Publications by authors named "Paola E J van der Meijden"

50 Publications

Soluble Platelet Release Factors as Biomarkers for Cardiovascular Disease.

Front Cardiovasc Med 2021 21;8:684920. Epub 2021 Jun 21.

Departments of Biochemistry and Internal Medicine, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, Netherlands.

Platelets are the main players in thrombotic diseases, where activated platelets not only mediate thrombus formation but also are involved in multiple interactions with vascular cells, inflammatory components, and the coagulation system. Although reactivity of platelets provides information on the function of circulating platelets, it is not a full reflection of the activation state, which may be relevant for thrombotic risk assessment in various disease conditions. Therefore, studying release markers of activated platelets in plasma is of interest. While this type of study has been done for decades, there are several new discoveries that highlight the need for a critical assessment of the available tests and indications for platelet release products. First, new insights have shown that platelets are not only prominent players in arterial vascular disease, but also in venous thromboembolism and atrial fibrillation. Second, knowledge of the platelet proteome has dramatically expanded over the past years, which contributed to an increasing array of tests for proteins released and shed from platelets upon activation. Identification of changes in the level of plasma biomarkers associated with upcoming thromboembolic events allows timely and individualized adjustment of the treatment strategy to prevent disease aggravation. Therefore, biomarkers of platelet activation may become a valuable instrument for acute event prognosis. In this narrative review based on a systematic search of the literature, we summarize the process of platelet activation and release products, discuss the clinical context in which platelet release products have been measured as well as the potential clinical relevance.
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http://dx.doi.org/10.3389/fcvm.2021.684920DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8255615PMC
June 2021

Tyrosine Kinase Inhibitor Sunitinib Delays Platelet-Induced Coagulation: Additive Effects of Aspirin.

Thromb Haemost 2021 Jun 15. Epub 2021 Jun 15.

Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, The Netherlands.

Background:  Sunitinib is a multitarget tyrosine kinase inhibitor (TKI) used for cancer treatment. In platelets, sunitinib affects collagen-induced activation under noncoagulating conditions. We investigated (1) the effects of sunitinib on thrombus formation induced by other TK-dependent receptors, and (2) the effects under coagulating conditions. Cardiovascular disease is a comorbidity in cancer patients, resulting in possible aspirin treatment. Sunitinib and aspirin are associated with increased bleeding risk, and therefore we also investigated (3) the synergistic effects of these compounds on thrombus and fibrin formation.

Methods:  Blood or isolated platelets from healthy volunteers or cancer patients were incubated with sunitinib and/or aspirin or vehicle. Platelet activation was determined by TK phosphorylation, flow cytometry, changes in [Ca], aggregometry, and whole blood perfusion over multiple surfaces, including collagen with(out) tissue factor (TF) was performed.

Results:  Sunitinib reduced thrombus formation and phosphatidylserine (PS) exposure under flow on collagen type I and III. Also, sunitinib inhibited glycoprotein VI-induced TK phosphorylation and Ca elevation. Upon TF-triggered coagulation, sunitinib decreased PS exposure and fibrin formation. In blood from cancer patients more pronounced effects of sunitinib were observed in lung and pancreatic as compared to neuroglioblastoma and other cancer types. Compared to sunitinib alone, sunitinib plus aspirin further reduced platelet aggregation, thrombus formation, and PS exposure on collagen under flow with(out) coagulation.

Conclusion:  Sunitinib suppresses collagen-induced procoagulant activity and delays fibrin formation, which was aggravated by aspirin. Therefore, we urge for awareness of the combined antiplatelet effects of TKIs with aspirin, as this may result in increased risk of bleeding.
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http://dx.doi.org/10.1055/s-0041-1730312DOI Listing
June 2021

Increased platelet thrombus formation under flow conditions in whole blood from polycythaemia vera patients.

Blood Transfus 2021 Mar 30. Epub 2021 Mar 30.

Department of Immunohaematology and Transfusion Medicine, "Papa Giovanni XXIII" Hospital, Bergamo, Italy.

Background: Polycythaemia vera is a myeloproliferative neoplasm characterised by a high incidence of thrombosis. The contribution of platelets, key players in haemostasis, in this setting is still unclear. So far, the majority of studies have been focussed on specific platelet abnormalities but not on their actual capacity to form thrombi. The aim of this study was to characterise, ex vivo under flow conditions, the capacity of platelets from patients with polycythaemia vera to adhere to collagen and induce thrombus formation.

Materials And Methods: Thirty-nine patients and 30 healthy controls were studied. Thrombus formation was induced by perfusing whole blood over a collagen-coated surface, in a parallel-plate flow chamber coupled to a fluorescent microscope. This dynamic system enables platelet adhesion and thrombus formation to be followed in real time and also allows measurements of the extent of the thrombus and platelet surface antigen expression. Laboratory data were analysed in the light of the patients' main haematological parameters and therapies.

