Large platelets circulate in an activated state in diabetes mellitus

Viral infection and host immune response in diabetes

Diabetes, a chronic metabolic disorder disrupting blood sugar regulation, has emerged as a prominent silent pandemic. Uncontrolled diabetes predisposes an individual to develop fatal complications like cardiovascular disorders, kidney damage, and neuropathies and aggravates the severity of treatable infections. Escalating cases of Type 1 and Type 2 diabetes correlate with a global upswing in diabetes-linked mortality. As a growing global concern with limited preventive interventions, diabetes necessitates extensive research to mitigate its healthcare burden and assist ailing patients. An altered immune system exacerbated by chronic hyperinflammation heightens the susceptibility of diabetic individuals to microbial infections, including notable viruses like SARS-CoV-2, dengue, and influenza. Given such a scenario, we scrutinized the literature and compiled molecular pathways and signaling cascades related to immune compartments in diabetics that escalate the severity associated with the above-mentioned viral infections in them as compared to healthy individuals. The pathogenesis of these viral infections that trigger diabetes compromises both innate and adaptive immune functions and pre-existing diabetes also leads to heightened disease severity. Lastly, this review succinctly outlines available treatments for diabetics, which may hold promise as preventive or supportive measures to effectively combat these viral infections in the former.

Relationship between platelet mass index and postoperative atrial fibrillation after elective coronary artery bypass surgery: a retrospective study

BACKGROUND

Atrial fibrillation (AF) is the most common complication after cardiac surgery. The pathogenesis of postoperative atrial fibrillation (POAF) is multifactorial and one of the known factors is inflammation. Platelet mass index (PMI) is an indicator of platelet activation and a better inflammatory marker than mean platelet volume (MPV). In this retrospective study, we investigated the relationship between POAF and PMI.

METHODS

The study included 848 consecutive patients (655 male and 193 female) who had elective isolated coronary artery by-pass grafting (CABG) or combined CABG and valvular surgery. Platelet count and MPV were measured from preoperative blood samples to calculate PMI. Post-operative atrial fibrillation was defined as irregular and fibrillatory P waves occurring 48-96 h after cardiac surgery and lasting at least 30 s. The PMI values in patients who developed POAF were compared with those in patients who did not develop POAF.

RESULTS

Patients who developed POAF had higher PMI values (2549.3 ± 1077.1) when compared with patients in sinus rhythm (2248.1 ± 683.4; p < 0.01). In multivariate regression analysis, age (OR: 1.05; 95% CI: 1.02-1.09; p = 0.01), left atrial diameter (OR: 1.05; 95% CI: 1.03-1.09; p = 0.02), hs-CRP (OR: 1.09; 95%CI: 1.05-1.13; p < 0.01), EuroSCORE II (OR: 1.27; 95% CI: 1.14-1.41; p < 0.01), and PMI (OR: 1.01; 95% CI: 1.001-1.02; p < 0.01) were independent predictors of POAF. In ROC analysis, PMI ≥ 2286 predicted POAF development with a sensitivity of 69% and a specificity of 58% (AUC: 0.66; p < 0.01) CONCLUSION: A significant relationship was found between preoperatively calculated PMI and POAF. We showed that PMI may be used to predict patients who are at high risk of developing POAF.

Type 2 Diabetes Related Mitochondrial Defects in Peripheral Mononucleated Blood Cells from Overweight Postmenopausal Women

Type 2 diabetes (T2D) is a multisystem disease that is the subject of many studies, but the earliest cause of the disease has yet to be elucidated. Mitochondrial impairment has been associated with diabetes in several tissues. To extend the association between T2D and mitochondrial impairment to blood cells, we investigated T2D-related changes in peripheral mononucleated blood cells’ (PBMCs) mitochondrial function in two groups of women (CTRL vs. T2D; mean age: 54.1 ± 3.8 vs. 60.9 ± 4.8; mean BMI 25.6 ± 5.2 vs. 30.0 ± 5), together with a panel of blood biomarkers, anthropometric measurements and physiological parameters (VO2max and strength tests). Dual-energy X-ray absorptiometry (DXA) scan analysis, cardio-pulmonary exercise test and blood biomarkers confirmed hallmarks of diabetes in the T2D group. Mitochondrial function assays performed with high resolution respirometry highlighted a significant reduction of mitochondrial respiration in the ADP-stimulated state (OXPHOS; −30%, p = 0.006) and maximal non-coupled respiration (ET; −30%, p = 0.004) in PBMCs samples from the T2D group. The total glutathione antioxidant pool (GSHt) was significantly reduced (−38%: p = 0.04) in plasma samples from the T2D group. The fraction of glycated hemoglobin (Hb1Ac) was positively associated with markers of inflammation (C-reactive protein-CRP r = 0.618; p = 0.006) and of dyslipidemia (triglycerides-TG r = 0.815; p < 0.0001). The same marker (Hb1Ac) was negatively associated with mitochondrial activity levels (OXPHOS r = −0.502; p = 0.034; ET r = −0.529; p = 0.024). The results obtained in overweight postmenopausal women from analysis of PBMCs mitochondrial respiration and their association with anthropometric and physiological parameters indicate that PBMC could represent a reliable model for studying T2D-related metabolic impairment and could be useful for testing the effectiveness of interventions targeting mitochondria.

The role of the platelet pool of Plasminogen Activator Inhibitor-1 in well-controlled type 2 diabetes patients

Background

The main inhibitor of the fibrinolytic system, Plasminogen Activator Inhibitor -1 (PAI-1), irreversibly binds tissue-type Plasminogen Activator (t-PA) and thereby inhibits the protective action of tPA against thrombus formation. Elevated levels of plasma PAI-1 are associated with an increased risk of cardiovascular events and are observed in subjects with type 2 diabetes (T2D) and obesity. Platelets contain the majority of PAI-1 present in blood and exhibit the ability to synthesis active PAI-1. Diabetic platelets are known to be hyper-reactive and larger in size; however, whether these features affect their contribution to the elevated levels of plasma PAI-1 in T2D is not established.

Objectives

To characterize the PAI-1 antigen content and the mRNA expression in platelets from T2D subjects compared to obese and lean control subjects, in order to elucidate the role of platelet PAI-1 in T2D.

Methods

Nine subjects with T2D and obesity were recruited from Primary Care Centers together with 15 healthy control subjects (8 lean subjects and 7 with obesity). PAI-1 antigen levels in plasma, serum and platelets were determined by ELISA, and PAI-1 mRNA expression was analyzed by qPCR.

