The Role of Circulating Platelets Microparticles and Platelet Parameters in Acute Ischemic Stroke Patients

MicroRNAs as Diagnostic and Prognostic Biomarkers in Ischemic Stroke-A Comprehensive Review and Bioinformatic Analysis

Stroke is the second-most common cause of death worldwide. The pathophysiology of ischemic stroke (IS) is related to inflammation, atherosclerosis, blood coagulation, and platelet activation. MicroRNAs (miRNAs) play important roles in physiological and pathological processes of neurodegenerative diseases and progression of certain neurological diseases, such as IS. Several different miRNAs, and their target genes, are recognized to be involved in the pathophysiology of IS. The capacity of miRNAs to simultaneously regulate several target genes underlies their unique value as diagnostic and prognostic markers in IS. In this review, we focus on the role of miRNAs as diagnostic and prognostic biomarkers in IS. We discuss the most common and reliable detection methods available and promising tests currently under development. We also present original results from bioinformatic analyses of published results, identifying the ten most significant genes (HMGB1, YWHAZ, PIK3R1, STAT3, MAPK1, CBX5, CAPZB, THBS1, TNFRSF10B, RCOR1) associated with inflammation, blood coagulation, and platelet activation and targeted by miRNAs in IS. Additionally, we created miRNA-gene target interaction networks based on Gene Ontology (GO) information derived from publicly available databases. Among our most interesting findings, miR-19a-3p is the most widely modulated miRNA across all selected ontologies and might be proposed as novel biomarker in IS to be tested in future studies.

Genetically Determined Platelet Count and Risk of Cardiovascular Disease

Objective- Cardiovascular disease, including coronary artery disease (CAD) and ischemic stroke, is the leading cause of death worldwide. This Mendelian randomization study uses genetic variants as instruments to investigate whether there is a causal effect of genetically determined platelet count on CAD and ischemic stroke risk. Approach and Results- A genome-wide association study of 166 066 subjects was used to identify instruments and genetic association estimates for platelet count. Genetic association estimates for CAD and ischemic stroke were obtained from genome-wide association studies, including 60 801 CAD cases and 123 504 controls, and 60 341 ischemic stroke cases and 454 450 controls, respectively. The inverse-variance weighted meta-analysis of ratio method Mendelian randomization estimates was the main method used to obtain estimates for the causal effect of genetically determined platelet count on risk of cardiovascular outcomes. We found no significant Mendelian randomization effect of genetically determined platelet count on risk of CAD (odds ratio of CAD per SD unit increase in genetically determined platelet count, 1.01; 95% CI, 0.98-1.04; P=0.60). However, higher genetically determined platelet count was causally associated with an increased risk of ischemic stroke (odds ratio, 1.07; 95% CI, 1.04-1.11; P<1×10-5), including all major ischemic stroke subtypes. Similar results were obtained in sensitivity analyses more robust to the inclusion of pleiotropic genetic variants. Conclusions- This Mendelian randomization study found evidence that higher genetically determined platelet count is causally associated with higher risk of ischemic stroke.

The Impact of Vascular Disease Treatment on Platelet-Derived Microvesicles

Platelet-derived microvesicles (pMVs) are small, heterogeneous vesicles released from platelet membranes as a result of activation. These microvesicles possess a wide range of properties, including prothrombotic, proatherogenic, proinflammatory, immunomodulatory, and even anticoagulant activity. The elevated release of these microvesicles has been observed in various metabolic, inflammatory, thrombotic, and vascular diseases, including ischemic heart disease, stroke, hypertension, diabetes, and connective tissue disease. Modulation of both pMV generation and the expression of their surface molecules may have beneficial clinical implications and could become a novel therapeutic target. However, mechanisms by which pharmacological agents can modify pMV formation are elusive. The purpose of this review is to discuss the effects of drugs routinely used in primary and secondary prevention of vascular disease on the release of pMV and expression of their surface procoagulant and proinflammatory molecules.

