Platelet-derived Microparticle Levels Research Articles

Improving platelet function following prophylactic platelet transfusion in patients with hematological malignancies.

Platelet transfusion is a standard treatment to prevent bleeding in patients with hematological malignancies. Although transfusions can improve platelet count, their impact on platelet function remains controversial. We conducted flow cytometry to assess platelet function before and after transfusion and performed subgroup analyses to examine differences based on blood type, corrected count increment (CCI), and platelet microparticles. Overall, 50 patients who received prophylactic platelet transfusion were enrolled. CD42b expression increased, whereas CD41 expression decreased after transfusion. Apheresis platelets exhibited the lowest expression of PAC-1 and P-selectin when exposed to agonist stimulations. PAC-1 expression increased under high adenosine diphosphate (ADP) stimulation, while P-selectin expression increased under both high ADP and thrombin receptor-activating peptide stimulation. In the subgroup analysis, patients with a CCI >4500 and those with the same blood types exhibited a more significant increase in PAC-1 and P-selectin expression under agonist stimulation. When comparing apheresis platelets collected on different days, only the percentage of platelet-derived microparticles showed a significantincrease. Prophylactic transfusion improved platelet function. Platelet function significantly improved in patients with a CCI >4500, those with the same blood types as that of apheresis platelets, or those with platelet-derived microparticle levels <4.7%. No significant improvement in platelet function was noted after the transfusion of different blood types with acceptable compatibility or the transfusion of incompatible blood types. Our results suggest that transfusing platelets with the same blood type remains the optimal choice.

New prognostic biomarkers and therapeutic effect of bevacizumab for patients with non-small-cell lung cancer.

BackgroundSeveral biomarkers have emerged as potential prognostic and predictive markers for non-small-cell lung cancer (NSCLC). Successful inhibition of angiogenesis with the antivascular endothelial growth factor antibody, bevacizumab, has improved the efficacy seen with standard cytotoxic therapy of NSCLC. However, despite such enhanced treatment strategies, the prognosis for patients with advanced NSCLC remains poor.Patients and methodsWe assessed potential biomarkers in 161 NSCLC patients and 42 control patients. Enzyme-linked immunosorbent assay methods were used to evaluate three biomarkers: platelet-derived microparticle (PDMP), high-mobility group box-1 (HMGB1), and plasminogen activator inhibitor-1 (PAI-1). We studied the effects of bevacizumab on the expression of these markers. We also analyzed the relationship of the newly designed risk factor (NDRF) to overall survival and disease-free survival. The NDRF classification of patients was determined from the levels of PDMP, HMGB1, and PAI-1. To determine the individual prognostic power of PDMP, HMGB1, and PAI-1, we evaluated associations between their levels and patient outcomes by Kaplan–Meier survival analysis in a derivation cohort.ResultsPDMP, HMGB1, and PAI-1 levels were higher in NSCLC patients compared with control patients. Notably, the difference in PDMP levels exhibited the strongest statistical significance (p<0.001). Multivariate analysis showed that HMGB1 and PAI-1 levels were significantly correlated with PDMP levels. Patients who received standard chemotherapy with bevacizumab exhibited significantly reduced levels of all three markers compared with patients who received standard chemotherapy. NDRF3 status (high levels of all three markers) was significantly correlated with a poor prognosis (p<0.05 for overall survival and disease-free survival).ConclusionOur results demonstrate that abnormal levels of PDMP, HMGB1, and PAI-1 are related to each other in NSCLC. Moreover, our findings suggest that the vascular complications associated with these markers may contribute to a poor prognosis for NSCLC patients.