Results

There was no significant difference in PAI-1 mRNA expression or PAI-1 antigen in platelets in T2D subject in comparison to obese and lean control subjects. An elevated level of plasma PAI-1 was seen in both T2D and obese subjects. PAI-1 gene expression was significantly higher in both obese groups compared to lean.

Conclusion

Similar levels of protein and mRNA expression of PAI-1 in platelets from T2D, obese and lean subjects indicate a limited role of platelets for the elevated plasma PAI-1 levels. However, an increased synthesis rate of mRNA transcripts in platelets from T2D and an increased release of PAI-1 could also result in similar mRNA and protein levels. Hence, synthesis and release rates of PAI-1 from platelets in T2D and obesity need to be investigated to further elucidate the role of platelets in obesity and T2D.

Role of Reticulated Platelets in Cardiovascular Disease

Human platelets differ considerably with regard to their size, RNA content and thrombogenicity. Reticulated platelets (RPs) are young, hyper-reactive platelets that are newly released from the bone marrow. They are larger and contain more RNA compared to older platelets. In comparison to more mature platelets, they exhibit a significantly higher thrombogenicity and are known to be elevated in patients with an increased platelet turnover such as, diabetics and after acute myocardial infarction. Several studies have shown that RPs correlate with an insufficient antiplatelet response to aspirin and specific P2Y₁₂ receptor inhibitors. In addition, RPs are promising novel biomarkers for the prediction of adverse cardiovascular events in cardiovascular disease. However, the reason for RPs intrinsic hyper-reactivity and their association with ischemic events is not completely understood and the biology of RPs is still under investigation. We here present a structured review of preclinical and clinical findings concerning the role of RPs in cardiovascular disease.

Comprehensive Management of Cardiovascular Risk Factors for Adults With Type 2 Diabetes: A Scientific Statement From the American Heart Association

Cardiovascular disease remains the leading cause of death in patients with diabetes. Cardiovascular disease in diabetes is multifactorial, and control of the cardiovascular risk factors leads to substantial reductions in cardiovascular events. The 2015 American Heart Association and American Diabetes Association scientific statement, "Update on Prevention of Cardiovascular Disease in Adults With Type 2 Diabetes Mellitus in Light of Recent Evidence," highlighted the importance of modifying various risk factors responsible for cardiovascular disease in diabetes. At the time, there was limited evidence to suggest that glucose-lowering medications reduce the risk of cardiovascular events. At present, several large randomized controlled trials with newer antihyperglycemic agents have been completed, demonstrating cardiovascular safety and reduction in cardiovascular outcomes, including cardiovascular death, myocardial infarction, stroke, and heart failure. This AHA scientific statement update focuses on (1) the evidence and clinical utility of newer antihyperglycemic agents in improving glycemic control and reducing cardiovascular events in diabetes; (2) the impact of blood pressure control on cardiovascular events in diabetes; and (3) the role of newer lipid-lowering therapies in comprehensive cardiovascular risk management in adults with diabetes. This scientific statement addresses the continued importance of lifestyle interventions, pharmacological therapy, and surgical interventions to curb the epidemic of obesity and metabolic syndrome, important precursors of prediabetes, diabetes, and comorbid cardiovascular disease. Last, this scientific statement explores the critical importance of the social determinants of health and health equity in the continuum of care in diabetes and cardiovascular disease.

Efficacy of Lusutrombopag for Thrombocytopenia in Patients with Chronic Liver Disease Scheduled to Undergo Invasive Procedures

Objective Lusutrombopag is a thrombopoietin receptor agonist that improves thrombocytopenia in patients with chronic liver disease scheduled to undergo invasive procedures. However, information on the efficacy of repeated lusutrombopag treatment and factors associated with the treatment is scarce. We analyzed the efficacy of repeated lusutrombopag treatment and the factors associated with a response to lusutrombopag. Methods Thirty-nine patients with chronic liver disease who received lusutrombopag treatment before undergoing invasive procedures were enrolled in this retrospective study. Of the 39 patients, 10 received lusutrombopag treatment multiple times for a total of 53 regimens of lusutrombopag treatment. Changes in platelet counts, the effects of repeated lusutrombopag treatment, and factors associated with response to lusutrombopag were analyzed. Results The median platelet count increased significantly from 4.5×10⁴/μL before lusutrombopag treatment to 7.2×10⁴/μL before the invasive procedure (p<0.01), and patients undergoing 49 of the 53 (92%) treatment regimens succeeded in undergoing invasive procedures without needing platelet transfusions. In patients who received lusutrombopag treatment repeatedly, the median platelet count significantly increased following the second administration of lusutrombopag, and the effects of lusutrombopag were similar between the first and second administration. A multivariate analysis identified the absence of diabetes mellitus (odds ratio, 5.56 for presence; p=0.04) as a significant and independent predictor of a response to lusutrombopag. Conclusion Lusutrombopag treatment significantly increased platelet counts in patients with chronic liver disease, making it possible to receive invasive procedures. The treatment produced identical effects when it was repeated. The efficacy of lusutrombopag might be decreased in patients with diabetes mellitus.

Apoptotic Ablation of Platelets Reduces Atherosclerosis in Mice With Diabetes

OBJECTIVE

People with diabetes are at a significantly higher risk of cardiovascular disease, in part, due to accelerated atherosclerosis. Diabetic subjects have increased number of platelets that are activated, more reactive, and respond suboptimally to antiplatelet therapies. We hypothesized that reducing platelet numbers by inducing their premature apoptotic death would decrease atherosclerosis. Approach and Results: This was achieved by targeting the antiapoptotic protein Bcl-x_L (B-cell lymphoma-extra large; which is essential for platelet viability) via distinct genetic and pharmacological approaches. In the former, we transplanted bone marrow from mice carrying the Tyr15 to Cys loss of function allele of Bcl-x (known as Bcl-x^Plt20) or wild-type littermate controls into atherosclerotic-prone Ldlr^+/- mice made diabetic with streptozotocin and fed a Western diet. Reduced Bcl-x_L function in hematopoietic cells significantly decreased platelet numbers, exclusive of other hematologic changes. This led to a significant reduction in atherosclerotic lesion formation in Bcl-x^Plt20 bone marrow transplanted Ldlr^+/- mice. To assess the potential therapeutic relevance of reducing platelets in atherosclerosis, we next targeted Bcl-x_L with a pharmacological strategy. This was achieved by low-dose administration of the BH3 (B-cell lymphoma-2 homology domain 3) mimetic, ABT-737 triweekly, in diabetic Apoe^-/- mice for the final 6 weeks of a 12-week study. ABT-737 normalized platelet numbers along with platelet and leukocyte activation to that of nondiabetic controls, significantly reducing atherosclerosis while promoting a more stable plaque phenotype.