Identification of active ingredients mediating anti-platelet aggregation effects of BuyangHuanwu decoction using a platelet binding assay, solid phase extraction, and HPLC-MS/MS

BuyangHuanwu decoction (BHD) is widely used as a traditional herbal medicine because of its antithrombotic effect, which is attributed to the inhibition of platelet aggregation; however, its active compounds remain unknown. In this study, we developed a method involving platelet binding, solid-phase extraction, and HPLC-MS/MS for screening BHD compounds with potential anti-platelet aggregation properties. Five compounds showing platelet binding affinity were identified as 6-hydroxykaempferol-di-O-glucoside, paeoniflorin, calycosin-7-O-β-d-glucoside, galloylpaeoniflorin, and formononetin-7-O-β-d-glucoside. The results of anti-platelet aggregation experiments in vitro confirmed that these compounds inhibited adenosine diphosphate-induced platelet aggregation. Our results suggest that a platelet binding assay combined with solid-phase extraction and HPLC-MS/MS is an effective method for screening anti-platelet aggregation agents in traditional Chinese medicines.

Mean Platelet Volume, C-Reactive Protein, and Prognosis in Patients with Acute Ischemic Stroke Following Intravenous Thrombolytic Treatment

BACKGROUND The aim of this study was to investigate the association between mean platelet volume (MPV), C-reactive protein (CRP), and prognosis in patients with acute ischemic stroke (AIS) following intravenous (IV) thrombolytic treatment. MATERIAL AND METHODS A retrospective clinical study included 129 patients within 4.5 hours from the onset of AIS, who received IV thrombolytic treatment. Clinical data were retrieved from electronic medical records. MPV, CRP, and National Institutes of Health (NIH) Stroke Scale and the modified Rankin Scale (MRS) scores for physical disability were recorded. RESULTS Of the 129 patients, 65.9% were men, and more than half received IV thrombolytic treatment within between 3-4.5 hours. The NIH Stroke Scale scores at 24 hours and at three months after hospital admission were compared with the NIH Stroke Scale scores on hospital admission. A significant correlation was found between the MPV values at 24 hours (r=0.221; p=0.012) and at three months after hospital admission (r=196; p=0.026). There was a significant correlation between CRP values at 24 hours (r=0.224; p=0.021), the difference in NIH Stroke Scale score between 24 hours and three months (r=0.249; p=0.005), and the MPV score at three months (r=0.186; p=0.035). CONCLUSIONS MPV and CRP values were significantly associated with improvement in the NIH Stroke Scale and MRS scores in AIS when patients were treated with IV thrombolytic therapy within 4.5 hours of the onset of symptoms.

Circulating microparticles in patients after ischemic stroke: a systematic review and meta-analysis

Microparticles (MPs), a class of cell products with biological activities, have been found to participate in a series of vascular activities. The aim of this article is to investigate the changes in the concentrations of MPs after ischemic stroke by meta-analysis. According to pre-established criteria, a strict screening of articles was performed through the Medline and Embase databases. Subsequently, the included studies were subjected to quality assessment and data extraction. Finally, a meta-analysis was performed on seven major outcomes from 985 noncerebrovascular disease controls and 988 ischemic stroke patients. The pooled concentrations of total MPs (TMPs), endotheliocyte-derived MPs (EMPs), platelet-derived MPs (PMPs), erythrocyte-derived MPs (RMPs), leukocyte-derived MPs (LMPs), and monocyte-derived MPs (MMPs) were significantly increased in the ischemic stroke patients compared to the noncerebrovascular disease controls, with the results as follows: TMPs [standardized mean difference (SMD), 1.12; 95% confidence interval (CI), 0.26-1.97; p=0.01], EMPs (SMD, 0.90; 95% CI, 0.67-1.13; p<0.00001), PMPs (SMD, 1.15; 95% CI, 0.69-1.60; p<0.00001), RMPs (SMD, 1.14; 95% CI, 0.57-1.71; p<0.0001), LMPs (SMD, 1.42; 95% CI, 0.74-2.10; p<0.0001), and MMPs (SMD, 1.09; 95% CI, 0.59-1.60; p<0.0001). However, the pooled concentration of lymphocyte-derived MPs (LyMPs) demonstrated no significant difference between the patients and the controls (SMD, 0.22; 95% CI, -0.19 to 0.63; p=0.29). The available data indicated that the circulating MPs, except for LyMPs, play an important role in the development and prognosis of ischemic stroke.