Platelet activation in the pathogenesis of obesity and vascular disease

The pathogenesis of atherosclerotic disease is complex, and very topical, as clearly highlighted in a recent position paper of the European Society of Cardiology (ESC) Working Group on Atherosclerosis and Vascular Biology in this journal, which deals with atherosclerotic plaques and their ‘stabilisation’ per se (1). A number of associations have been observed between lipid abnormalities, markers of metabolic syndrome and platelet activation (1–5). In recent years, many studies have explored associations for platelet activation markers to gain insights on the pathogenesis of obesity and atherosclerotic disease (6–13). In this issue of Thrombosis and Haemo stasis, Csongradi et al. report on a large cross-sectional cohort study that explored relationships for platelet activation markers in obese subjects, including those with and without common co-morbidities for atherosclerotic disease (14). Key findings of their study were that platelet and plasma P-selectin levels, and the plasma levels of platelet microparticles, were associated with carotid intimal medial thickness and a variety of other vascular risk factors, including fasting plasma glucose, insulin levels and triglycerides (14). These observations imply that the extent of atherosclerotic disease, and the metabolic derangements associated with obesity and atherosclerotic disease, influence the generation of platelet microparticles. This possibility is supported by a recent study that showed weight loss-induced improvements in insulin resistance, among women with obesity, reduced markers of platelet activation (6). While association studies cannot determine causation, they are important to developing new hypotheses on the pathogenesis of atherosclerotic disease. Platelet microparticles have attracted much interest both experimentally and clinically (15–19). Indeed, given their significant procoagulant activity (18, 19), their elevation in pathogenic states could contribute to the progression of vascular disease and acute thrombotic events. Nonetheless, uncertainties remain about whether observed associations between elevated levels of platelet-derived microparticles with prothrombotic, metabolic and inflammatory parameters are correlative or causative, and how much platelet microparticle generation, and other aspects of platelet activation, contribute to the pathogenesis of atherosclerotic disease in obese individuals. The “independent” associations that Csongradi et al. found between platelet-derived microparticle levels with body mass index, and between soluble P-selectin and fibrinogen, and platelet P-selectin and both carotid intimal medial thickness and PAI-1 (14) provide further evidence that platelet activation is influenced by the complex metabolic and inflammatory parameters that participate in the pathogenesis of atherosclerotic disease. Despite these advances, uncertainties still remain about whether measuring platelet activation markers has a role in diagnostic or therapeutic decision making for obese and non-obese individuals who have or do not have evidence of atherosclerotic disease. This still remains an exciting and expanding field of research.

Platelet-derived microparticle levels are significantly elevated in patients treated by elective stenting compared to subjects with diagnostic catheterization alone

Significant platelet reactivity with endothelial damage may occur during percutaneous coronary intervention such as balloon angioplasty and elective stenting in patients with stenotic or occluded arteries in coronary artery disease. Activated platelets express several surface epitopes to aggregate and form heterotypic interactions with leukocytes and endothelial cells, secrete biomarkers to enhance their prothrombotic properties and also generate increased level of microparticles (PMPs). These events may contribute to subacute stent thrombosis induced by the procedure-mediated trauma. Our aim was to study the level of PMPs and other platelet activation markers at an early time point after stenting with bare metal stent in patients on aspirin antiplatelet pre-treatment, and these results were compared to data obtained from subjects with diagnostic catheterization alone. We found that at 15 minutes after the completion of stenting, the levels of PMPs (557 ± 83/µl versus 325 ± 42/µl), the platelet P-selectin expression (2.7 ± 0.3% versus 1.99 ± 0.1%) and the ratio of platelet-monocyte heterotypic aggregates (48 ± 4% versus 38 ± 3%) were significantly (p < 0.05) elevated in patients compared to unstented subjects, but no difference was found in soluble P-selectin values. We suggest that the observed cellular changes are early and sensitive markers to detect the platelet-activating effect of stent implantation.

Evaluation of Factors Associated With Elevated Levels of Platelet-Derived Microparticles in the Acute Phase of Cerebral Infarction

Platelet-derived microparticles (PDMPs) have attracted attention as blood coagulation-promoting, endothelial cell-activating factors. The objective of this study was to determine the parameters associated with elevated PDMP levels and examine their relationship with atherosclerotic lesions of main intracranial and extracranial arteries. Participants included a control group (C) of 61 patients with no apparent cerebral vascular lesions and 110 patients with acute-phase cerebral infarction, consisting of a small-vessel occlusion group (S) of 34 patients, a large-artery atherosclerosis group (L) of 41 patients, a cardioembolism group (CE) of 20 patients, and a stroke of undetermined etiology group (U) of 15 patients. Platelet-derived microparticle levels were measured using enzyme-linked immunosorbent assay (ELISA) at the time of admission, and the patients were reclassified into group CP (control level PDMPs), consisting of 70 patients with control PDMP levels, and group HP (high PDMPs), consisting of 40 patients with elevated PDMP levels. All patients underwent cranial magnetic resonance (MR) and carotid ultrasound examinations. Platelet-derived microparticle levels were significantly higher in groups S and L than in group C (P < .01). Concomitant intima-media thickness (IMT; odds ratio [OR] = 1.29, P < .05) and concomitant intracranial stenosis (OR = 3.95, P < .01) were significantly correlated with elevated PDMP levels. Fibrinogen and high-sensitivity CRP levels were significantly higher in group HP than in group CP. Alterations in PDMP levels correlated with the presence of atherothrombotic lesions, and PDMP levels are expected to be useful as a clinical indicator, reflecting the presence of intracranial atherosclerotic lesions in the acute phase of cerebral infarction.

