested the hypothesis that urinary pEV levels would be elevated in patients with renovascular hypertension (RVH) compared with essential hypertension (EH) or healthy volunteers (HVs).

METHODS

We prospectively enrolled patients with EH ( n = 30) or RVH ( n = 31) to study renal blood flow (RBF) and cortical perfusion using multidetector computed tomography under controlled condition (regulated sodium intake and renin-angiotensin blockade). After isolation from urine samples, pEVs (nephrin and podocalyxin positive) were characterized by flow cytometry. Fourteen RVH patients were studied again 3 months after stenting or continued medical therapy. HVs ( n = 15) served as controls.

RESULTS

The fraction of pEV among urinary EVs was elevated in RVH compared with HVs and EH (11.4 ± 6.4, 6.8 ± 3.4 and 6.3 ± 3.7%, respectively; P < 0.001) and remained unchanged after 3 additional months of therapy and after controlling for clinical parameters. However, eGFR- and age-adjusted pEV levels did not correlate with any clinical or renal parameters.

CONCLUSIONS

In hypertensive patients under controlled conditions, urinary pEV levels are elevated in patients with RVH and low eGFR compared with patients with EH and relatively preserved renal function. These pEVs may reflect podocyte injury secondary to kidney damage, and their levels might represent a novel therapeutic target.

Circulating endothelial-derived apoptotic microparticles and insulin resistance in non-diabetic patients with chronic heart failure

BACKGROUND

The objective of this study was to assess the relationship between insulin resistance and apoptotic endothelial-derived microparticles (EMPs) in patients with chronic heart failure (CHF).

METHODS

The study involved 300 CHF patients (186 males) aged 48-62 years with angiographically proven coronary artery disease and/or previously defined myocardial infarction. Insulin resistance was assessed by the homeostasis model assessment for insulin resistance (HOMA-IR). EMPs phenotype was determined by flow cytofluorometry.

RESULTS

Depending on HOMA-IR cut-off point (over and <2.77 mmol/L×μU/mL) all patients were divided into two cohorts with (n=171) or without (n=129) IR, respectively. Circulating EMPs were higher in CHF patients with IR than in patients without IR. Interestingly, EMPs were directly related to NYHA functional class of CHF, HOMA-IR, NT-pro-BNP, hs-CRP and BMI. There was a significant association between the level of EMPs and HbA1c, gender (r=0.318, p<0.001 for male), age and smoking. On univariate and multivariate regression analysis we found that the NYHA class of CHF,NT-pro-BNP, hs-CRP, and left ventricular ejection fraction (LVEF) appeared to be independent predictors of increased circulatory apoptotic EMPs. The addition of HOMA-IR to the standard model (NYHA class CHF) improved the relative IDI by 19.9% for increased EMPs. For category-free NRI, 10% of events and 24% of non-events were correctly reclassified by the addition of HOMA-IR to the standard model for increased circulating EMPs.

CONCLUSIONS

IR may be a contributing factor increasing circulating levels of apoptotic EMPs in non-diabetic CHF patients.

In vitro Study of the Thrombogenic Activity of Platelet-derived Microparticles from Patients with Acute Coronary Syndrome

BACKGROUND

To observe the thrombogenic activity of platelet-derived microparticles (PMPs) in PMP-free plasma from non-coronary artery disease (non-CAD) patients and explore the relationship between PMPs and thrombosis in acute coronary syndrome (ACS) patients.

METHODS

Patients with ACS who were diagnosed at the outpatient department of cardiology in the People's Hospital of Xinjiang Uygur Autonomous Region, and non-CAD subjects were enrolled in the study from January 2011 to December 2014. Subjects were assigned to the ACS group (n=200) (which consisted of patients with acute myocardial infarction (AMI, n=100) and patients with unstable angina pectoris) (UAP, n=100), or to the non-CAD group (n=100). After informed consent was obtained from subjects, peripheral blood was collected from ACS patients and non-CAD subjects and then put into sodium citrate anticoagulant tubes. The PMPs were analyzed by flow cytometry using flow cytometry. The plasma of non-CAD patients was thawed and centrifuged to obtain MP-free plasma. MP-free plasma was placed into a black 96-well microplate at 40 μl per well. 10 μl PMP suspension containing 1×10³, 1×10⁴ or 1×10⁵ PMPs from ACS patients or non-CAD patients was added into the MP-free plasma. The coagulation reaction was induced by adding 50 μl of fluorescence-labeled thrombin substrate, and the microplate was placed into the microplate reader.

RESULTS

Compared with the PMP levels in the non-CAD patient group (40×10³), the PMPs were increased in the AMI sub-group (250×10³) and the UAP sub-group (126×10³) of the ACS patients, and the differences were statistically significant (P<0.05). The relative fluorescence intensity of the ACS group was higher than that of the non-CAD group at every time point, and the differences were of statistical significance (P<0.05). The peak thrombogenic activity of 1×10⁵, 1×10⁴, 1×10³ PMPs in ACS patients was at 6 min, 8 min, and 11 min respectively, whereas the thrombogenic activity of 1×10⁵, 1×10⁴, 1×10³ PMPs in non-CAD patients was at 16 min, 21 min, and 41 min respectively.

CONCLUSION

The levels of platelets and PMPs in ACS patients were higher than those in non-CAD patients, implying that rupture of the coronary atherosclerotic plaques led to an increase in platelets and the subsequent massive release of PMPs by the activated platelets. The plaques in the ACS patients are prone to rupture such that the platelets are in an activated state and release a large amount of PMPs, therefore promoting thrombosis.

A direct-imaging cryo-EM study of shedding extracellular vesicles from leukemic monocytes

The human leukemia monocytic cell line (THP-1) is known to shed extracellular vesicles (EVs) under various stimulations. We studied the effects of two types of common stimulation types, lipopolysaccharide (LPS) and starvation conditions by high resolution cryogenic electron microscopy, namely, cryo-SEM and cryo-TEM. Cryo-SEM data of cells undergoing EV blebbing and shedding is presented here for the first time. The high-resolution images show good agreement with models describing the membrane processes of shedding. Cells that underwent a 48-h starvation treatment exhibited differing morphological features, including shrunken nucleus and elongated membrane protrusions. LPS treated cells, however, showed extensive blebbing originating from the cell membrane, in good agreement with the sizes of EVs imaged by cryo-TEM. EVs isolated from both types of stimulations were measured by nanoparticle tracking analysis (NanoSight), by which LPS-EVs samples exhibited higher concentration and smaller mean diameter, as compared to starvation-EVs. Our results suggest a difference in the effects of the two stimulation types on the shedding process and possibly on the type of EVs shed. Our unique methodologies provide an important and innovative outlook of the shedding process and on its products, paving the way to further discoveries in this developing field of research, in which much is still unknown.

Extracellular vesicles swarm the cancer microenvironment: from tumor-stroma communication to drug intervention

Intercellular communication sets the pace for transformed cells to survive and to thrive. Extracellular vesicles (EVs), such as exosomes, microvesicles and large oncosomes, are involved in this process shuttling reciprocal signals and other molecules between transformed and stromal cells, including fibroblasts, endothelial and immune cells. As a result, these cells are adapted or recruited to a constantly evolving cancer microenvironment. Moreover, EVs take part in the response to anticancer therapeutics not least by promoting drug resistance throughout the targeted tumor. Finally, circulating EVs can also transport important molecules to remote destinations in order to prime metastatic niches in an otherwise healthy tissue. Although the understanding of EV biology remains a major challenge in the field, their characteristics create new opportunities for advances in cancer diagnostics and therapeutics.

Circulating Microvesicles Are Elevated Acutely following Major Burns Injury and Associated with Clinical Severity

Microvesicles are cell-derived signaling particles emerging as important mediators and biomarkers of systemic inflammation, but their production in severe burn injury patients has not been described. In this pilot investigation, we measured circulating microvesicle levels following severe burns, with severe sepsis patients as a comparator group. We hypothesized that levels of circulating vascular cell-derived microvesicles are elevated acutely following burns injury, mirroring clinical severity due to the early onset and prevalence of systemic inflammatory response syndrome (SIRS) in these patients. Blood samples were obtained from patients with moderate to severe thermal injury burns, with severe sepsis, and from healthy volunteers. Circulating microvesicles derived from total leukocytes, granulocytes, monocytes, and endothelial cells were quantified in plasma by flow cytometry. All circulating microvesicle subpopulations were elevated in burns patients on day of admission (day 0) compared to healthy volunteers (leukocyte-microvesicles: 3.5-fold, p = 0.005; granulocyte-microvesicles: 12.8-fold, p<0.0001; monocyte-microvesicles: 20.4-fold, p<0.0001; endothelial- microvesicles: 9.6-fold, p = 0.01), but decreased significantly by day 2. Microvesicle levels were increased with severe sepsis, but less consistently between patients. Leukocyte- and granulocyte-derived microvesicles on day 0 correlated with clinical assessment scores and were higher in burns ICU non-survivors compared to survivors (leukocyte MVs 4.6 fold, p = 0.002; granulocyte MVs 4.8 fold, p = 0.003). Mortality prediction analysis of area under receiver operating characteristic curve was 0.92 (p = 0.01) for total leukocyte microvesicles and 0.85 (p = 0.04) for granulocyte microvesicles. These findings demonstrate, for the first time, acute increases in circulating microvesicles following burns injury in patients and point to their potential role in propagation of sterile SIRS-related pathophysiology.