Systemic lupus erythematosus and systemic sclerosis: All roads lead to platelets

Systemic lupus erythematosus (SLE) and systemic sclerosis (SSc) are two phenotypically distincts inflammatory systemic diseases. However, SLE and SSc share pathogenic features such as interferon signature, loss of tolerance against self-nuclear antigens and increased tissue damage such as fibrosis. Recently, platelets have emerged as a major actor in immunity including auto-immune diseases. Both SLE and SSc are characterized by strong platelet system activation, which is likely to be both the witness and culprit in their pathogenesis. Platelet activation pathways are multiple and sometimes redundant. They include immune complexes, Toll-like receptors activation, antiphospholipid antibodies and ischemia-reperfusion associated with Raynaud phenomenon. Once activated, platelet promote immune dysregulation by priming interferon production by immune cells, providing CD40L supporting B lymphocyte functions and providing a source of autoantigens. Platelets are actively implicated in SLE and SSc end-organ damage such as cardiovascular and renal disease and in the promotion of tissue fibrosis. Finally, after understanding the main pathogenic implications of platelet activation in both diseases, we discuss potential therapeutics targeting platelets.

The relationship between hematological parameters and prognosis of children with acute ischemic stroke

BACKGROUND

Stroke is rarely seen in children, but it is a major cause of morbidity and mortality. Therefore, there is a need for inexpensive and noninvasive diagnostic methods for estimating the prognosis. Although the prognostic importance of hematological parameters in acute ischemic stroke were reported in adult studies, there is a lack in pediatric ages. The aim of the study is to investigate the relationship between hematological parameters and prognosis of acute ischemic stroke in children.

METHODS

Retrospectively scanned in the study were 106 pediatric patients with acute ischemic stroke who managed at the Medical Faculty of Erciyes University, Kayseri, between the years of 2000 and 2014. White blood count (WBC); neutrophil, lymphocyte, and platelet count; mean platelet volume (MPV); platelet distribution width (PDW); neutrophil count/lymphocyte count (N/L) ratio values obtained from the measurements and initial symptoms; demographical features; risk factors; neurological examination; and clinical follow-up were recorded. Their hematological parameters were compared with those of 106 age and sex-matched healthy individuals.

RESULTS

MPV and PDW values were found similar in patient and control groups, and the platelet count was found significantly low in the control group (p = 0,028). WBC, neutrophil count, and N/L ratio were found considerably high in the patient group (p < 0.001). Lymphocyte count, however, was found significantly low in the control group (p < 0.001). No statistically significant difference was detected in WBC, neutrophil count, lymphocyte count, platelet count, N/L ratio, and MPV and PDW values between the group with sequelae and the one without sequelae. In addition, it was determined that WBC, neutrophil count, lymphocyte count, platelet count, N/L ratio, and MPV and PDW values in the univariate Cox-regression analysis of the patient group had no effect on survival and disease-free survival. When receiver operating characteristic curve was applied, it was observed that the area below WBC, N/L ratio curve was important in the patient group in terms of predicting acute ischemic stroke.

CONCLUSION

The values of WBC, neutrophil count, and N/L ratio differ significantly from those of the control group. The WBC and N/L ratio may help for an earlier diagnosis in children with acute ischemic stroke. WBC, thrombocyte count, MPV, PDW, and N/L ratio do not constitute a risk in overall survival, disease-free survival, and sequelae development.

Microparticles as new markers of cardiovascular risk in diabetes and beyond

The term microparticle (MP) identifies a heterogeneous population of vesicles playing a relevant role in the pathogenesis of vascular diseases, cancer and metabolic diseases such as diabetes mellitus. MPs are released by virtually all cell types by shedding during cell growth, proliferation, activation, apoptosis or senescence processes. MPs, in particular platelet- and endothelial-derived MPs (PMPs and EMPs), are increased in a wide range of thrombotic disorders, with an interesting relationship between their levels and disease pathophysiology, activity or progression. EMP plasma levels have been associated with several cardiovascular diseases and risk factors. PMPs are also shown to be involved in the progressive formation of atherosclerotic plaque and development of arterial thrombosis, especially in diabetic patients. Indeed, diabetes is characterised by an increased procoagulant state and by a hyperreactive platelet phenotype, with enhanced adhesion, aggregation, and activation. Elevated MP levels, such as TF+ MPs, have been shown to be one of the procoagulant determinants in patients with type 2 diabetes mellitus. Atherosclerotic plaque constitutes an opulent source of sequestered MPs, called “plaque” MPs. Otherwise, circulating MPs represent a TF reservoir, named “blood-borne” TF, challenging the dogma that TF is a constitutive protein expressed in minute amounts. “Blood-borne” TF is mainly harboured by PMPs, and it can be trapped within the developing thrombus. MP detection and enumeration by polychromatic flow cytometry (PFC) have opened interesting perspectives in clinical settings, particularly for the evaluation of MP numbers and phenotypes as independent marker of cardiovascular risk, disease and outcome in diabetic patients.