Measurement of platelet‐derived microparticle levels using an enzyme‐linked immunosorbent assay in polymyositis and dermatomyositis patients

Platelet-derived microparticle (PDMP) levels were measured using an enzyme-linked immunosorbent assay (ELISA) to elucidate the role of platelet activation in patients with polymyositis or dermatomyositis (PM/DM). PDMP levels in active PM/DM patients (median 13.3 U/ml, interquartile range 9.9-20.7 U/ml, n = 16) and those in patients undergoing treatment (12.1 U/ml, 7.4-16.7 U/ml, n = 12) were significantly higher than in controls (6.5 U/ml, 5.0-8.4 U/ml, n = 26, vs. active, P = 0.0001; vs. treatment, P = 0.004). In a paired sampling study, PDMP decreased significantly after glucocorticoid treatment (P = 0.04). PDMP in the active PM/DM patients correlated significantly with serum C-reactive protein levels (r(s) = 0.67, P = 0.01). These results suggest that platelets may play an important role in the inflammatory process, and that PDMP level could be a useful marker of inflammatory activity in PM/DM patients. Muscle Nerve 39: 586-590, 2009.

Platelet-derived microparticle levels in women with recurrent spontaneous abortion

Objective To investigate the significance of platelet-derived microparticles (PMPs) in women with recurrent spontaneous abortion. Methods We measured platelet P-selectin (CD62P) as a platelet activation marker and CD42b + microparticles as PMPs by flow cytometry in whole blood of 20 women with recurrent spontaneous abortion and 20 age-matched healthy controls with no previous history of spontaneous abortion. Results PMP levels in women with recurrent spontaneous abortion were higher than in women in the control group (4.79 ± 1.18% vs 3.06 ± 0.92%; P < 0.000). CD62P levels were not significantly higher in the study group compared with the control group (13.78 ± 8.62% vs 10.78 ± 7.35%; P > 0.05). Conclusion Our findings suggest that PMPs may have a role in the pathogenesis of recurrent spontaneous abortion.

Measurement of platelet-derived microparticle levels in the chronic phase of cerebral infarction using an enzyme-linked immunosorbent assay.

Assessment of platelet function is a critical component of the treatment and secondary prevention of cerebral infarction, and measurement of platelet-derived microparticle (PDMP) levels using flow cytometry may be a good indicator of platelet function. However, the flow cytometric analysis is not feasible in a variety of clinical situations. The goal of the present study was to measure PDMP levels using an enzyme-linked immunosorbent assay (ELISA) in chronic cerebral infarction patients and to determine the utility of PDMP level measurement for the monitoring of the effect of cilostazol and aspirin. A crossover study was performed using 4-weeks of aspirin (100 mg/day) and 4-weeks of cilostazol (200 mg/day) in 18 patients. PDMP levels were also measured in 20 volunteers as controls. Experiments demonstrated that PDMP levels were significantly higher in chronic cerebral infarction patients (median 8.8 U/ml, interquartile range 5.1-14.9 U/ml, n=18) than in controls (median 5.5 U/ml, interquartile range 5.0-8.2 U/ml, n=20) (P=0.047). PDMP levels did not decrease after therapy with either aspirin (median 10.9 U/ml, interquartile range 6.2-17.9 U/ml, n=12) or cilostazol (median 9.2 U/ml, interquartile range 6.1-14.3 U/ml, n=12) compared with baseline PDMP levels in the 12 patients who completed this trial (median 11.4 U/ml, interquartile range 5.2-23.7 U/ml, n=12). There were no significant differences in PDMP levels between aspirin and cilostazol (P=0.61). In conclusion, PDMP levels as measured by ELISA were increased in patients with chronic cerebral infarction regardless of the anti-platelet therapy. This methodology may be a useful strategy of assessing platelet function in chronic cerebral infarction patients.