CONCLUSIONS

These studies suggest that selectively reducing circulating platelets, by targeting Bcl-x_L to promote platelet apoptosis, can reduce atherosclerosis and lower cardiovascular disease risk in diabetes. Graphic Abstract: A graphic abstract is available for this article.

Clinical Management of Stable Coronary Artery Disease in Patients With Type 2 Diabetes Mellitus: A Scientific Statement From the American Heart Association

Although cardiologists have long treated patients with coronary artery disease (CAD) and concomitant type 2 diabetes mellitus (T2DM), T2DM has traditionally been considered just a comorbidity that affected the development and progression of the disease. Over the past decade, a number of factors have shifted that have forced the cardiology community to reconsider the role of T2DM in CAD. First, in addition to being associated with increased cardiovascular risk, T2DM has the potential to affect a number of treatment choices for CAD. In this document, we discuss the role that T2DM has in the selection of testing for CAD, in medical management (both secondary prevention strategies and treatment of stable angina), and in the selection of revascularization strategy. Second, although glycemic control has been recommended as a part of comprehensive risk factor management in patients with CAD, there is mounting evidence that the mechanism by which glucose is managed can have a substantial impact on cardiovascular outcomes. In this document, we discuss the role of glycemic management (both in intensity of control and choice of medications) in cardiovascular outcomes. It is becoming clear that the cardiologist needs both to consider T2DM in cardiovascular treatment decisions and potentially to help guide the selection of glucose-lowering medications. Our statement provides a comprehensive summary of effective, patient-centered management of CAD in patients with T2DM, with emphasis on the emerging evidence. Given the increasing prevalence of T2DM and the accumulating evidence of the need to consider T2DM in treatment decisions, this knowledge will become ever more important to optimize our patients' cardiovascular outcomes.

Coagulatory Defects in Type-1 and Type-2 Diabetes

Diabetes (both type-1 and type-2) affects millions of individuals worldwide. A major cause of death for individuals with diabetes is cardiovascular diseases, in part since both types of diabetes lead to physiological changes that affect haemostasis. Those changes include altered concentrations of coagulatory proteins, hyper-activation of platelets, changes in metal ion homeostasis, alterations in lipid metabolism (leading to lipotoxicity in the heart and atherosclerosis), the presence of pro-coagulatory microparticles and endothelial dysfunction. In this review, we explore the different mechanisms by which diabetes leads to an increased risk of developing coagulatory disorders and how this differs between type-1 and type-2 diabetes.

Risk factors for major amputation in hospitalized diabetic patients with forefoot ulcers

AIMS

The purpose of this study was to investigate the risk factors for major amputation in patients hospitalized with diabetic forefoot ulcers.

METHODS

Between January 2003 and December 2018, a total of 1792 diabetic patients were admitted to the diabetic wound center for the management of diabetic foot ulcers. Among the patients, 1032 diabetic patients with forefoot ulcers were included in this study. Nine hundred and eighty-three patients (95%) healed without major amputations while 49 patients (5%) healed after major amputations. Data related to 88 potential risk factors including demographics, ulcer condition, vascularity, bioburden, neurology, and serology were collected from the patients in these two groups for comparison.

RESULTS

Among the 88 potential risk factors, 34 showed statistically significant differences between the two groups. In the univariate analysis of 88 risk factors, 33 showed statistically significant differences. In stepwise multiple logistic regression analysis, four of the 33 risk factors remained statistically significant. The multivariate-adjusted odds ratios for gender, magnesium levels, platelet levels, and glycated hemoglobin (HbA1c) levels were 8.216, 2.480, 1.009, and 0.570, respectively.

CONCLUSION

Risk factors for major amputation in patients hospitalized with diabetic forefoot ulcers include male gender, increased magnesium, increased platelet levels, and low levels of HbA1c.

High Residual Platelet Reactivity during Aspirin Therapy in Patients with Non-St Segment Elevation Acute Coronary Syndrome: Comparison Between Initial and Late Phases

Background

High platelet reactivity (HPR) during therapy with acetylsalicylic acid (ASA) is a poor prognostic factor in acute coronary syndromes (ACS). The prevalence of HPR during ACS is greater than that reported in stable diseases. However, it is unclear whether this prevalence of HPR is a transient phenomenon or a characteristic of this high-risk population.

Objective

The main objective is to compare the effects of ASA on platelet function in the initial and late phases of ACS in a single population. Secondary objectives are: correlation between the tests between themselves and the relationship between the tests and the variation of the inflammatory markers (C-reactive protein and interleukin-6).

Methods

Seventy patients with non-ST segment elevation (NSTE) ACS in use of 100-200 mg of ASA per day for at least 7 days were prospectively studied. Platelet function was assessed in the first 48 hours and subsequently after 3 months using four methods: VerifyNow™ (VFN), whole blood platelet aggregation (WBPA) with arachidonic acid (AA) and collagen as agonists, and platelet function analyzer (PFA). The level of statistical significance considered was < 0.05.

Results

According to the more specific methods (WBPA with AA and VFN), the incidence of HPR was significantly higher in the early phase than in the late phase: WBPA with AA: 31% versus 13%, p = 0.015; VFN: 32% versus 16%, p = 0.049. The other methods tested, which were less specific for ASA, did not show significant differences between phases. The correlation between the methods was weak or moderate (r ranging from 0.3 to 0.5, p < 0.05), and there were no significant associations between HPR and inflammatory markers.

Conclusion

The prevalence of HPR during AAS therapy, assessed by specific methods for cyclooxygenase 1 (COX-1), is higher during the acute phase than in the late phase of NSTE ACS.