Investigation of neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio and mean platelet volume in patients with tinnitus

OBJECTIVE

This study aimed to evaluate patients with tinnitus in terms of mean platelet volume and platelet distribution width, and to explore neutrophil-to-lymphocyte ratio and platelet-to-lymphocyte ratio, recently reported in the literature as being possible inflammation markers.

METHODS

This study comprised 64 tinnitus patients and 64 age-matched healthy controls. Statistical significance level was accepted as p < 0.05.

RESULTS

Mean platelet volume (t = 3.245, p = 0.002) and platelet distribution width (Z = 3.945, p < 0.001) were significantly higher in the patient group than the control group.

CONCLUSION

The results suggest that a prothrombotic condition might play a role in the pathophysiology of tinnitus.

Correlation between antiplatelet therapy in secondary prevention of acute cerebral infarction and cerebral microbleeds: A susceptibility-weighted imaging (SWI) study

OBJECTIVE

To investigate the clinical significance of antiplatelet aggregation therapy for patients diagnosed with acute cerebral infarction (ACI) complicated with the cerebral microbleeds (CMBs).

METHODS

Thirty patients with ACI and 36 patients with intracerebral hemorrhage (ICH) were included in this research. Two groups, studied by susceptibility-weighted imaging (SWI), were compared in terms of the number, location, and severity of CMBs. Then, 30 cases of ACI patients were divided into CMBs sub-group and non-CMBs sub-group. Univariate analysis between these two sub-groups was performed to determine the risk factors regarding the incidence of CMBs. For ACI patients, the number of CMBs before and after applying anti-platelet treatment were compared to examine the impacts of anti-platelet treatment on hemorrhagic transformation.

RESULTS

CMBs were found to be more prevalent and severe in ICH patients than in ACI patients. CMBs in patients with ICH were more severe than in patients with ischemic stroke (IS), which indicates that CMBs closely relate to ICH. Hypertension and leukoaraiosis were found to have significant effects on the incidence of CMBs. After anti-platelet treatment, patients with CMBs (≥5) increased the number of CMB, whereas there was no obvious effect on patients with the CMBs less than 5 or no CMBs.

CONCLUSIONS

The number of CMBs increased significantly among ACI patients with 5 or more CMBs before the anti-platelet treatment. CMBs are more frequently found in patients with hemorrhagic stroke than in patients with ischemic stroke, and more severe than the latter, which suggests that the clinical impact of higher association between the increase of the number of the CMBs and the hemorrhagic stroke.

Baseline platelet parameters for predicting early platelet response and clinical outcomes in patients with non-cardioembolic ischemic stroke treated with clopidogrel

Purpose

The present study investigated whether routine baseline platelet parameters(BPPs) detected before clopidogrel therapy in acute non-cardioembolic ischemic stroke(NCIS) could predict early platelet response and future clinical outcomes.

Results

The CYP2C19 polymorphisms constituted independent risk factors for LCR. The number of female patients, the incidence of diabetes mellitus (DM), the level of low-density lipoprotein(LDL) cholesterol, and the neutrophil-to-lymphocyte ratio(NLR) were significantly high in the clinical clopidogrel resistance (CCR) group. However, none of the BPPs had a significant association with laboratory clopidogrel resistance (LCR) or discriminated with the cut-off values regarding LCR or CCR. The patients were divided into two groups according to the average mean platelet volume(MPV) or platelet count(PC). We found that the HbA1c level, the number of female patients, and the CCR were higher in the groups with elevated MPV (≥ 10.6fL) and PC (≥ 235 × 10⁹/L); the LCR, the NIHSS score at discharge, and elevated MPV and PC were risk predictors for CCR.

Materials and Methods

This study included 196 patients with acute NCIS who underwent routine blood tests upon admission, were treated with clopidogrel, and were followed up for 6 months. Early platelet response was assessed and the CYP2C19 genetic variants were screened for. All participants were categorized into either laboratory clopidogrel resistance(LCR) or clinical clopidogrel resistance (CCR) groups.

Conclusions

Elevated baseline MPV and PC before clopidogrel therapy, as well as CYP2C19 gene variants, should be included in a risk algorithm for NCIS. Furthermore, other nongenetic clinical risk factors should be assessed for optimal prediction of the risk for thrombotic events because of individual variability in platelet response to clopidogrel.