Increased thrombin generation in women with a history of preeclampsia

Introduction Women with a history of preeclampsia have an increased risk for cardiovascular disease in later life. We evaluated thrombogenic characteristics of women with a previous history of preeclampsia, expressed in levels of thrombin generation, number of microparticles and related to menstrual cycle and endothelial function, measured as flow-mediated dilatation. Materials and methods We included 18 primipara women with a history of preeclampsia and 17 healthy primipara controls, 15 (± 3) months after the index pregnancy. Thrombin generation was measured by tissue factor triggered assay, microparticle levels were measured by flow cytometry and the endothelial function was previously examined by measuring flow-mediated dilatation by high-resolution ultrasound, during follicular and luteal phases of the menstrual cycle. Results Women with previous preeclampsia produced more total amount of thrombin as calculated from thrombin max, thrombin potential and max slope levels p < 0.05, 0.01 and 0.01 respectively. Platelet derived microparticle levels were higher in women with a history of preeclampsia, p = 0.07. Flow-mediated dilatation was significantly decreased in comparison to healthy controls (p < 0.0001). There were no variation in levels of thrombin, microparticles and flow-mediated dilatation during the menstrual phases. Conclusion Women with a history of preeclampsia show signs of hypercoagulability as indicated by higher thrombin generation and higher platelet derived microparticle levels. Since these women were investigated more than one year after delivery, these results may be indicative of an increased risk of cardiovascular events later in life.

Combined Antithrombotic Therapy but Not Single-Agent Therapy with Low-Dose Aspirin Deteriorated Platelet Activation in Patients with Antiphospholipid Syndrome (APS).

Antiphospholipid syndrome (APS) is one of autoimmune disorders characterized with recurrent thromboses. It is considered that plasma levels of D-dimer and prothrombin fragment 1+2 (F1+2) could reflect hypercoagulable state in APS patients and those monitoring may be useful for a predictor of venous thromboses. In contrast, the estimation of platelet activation is difficult. Recently, plasma levels of platelet-derived microparticle (PDMP), which released from activated platelets, could be measured using ELISA supplied from JIMRO Co. JAPN (“JIMRO test PDMP”). We previously presented that plasma levels of PDMP were significantly elevated in APS-patients with arterial thromboses and that could reflect platelet activated condition in vivo. To evaluate the preventory effect of thromboses and the inhibitory effects for platelet activation by several kinds of antithrombotic agents in APS, 30 APS patients with cerebral infarctions were randomly treated with low-dose aspirin alone (Group A, n=10), aspirin plus warfarin (Group B, n=10), or aspirin plus cirostazole (Group C, n=10). Their plasma PDMP levels were measured using “JIMRO test PDMP” (JIMRO Co., JAPAN) before and after antithromboitic treatment on a regular schedule, and MRI brain scans were also underwent in every six months. Plasma PDMP levels in group B and group C significantly decreased by combined antithrombotic therapy (18.0 ± 7.1 to 13.0 ± 8.2 U/mL, 17.8 ± 6.7 to 12.4 ± 7.8 U/mL, p < 0.03 and < 0.01, respectively) but not in Group A (18.2 ± 8.1 to 17.9 ± 9.1, NS). Brain MRI revealed worsening of lacuna infarctions in only one patient in Group A. No serious adverse effects were shown in any patients. These findings suggest that single use of aspirin could be enough for prevention of arterial thrombosis in APS patients and that plasma PDMP levels may be useful for an indicator of antiplatelet therapy.

Modulation of platelet aggregation responses by leukocytapheresis therapy in patients with active ulcerative colitis

Recent studies suggest that platelet activation plays an important role in the pathophysiology of inflammatory bowel disease. In this study, we evaluated the effects of leukocytapheresis (LCAP) on platelet functions in patients with ulcerative colitis (UC). Thirteen patients with active UC (five women and eight men) were treated with LCAP therapy. Platelet-rich plasma (PRP) was prepared, and platelet aggregation in response to agonist solution (epinephrine, collagen, and ADP) was measured with a platelet aggregometer. Platelet-derived microparticle (PDMP) plasma levels were determined by enzyme-linked immunosorbent assay. Nine patients responded to LCAP therapy, but no clinical responses were observed in four patients. The aggregation response to 0.1 microg/ml epinephrine was enhanced in all patients. In all responders, enhanced epinephrine aggregation was normalized after the LCAP session. However, in the four nonresponders, enhanced epinephrine aggregation was maintained after the LCAP session. In responders, the mean maximum aggregation induced by 0.1 microg/ml epinephrine was 76.8 +/- 5.0% before and 15.4 +/- 3.8% after LCAP, respectively (P < 0.05). Increased aggregation responses to both 0.2 microg/ml collagen and 1.0 microM ADP were observed, and LCAP also normalized these enhanced responses. LCAP significantly reduced circulating PDMP levels (56.8 +/- 28.3 U/ml before and 46.3 +/- 30.4 U/ml after LCAP, P < 0.05). LCAP reduced enhanced platelet aggregation responses in active UC patients. Because platelets play an important role in inflammatory and immune responses, therapeutic effects of LCAP may be partially mediated by reduction of increased platelet aggregation activities.