The secretome of periodontal ligament stem cells from MS patients protects against EAE

Manipulation of stem cells or stem cells-derived secretome has emerged as a novel alternative therapeutic option for multiple sclerosis (MS). Here we show that human periodontal ligament stem cells (hPDLSCs)-derived conditioned medium (hPDLSCs-CM) and purified exosomes/microvesicles (hPDLSCs-EMVs) obtained from Relapsing Remitting (RR)-MS patients and healthy donors block experimental autoimmune encephalomyelitis (EAE), a mouse model of MS, by inducing anti-inflammatory and immunosuppressive effects in spinal cord and spleen, and reverse disease progression by restoring tissue integrity via remyelination in the spinal cord. We show that hPDLSCs-CM and hPDLSCs-EMVs reduce pro-inflammatory cytokines IL-17, IFN-γ, IL-1β, IL-6, TNF-α, and induce anti-inflammatory IL-10. In addition, apoptosis related STAT1, p53, Caspase 3, and Bax expressions were attenuated. Our findings unravel the immunosuppressive effects of hPDLSCs-CM and hPDLSCs-EMVs in EAE mice, and suggest simple alternative autologous source for patient-customized cell-free targeting treatment in MS patients.

Extracellular Vesicles in Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is characterized by the progression of irreversible airflow limitation and is a leading cause of morbidity and mortality worldwide. Although several crucial mechanisms of COPD pathogenesis have been studied, the precise mechanism remains unknown. Extracellular vesicles (EVs), including exosomes, microvesicles, and apoptotic bodies, are released from almost all cell types and are recognized as novel cell–cell communication tools. They have been shown to carry and transfer a wide variety of molecules, such as microRNAs, messenger RNAs, and proteins, which are involved in physiological functions and the pathology of various diseases. Recently, EVs have attracted considerable attention in pulmonary research. In this review, we summarize the recent findings of EV-mediated COPD pathogenesis. We also discuss the potential clinical usefulness of EVs as biomarkers and therapeutic agents for the treatment of COPD.

Cancer-associated fibroblast-derived annexin A6+ extracellular vesicles support pancreatic cancer aggressiveness

The intratumoral microenvironment, or stroma, is of major importance in the pathobiology of pancreatic ductal adenocarcinoma (PDA), and specific conditions in the stroma may promote increased cancer aggressiveness. We hypothesized that this heterogeneous and evolving compartment drastically influences tumor cell abilities, which in turn influences PDA aggressiveness through crosstalk that is mediated by extracellular vesicles (EVs). Here, we have analyzed the PDA proteomic stromal signature and identified a contribution of the annexin A6/LDL receptor-related protein 1/thrombospondin 1 (ANXA6/LRP1/TSP1) complex in tumor cell crosstalk. Formation of the ANXA6/LRP1/TSP1 complex was restricted to cancer-associated fibroblasts (CAFs) and required physiopathologic culture conditions that improved tumor cell survival and migration. Increased PDA aggressiveness was dependent on tumor cell-mediated uptake of CAF-derived ANXA6+ EVs carrying the ANXA6/LRP1/TSP1 complex. Depletion of ANXA6 in CAFs impaired complex formation and subsequently impaired PDA and metastasis occurrence, while injection of CAF-derived ANXA6+ EVs enhanced tumorigenesis. We found that the presence of ANXA6+ EVs in serum was restricted to PDA patients and represents a potential biomarker for PDA grade. These findings suggest that CAF-tumor cell crosstalk supported by ANXA6+ EVs is predictive of PDA aggressiveness, highlighting a therapeutic target and potential biomarker for PDA.

Regulation of chronic inflammatory and immune processes by extracellular vesicles

Almost all cell types release extracellular vesicles (EVs), which are derived either from multivesicular bodies or from the plasma membrane. EVs contain a subset of proteins, lipids, and nucleic acids from the cell from which they are derived. EV factors, particularly small RNAs such as miRNAs, likely play important roles in cell-to-cell communication both locally and systemically. Most of the functions associated with EVs are in the regulation of immune responses to pathogens and cancer, as well as in regulating autoimmunity. This Review will focus on the different modes of immune regulation, both direct and indirect, by EVs. The therapeutic utility of EVs for the regulation of immune responses will also be discussed.

Molecular characterization and expression analysis of the first Porifera tumor necrosis factor superfamily member and of its putative receptor in the marine sponge Chondrosia reniformis

Here we report the molecular cloning and characterization of the first Tumor Necrosis Factor homologous and of its putative receptor in the marine sponge Chondrosia reniformis: chTNF and chTNFR, respectively. The deduced chTNF amino acid sequence is a type II transmembrane protein containing the typical TNFSF domain. Phylogenetic analysis reveals that chTNF is more related to Chordata TNFs rather than to other invertebrates. chTNF and chTNFR are constitutively expressed both in the ectosome and in the choanosome of the sponge, with higher levels in the ectosome. chTNF and chTNFR mRNAs were monitored in sponge fragmorphs treated with Gram(+) or Gram(-) bacteria. chTNF was significantly upregulated in Gram(+)-treated fragmorphs as compared to controls, while chTNFR was upregulated by both treatments. Finally, the possible chTNF fibrogenic role in sponge fragmorphs was studied by TNF inhibitor treatment measuring fibrillar and non fibrillar collagen gene expression; results indicate that the cytokine is involved in sponge collagen deposition and homeostasis.

Extracellular vesicles and infectious diseases: new complexity to an old story

Exosomes and other extracellular microvesicles (ExMVs) have important functions in intercellular communication and regulation. During the course of infection, these vesicles can convey pathogen molecules that serve as antigens or agonists of innate immune receptors to induce host defense and immunity, or that serve as regulators of host defense and mediators of immune evasion. These molecules may include proteins, nucleic acids, lipids, and carbohydrates. Pathogen molecules may be disseminated by incorporation into vesicles that are created and shed by host cells, or they may be incorporated into vesicles shed from microbial cells. Involvement of ExMVs in the induction of immunity and host defense is widespread among many pathogens, whereas their involvement in immune evasion mechanisms is prominent among pathogens that establish chronic infection and is found in some that cause acute infection. Because of their immunogenicity and enrichment of pathogen molecules, exosomes may also have potential in vaccine preparations and as diagnostic markers. Additionally, the ability of exosomes to deliver molecules to recipient cells raises the possibility of their use for drug/therapy delivery. Thus, ExMVs play a major role in the pathogenesis of infection and provide exciting potential for the development of novel diagnostic and therapeutic approaches.

Microparticle-Induced Coagulation Relates to Coronary Artery Atherosclerosis in Severe Aortic Valve Stenosis

Background

Circulating microparticles (MPs) derived from endothelial cells and blood cells bear procoagulant activity and promote thrombin generation. Thrombin exerts proinflammatory effects mediating the progression of atherosclerosis. Aortic valve stenosis may represent an atherosclerosis-like process involving both the aortic valve and the vascular system. The aim of this study was to investigate whether MP-induced thrombin generation is related to coronary atherosclerosis and aortic valve calcification.

Methods

In a cross-sectional study of 55 patients with severe aortic valve stenosis, we assessed the coronary calcification score (CAC) as indicator of total coronary atherosclerosis burden, and aortic valve calcification (AVC) by computed tomography. Thrombin-antithrombin complex (TATc) levels were measured as a marker for thrombin formation. Circulating MPs were characterized by flow cytometry according to the expression of established surface antigens and by measuring MP-induced thrombin generation.

Results

Patients with CAC score below the median were classified as patients with low CAC, patients with CAC Score above the median as high CAC. In patients with high CAC compared to patients with low CAC we detected higher levels of TATc, platelet-derived MPs (PMPs), endothelial-derived MPs (EMPs) and MP-induced thrombin generation. Increased level of PMPs and MP-induced thrombin generation were independent predictors for the severity of CAC. In contrast, AVC Score did not differ between patients with high and low CAC and did neither correlate with MPs levels nor with MP-induced thrombin generation.

Conclusion

In patients with severe aortic valve stenosis MP-induced thrombin generation was independently associated with the severity of CAC but not AVC indicating different pathomechanisms involved in coronary artery and aortic valve calcification.