[Regression analysis of red cell distribution width and mean platelet volume in patients with acute myocardial infarction]

OBJECTIVE

To investigate clinical implications of changes in red cell distribution width (RDW) and mean platelet volume (MPV) in patients with acute myocardial infarction.

METHODS

A total of 127 patients (90 men and 37 women) were enrolled in this analysis, including 66 with acute myocardial infarction (AMI) and 61 with unstable angina (UA). The patients' baseline demographic and clinical data were compared between the two groups including age, hypertension, diabetes, smoking, BMI, blood biochemical profiles, cardiac functions and platelet and red blood cell parameters. The patients were further divided into subgroups according to the RDW 50% cumulative frequency, and the MPV, P-LCR, hsCRP, NT-proBNP, RBC, Dimer and MCV were compared. The correlations between platelet and erythrocyte test results were evaluated in both the AMI and UA patients. Regression analysis was performed to identify the factors affecting the RDW in the AMI group and a regression model was established.

RESULTS

The platelet and red blood cell test results, P-LCR, MPV, and RDW differed significantly between AMI and UA groups (P<0.01 or 0.05). Correlation analysis showed a significant positive correlation between RDW and MPV in AMI group (r=0.34, P<0.01). Between the subgroups with different RDW 50% cumulative frequencies, MPV, P-LCR, hsCRP, D-Dimer, and NT-proBNP all differed significantly (P<0.05 or 0.01). In AMI group, with RDW as the dependent variable, we established a multivariate regression model of RDW=0.19MPV+10.83.

CONCLUSION

RDW and MPV are closely correlated in patients with AMI. In multiple regression analysis, MPV can explain the changes in RDW in patients with AMI.

Measurement and Clinical Significance of Biomarkers of Oxidative Stress in Humans

Oxidative stress is the result of the imbalance between reactive oxygen species (ROS) formation and enzymatic and nonenzymatic antioxidants. Biomarkers of oxidative stress are relevant in the evaluation of the disease status and of the health-enhancing effects of antioxidants. We aim to discuss the major methodological bias of methods used for the evaluation of oxidative stress in humans. There is a lack of consensus concerning the validation, standardization, and reproducibility of methods for the measurement of the following: (1) ROS in leukocytes and platelets by flow cytometry, (2) markers based on ROS-induced modifications of lipids, DNA, and proteins, (3) enzymatic players of redox status, and (4) total antioxidant capacity of human body fluids. It has been suggested that the bias of each method could be overcome by using indexes of oxidative stress that include more than one marker. However, the choice of the markers considered in the global index should be dictated by the aim of the study and its design, as well as by the clinical relevance in the selected subjects. In conclusion, the clinical significance of biomarkers of oxidative stress in humans must come from a critical analysis of the markers that should give an overall index of redox status in particular conditions.

Membrane Ballooning in Aggregated Platelets is Synchronised and Mediates a Surge in Microvesiculation

Human platelet transformation into balloons is part of the haemostatic response and thrombus architecture. Here we reveal that in aggregates of platelets in plasma, ballooning in multiple platelets occurs in a synchronised manner. This suggests a mechanism of coordination between cells, previously unrecognised. We aimed to understand this mechanism, and how it may contribute to thrombus development. Using spinning-disc confocal microscopy we visualised membrane ballooning in human platelet aggregates adherent to collagen-coated surfaces. Within an aggregate, multiple platelets undergo ballooning in a synchronised fashion, dependent upon extracellular calcium, in a manner that followed peak cytosolic calcium levels in the aggregate. Synchrony was observed in platelets within but not between aggregates, suggesting a level of intra-thrombus communication. Blocking phosphatidylserine, inhibiting thrombin or blocking PAR1 receptor, largely prevented synchrony without blocking ballooning itself. In contrast, inhibition of connexins, P2Y₁₂, P2Y₁ or thromboxane formation had no effect on synchrony or ballooning. Importantly, synchronised ballooning was closely followed by a surge in microvesicle formation, which was absent when synchrony was blocked. Our data demonstrate that the mechanism underlying synchronised membrane ballooning requires thrombin generation acting effectively in a positive feedback loop, mediating a subsequent surge in procoagulant activity and microvesicle release.