Mean Platelet Volume Predicts Short-term Prognosis in Young Patients with St-segment Elevation Myocardial Infarction

Background: Acute ST-elevation myocardial infarction (STEMI) is an uncommon diagnosis in patients less than 40 years of age. Over the last two decades, there is an increase in the frequency of cardiovascular events among young adults. However, at present there is only limited clinical data on the clinical characteristics and outcomes of STEMI in young patients who were treated with primary percutaneous coronary intervention (pPCI). Plaque erosion is the underlying pathological mechanism leading to STEMI in the vast majority of young adults. Thrombi that complicate superficial erosion seem more platelet-rich than the fibrinous clots precipitated by plaque rupture. Mean platelet volume (MPV) is recognized as a marker of the platelet activation process and may be a better indicator of short-term prognosis than the inflammatory markers in young patients with STEMI. Therefore, we aimed to investigate clinical and angiographic characteristics, risk factors and the independent value of MPV on predicting short-term major adverse cardiovascular events (MACEs) in young adults with STEMI. Methods: A total of 349 patients aged 40 years or younger who underwent pPCI at our center between 2010–2015 with the diagnosis of STEMI were retrospectively analyzed. Results: The mean age of the patients was 36.4 ± 3.6 years and 90% of them were men. Smoking was by far the most frequent cardiovascular risk factor. MACEs were observed in 23 patients (6.6%), and according to the multivariate regression analysis, Killip IIIIV (OR 7.52, 95% CI 1.25–45.24, p = 0.03), lower admission SBP (OR 0.94, 95% CI 0.90–0.98, p <0.01) and increased MPV (OR 1.67, 95% CI 1.05–2.67, p = 0.03) were found to be independently correlated with MACE in the study population. Conclusion: Our results indicate that MPV is an independent predictor of MACEs at the short-term follow-up in young patients with STEMI undergoing pPCI. Accordingly, we suggested that MPV, a marker of platelet activation, could play a significant role in predicting clinical evolution in young patients with STEMI.

Assessment of platelet respiration as emerging biomarker of disease

Mitochondrial dysfunction is currently acknowledged as a central pathomechanism of most common diseases of the 21(st) century. Recently, the assessment of the bioenergetic profile of human peripheral blood cells has emerged as a novel research field with potential applications in the development of disease biomarkers. In particular, platelets have been successfully used for the ex vivo analysis of mitochondrial respiratory function in several acute and chronic pathologies. An increasing number of studies support the idea that evaluation of the bioenergetic function in circulating platelets may represent the peripheral signature of mitochondrial dysfunction in metabolically active tissues (brain, heart, liver, skeletal muscle). Accordingly, impairment of mitochondrial respiration in peripheral platelets might have potential clinical applicability as a diagnostic and prognostic tool as well as a biomarker in treatment monitoring. The aim of this minireview is to summarize current information in the field of platelet mitochondrial dysfunction in both acute and chronic diseases.

Effects of sarpogrelate, eicosapentaenoic acid and pitavastatin on arterioslcerosis obliterans-related biomarkers in patients with type 2 diabetes (SAREPITASO study)

BACKGROUND

The aim was to evaluate the significance of arteriosclerosis obliterans-related biomarkers in patients with type 2 diabetes mellitus (T2DM), and to compare the effects of sarpogrelate, eicosapentaenoic acid (EPA) and pitavastatin on these markers.

PATIENTS AND METHODS

Seventy-two arteriosclerosis obliterans patients with T2DM were classified into two groups, pitavastatin with either sarpogrelate (PS) or EPA (PE). We observed no differences in all biomarkers between the PS and PE groups before treatments.

RESULTS

The levels of body mass index, hemoglobin A1c, soluble E-selectin, soluble vascular cell adhesion molecule 1, plasminogen activator inhibitor-1 and platelet-derived microparticle in the PE group decreased significantly after treatment. The ankle branchial pressure index and adiponectin levels significantly increased in the PE group after treatment compared with the PS group.

CONCLUSION

These results suggest that combination therapy using pitavastatin and EPA possesses an antiatherosclerotic effect and may be beneficial for prevention of vascular complications in patients with T2DM.

Increased mitochondrial common deletion in platelets from patients with type 2 diabetes is not associated with abnormal platelet activity or mitochondrial function

The present study examined the presence and frequency of the 4,977‑base pair mitochondrial (mt)DNA (mtDNA4977) deletion in blood platelets, and whether increased mtDNA4977 deletion was associated with abnormal mitochondrial and platelet function in type 2 diabetes mellitus. A total of 66 patients with type 2 diabetes mellitus and 23 healthy subjects were included in the present study. Patients were divided into three subgroups according to glycemic control, and the presence or absence of chronic diabetic complications: i) Good glycemic control [glycated hemoglobin (HbA1c) <7] without complications; ii) poor glycemic control (HbA1c ≥7) without complications; and iii) poor glycemic control (HbA1c ≥7) with complications. mtDNA4977 deletion, mtDNA copy number, adenine nucleotides, mitochondrial membrane potential and P‑selectin expression levels were analyzed in platelets. Although the frequency of mtDNA4977 deletion in platelets of the patient (96.9%) and control groups (95.6%) was extremely similar, the deletion level significantly increased in all the diabetic groups, compared with the healthy control group. However, the data from the present study revealed that an increased deletion frequency in platelets was not associated with disease severity, although there was clear interindividual variability. Furthermore, all other parameters were not significantly different among the groups, and there were no correlations between mtDNA4977 deletion frequency and all other studied parameters for any of the case groups. The results indicated that the mtDNA4977 deletion occurred in platelets, and increased deletion in patients with type 2 diabetes did not have a marked influence on mitochondrial and/or platelet dysfunction, when compared with the non‑diabetic subjects. Further research is required to elucidate the sources of inter‑individual variability observed in certain parameters.

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.

Antiplatelet effect of aspirin during 24h in patients with type 2 diabetes without cardiovascular disease

INTRODUCTION

The antiplatelet effect of low-dose aspirin in patients with type 2 diabetes (T2DM) without cardiovascular disease (CVD) has not been thoroughly explored. We investigated if platelet aggregation increased during the standard 24-hour aspirin dosing interval in patients with T2DM compared to non-diabetic controls. Furthermore, we evaluated baseline platelet aggregation, the acute effects of aspirin on platelet aggregation and platelet turnover.

MATERIALS AND METHODS

We included 21 patients with T2DM and 21 age and sex-matched controls. Platelet aggregation was measured by impedance aggregometry (Multiplate® Analyzer) and markers of platelet turnover by flow cytometry (Sysmex® XE-5000). Blood samples were obtained at baseline and 1h after administration of 75mg of aspirin. Participants were then treated for 6days with once-daily aspirin, and blood sampling was repeated 1h and 24h after aspirin intake.

RESULTS

After 6days of treatment, platelet aggregation levels increased during the 24-hour aspirin dosing interval in both patients and controls (p<0.001) with no difference between patients and controls. At baseline, patients with diabetes had increased platelet aggregation compared to controls (p=0.03). Platelet aggregation was reduced after the first dose of aspirin and significantly further reduced after six days of treatment (p<0.001). Patients with T2DM had numerically higher immature platelet count compared to controls (p=0.09), indicating an increased platelet turnover.

CONCLUSION

Patients with T2DM without a history of CVD and controls had increased platelet aggregation at the end of the standard 24-hour dosing interval of aspirin. Further, aspirin-naïve T2DM patients had increased platelet aggregation compared to controls.

Thrombosis in diabetes: a shear flow effect?