Versatile roles of extracellular vesicles in cancer

Numerous studies have shown that non-cell-autonomous regulation of cancer cells is an important aspect of tumorigenesis. Cancer cells need to communicate with stromal cells by humoral factors such as VEGF, FGFs, and Wnt in order to survive. Recently, extracellular vesicles (EVs) have also been shown to be involved in cell-cell communication between cancer cells and the surrounding microenvironment and to be important for the development of cancer. In addition, these EVs contain small noncoding RNAs, including microRNAs (miRNAs), which contribute to the malignancy of cancer cells. Here, we provide an overview of current research on EVs, especially miRNAs in EVs. We also propose strategies to treat cancers by targeting EVs around cancer cells.

Measurement of microparticle tissue factor activity in clinical samples: A summary of two tissue factor-dependent FXa generation assays

Thrombosis is a leading cause of morbidity and mortality. Detection of a prothrombotic state using biomarkers would be of great benefit to identify patients at risk of thrombosis that would benefit from thromboprophylaxis. Tissue factor (TF) is a highly procoagulant protein that under normal conditions is not present in the blood. However, increased levels of TF in the blood in the form of microparticles (MPs) (also called extracellular vesicles) are observed under various pathological conditions. In this review, we will discuss studies that have measured MP-TF activity in a variety of diseases using two similar FXa generation assay. One of the most robust signals for MP-TF activity (16-26 fold higher than healthy controls) is observed in pancreatic cancer patients with venous thromboembolism. In this case, the TF+ MPs appear to be derived from the cancer cells. Surprisingly, cirrhosis and acute liver injury are associated with 17-fold and 38-fold increases in MP-TF activity, respectively. Based on mouse models, we speculate that the TF+ MPs are derived from hepatocytes. More modest increases are observed in patients with urinary tract infections (6-fold) and in a human endotoxemia model (9-fold) where monocytes are the likely source of the TF+ MPs. Finally, there is no increase in MP-TF activity in the majority of cardiovascular disease patients. These studies indicate that MP-TF activity may be a useful biomarker to identify patients with particular diseases that have an increased risk of thrombosis.

Prostate extracellular vesicles in patient plasma as a liquid biopsy platform for prostate cancer using nanoscale flow cytometry

BACKGROUND

Extracellular vesicles released by prostate cancer present in seminal fluid, urine, and blood may represent a non-invasive means to identify and prioritize patients with intermediate risk and high risk of prostate cancer. We hypothesize that enumeration of circulating prostate microparticles (PMPs), a type of extracellular vesicle (EV), can identify patients with Gleason Score≥4+4 prostate cancer (PCa) in a manner independent of PSA.

PATIENTS AND METHODS

Plasmas from healthy volunteers, benign prostatic hyperplasia patients, and PCa patients with various Gleason score patterns were analyzed for PMPs. We used nanoscale flow cytometry to enumerate PMPs which were defined as submicron events (100-1000nm) immunoreactive to anti-PSMA mAb when compared to isotype control labeled samples. Levels of PMPs (counts/µL of plasma) were also compared to CellSearch CTC Subclasses in various PCa metastatic disease subtypes (treatment naïve, castration resistant prostate cancer) and in serially collected plasma sets from patients undergoing radical prostatectomy.

RESULTS

PMP levels in plasma as enumerated by nanoscale flow cytometry are effective in distinguishing PCa patients with Gleason Score≥8 disease, a high-risk prognostic factor, from patients with Gleason Score≤7 PCa, which carries an intermediate risk of PCa recurrence. PMP levels were independent of PSA and significantly decreased after surgical resection of the prostate, demonstrating its prognostic potential for clinical follow-up. CTC subclasses did not decrease after prostatectomy and were not effective in distinguishing localized PCa patients from metastatic PCa patients.

CONCLUSIONS

PMP enumeration was able to identify patients with Gleason Score ≥8 PCa but not patients with Gleason Score 4+3 PCa, but offers greater confidence than CTC counts in identifying patients with metastatic prostate cancer. CTC Subclass analysis was also not effective for post-prostatectomy follow up and for distinguishing metastatic PCa and localized PCa patients. Nanoscale flow cytometry of PMPs presents an emerging biomarker platform for various stages of prostate cancer.

Colorectal cancer-derived microvesicles modulate differentiation of human monocytes to macrophages

BACKGROUND

Tumour-derived microvesicles (TMVs) are important players in tumour progression, modulating biological activity of immune cells e.g. lymphocytes, monocytes and macrophages. This phenomenon is particularly interesting in the progression of colon cancer, as macrophages in this type of tumour are relevant for the recovery processes. In the present study, the role of colon cancer cell-derived microvesicles in monocyte differentiation and activity profile (polarization) was investigated.

METHODS

Monocyte-derived macrophages (MDM) were differentiated in vitro in the presence of TMVs obtained from colon cancer: Caco-2, SW620, LoVo or SW480 cell lines and analysed according to their morphology and biological functions, as defined by cytokine secretion, reactive oxygen intermediate (ROI) production and cytotoxic activity against respective colon cancer cells.

RESULTS

Monocytes differentiated with TMVs exhibited morphological and phenotypical characteristics of macrophages. An early contact (beginning with the first day of the in vitro culture) of monocytes with TMVs resulted in increased IL-10 secretion and only slightly elevated TNF release. Early, or prolonged contact resulted in low ROI production and low cytotoxicity against tumour cells. On the other hand, late contact of MDM with TMVs, stimulated MDM to significant TNF and IL-12 secretion, ROI production and enhanced cytotoxicity against tumour cells in vitro. In addition, differences in MDM response to TMVs from different cell lines were observed (according to cytokine secretion, ROI production and cytotoxicity against tumour cells in vitro). Biological activity, STATs phosphorylation and microRNA profiling of MDMs indicated differences in their polarization/activation status which may suggest mixed polarization type M1/M2 with the predominance of proinflammatory cells after late contact with TMVs.

CONCLUSIONS

Macrophage activity (polarization status) may be regulated by contact with not only tumour cells but also with TMVs. Their final polarization status depends on the contact time, and probably on the vesicle "cargo", as signified by the distinct impact of TMVs which enabled the switching of MDM maturation to regulatory macrophages.

Microparticle Shedding from Neural Progenitor Cells and Vascular Compartment Cells Is Increased in Ischemic Stroke

Purpose

Ischemic stroke has shown to induce platelet and endothelial microparticle shedding, but whether stroke induces microparticle shedding from additional blood and vascular compartment cells is unclear. Neural precursor cells have been shown to replace dying neurons at sites of brain injury; however, if neural precursor cell activation is associated to microparticle shedding, and whether this activation is maintained at long term and associates to stroke type and severity remains unknown. We analyzed neural precursor cells and blood and vascular compartment cells microparticle shedding after an acute ischemic stroke.

Methods

Forty-four patients were included in the study within the first 48h after the onset of stroke. The cerebral lesion size was evaluated at 3–7 days of the stroke. Circulating microparticles from neural precursor cells and blood and vascular compartment cells (platelets, endothelial cells, erythrocytes, leukocytes, lymphocytes, monocytes and smooth muscle cells) were analyzed by flow cytometry at the onset of stroke and at 7 and 90 days. Forty-four age-matched high cardiovascular risk subjects without documented vascular disease were used as controls.

Results

Compared to high cardiovascular risk controls, patients showed higher number of neural precursor cell- and all blood and vascular compartment cell-derived microparticles at the onset of stroke, and after 7 and 90 days. At 90 days, neural precursor cell-derived microparticles decreased and smooth muscle cell-derived microparticles increased compared to levels at the onset of stroke, but only in those patients with the highest stroke-induced cerebral lesions.

Conclusions

Stroke increases blood and vascular compartment cell and neural precursor cell microparticle shedding, an effect that is chronically maintained up to 90 days after the ischemic event. These results show that stroke induces a generalized blood and vascular cell activation and the initiation of neuronal cell repair process after stroke. Larger cerebral lesions associate with deeper vessel injury affecting vascular smooth muscle cells.

Cardiac Extracellular Vesicles in Normal and Infarcted Heart

Heart is a complex assembly of many cell types constituting myocardium, endocardium and epicardium that intensively communicate to each other in order to maintain the proper cardiac function. There are many types of intercellular intracardiac signals, with a prominent role of extracellular vesicles (EVs), such as exosomes and microvesicles, for long-distant delivering of complex messages. Cardiomyocytes release EVs, whose content could significantly vary depending on the stimulus. In stress, such as hypoxia, inflammation or injury, cardiomyocytes increase secretion of EVs. In hypoxic conditions, cardiac EVs are enriched with angiogenic and prosurvival factors. In acute myocardial infarction (AMI), damaged cardiac muscle cells produce EVs with increased content of angiogenic, anti-apoptotic, mitogenic and growth factors in order to induce repair and healing of the infarcted myocardium. Exosomal microRNAs play a central role in cardiac regeneration. In AMI, circulating cardiac EVs abundantly contain cardiac-specific miRNAs that serve as indicators of cardiac damage and have a big diagnostic potential as AMI biomarkers. Cardioprotective and regenerative properties of exosomes derived from cardiac and non-cardiac stem/progenitor cells are very helpful to be used in cell-free cardiotherapy and regeneration of post-infarct myocardium.