5-HT2A receptor antagonist increases circulating adiponectin in patients with type 2 diabetes

We compared the levels of plasma adiponectin, platelet activation markers (P-selectin, CD63, PAC-1, annexin V, and platelet-derived microparticles), and endothelial injury markers (soluble E-selectin and soluble vascular cell adhesion molecule-1) in 53 patients with type 2 diabetes mellitus to investigate potential contributions to diabetic vascular complications. In addition, we administered serotonin antagonist (sarpogrelate hydrochloride) to type 2 diabetes patients who had increased soluble E-selectin levels. The concentrations of platelet activation markers and endothelial injury markers in diabetic patients were significantly higher than those in normal subjects. However, levels of adiponectin were lower in type 2 diabetes patients than in control subjects. A total of 32 patients had high-soluble E-selectin levels (soluble E-selectin >or= 62 ng/ml); a subset of patients that also had significant elevation of platelet activation and endothelial injury markers compared with patients without high soluble E-selectin. In addition, both platelet-P-selectin and platelet-derived microparticle levels negatively correlated with the adiponectin level. Patients with high soluble E-selectin exhibited significant improvement of all markers after sarpogrelate hydrochloride treatment. These findings suggest that there is a link between vascular change in type 2 diabetes and activated platelets, endothelial dysfunction, and an adiponectin abnormality.

Platelet-Derived Microparticles in Patients with Arteriosclerosis Obliterans: Enhancement of High Shear-Induced Microparticle Generation by Cytokines

We evaluated the plasma concentrations of cytokines and platelet-derived microparticles in patients with arteriosclerosis obliterans and studied the effect of cytokines on platelet-derived microparticle generation under high shear stress. Interleukin-6 levels peaked at 48 hours after vascular surgery, while thrombopoietin started to increase at 24 to 48 hours postoperatively and peaked on the seventh day. Platelet activation markers were increased in the arteriosclerosis obliterans patients preoperatively. Levels of P-selectin and CD63 both increased further, peaking at 6 to 24 hours postoperatively. Platelet-derived microparticle levels were also increased preoperatively. At 6 hours postoperatively, the plasma level of platelet-derived microparticles was significantly increased. Plasma platelet-derived microparticle level was lower at 12 hours but only returned to the preoperative value at 7 days after grafting. There was a difference in the platelet-derived microparticle level at 7 days between patients with or without antiplatelet therapy (cilostazol). The effect of cytokines on platelet activation under high shear stress was also studied. Interleukin-6 and thrombopoietin enhanced both P-selectin expression and platelet-derived microparticle generation under high shear stress. These results suggest that platelet-derived microparticles are released by platelet activation after vascular grafting when certain cytokines increase under high shear stress and that antiplatelet therapy may reduce platelet-derived microparticle levels postoperatively.

Platelet Procoagulant Activity During,Peripheral Blood Stem Cell Harvest

We used flow cytometry to measure platelet-derived microparticle levels in plasma obtained from 16 patients during peripheral blood stem cell harvest (PBSC) and in platelet concentrates prepared by apheresis from 10 normal controls. We also studied the binding of an anti-P-selectin antibody and annexin-V to platelets. When all 60 harvests were assessed, we noted a significant difference in microparticle levels between patients with a platelet count &gt;10 x 104/μl and those with a platelet count &lt;10 X 104/μl (12.3 ± 4.4 vs. 75 ± 3.9%). In both the first and total harvests, the percentage of platelets and microparticles positive for anti-P-selectin and annexin-V were significantly higher than the normal control levels. These results suggest that patients undergoing mobilization by granulocyte colony-stimulating factor (G-CSF) who have a platelet count &gt;10 X 104/μl are at risk of increased procoagulant activity after retransfusion following PBSC harvest. Key Words: Platelet-derived microparticle— Peripheral blood stem cell harvest—Granulocyte colony-stimulating factor.