Neutrophil to Lymphocyte Ratio, Platelet to Lymphocyte Ratio, Mean Platelet Volume and Red Cell Distribution Width Measures in Bells Palsy

AIM:

The purpose of this study was to investigate the usefulness of the neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR) Mean Platelet Volume (MPV) and Red Cell Distribution Width (RDW) in the differential diagnosis and follow-up of patients with Bells Palsy.

MATERIAL AND METHODS:

Twenty-eight patients diagnosed with Bells Palsy and 28 control patients were included in the study. Serum samples were analysed retrospectively on the initial presentation and the seventh day of admission.

RESULTS:

On admission, the NLR was 1.7±1.2. The mean absolute neutrophil count was 6100 ± 900/mm^3 in Bells Palsy Group. NLR was 0.9 ± 0.2. The mean absolute neutrophil count was 4400 ± 1100/mm^3 in control group. Statistically, significant changes were not observed in NLR, PLR, MPV and RDW measurements in Bells Palsy group between House-Brackman Staging.

CONCLUSION:

Statistically significant changes in the neutrophil count and NLR were determined in the measurements between Bells Palsy and control group (p = 0.013, p = 0.016 respectively) on admission. A grade of the disease and NLR measurements had no statistically significant connection. RDW value was investigated for the first time in the literature for Bells Palsy patients.

Platelet extracellular vesicles as biomarkers for arterial thrombosis

Arterial thrombosis is a major and global cause of human death and disability. Considering the socioeconomic costs of arterial thrombosis, identification of biomarkers to predict and detect arterial thrombosis at an early stage is an important public health goal. Platelet extracellular vesicles (PEV) are a new candidate biomarker of arterial thrombosis. PEV can be measured in biorepositories, thereby offering the possibility to validate PEV in multicenter clinical trials. PEV analysis has been hitherto hampered by lack of standardized methodology, but substantial technological improvements of PEV detection techniques have been achieved recently. However, before PEV emerge from research tools to clinical applications, a number of issues should be clarified. To facilitate validation of PEV as biomarkers of thrombosis, we discuss (i) whether PEV are useful as biomarkers of thrombosis, (ii) why previous conclusions on PEV concentrations, composition and functions require re-evaluation, and (iii) which questions have to be answered before PEV become clinically useful.

Cell-derived microvesicles in cardiovascular diseases and antiplatelet therapy monitoring - A lesson for future trials? Current evidence, recent progresses and perspectives of clinical application

Circulating cell-derived microvesicles (MV) represent a subject of increasing interest in recent years as potential effectors in thrombosis, inflammation and vascular injury. Although several studies demonstrated an association between MV plasma concentrations and clinical manifestations of atherosclerosis as well as a clear effect of cardiovascular pharmacotherapy on MV formation pattern, the application of this promising biomarkers in clinical cardiology has been hindered so far due to heterogeneity of the hitherto studies employing non-standardized methodologies. Recently great progresses have been done and international initiatives were started to unify the pre-analytical and analytical procedures, improve the comparison of measurements between the laboratories and increase detector sensitivity of flow cytometry - a golden standard for MV assessment. Likewise, the concept of a "therapeutic window" of P2Y12 inhibitor therapy was introduced, as the prognostic significance of bleeding consequences is equally important with that of ischemic events, particularly with the expanding use of more potent P2Y12 inhibitors. In this review we summarize currently available studies on circulating MV in terms of cardiovascular diagnosis, risk stratification and influence of antiplatelet agents on the MV release to postulate possible future role of MV as supplementary biomarker in monitoring of individual response to antiplatelet therapy. Methodological pitfalls faced in the previous studies and obstacles that need to be addressed before further trials and translation of MV-based assays into clinical practice were defined.

Recombinant tissue plasminogen activator enhances microparticle release from mouse brain-derived endothelial cells through plasmin