Increased monocyte/neutrophil and pro-coagulant microparticle levels and overexpression of aortic endothelial caveolin-1β in dyslipidemic sand rat, Psammomys obesus

AIMS

To compare the effects of a high-energy diet (HED) with those of a low-energy diet (LED) on biochemical parameters, microparticle (MP) subpopulations and endothelial caveolin-1 (cav-1) protein expression in Psammomys obesus (P. obesus).

METHODS

After 12weeks of feeding with either the HED or LED, fasting plasma glucose and lipid parameters were measured using an enzymatic colorimetric kit while serum insulin concentration was determined with radioimmunoassay kits. MP subpopulations and cav-1 protein expression were quantified using flow cytometry and western blot analysis, respectively.

RESULTS

We observed that the HED caused a marked increase in lipid parameters, even in normoglycemic P. obesus. The total number of circulating MPs and the numbers of platelet-, leukocyte-, and erythrocyte-derived MPs were unaltered in the HED group. However, the HED induced increases in the numbers of monocytes/neutrophils and procoagulant MPs and a decrease in the endothelial MP levels. Cav-1β protein expression and reactive oxygen species production were increased in the vascular endothelium of HED-treated P. obesus.

CONCLUSION

From these findings, it is indicated that the HED exerts deleterious effects on the vascular system by increasing the monocyte/neutrophil and procoagulant MP levels, which may lead to cav-1β protein overexpression in dyslipidemic P. obesus.

Biobanking of Exosomes in the Era of Precision Medicine: Are We There Yet?

The emerge of personalized medicine demands high-quality human biospecimens with appropriate clinical annotation, especially in complex diseases such as cancer, neurodegenerative, cardiovascular, and metabolic alterations in which specimen heterogeneity and individual responses often complicate the development of precision therapeutic programs. In the growing field of extracellular vesicles (EVs) research, exosomes (EXOs)—a particular type of EVs—have been proposed as an advantageous diagnostic tool, as effective delivery vehicles and as therapeutic targets. However, the lack of consensus on isolation methods and rigorous criteria to characterize them puts the term EXO into question at the time that might explain some of the controversial results found in the literature. A lack of response in the biobank network to warrant standard optimized procedures for the isolation, characterization, and storage of EXOs will undoubtedly lead to a waste of resources and failure. This review is aimed at highlighting the increasing importance of EXOs for the clinic, especially in the cancer field, and at summarizing the initiatives taken to improve current isolation procedures, classification criteria, and storage conditions of EXOs as an effort to identify technological demands that biobank platforms face for the incorporation of EXOs and other extracellular vesicle fractions as valuable biospecimens for research.

Complement Interactions with Blood Cells, Endothelial Cells and Microvesicles in Thrombotic and Inflammatory Conditions

The complement system is activated in the vasculature during thrombotic and inflammatory conditions. Activation may be associated with chronic inflammation on the endothelial surface leading to complement deposition. Complement mutations allow uninhibited complement activation to occur on platelets, neutrophils, monocytes, and aggregates thereof, as well as on red blood cells and endothelial cells. Furthermore, complement activation on the cells leads to the shedding of cell derived-microvesicles that may express complement and tissue factor thus promoting inflammation and thrombosis. Complement deposition on red blood cells triggers hemolysis and the release of red blood cell-derived microvesicles that are prothrombotic. Microvesicles are small membrane vesicles ranging from 0.1 to 1 μm, shed by cells during activation, injury and/or apoptosis that express components of the parent cell. Microvesicles are released during inflammatory and vascular conditions. The repertoire of inflammatory markers on endothelial cell-derived microvesicles shed during inflammation is large and includes complement. These circulating microvesicles may reflect the ongoing inflammatory process but may also contribute to its propagation. This overview will describe complement activation on blood and endothelial cells and the release of microvesicles from these cells during hemolytic uremic syndrome, thrombotic thrombocytopenic purpura and vasculitis, clinical conditions associated with enhanced thrombosis and inflammation.

Relationship between the Level of Circulating Endothelial Micro-Particles in the Blood and Blood Lipid Content in Uyghur and Han Patients with Acute Coronary Syndrome

BACKGROUND

The aim of this study was to analyze the relationships between the endothelial cell micro-particles (EMPs) blood level and the blood lipid in Uygur and Han patients with acute coronary syndrome (ACS) in order to provide a theoretical basis for the pathogenesis study of ACS.

METHODS

100 ACS patients (50 cases for each ethnic group) were selected as the patient group from January 2012 to August 2013 from the Cardiology Sector of the People's Hospital of the Xinjiang Uygur Autonomous Region, and 100 healthy subjects (50 cases for each ethnic group) were selected as the control group. Blood samples were collected. Flow cytometry was used to detect the EMP levels. An automatic biochemical analyzer was used to detect the levels of the blood lipids and the related indicators.

RESULTS

The EMP levels in the patient group of both ethnicities were higher than those in the control group (p < 0.05), although no statistically significant differences were found in the EMP levels between Uygur and Han in the patient groups, nor in the control group (p > 0.05). Multiple linear regression analysis showed significant correlations between the EMP levels and the blood lipid related indexes (p < 0.05), with a degree of correlation of 86.70%. Path analysis indicated that the EMP level was mainly affected by high density lipoprotein cholesterol (HDL-C) (p < 0.05).

CONCLUSIONS

The EMP level in the blood of ACS patients is significantly higher than in the control group, and the levels between HDL-C and EMPs are negatively correlated. The pathogenesis of ACS could be associated with the increase of the EMP level in the blood, and HDL-C might affect the level of circulating EMPs.

Impaired phenotype of circulating endothelial microparticles in chronic heart failure patients: Relevance to body mass index

AIMS

The objective of the study was to investigate the relationship of circulating endothelial-derived microparticls (EMP) pattern with body mass index (BMI) in CHF patients.

METHODS

The study retrospectively evolved 153 patients (86 males) who were underwent multispiral contrast-enhanced computed tomography angiography or conventional angiographic examination of coronary arteries. Flowcytometry analysis for quantifying the number of EMPs was used at baseline.

RESULTS

Using C-statistics for models with CHF, BMI, and circulating biomarkers (NT-pro-BNP, OPG and adiponectin) as continuous variables we found that adding of BMI to the based model (NYHA class of CHF) improved the relative IDI by 12.5% for increased CD31+/annexin V+ EMPs to CD62E+ EMPs ratio. When we used other model constructed on entering variables IDI appears to be improved up to 5.8% for increased EMPs (available for NT-pro-BNP as continuous variable). Three biomarkers (NYHA class of CHF+NT-pro-BNP+OPG) and four biomarkers (NYHA class of CHF+NT-pro-BNP+OPG+adiponectin) could not significantly improve predictive model based on combination of BMI and NYHA class of CHF for increased CD31+/annexin V+ EMPs to CD62E+ EMPs ratio.

CONCLUSION

We suggested that lower BMI is significant predictor for impaired phenotype of circulating EMPs in CHF patients.

[The role of erythrocyte microvesiculation and hemoglobin glycation in hemorheological disordes during burn injury]

INTRODUCTION

Hemorheological disorders play an important part in pathogenesis of acute period of burn injury. This mechanism remains practically unstudied. Thus, unknown is the role of hemoglobin glycation and erythrocyte microvesiculation in the decrease in erythrocyte deformability after thermal trauma.

METHODS

Research was performed on 30 blood samples of burn patients in the acute period and 40 blood samples of healthy donors. The number of erythrocyte-derived microvesicles was determined by flow cytometry and then standardized in the samples; the microvesicles were preliminarily separated by ultracentrifugation at 100,000 g, for 60 minutes. Electrophoretic mobility of erythrocytes was measured in a processing chamber of the optical cuvette under the light microscope. Deformability of erythrocytes was assessed by the level of their extension in the artificial shear flow.

RESULTS

It was found that the amount of HbA₁c in red blood cells of burn patients demonstrated a 2-fold increase compared to healthy donors. In the experiments in vitro it was proved that deformability of erythrocytes correlates with the level of hemoglobin glycation. Hb glycation leads to the increased rigidity of erythrocytes also by increasing their microvesiculation. The number of microvesicles derived from red blood cells of burn patients demonstrated a 3.47-fold increase compared to healthy donors. An important reason for microvesiculation is the destabilization of lipid complex of erythrocyte membrane, which is accompanied by the increase in the erythrocyte negative charge. It can be concluded that Hb glycation and redistribution of erythrocyte membrane phospholipids are he important reasons for the increase erythrocyte microvesiculation and are accompanied by the decrease in erythrocyte deformability after thermal trauma.