Cardiovascular events are the major cause of morbidity and mortality in Type 2 diabetes (T2D). This condition is associated with heightened platelet reactivity, contributing to increased atherothrombotic risk. Indeed, individuals with diabetes respond inadequately to standard antiplatelet therapy. Furthermore, they often experience recurrent events as well as side effects that include excess bleeding. This highlights the need for identification of novel regulators of diabetes-associated thrombosis to target for therapeutic intervention. It is well established that platelet aggregation, a process essential for thrombus formation, is tightly regulated by shear stress; however, the mechanisms underlying shear activation of platelets, particularly in the setting of diabetes, are still poorly understood. This review will address the limitations of current diagnostic systems to assess the importance of shear stress in the regulation of thrombus formation in T2D, and the inability to recapitulate the pro-thrombotic phenotype seen clinically in the setting of T2D. Moreover, we will discuss recent findings utilizing new technologies to define the importance of shear stress in thrombus formation and their potential application to the setting of diabetes. Finally, we will discuss the potential of targeting shear-dependent mechanisms of thrombus formation as a novel therapeutic approach in the setting of T2D.

Epac1-deficient mice have bleeding phenotype and thrombocytes with decreased GPIbβ expression

Epac1 (Exchange protein directly activated by cAMP 1) limits fluid loss from the circulation by tightening the endothelial barrier. We show here that Epac1-/- mice, but not Epac2-/- mice, have prolonged bleeding time, suggesting that Epac1 may limit fluid loss also by restraining bleeding. The Epac1-/- mice had deficient in vitro secondary hemostasis. Quantitative comprehensive proteomics analysis revealed that Epac1-/- mouse platelets (thrombocytes) had unbalanced expression of key components of the glycoprotein Ib-IX-V (GPIb-IX-V) complex, with decrease of GP1bβ and no change of GP1bα. This complex is critical for platelet adhesion under arterial shear conditions. Furthermore, Epac1-/- mice have reduced levels of plasma coagulation factors and fibrinogen, increased size of circulating platelets, increased megakaryocytes (the GP1bβ level was decreased also in Epac1-/- bone marrow) and higher abundance of reticulated platelets. Viscoelastic measurement of clotting function revealed Epac1-/- mice with a dysfunction in the clotting process, which corresponds to reduced plasma levels of coagulation factors like factor XIII and fibrinogen. We propose that the observed platelet phenotype is due to deficient Epac1 activity during megakaryopoiesis and thrombopoiesis, and that the defects in blood clotting for Epac1-/- is connected to secondary hemostasis.

Mean platelet volume predicts prognosis in patients with diffuse large B-cell lymphoma

To determine the prognostic value of baseline mean platelet volume (MPV) in diffuse large B-cell lymphoma (DLBCL) patients. We retrospectively analyzed 161 DLBCL patients who received R-CHOP chemotherapy. The associations between MPV and clinicopathological factors were assessed. A low MPV (MPV ≤ 9.1 fl, cut-off was calculated by receiver operating characteristics) was not associated with any other clinicopathological factors. Patients with MPV ≤ 9.1 fl experienced a shorter progression-free survival (PFS) (2-year PFS rate, 60.6% vs 84.0%, P = 0.003) and overall survival (OS) (2-year OS rate, 70.4% vs 87.9%, P = 0.030), compared with those with MPV > 9.1 fl. The multivariate analysis demonstrated that MPV ≤ 9.1 fl was an independent prognostic factor of OS (Hazard Ratio [HR] = 0.588, P = 0.045) and PFS (HR = 0.456, P = 0.010). Therefore, we demonstrated that low baseline MPV is an independent prognostic marker of poor outcome in patients with DLBCL.

Sugar makes neutrophils RAGE: linking diabetes-associated hyperglycemia to thrombocytosis and platelet reactivity

Diabetes mellitus is associated with an increased risk for cardiovascular disease, but the link between hyperglycemia and atherothrombotic disease is not completely understood. Patients with diabetes often show hyporesponsiveness to antiplatelet therapies, and it has been suggested that hyperreactive reticulated platelets underlie this altered therapeutic response. In this issue of the JCI, Kraakman et al. uncover a previously unknown link between hyperglycemia and enhanced platelet production and reactivity. The authors demonstrate that high blood glucose levels trigger neutrophil release of S100 calcium-binding protein A8/A9 (S100A8/A9), which binds to the receptor for advanced glycation end products (RAGE) on Kupffer cells, ultimately leading to increased thrombopoietin (TPO) production in the liver. TPO causes megakaryocyte proliferation and increased platelet production. This study demonstrates the importance of glycemic control and identifies potential therapeutic targets in the normalization of platelet numbers and function in diabetes.

Neutrophil-derived S100 calcium-binding proteins A8/A9 promote reticulated thrombocytosis and atherogenesis in diabetes

Platelets play a critical role in atherogenesis and thrombosis-mediated myocardial ischemia, processes that are accelerated in diabetes. Whether hyperglycemia promotes platelet production and whether enhanced platelet production contributes to enhanced atherothrombosis remains unknown. Here we found that in response to hyperglycemia, neutrophil-derived S100 calcium-binding proteins A8/A9 (S100A8/A9) interact with the receptor for advanced glycation end products (RAGE) on hepatic Kupffer cells, resulting in increased production of IL-6, a pleiotropic cytokine that is implicated in inflammatory thrombocytosis. IL-6 acts on hepatocytes to enhance the production of thrombopoietin, which in turn interacts with its cognate receptor c-MPL on megakaryocytes and bone marrow progenitor cells to promote their expansion and proliferation, resulting in reticulated thrombocytosis. Lowering blood glucose using a sodium-glucose cotransporter 2 inhibitor (dapagliflozin), depleting neutrophils or Kupffer cells, or inhibiting S100A8/A9 binding to RAGE (using paquinimod), all reduced diabetes-induced thrombocytosis. Inhibiting S100A8/A9 also decreased atherogenesis in diabetic mice. Finally, we found that patients with type 2 diabetes have reticulated thrombocytosis that correlates with glycated hemoglobin as well as increased plasma S100A8/A9 levels. These studies provide insights into the mechanisms that regulate platelet production and may aid in the development of strategies to improve on current antiplatelet therapies and to reduce cardiovascular disease risk in diabetes.