Thrombolysis with recombinant tissue plasminogen activator (rt-PA) is currently the only approved pharmacological strategy for acute ischemic stroke. However, rt-PA exhibits vascular toxicity mainly due to endothelial damage. To investigate the mechanisms underlying rt-PA-induced endothelial alterations, we assessed the role of rt-PA in the generation of endothelial microparticles (EMPs), emerging biological markers and effectors of endothelial dysfunction. The mouse brain-derived endothelial cell line bEnd.3 was used. Cells were treated with rt-PA at 20, 40 or 80μg/ml for 15 or 24h, and EMPs were quantified in the culture media using Annexin-V staining coupled with flow cytometry. Rt-PA enhanced EMP release from bEnd.3 cells with a maximal increase at the 40μg/ml dose for 24h (+78% compared to controls). Using tranexamic acid and aprotinin we demonstrated that plasmin is responsible for rt-PA-induced EMP release. The p38 MAPK inhibitor SB203580 and the poly(ADP-ribose)polymerase (PARP) inhibitor PJ34 also reduced rt-PA-induced EMP production, suggesting that p38 MAPK and PARP are downstream intracellular effectors of rt-PA/plasmin. Rt-PA also altered through plasmin the morphology and the confluence of bEnd.3 cells. By contrast, these changes did not implicate p38 MAPK and PARP. This study demonstrates that rt-PA induces the production of microparticles by cerebral endothelial cells, through plasmin, p38 MAPK and PARP pathways. Determining the phenotype of these EMPs to clarify their role on the endothelium in ischemic conditions could thus be of particular interest.

Platelet Activation: The Mechanisms and Potential Biomarkers

Beyond hemostasis and thrombosis, an increasing number of studies indicate that platelets play an integral role in intercellular communication, mediating inflammatory and immunomodulatory activities. Our knowledge about how platelets modulate inflammatory and immunity has greatly improved in recent years. In this review, we discuss recent advances in the pathways of platelet activation and potential application of platelet activation biomarkers to diagnosis and prediction of disease states.

Evidence-Based Clinical Use of Nanoscale Extracellular Vesicles in Nanomedicine

Recent research has demonstrated that all body fluids assessed contain substantial amounts of vesicles that range in size from 30 to 1000 nm and that are surrounded by phospholipid membranes containing different membrane microdomains such as lipid rafts and caveolae. The most prominent representatives of these so-called extracellular vesicles (EVs) are nanosized exosomes (70-150 nm), which are derivatives of the endosomal system, and microvesicles (100-1000 nm), which are produced by outward budding of the plasma membrane. Nanosized EVs are released by almost all cell types and mediate targeted intercellular communication under physiological and pathophysiological conditions. Containing cell-type-specific signatures, EVs have been proposed as biomarkers in a variety of diseases. Furthermore, according to their physical functions, EVs of selected cell types have been used as therapeutic agents in immune therapy, vaccination trials, regenerative medicine, and drug delivery. Undoubtedly, the rapidly emerging field of basic and applied EV research will significantly influence the biomedicinal landscape in the future. In this Perspective, we, a network of European scientists from clinical, academic, and industry settings collaborating through the H2020 European Cooperation in Science and Technology (COST) program European Network on Microvesicles and Exosomes in Health and Disease (ME-HAD), demonstrate the high potential of nanosized EVs for both diagnostic and therapeutic (i.e., theranostic) areas of nanomedicine.

Potential Therapies by Stem Cell-Derived Exosomes in CNS Diseases: Focusing on the Neurogenic Niche

Neurodegenerative disorders are one of the leading causes of death and disability and one of the biggest burdens on health care systems. Novel approaches using various types of stem cells have been proposed to treat common neurodegenerative disorders such as Alzheimer's Disease, Parkinson's Disease, or stroke. Moreover, as the secretome of these cells appears to be of greater benefit compared to the cells themselves, the extracellular components responsible for its therapeutic benefit have been explored. Stem cells, as well as most cells, release extracellular vesicles such as exosomes, which are nanovesicles able to target specific cell types and thus to modify their function by delivering proteins, lipids, and nucleic acids. Exosomes have recently been tested in vivo and in vitro as therapeutic conveyors for the treatment of diseases. As such, they could be engineered to target specific populations of cells within the CNS. Considering the fact that many degenerative brain diseases have an impact on adult neurogenesis, we discuss how the modulation of the adult neurogenic niches may be a therapeutic target of stem cell-derived exosomes. These novel approaches should be examined in cellular and animal models to provide better, more effective, and specific therapeutic tools in the future.

Possible roles of platelet-derived microparticles in atherosclerosis

Platelets and platelet-derived microparticles (PMPs) play important roles in cardiovascular diseases, especially atherosclerosis. Continued research has revealed that PMPs have numerous functions in atherosclerosis, not only in thrombosis formation, but also by induction of inflammation. PMPs also induce formation of foam cells. Recent evidence strongly indicates a significant role of PMPs in atherosclerosis. Here, current research on the function of PMPs in atherosclerosis is reviewed.