[The influence of erythrocyte-derived microvesicles on aggregation of platelets in burn injury]

Burn Injury is accompanied by a significant homeostasis disorder, including the disorder of primary homeostasis, associated with aggregation of platelets. The role of erythrocyte-derived microvesicles in this process has not undergone thorough research. Microvesicles were isolated from washed erythrocytes after one day of storage by ultracentrifugation at 100000 g. The number of MVs was determined by flow cytometry and was standardized in the samples. Heparin-dependent and heparin-independent antithrombin activity in erythrocyte microvesicles was studied by coagulation method. We studied platelet aggregation induced and not induced by ADP under the conditions of artificial shear flow. It was shown that at the early stage of bum injury the number of erythrocyte-derived microvesicles in blood demonstrated a 4.2-fold ncrease. We determined that microvesicles, derived from the erythrocytes of burn patients displayed a significantly less aggregation activity than the microvesicles from donors. The main reason is a considerably lower antithrombin activity in the erythrocyte microvesicles of bum patients. Thus, we can conclude that the decrease of antiaggregation and antithrombin activity of erythrocyte microvesicles associated with the increase in their concentration in blood contributes to thrombophilia of bum patients. Keywords: erythrocytes, microvesicles, bum injury, platelet aggregation, antithrombin activity

On-chip immunoelectrophoresis of extracellular vesicles released from human breast cancer cells

Extracellular vesicles (EVs) including exosomes and microvesicles have attracted considerable attention in the fields of cell biology and medicine. For a better understanding of EVs and further exploration of their applications, the development of analytical methods for biological nanovesicles has been required. In particular, considering the heterogeneity of EVs, methods capable of measuring individual vesicles are desired. Here, we report that on-chip immunoelectrophoresis can provide a useful method for the differential protein expression profiling of individual EVs. Electrophoresis experiments were performed on EVs collected from the culture supernatant of MDA-MB-231 human breast cancer cells using a measurement platform comprising a microcapillary electrophoresis chip and a laser dark-field microimaging system. The zeta potential distribution of EVs that reacted with an anti-human CD63 (exosome and microvesicle marker) antibody showed a marked positive shift as compared with that for the normal immunoglobulin G (IgG) isotype control. Thus, on-chip immunoelectrophoresis could sensitively detect the over-expression of CD63 glycoproteins on EVs. Moreover, to explore the applicability of on-chip immunoelectrophoresis to cancer diagnosis, EVs collected from the blood of a mouse tumor model were analyzed by this method. By comparing the zeta potential distributions of EVs after their immunochemical reaction with normal IgG, and the anti-human CD63 and anti-human CD44 (cancer stem cell marker) antibodies, EVs of tumor origin circulating in blood were differentially detected in the real sample. The result indicates that the present method is potentially applicable to liquid biopsy, a promising approach to the low-invasive diagnosis of cancer.

Release of Intracoronary Microparticles during Stent Implantation into Stable Atherosclerotic Lesions under Protection with an Aspiration Device

OBJECTIVE

Stent implantation into atherosclerotic coronary vessels impacts on downstream microvascular function and induces the release of particulate debris and soluble substances, which differs qualitatively and quantitatively between native right coronary arteries (RCAs) and saphenous vein grafts on right coronary arteries (SVG-RCAs). We have now quantified the release of microparticles (MPs) during stent implantation into stable atherosclerotic lesions and compared the release between RCAs and SVG-RCAs.

METHODS

In symptomatic, male patients with stable angina and a stenosis in their RCA or SVG-RCA, respectively (n = 14/14), plaque volume and composition were analyzed using intravascular ultrasound before stent implantation. Coronary aspirate was retrieved during stent implantation with a distal occlusion/aspiration device and divided into particulate debris and plasma. Particulate debris was weighed. Platelet-derived MPs (PMPs) were distinguished by flow cytometry as CD41+, endothelium-derived MPs (EMPs) as CD144+, CD62E+ and CD31+/CD41-, leukocyte-derived MPs as CD45+, and erythrocyte-derived MPs as CD235+.

RESULTS

In patients with comparable plaque volume and composition in RCAs and SVG-RCAs, intracoronary PMPs and EMPs were increased after stent implantation into their RCAs and SVG-RCAs (CD41+: 2729.6 ± 645.6 vs. 4208.7 ± 679.4 and 2355.9 ± 503.9 vs. 3285.8 ± 733.2 nr/µL; CD144+: 451.5 ± 87.9 vs. 861.7 ± 147.0 and 444.6 ± 74.8 vs. 726.5 ± 136.4 nr/µL; CD62E+: 1404.1 ± 247.7 vs. 1844.3 ± 378.6 and 1084.6 ± 211.0 vs. 1783.8 ± 384.3 nr/µL, P < 0.05), but not different between RCAs and SVG-RCAs.

CONCLUSION

Stenting in stable atherosclerotic lesions is associated with a substantial release not only of PMPs, but also of EMPs in RCAs and SVG-RCAs. Their release does not differ between RCAs and SVG-RCAs.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01430884.

Elevated atherosclerosis-related gene expression, monocyte activation and microparticle-release are related to increased lipoprotein-associated oxidative stress in familial hypercholesterolemia

Objective

Animal and in vitro studies have suggested that hypercholesterolemia and increased oxidative stress predisposes to monocyte activation and enhanced accumulation of oxidized LDL cholesterol (oxLDL-C) through a CD36-dependent mechanism. The aim of this study was to investigate the hypothesis that elevated oxLDL-C induce proinflammatory monocytes and increased release of monocyte-derived microparticles (MMPs), as well as up-regulation of CD36, chemokine receptors and proinflammatory factors through CD36-dependent pathways and that this is associated with accelerated atherosclerosis in subjects with heterozygous familial hypercholesterolemia (FH), in particular in the presence of Achilles tendon xanthomas (ATX).

Approach and Results

We studied thirty FH subjects with and without ATX and twenty-three healthy control subjects. Intima-media thickness (IMT) and Achilles tendon (AT) thickness were measured by ultrasonography. Monocyte classification and MMP analysis were performed by flow cytometry. Monocyte expression of genes involved in atherosclerosis was determined by quantitative PCR. IMT and oxLDL-C were increased in FH subjects, especially in the presence of ATX. In addition, FH subjects had elevated proportions of intermediate CD14++CD16+ monocytes and higher circulating MMP levels. Stepwise linear regression identified oxLDL-C, gender and intermediate monocytes as predictors of MMPs. Monocyte expression of pro-atherogenic and pro-inflammatory genes regulated by oxLDL-C-CD36 interaction was increased in FH, especially in ATX+ subjects. Monocyte chemokine receptor CX₃CR1 was identified as an independent contributor to IMT.

Conclusions

Our data support that lipoprotein-associated oxidative stress is involved in accelerated atherosclerosis in FH, particularly in the presence of ATX, by inducing pro-inflammatory monocytes and increased release of MMPs along with elevated monocyte expression of oxLDL-C-induced atherosclerosis-related genes.

Brain-derived microparticles induce systemic coagulation in a murine model of traumatic brain injury

Traumatic brain injury (TBI) is associated with coagulopathy, although it often lacks 2 key risk factors: severe bleeding and significant fluid resuscitation associated with hemorrhagic shock. The pathogenesis of TBI-associated coagulopathy remains poorly understood. We tested the hypothesis that brain-derived microparticles (BDMPs) released from an injured brain induce a hypercoagulable state that rapidly turns into consumptive coagulopathy. Here, we report that mice subjected to fluid percussion injury (1.9 ± 0.1 atm) developed a BDMP-dependent hypercoagulable state, with peak levels of plasma glial cell and neuronal BDMPs reaching 17 496 ± 4833/μL and 18 388 ± 3657/μL 3 hours after TBI, respectively. Uninjured mice injected with BDMPs developed a dose-dependent hyper-turned hypocoagulable state measured by a progressively prolonged clotting time, fibrinogen depletion, and microvascular fibrin deposition in multiple organs. The BDMPs were 50 to 300 nm with intact membranes, expressing neuronal or glial cell markers and procoagulant phosphatidylserine and tissue factor. Their procoagulant activity was greater than platelet microparticles and was dose-dependently blocked by lactadherin. Microparticles were produced from injured hippocampal cells, transmigrated through the disrupted endothelial barrier in a platelet-dependent manner, and activated platelets. These data define a novel mechanism of TBI-associated coagulopathy in mice, identify early predictive markers, and provide alternative therapeutic targets.