Disordered haematopoiesis and athero-thrombosis

Atherosclerosis, the major underlying cause of cardiovascular disease, is characterized by a lipid-driven infiltration of inflammatory cells in large and medium arteries. Increased production and activation of monocytes, neutrophils, and platelets, driven by hypercholesterolaemia and defective high-density lipoproteins-mediated cholesterol efflux, tissue necrosis and cytokine production after myocardial infarction, or metabolic abnormalities associated with diabetes, contribute to atherogenesis and athero-thrombosis. This suggests that in addition to traditional approaches of low-density lipoproteins lowering and anti-platelet drugs, therapies directed at abnormal haematopoiesis, including anti-inflammatory agents, drugs that suppress myelopoiesis, and excessive platelet production, rHDL infusions and anti-obesity and anti-diabetic agents, may help to prevent athero-thrombosis.

The relationship of mean platelet volume with microalbuminuriain type 2 diabetic patients

BACKGROUND/AIM

Activation and size of platelets have been suggested to be involved in the pathogenesis of vascular complications in diabetes mellitus. The purpose of the present study was to investigate the association of mean platelet volume with microalbuminuria in type 2 diabetic patients.

MATERIALS AND METHODS

Mean platelet volume levels were investigated in healthy participants and type 2 diabetic patients with and without microalbuminuria. After their mean platelet volume values were compared, correlation of mean platelet volume with sex, duration of diabetes, microalbuminuria, fasting blood glucose, hemoglobin A1c, creatinine clearance, and body mass index was examined.

RESULTS

Mean platelet volume levels were higher in all diabetic patients than those in controls. Mean platelet volume levels were highest in diabetics with microalbuminuria. The mean platelet volume levels had a positive correlation with microalbuminuria.

CONCLUSION

Mean platelet volume values of diabetic patients were higher than those of nondiabetics, the highest levels being in diabetics with microalbuminuria. Our results suggest that microalbuminuria might be related with mean platelet volume in diabetic patients.

Higher mitochondrial potential and elevated mitochondrial respiration are associated with excessive activation of blood platelets in diabetic rats

AIMS

The high glucose concentration observed in diabetic patients is a recognized factor of mitochondrial damage in various cell types. Its impact on mitochondrial bioenergetics in blood platelets remains largely vague. The aim of the study was to determine how the metabolism of carbohydrates, which has been impaired by streptozotocin-induced diabetes may affect the functioning of platelet mitochondria.

MATERIALS AND METHODS

Diabetes was induced in Sprague Dawley rats by intraperitoneal injection of streptozotocin. Platelet mitochondrial respiratory capacity was monitored as oxygen consumption (high-resolution respirometry). Mitochondrial membrane potential was assessed using a fluorescent probe, JC-1. Activation of circulating platelets was monitored by flow cytometry measuring of the expressions of CD61 and CD62P on a blood platelet surface. To determine mitochondrial protein density in platelets, Western Blot technique was used.

KEY FINDINGS

The results indicate significantly elevated mitochondria mass, increased mitochondrial membrane potential (ΔΨm) and enhanced respiration in STZ-diabetic animals, although the respiration control ratios appear to remain unchanged. Higher ΔΨm and elevated mitochondrial respiration were closely related to the excessive activation of circulating platelets in diabetic animals.

SIGNIFICANCE

Long-term diabetes can result in increased mitochondrial mass and may lead to hyperpolarization of blood platelet mitochondrial membrane. These alterations may be a potential underlying cause of abnormal platelet functioning in diabetes mellitus and hence, a potential target for antiplatelet therapies in diabetes.

Is platelet mass a more significant indicator than platelet count of closure of patent ductus arteriosus?

BACKGROUND

The purpose of this study was to evaluate whether or not platelet mass contributes to closure of patent ductus arteriosus (PDA) in premature newborns.

STUDY DESIGN AND SUBJECTS

This retrospective study included 115 preterm newborns with hemodynamically significant PDA (hPDA) and 120 newborns without PDA. The newborns' platelet count, mean platelet volume (MPV) and platelet distribution width (PDW) were noted from their files and the platelet mass (platelet count plus MPV/10(3)) was calculated. Patients with congenital abnormality, persistent pulmonary hypertension or sepsis were not included in the study.

RESULTS

Platelet count and PDW were found to not be risk factors for closure of hPDA (p > 0.05), but both high platelet mass (OR 1.25; 95% CI 1.12-1.41) and MPV (OR 1.87; 95% CI 2.52-3.85) were determined to be independent risk factors for hPDA.

CONCLUSIONS

Platelet mass may be a more significant indicator than platelet count of closure of hPDA in preterm newborns.

High-risk type-2 diabetes mellitus patients, without prior ischemic events, have normal blood platelet functionality profiles: a cross-sectional study

Background

Patients with type 2 diabetes mellitus (DM) display a predisposition for vascular disease. Platelets taken from vasculopathic diabetic patients, show enhanced stimuli-induced activation and aggregation responses. Aspirin remains the cornerstone antiplatelet agent for secondary prevention of vascular complications among diabetic patients, yet evidence of its efficacy and safety in primary prevention are conflicting. Our aim was to assess whether high risk diabetic patients, without previous ischemic events, have abnormal platelet functionality profiles.

Methods

The study included 82 diabetic patients and 86 matched non-diabetic patients without prior ischemic events nor treatment with anti-platelet medications. Blood samples were analyzed for platelet markers of activation, turnover and leukocyte-platelet interactions.

Results

Our final analysis included 122 males (74 %), with a mean age of 61 years. Mean platelet volume (MPV) was similar between the diabetic patients and controls (9.2 fL for both). Following activation, PAC-1 binding and P-selectin expression were found comparable between the diabetic patients and controls (83 % versus 81 % and 76 % versus 74 %, respectively). Leukocyte-platelet aggregates (LPAs) were similar between the diabetic patients and controls (18 % versus 17 %, respectively). Neutrophil-platelet aggregates (NPAs) and monocyte-platelet aggregates (MPAs) were also found similar in the diabetic patients and controls. Elevated fasting plasma glucose was associated with increased LPAs rates.

Conclusions

High risk type-2 diabetes mellitus patients, without prior ischemic events, have normal blood platelet functionality profiles.

Rosuvastatin Decreases Mean Platelet Volume in Patients With Diabetes Mellitus

Statins have multiple effects (also known as pleiotropic effects) on inflammation, plaque stabilization, endothelial function, and hemostasis. We evaluated the effects of rosuvastatin on mean platelet volume (MPV)--a marker for platelet activity--in patients with diabetes mellitus (DM) on rosuvastatin medication. Patients (n = 178) who were to be prescribed high-intensity rosuvastatin were retrospectively enrolled according to their medical records. Baseline and 6-month biochemical tests, automated blood count, cell-volume analysis, and their cardiovascular risk factors were recorded. Rosuvastatin significantly reduced the MPV and the lipid parameters including total cholesterol, triglyceride, and low-density lipoprotein cholesterol (LDL-C). However, there was no correlation between MPV and LDL-C before (r = -.66; P = .383) and after (r = -.112; P = .135) rosuvastatin treatment or between ΔMPV and ΔLDL-C after 40 mg rosuvastatin daily therapy (r = -.155; P = .073). Rosuvastatin significantly decreases the MPV as well as cholesterol levels. The antiplatelet activation properties of high-dose rosuvastatin treatment in patients with DM are not lipid dependent.

Altered platelets' morphological parameters in children with type 1 diabetes – a case-control study

BACKGROUND

Platelet hyperreactivity is a factor which contributes towards increased risk of cardiovascular events in adults with type 2 diabetes (T2DM). However, little is known about platelets' disturbances among children with type 1 diabetes (T1DM). The aim of the study was to investigate whether platelets' morphology or function are altered in children with type 1 diabetes, potentially predisposing them to cardiovascular events in the future.

METHODS

The study group consisted of 389 children with T1DM during the 2008-2010 period. Patients with acute diabetes complications and ongoing infections were excluded from the study. An equinumerous (N = 389), age and sex-matched control group was assembled from children undergoing routine, minor surgical procedures in the same hospital. Platelet: count (PLT), mean volume (MPV), distribution width (PDW) and platelet large cell ratio (P-LCR) as well as HbA1c levels were measured. For statistical analysis we used Chi-square tests, the student's t-test, one-way analysis of variance (ANOVA), the Pearson's correlation coefficient and linear regression models in order to adjust for covariates.

RESULTS

MPV, PDW and P-LCR were significantly higher among children with diabetes in comparison with the control group (MPV 10.47+/-0.85 fL vs 10.23+/-0.94 fL, p = 0.0007; PDW 12.09+/-1.80% vs 11.66+/-1.90%, p = 0.0032; P-LCR 28.21+/-6.15% vs 26.29+/-6.38%, p < 0.0001). PLT however, were shown to be similar (263.55+/-60.04 vs 268.77+/-65.78 10(3)/μl; p = 0.5637). In both cases and controls age was inversely correlated with platelet count (for study group: r = -0.30, p < 0.0001; for control group: r = -0.34, p < 0.0001), positively correlated with MPVs (r = 0.20, p < 0.0001; r = 0.26, p < 0.0001), PDW (r = 0.25, p < 0.0001 and r = 0.24, p < 0.0001) and P-LCR (r = 0.26, p < 0.0001; r = 0.26, p < 0.0001). After adjustment for confounding factors, higher platelet counts were associated with poorer metabolic control (beta = 0.20; 0.0001).

CONCLUSIONS

Platelets of paediatric patients with T1DM show morphological evidence of hyperreactivity (higher MPV, PDW and P-LCR), while poorer metabolic control increases their number potentially predisposing the patients to future cardiovascular events.

Platelet distribution width and mean platelet volume in idiopathic pulmonary arterial hypertension

BACKGROUND

Previous studies have demonstrated that platelet activation occurs in patients with pulmonary arterial hypertension (PAH). Mean platelet volume (MPV) and platelet distribution width (PDW) are two markers of platelet activation, and have recently been recognised as risk predictors of cardiovascular diseases. This study aimed to investigate whether MPV and PDW would be useful to reflect disease severity and predict prognosis in idiopathic PAH (IPAH).

METHODS

MPV and PDW levels were measured in 82 IPAH patients without antiplatelet or anticoagulant treatment on admission and 82 healthy controls. Concurrent collected data included clinical, haemodynamic and biochemical variables. All patients were followed-up from the date of blood testing. The endpoint was all-cause mortality.

RESULTS

MPV and PDW were significantly higher in patients with IPAH than in age and sex-matched control subjects (11.4±0.9fl vs. 10.3±0.9fL and 14.3±2.9% vs. 11.9±1.9%, respectively; p=0.000). Pearson's correlation analysis revealed that MPV and PDW correlated positively with right ventricular systolic pressure, mean pulmonary arterial pressure and pulmonary vascular resistance. After a mean follow-up of 14±8 months, 12 patients died of right heart failure. Receiver operating characteristic analysis showed that MPV and PDW could not predict all-cause mortality. Multivariate Cox regression analysis suggested that right/left ventricular end-diastolic diameter ratio and NT-proBNP were independent predictive parameters of all-cause mortality.

CONCLUSIONS

Our results suggest that MPV and PDW were elevated in patients with IPAH. They could partly reflect disease severity, but did not predict prognosis.

Elucidating the correlation between treatment with tyrosine kinase inhibitors and mean platelet volume in patients with metastatic renal cell cancer

Patients with cancer are at increased risk of thrombosis. Additionally, an increased mean platelet volume (MPV) has been demonstrated to be associated with thromboembolism. Tyrosine kinase inhibitors (TKIs) may modulate the activation of systemic coagulation in cancer patients, rendering them more susceptible to thromboembolism. The aim of the current study was to investigate the association between antiangiogenic TKIs and MPV. A total of 45 patients with metastatic renal cell carcinoma (RCC), who were treated with TKIs and were patients at the Akdeniz University Hospital and Afyon Kocatepe University Ahmet Necdet Sezer Research and Practice Hospital, were retrospectively reviewed. The results prior to treatment and after three months for the MPV values and platelet levels were evaluated. The MPV values increased following the treatment with TKIs; however, no statistically significant difference was observed between the baseline and three month values (P=0.286). Conversely, a significant decrease was observed in the platelet levels following treatment (P=0.005). Treatment with TKIs in patients with metastatic RCC caused a modest increase in MPV, which is an indicator of thrombocytic reactivity; however, further studies are required to validate these results.

The mean platelet volume levels in children with PFAPA syndrome

OBJECTIVES

To assess whether mean platelet volume (MPV) can be used as a marker in the differential diagnosis of periodic fever, aphthous stomatitis, pharyngitis, adenitis (PFAPA) syndrome.

METHODS

The leucocyte counts, thrombocyte counts, and MPV values of 57 children with PFAPA syndrome were recorded during an attack and an attack free period. These values were compared with a healthy control group of 55 individuals. Demographic features of the PFAPA patients group including age, gender and age of first attack, age at diagnosis, frequency of attacks, serum reactive protein (CRP) and erythrocyte sedimentation rate (ESR) were also recorded.

RESULTS

The MPV values of the children with PFAPA both during an attack and attack free period were found significantly lower than the MPV values of healthy control group (p<0.001). Also, the MPV values of the children with PFAPA during an attack were significantly lower than in attack free periods (p<0.001). The MPV values showed no correlation with leucocytes counts, CRP, and ESR during attacks. A 8.30fl [area under the curve (AUC: 0.965)] optimal cutoff value of MPV with a sensitivity of 89.5% and specificity of 92.8% was determined during an attack in children with PFAPA.