Differential impact of acute high-intensity exercise on circulating endothelial microparticles and insulin resistance between overweight/obese males and females

Background

An acute bout of exercise can improve endothelial function and insulin sensitivity when measured on the day following exercise. Our aim was to compare acute high-intensity continuous exercise (HICE) to high-intensity interval exercise (HIIE) on circulating endothelial microparticles (EMPs) and insulin sensitivity in overweight/obese men and women.

Methods

Inactive males (BMI = 30 ± 3, 25 ± 6 yr, n = 6) and females (BMI = 28 ± 2, 21 ± 3 yr, n = 7) participated in three experimental trials in a randomized counterbalanced crossover design: 1) No exercise control (Control); 2) HICE (20 min cycling @ just above ventilatory threshold); 3) HIIE (10 X 1-min @ ∼90% peak aerobic power). Exercise conditions were matched for external work and diet was controlled post-exercise. Fasting blood samples were obtained ∼18 hr after each condition. CD62E⁺ and CD31⁺/CD42b^- EMPs were assessed by flow cytometry and insulin resistance (IR) was estimated by homeostasis model assessment (HOMA-IR).

Results

There was a significant sex X exercise interaction for CD62E+ EMPs, CD31+/CD42b- EMPs, and HOMA-IR (all P<0.05). In males, both HICE and HIIE reduced EMPs compared to Control (P≤0.05). In females, HICE increased CD62E+ EMPs (P<0.05 vs. Control) whereas CD31+/CD42b- EMPs were unaltered by either exercise type. There was a significant increase in HOMA-IR in males but a decrease in females following HIIE compared to Control (P<0.05).

Conclusions

Overweight/obese males and females appear to respond differently to acute bouts of high-intensity exercise. A single session of HICE and HIIE reduced circulating EMPs measured on the morning following exercise in males but in females CD62E+ EMPs were increased following HICE. Next day HOMA-IR paradoxically increased in males but was reduced in females following HIIE. Future research is needed to investigate mechanisms responsible for potential differential responses between males and females.

The CentriMag centrifugal blood pump as a benchmark for in vitro testing of hemocompatibility in implantable ventricular assist devices

Implantable ventricular assist devices (VADs) have proven efficient in advanced heart failure patients as a bridge-to-transplant or destination therapy. However, VAD usage often leads to infection, bleeding, and thrombosis, side effects attributable to the damage to blood cells and plasma proteins. Measuring hemolysis alone does not provide sufficient information to understand total blood damage, and research exploring the impact of currently available pumps on a wider range of blood cell types and plasma proteins such as von Willebrand factor (vWF) is required to further our understanding of safer pump design. The extracorporeal CentriMag (Thoratec Corporation, Pleasanton, CA, USA) has a hemolysis profile within published standards of normalized index of hemolysis levels of less than 0.01 g/100 L at 100 mm Hg but the effect on leukocytes, vWF multimers, and platelets is unknown. Here, the CentriMag was tested using bovine blood (n = 15) under constant hemodynamic conditions in comparison with a static control for total blood cell counts, hemolysis, leukocyte death, vWF multimers, microparticles, platelet activation, and apoptosis. The CentriMag decreased the levels of healthy leukocytes (P < 0.006), induced leukocyte microparticles (P < 10(-5) ), and the level of high molecular weight of vWF multimers was significantly reduced in the CentriMag (P < 10(-5) ) all compared with the static treatment after 6 h in vitro testing. Despite the leukocyte damage, microparticle formation, and cleavage of vWF multimers, these results show that the CentriMag is a hemocompatible pump which could be used as a standard in blood damage assays to inform the design of new implantable blood pumps.

Isolation and phenotypic characteristics of microparticles in acute respiratory distress syndrome

OBJECTIVE

To investigate the alterations of microparticles in acute respiratory distress syndrome (ARDS) in rats.

METHODS

18 Wistar male rats were randomly divided into three groups: no intervention, sham (saline control) group and ARDS group (LPS induced). Blood was collected from abdominal aorta and microparticles were extracted through multiple rounds of centrifugation. Particles were analyzed by flow cytometry and transmission electron microscope.

RESULTS

The circulating concentration of total microparticles of rats with ARDS induced by lipopolysaccharide (LPS) did not change compared with other two groups. However, ARDS rats expressed higher concentration of leukocyte- and endothelium- derived microparticles in the three groups.

CONCLUSION

Our results indicate that leukocyte and endothelial cell-derived particles may play an important role in ARDS. Thus it is important not only to monitor total microparticle levels but also the phenotypes, which may contribute to the prevention and early treatment of ARDS.

Transfer of human hepatocyte growth factor reduces inflammation and prevents pulmonary arterial remodeling in monocrotaline-induced

Inflammation and endothelial dysfunction contribute to the pathogenesis and development of pulmonary arterial hypertension (PAH). This study was to investigate the therapeutic effect of human hepatocyte growth factor (HGF) gene transfer on monocrotaline (MCT) induced PAH rat models. PAH was induced by injecting MCT for 4 weeks. The rats were randomly assigned to phosphate buffered saline control group, MCT group, and HGF treatment group. After 2 weeks of induction, measures of mean pulmonary artery pressure (mPAP), weight ratio of the RV to the LV plus septum, percent wall thickness index (TI) and area index (AI) were significantly increased in MCT-group and HGF treatment-group compared with those in control group (P < 0.05). Those measurements in MCT-group were significantly higher than those in HGF treatment-group (P < 0.05). IL-6 significantly decreased in HGF treatment-group compared with MCT-group, but higher than that of control group (all P < 0.05). IL-10 in HGF treatment-group significantly increased compared with MCT-group, but lower than that of control group (all P < 0.05). Endothelial microparticles (EMP) started to decrease in the HGF treatment-group 3 days after treatment and was most significant after 1 and 2 weeks of treatment (all P < 0.05). Our results showed that transfer of human HGF may attenuate the inflammatory cell infiltrate, reduce the expression of inflammatory factors, and those effects are possibly due to the inhibition of EMP production which may decrease pulmonary vascular wall damage in PAH.

Angiogenic microvascular endothelial cells release microparticles rich in tissue factor that promotes postischemic collateral vessel formation

OBJECTIVE

Therapeutic angiogenesis is a promising strategy for treating ischemia. Our previous work showed that endogenous endothelial tissue factor (TF) expression induces intracrine signaling and switches-on angiogenesis in microvascular endothelial cells (mECs). We have hypothesized that activated mECs could exert a further paracrine regulation through the release of TF-rich microvascular endothelial microparticles (mEMPs) and induce neovascularization of ischemic tissues.

APPROACH AND RESULTS

Here, we describe for the first time that activated mECs are able to induce reparative neovascularization in ischemic zones by releasing TF-rich microparticles. We show in vitro and in vivo that mEMPs released by both wild-type and TF-upregulated-mECs induce angiogenesis and collateral vessel formation, whereas TF-poor mEMPs derived from TF-silenced mECs are not able to trigger angiogenesis. Isolated TF-bearing mEMPs delivered to nonperfused adductor muscles in a murine hindlimb ischemia model enhance collateral flow and capillary formation evidenced by MRI. TF-bearing mEMPs increase angiogenesis operating via paracrine regulation of neighboring endothelial cells, signaling through the β1-integrin pathway Rac1-ERK1/2-ETS1 and triggering CCL2 (chemokine [C-C motif] ligand 2) production to form new and competent mature neovessels.

CONCLUSIONS

These findings demonstrate that TF-rich mEMPs released by microvascular endothelial cells can overcome the consequences of arterial occlusion and tissue ischemia by promoting postischemic neovascularization and tissue reperfusion.

Randomized study of washing 40- to 42-day-stored red blood cells

BACKGROUND

Pretransfusion washing of red blood cells (RBCs) stored for a longer duration may have theoretical advantages but few data exist to support this practice. In many hospital settings, use of a point-of-care cell washer could conceivably be used to quickly wash allogeneic RBCs before transfusion. The purpose of this preliminary study was to compare a point-of-care device with a common blood bank device for washing longer-stored RBCs.

STUDY DESIGN AND METHODS

Forty RBC units stored for 40 to 42 days were randomized to washing with the COBE 2991 device (Terumo BCT; FDA-cleared for washing stored RBCs) or the Cell Saver Elite (Haemonetics; FDA-cleared point-of-care device for processing and washing fresh autologous shed whole blood). Supernatant and unit RBCs from unwashed (baseline) and washed blood were assayed for potassium, lactate, intracellular ATP, percentage of RBC recovery, cell-free hemoglobin, RBC microparticles, and RBCs were examined for susceptibility to hemolysis by physical stress.

RESULTS

Both devices recovered a high percentage of RBCs and efficiently removed extracelluar potassium. Washing with the Elite resulted in significant increases in cell-free Hb, percent hemolysis, and RBC microparticle production, whereas washing with the COBE 2991 did not (fold Δ = 2.1 vs. 1.0, 4.6 vs. 1.2, 2.0 vs. 1.1, respectively; p < 0.05). Hemolysis induced by physical stress was not altered by washing.

CONCLUSION

Although point-of-care washing of longer-stored RBCs is appealing, these preliminary data suggest that transfusion of washed, longer-stored units could result in potentially greater exposure to plasma free Hb. More data are needed before this practice can be routinely recommended.

Isolation and characterization of CD34+ blast-derived exosomes in acute myeloid leukemia

Exosomes are membrane-bound vesicles found in all biological fluids. AML patients' plasma collected at diagnosis contains elevated exosome levels relative to normal donor (ND) plasma. The molecular profile of AML exosomes changes in the course of therapy and may serve as a measure of disease progression or response to therapy. However, plasma contains a mix of exosomes derived from various cell types. To be able to utilize blast-derived exosomes as biomarkers for AML, we have developed an immunoaffinity-based capture method utilizing magnetic microbeads coated with anti-CD34 antibody (Ab). This Ab is specific for CD34, a unique marker of AML blasts. The capture procedure was developed using CD34+ exosomes derived from Kasumi-1 AML cell culture supernatants. The capture capacity of CD34microbeads was shown to linearly correlate with the input exosomes. A 10 uL aliquot of CD34 microbeads was able to capture all of CD34+ exosomes present in 100-1,000 uL of AML plasma. The levels of immunocaptured CD34+ exosomes correlated with the percentages of CD34+ blasts in the AML patients' peripheral blood. The immunocaptured exosomes had a typical cup-shaped morphology by transmission electron microscopy, and their molecular cargo was similar to that of parental blasts. These exosomes were biologically-active. Upon co-incubation with natural killer (NK) cells, captured blast-derived exosomes down-regulated surface NKG2D expression, while non-captured exosomes reduced expression levels of NKp46. Our data provide a proof-of-principle that blast-derived exosomes can be quantitatively recovered from AML patients' plasma, their molecular profile recapitulates that of autologous blasts and they retain the ability to mediate immune suppression. These data suggest that immunocaptured blast-derived exosomes might be useful in diagnosis and/or prognosis of AML in the future.

Characterization of microparticles after hepatic ischemia-reperfusion injury

Background

Hepatic ischemia-reperfusion (I/R) is a well-studied model of liver injury and has demonstrated a biphasic injury followed by recovery and regeneration. Microparticles (MPs) are a developing field of study and these small membrane bound vesicles have been shown to have effector function in other physiologic and pathologic states. This study was designed to quantify the levels of MPs from various cell origins–platelets, neutrophils, and endolethial cells–following hepatic ischemia-reperfusion injury.

Methods

A murine model was used with mice undergoing 90 minutes of partial hepatic ischemia followed by various times of reperfusion. Following reperfusion, plasma samples were taken and MPs of various cell origins were labeled and levels were measured using flow cytometry. Additionally, cell specific MPs were further assessed by Annexin V, which stains for the presence of phosphatidylserine, a cell surface marker linked to apoptosis. Statistical analysis was performed using one-way analysis of variance with subsequent Student-Newman-Keuls test with data presented as the mean and standard error of the mean.

Results

MPs from varying sources show an increase in circulating levels following hepatic I/R injury. However, the timing of the appearance of different MP subtypes differs for each cell type. Platelet and neutrophil-derived MP levels demonstrated an acute elevation following injury whereas endothelial-derived MP levels demonstrated a delayed elevation.

Conclusion

This is the first study to characterize circulating levels of cell-specific MPs after hepatic I/R injury and suggests that MPs derived from platelets and neutrophils serve as markers of inflammatory injury and may be active participants in this process. In contrast, MPs derived from endothelial cells increase after the injury response during the reparative phase and may be important in angiogenesis that occurs in the regenerating liver.

The role of microparticles in chronic obstructive pulmonary disease

Accumulating evidence suggests that cell injury in lung tissues is closely connected to disease progression in chronic obstructive pulmonary disease (COPD). Microparticles (MPs) are shed membrane vesicles that are released from platelets, leukocytes, red blood cells, and endothelial cells when these cells are activated or undergo apoptosis under inflammatory conditions. Based on increasing evidence that endothelial injury in the pulmonary capillary vasculature leads to lung destruction, and because cardiovascular diseases are the main cause of death among individuals with COPD, endothelial MPs (EMPs) are now receiving attention as potential biomarkers for COPD. There are eight types of EMPs which are defined by the presence of different endothelial markers on the cell membrane: vascular endothelial-cadherin; platelet endothelial cell adhesion molecule; melanoma cell adhesion molecule; E-selectin; CD51; CD105; von Willebrand factor; and CD143 EMPs. Vascular endothelial-cadherin, platelet endothelial cell adhesion molecule, and E-selectin EMPs are increased in patients with stable COPD and are further increased in patients with exacerbated COPD compared to non-COPD patients. In addition, the levels of these three EMPs in patients with stable COPD are significantly correlated with lung destruction and airflow limitation. These results indicate that endothelial injury is closely connected to the pathophysiology of COPD. Interestingly, the variations in the levels of the eight EMP subtypes were not identical with changes in patient condition. Although the clinical significance of the differences in these eight EMP subtypes remains unclear, evaluating the expression pattern of endothelial antigens on circulating MPs might predict the presence and degree of endothelial injury in COPD patients. In addition, circulating MPs are proposed to have several physiological functions in vivo, such as intercellular crosstalk; the increase in EMPs in COPD seems to play a role in the pathophysiology of this disease.

Production, fate and pathogenicity of plasma microparticles in murine cerebral malaria

In patients with cerebral malaria (CM), higher levels of cell-specific microparticles (MP) correlate with the presence of neurological symptoms. MP are submicron plasma membrane-derived vesicles that express antigens of their cell of origin and phosphatidylserine (PS) on their surface, facilitating their role in coagulation, inflammation and cell adhesion. In this study, the in vivo production, fate and pathogenicity of cell-specific MP during Plasmodium berghei infection of mice were evaluated. Using annexin V, a PS ligand, and flow cytometry, analysis of platelet-free plasma from infected mice with cerebral involvement showed a peak of MP levels at the time of the neurological onset. Phenotypic analyses showed that MP from infected mice were predominantly of platelet, endothelial and erythrocytic origins. To determine the in vivo fate of MP, we adoptively transferred fluorescently labelled MP from mice with CM into healthy or infected recipient mice. MP were quickly cleared following intravenous injection, but microscopic examination revealed arrested MP lining the endothelium of brain vessels of infected, but not healthy, recipient mice. To determine the pathogenicity of MP, we transferred MP from activated endothelial cells into healthy recipient mice and this induced CM-like brain and lung pathology. This study supports a pathogenic role for MP in the aggravation of the neurological lesion and suggests a causal relationship between MP and the development of CM.

Cerebral malaria (CM) is a potentially fatal neurological syndrome characterised by unrousable coma. Since the detection of high levels of plasma microparticles (MP) in patients with CM, it has been demonstrated that inhibition of MP production confers protection from murine CM. However, the precise mechanisms of action of these MP during CM have not been completely deciphered. In this study, we used experimental models of CM to measure the production and origins of MP over the course of infection. We found low baseline circulating MP in healthy mice and these were subsequently raised at the time of the neurological syndrome. Phenotypic analyses showed that circulating MP were predominantly from activated host cells that have previously been established to participate in CM pathogenesis. We show for the first time transferred MP impairing endothelial integrity and inducing CM-like pathology in the brain and lung of healthy animals. Our study dissects what tissues these MP localise to exert their effects, as little is known about their fate following the initial release. These data suggest a causal relationship between MP and the development of CM and also warrant further investigation into the representation of MP as a marker of CM risk.

Microvesicular caspase-1 mediates lymphocyte apoptosis in sepsis

Objective

Immune dysregulation during sepsis is poorly understood, however, lymphocyte apoptosis has been shown to correlate with poor outcomes in septic patients. The inflammasome, a molecular complex which includes caspase-1, is essential to the innate immune response to infection and also important in sepsis induced apoptosis. Our group has recently demonstrated that endotoxin-stimulated monocytes release microvesicles (MVs) containing caspase-1 that are capable of inducing apoptosis. We sought to determine if MVs containing caspase-1 are being released into the blood during human sepsis and induce apoptosis..

Design

Single-center cohort study

Measurements

50 critically ill patients were screened within 24 hours of admission to the intensive care unit and classified as either a septic or a critically ill control. Circulatory MVs were isolated and analyzed for the presence of caspase-1 and the ability to induce lymphocyte apoptosis. Patients remaining in the ICU for 48 hours had repeated measurement of caspase-1 activity on ICU day 3.