CONCLUSIONS

The MPV values during an attack and attack free period of patients with PFAPA is lower than in controls. The MPV values may be used as a marker in the differential diagnosis of PFAPA syndrome but more studies are needed and they should be prospective in order to validate this data.

Aldose reductase-mediated phosphorylation of p53 leads to mitochondrial dysfunction and damage in diabetic platelets

BACKGROUND

Platelet abnormalities are well-recognized complications of diabetes mellitus. Mitochondria play a central role in platelet metabolism and activation. Mitochondrial dysfunction is evident in diabetes mellitus. The molecular pathway for hyperglycemia-induced mitochondrial dysfunction in platelets in diabetes mellitus is unknown.

METHODS AND RESULTS

Using both human and humanized mouse models, we report that hyperglycemia-induced aldose reductase activation and subsequent reactive oxygen species production lead to increased p53 phosphorylation (Ser15), which promotes mitochondrial dysfunction, damage, and rupture by sequestration of the antiapoptotic protein Bcl-xL. In a glucose dose-dependent manner, severe mitochondrial damage leads to loss of mitochondrial membrane potential and platelet apoptosis (cytochrome c release, caspase 3 activation, and phosphatidylserine exposure). Although platelet hyperactivation, mitochondrial dysfunction, aldose reductase activation, reactive oxygen species production, and p53 phosphorylation are all induced by hyperglycemia, we demonstrate that platelet apoptosis and hyperactivation are 2 distinct states that depend on the severity of the hyperglycemia and mitochondrial damage. Combined, both lead to increased thrombus formation in a mouse blood stasis model.

CONCLUSIONS

Aldose reductase contributes to diabetes-mediated mitochondrial dysfunction and damage through the activation of p53. The degree of mitochondrial dysfunction and damage determines whether hyperactivity (mild damage) or apoptosis (severe damage) will ensue. These signaling components provide novel therapeutic targets for thrombotic complications in diabetes mellitus.

Platelet size and density affect shear-induced thrombus formation in tortuous arterioles

Thrombosis accounts for 80% of deaths in patients with diabetes mellitus. Diabetic patients demonstrate tortuous microvessels and larger than normal platelets. Large platelets are associated with increased platelet activation and thrombosis, but the physical effects of large platelets in the microscale processes of thrombus formation are not clear. Therefore, the objective of this study was to determine the physical effects of mean platelet volume (MPV), mean platelet density (MPD) and vessel tortuosity on platelet activation and thrombus formation in tortuous arterioles. A computational model of the transport, shear-induced activation, collision, adhesion and aggregation of individual platelets was used to simulate platelet interactions and thrombus formation in tortuous arterioles. Our results showed that an increase in MPV resulted in a larger number of activated platelets, though MPD and level of tortuosity made little difference on platelet activation. Platelets with normal MPD yielded the lowest amount of mural thrombus. With platelets of normal MPD, the amount of mural thrombus decreased with increasing level of tortuosity but did not have a simple monotonic relationship with MPV. The physical mechanisms associated with MPV, MPD and arteriole tortuosity play important roles in platelet activation and thrombus formation.

Platelet-rich plasma promotes the proliferation of human muscle derived progenitor cells and maintains their stemness

Human muscle-derived progenitor cells (hMDPCs) offer great promise for muscle cell-based regenerative medicine; however, prolonged ex-vivo expansion using animal sera is necessary to acquire sufficient cells for transplantation. Due to the risks associated with the use of animal sera, the development of a strategy for the ex vivo expansion of hMDPCs is required. The purpose of this study was to investigate the efficacy of using platelet-rich plasma (PRP) for the ex-vivo expansion of hMDPCs. Pre-plated MDPCs, myoendothelial cells, and pericytes are three populations of hMDPCs that we isolated by the modified pre-plate technique and Fluorescence Activated Cell Sorting (FACS), respectively. Pooled allogeneic human PRP was obtained from a local blood bank, and the effect that thrombin-activated PRP-releasate supplemented media had on the ex-vivo expansion of the hMDPCs was tested against FBS supplemented media, both in vitro and in vivo. PRP significantly enhanced short and long-term cell proliferation, with or without FBS supplementation. Antibody-neutralization of PDGF significantly blocked the mitogenic/proliferative effects that PRP had on the hMDPCs. A more stable and sustained expression of markers associated with stemness, and a decreased expression of lineage specific markers was observed in the PRP-expanded cells when compared with the FBS-expanded cells. The in vitro osteogenic, chondrogenic, and myogenic differentiation capacities of the hMDPCs were not altered when expanded in media supplemented with PRP. All populations of hMDPCs that were expanded in PRP supplemented media retained their ability to regenerate myofibers in vivo. Our data demonstrated that PRP promoted the proliferation and maintained the multi-differentiation capacities of the hMDPCs during ex-vivo expansion by maintaining the cells in an undifferentiated state. Moreover, PDGF appears to be a key contributing factor to the beneficial effect that PRP has on the proliferation of hMDPCs.

Platelet function profiles in patients with diabetes mellitus

Patients with diabetes mellitus (DM) are at high risk for several cardiovascular disorders such as coronary heart disease, stroke, peripheral arterial disease, and congestive heart failure. DM has reached epidemic proportions and its strong association with coronary artery disease is responsible for increased cardiovascular morbidity and mortality. DM patients are characterized by platelet hyperreactivity, which contribute to the enhanced atherothrombotic risk of these subjects. Several mechanisms are involved in the hyperreactive platelet phenotype characterizing DM patients. Furthermore, a large proportion of DM patients show inadequate response to standard antiplatelet treatments and high rate of adverse recurrent cardiovascular events despite compliance with standard antiplatelet treatment regimens. Therefore, new antiplatelet treatment regimens are warranted in DM patients to reduce their atherothrombotic risk. The present manuscript provides an overview on the current status of knowledge on platelet function profiles in patients with DM and therapeutic considerations.

Platelet flow cytometry

Flow cytometry is a powerful and versatile tool which can be used to provide substantial phenotypic data on platelets by yielding quantitative information of their physical and antigenic properties. This includes surface expression of functional receptors, bound ligands, expression of granule components, interaction of platelets with other platelets via aggregation, or interaction with other blood components, such as leukocytes or the plasma coagulation system. Quantitative assessment of these parameters may facilitate the diagnosis of inherited or acquired platelet disorders, assist in the diagnosis of diseases associated with platelet activation, or assist in the monitoring of safety and efficacy of antiplatelet therapy.