Main Results

Septic patients had higher microvesicular caspase-1 activity 0.05 (0.04, 0.07) AFU versus 0.0 AFU (0, 0.02) (p<0.001) on day 1 and this persisted on day 3, 0.12 (0.1, 0.2) versus 0.02 (0, 0.1) (p<0.001). MVs isolated from septic patients on day 1 were able to induce apoptosis in healthy donor lymphocytes compared with critically ill control patients (17.8±9.2% versus 4.3±2.6% apoptotic cells, p<0.001) and depletion of MVs greatly diminished this apoptotic signal. Inhibition of caspase-1 or the disruption of MV integrity abolished the ability to induce apoptosis.

Conclusion

These findings suggest that microvesicular caspase-1 is important in the host response to sepsis, at least in part, via its ability to induce lymphocyte apoptosis. The ability of microvesicles to induce apoptosis requires active caspase-1 and intact microvesicles.

Circulating contact-pathway-activating microparticles together with factors IXa and XIa induce spontaneous clotting in plasma of hematology and cardiologic patients

Background and Objective

Using an in vitro experimental model of immobilized tissue factor-initiated clot growth in platelet-free plasma (thrombodynamics), we observed formation of activator-independent isolated spontaneous clots (SC) throughout the plasma volume in patients with cardiac infarction, acute leukemia, hemolytic anemia, and some other disorders. The aim of this work was to characterize this phenomenon and to identify the mechanisms of SC formation.

Methods and Results

Tissue factor inhibitor (VIIai) prevented SC in only 2 out of 23 patient plasma samples. Specific inhibitors of factors IXa and XIa were efficient in all 8 cases that we tested. Also, only factors IXa and XIa added to normal donors’ plasma induced SC formations from isolated centers, in a pattern similar to that in patients’ plasma. In contrast, factors VIIa, Va, tissue factor induced uniform plasma clotting. SC disappeared after high-speed centrifugation. However, phospholipid supplementation of centrifuged plasma returned them at least partially in 5 out of 22 patients’ plasmas, indicating some other role of microparticles than providing phospholipid surface. Circulating procoagulant microparticles isolated from plasma directly activated factor XII in buffer and in diluted plasma. Flow cytometry revealed an increase in procoagulant microparticles in patients’ plasmas with SC.

Conclusion

Our data suggest that combination of circulating active factors (specifically, factors IXa and XIa) with circulating procoagulant and contact-pathway-activating microparticles is the predominant mechanism causing spontaneous clotting in patient plasma.

Plasma concentration of platelet-derived microparticles is related to painful vaso-occlusive phenotype severity in sickle cell anemia

High plasma level of microparticles (MPs) deriving mainly from erythrocytes and platelets has been detected in sickle cell anemia (SCA) patients. Flow cytometry was used to determine the concentration of MPs in two groups of SCA patients exhibiting marked differences in painful vaso-occlusive crisis rates [a non-severe group (n = 17) and a severe group (n = 12)], and in a control group composed of healthy subjects (n = 20). A 3- to 4-fold increase of total MP plasma concentration was detected in SCA patients. Higher platelet-derived MPs concentration was detected in the severe SCA group while erythrocyte-derived MPs concentration was increased in the non-severe SCA patient group only. Our results suggest that plasma concentration of MPs shed by platelets is a biomarker of the vaso-occlusive phenotype-related severity.

Endothelial microparticles: sophisticated vesicles modulating vascular function

Endothelial microparticles (EMPs) belong to a family of extracellular vesicles that are dynamic, mobile, biological effectors capable of mediating vascular physiology and function. The release of EMPs can impart autocrine and paracrine effects on target cells through surface interaction, cellular fusion, and, possibly, the delivery of intra-vesicular cargo. A greater understanding of the formation, composition, and function of EMPs will broaden our understanding of endothelial communication and may expose new pathways amenable for therapeutic manipulation.

Circulating endothelial progenitor cell and platelet microparticle impact on platelet activation in hypertension associated with hypercholesterolemia

Aim

The purpose of this project was to evaluate the influence of circulating endothelial progenitor cells (EPCs) and platelet microparticles (PMPs) on blood platelet function in experimental hypertension associated with hypercholesterolemia.

Methods

Golden Syrian hamsters were divided in six groups: (i) control, C; (ii) hypertensive-hypercholesterolemic, HH; (iii) ‘prevention’, HHin-EPCs, HH animals fed a HH diet and treated with EPCs; (iv) ‘regression’, HHfin-EPCs, HH treated with EPCs after HH feeding; (v) HH treated with PMPs, HH-PMPs, and (vi) HH treated with EPCs and PMPs, HH-EPCs-PMPs.

Results

Compared to HH group, the platelets from HHin-EPCs and HHfin-EPCs groups showed a reduction of: (i) activation, reflected by decreased integrin 3β, FAK, PI3K, src protein expression; (ii) secreted molecules as: SDF-1, MCP-1, RANTES, VEGF, PF4, PDGF and (iii) expression of pro-inflammatory molecules as: SDF-1, MCP-1, RANTES, IL-6, IL-1β; TFPI secretion was increased. Compared to HH group, platelets of HH-PMPs group showed increased activation, molecules release and proteins expression. Compared to HH-PMPs group the combination EPCs with PMPs treatment induced a decrease of all investigated platelet molecules, however not comparable with that recorded when EPC individual treatment was applied.

Conclusion

EPCs have the ability to reduce platelet activation and to modulate their pro-inflammatory and anti-thrombogenic properties in hypertension associated with hypercholesterolemia. Although, PMPs have several beneficial effects in combination with EPCs, these did not improve the EPC effects. These findings reveal a new biological role of circulating EPCs in platelet function regulation, and may contribute to understand their cross talk, and the mechanisms of atherosclerosis.

Systemic inflammatory stimulation by microparticles derived from hypoxic trophoblast as a model for inflammatory response in preeclampsia

OBJECTIVE

To determine whether trophoblast-derived microparticles can induce different inflammatory responses of the peripheral blood mononuclear cells depending upon the state of trophoblast when the microparticles are generated.

STUDY DESIGN

A trophoblast-derived cell line (ATCC no. CRL-1584) was cultured under normal or hypoxic conditions. Microparticles were isolated from the cell culture supernatants (microparticles from normal trophoblast; microparticles from hypoxic trophoblast). Peripheral blood mononuclear cells were cultured alone or cocultured with either microparticles from normal trophoblast or microparticles from hypoxic trophoblast.

RESULTS

After 48 hours, the peripheral blood mononuclear cells cocultured with microparticles from normal trophoblast released higher concentrations of interleukin-6 than peripheral blood mononuclear cells cultured alone. The peripheral blood mononuclear cells cocultured with microparticles from hypoxic trophoblast showed higher concentration of interleukin-6 and tumor necrosis factor alpha than peripheral blood mononuclear cells cocultured with microparticles from normal trophoblast, after 24 hours and 48 hours.

CONCLUSION

More intense and rapid inflammatory response of peripheral blood mononuclear cells was observed with microparticles from hypoxic trophoblast than with microparticles from normal trophoblast. This difference might explain the exaggerated systemic inflammatory response as a result of placental hypoxia in preeclampsia.

Increased microparticle production and impaired microvascular endothelial function in aldosterone-salt-treated rats: protective effects of polyphenols

We aimed to characterize circulating microparticles in association with arterial stiffness, inflammation and endothelial dysfunction in aldosterone-salt-induced hypertension in rats and to investigate the preventive effects of red wine polyphenols. Uninephrectomized male Sprague-Dawley rats were treated with aldosterone-salt (1 µg.h⁻¹), with or without administration of either red wine polyphenols, Provinols™ (20 mg.kg⁻¹.day⁻¹), or spironolactone (30 mg.kg⁻¹.day⁻¹) for 4 weeks. Microparticles, arterial stiffness, nitric oxide (NO) spin trapping, and mesenteric arterial function were measured. Aldosterone-salt rats showed increased microparticle levels, including those originating from platelets, endothelium and erythrocytes. Hypertension resulted in enhanced aortic stiffness accompanied by increased circulating and aortic NO levels and an upregulation of aortic inducible NO-synthase, NFκB, superoxide anions and nitrotyrosine. Flow-induced dilatation was reduced in mesenteric arteries. These effects were prevented by spironolactone. Provinols™ did not reduce arterial stiffness or systolic hypertension but had effects similar to those of spironolactone on endothelial function assessed by flow-mediated vasodilatation, microparticle generation, aortic NO levels and oxidative stress and apoptosis in the vessel wall. Neither the contractile response nor endothelium-dependent relaxation in mesenteric arteries differed between groups. The in vivo effects of Provinols™ were not mediated by mineralocorticoid receptors or changes in shear stress. In conclusion, vascular remodelling and endothelial dysfunction in aldosterone-salt-mediated hypertension are associated with increased circulating microparticles. Polyphenols prevent the enhanced release of microparticles, macrovascular inflammation and oxidative stress, and microvascular endothelial dysfunction independently of blood pressure, shear stress and mineralocorticoid receptor activation in a model of hyperaldosteronism.