Results: Platelet adhesion was significantly greater in patients than in control subjects. Patient thrombi were usually larger and more complex than those formed by control platelets. A significant positive correlation was found between platelet adhesion and both the haematocrit and red blood cell count. These parameters remained significantly correlated with platelet adhesion also after multivariable analysis adjusted for gender, age, therapy and JAK2V617F allele burden. Furthermore, subjects with a haematocrit >45% had significantly greater platelet adhesion than subjects with a haematocrit <45%.

Discussion: Our data indicate that increased platelet adhesion participates in the thrombotic diathesis of patients with polycythaemia vera, and that the haematocrit level can affect the adhesive and thrombus forming capacities of platelets.
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http://dx.doi.org/10.2450/2021.0456-20DOI Listing
March 2021

Exogenous Integrin αIIbβ3 Inhibitors Revisited: Past, Present and Future Applications.

Int J Mol Sci 2021 Mar 25;22(7). Epub 2021 Mar 25.

Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, 6229 ER Maastricht, The Netherlands.

The integrin αIIbβ3 is the most abundant integrin on platelets. Upon platelet activation, the integrin changes its conformation (inside-out signalling) and outside-in signalling takes place leading to platelet spreading, platelet aggregation and thrombus formation. Bloodsucking parasites such as mosquitoes, leeches and ticks express anticoagulant and antiplatelet proteins, which represent major sources of lead compounds for the development of useful therapeutic agents for the treatment of haemostatic disorders or cardiovascular diseases. In addition to hematophagous parasites, snakes also possess anticoagulant and antiplatelet proteins in their salivary glands. Two snake venom proteins have been developed into two antiplatelet drugs that are currently used in the clinic. The group of proteins discussed in this review are disintegrins, low molecular weight integrin-binding cysteine-rich proteins, found in snakes, ticks, leeches, worms and horseflies. Finally, we highlight various oral antagonists, which have been tested in clinical trials but were discontinued due to an increase in mortality. No new αIIbβ3 inhibitors are developed since the approval of current platelet antagonists, and structure-function analysis of exogenous disintegrins could help find platelet antagonists with fewer adverse side effects.
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http://dx.doi.org/10.3390/ijms22073366DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8036306PMC
March 2021

Nonredundant Roles of Platelet Glycoprotein VI and Integrin αIIbβ3 in Fibrin-Mediated Microthrombus Formation.

Arterioscler Thromb Vasc Biol 2021 02 3;41(2):e97-e111. Epub 2020 Dec 3.

Department of Biochemistry, CARIM, Maastricht University, the Netherlands (G.P., J.H., I.P., F.S., P.E.J.v.d.M., R.A.S.A., S.P.W., J.W.M.H.).

Objective: Fibrin is considered to strengthen thrombus formation via integrin αIIbβ3, but recent findings indicate that fibrin can also act as ligand for platelet glycoprotein VI. Approach and Results: To investigate the thrombus-forming potential of fibrin and the roles of platelet receptors herein, we generated a range of immobilized fibrin surfaces, some of which were cross-linked with factor XIIIa and contained VWF-BP (von Willebrand factor-binding peptide). Multicolor microfluidics assays with whole-blood flowed at high shear rate (1000 s) indicated that the fibrin surfaces, regardless of the presence of factor XIIIa or VWF-BP, supported platelet adhesion and activation (P-selectin expression), but only microthrombi were formed consisting of bilayers of platelets. Fibrinogen surfaces produced similar microthrombi. Markedly, tiggering of coagulation with tissue factor or blocking of thrombin no more than moderately affected the fibrin-induced microthrombus formation. Absence of αIIbβ3 in Glanzmann thrombasthenia annulled platelet adhesion. Blocking of glycoprotein VI with Fab 9O12 substantially, but incompletely reduced platelet secretion, Ca signaling and aggregation, while inhibition of Syk further reduced these responses. In platelet suspension, glycoprotein VI blockage or Syk inhibition prevented fibrin-induced platelet aggregation. Microthrombi on fibrin surfaces triggered only minimal thrombin generation, in spite of thrombin binding to the fibrin fibers.

Conclusions: Together, these results indicate that fibrin fibers, regardless of their way of formation, act as a consolidating surface in microthrombus formation via nonredundant roles of platelet glycoprotein VI and integrin αIIbβ3 through signaling via Syk and low-level Ca rises.
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http://dx.doi.org/10.1161/ATVBAHA.120.314641DOI Listing
February 2021

Platelet-primed interactions of coagulation and anticoagulation pathways in flow-dependent thrombus formation.

Sci Rep 2020 07 17;10(1):11910. Epub 2020 Jul 17.

Departments of Biochemistry and Internal Medicine, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University Medical Centre+, P.O. Box 616, 6200 MD, Maastricht, The Netherlands.

In haemostasis and thrombosis, platelet, coagulation and anticoagulation pathways act together to produce fibrin-containing thrombi. We developed a microspot-based technique, in which we assessed platelet adhesion, platelet activation, thrombus structure and fibrin clot formation in real time using flowing whole blood. Microspots were made from distinct platelet-adhesive surfaces in the absence or presence of tissue factor, thrombomodulin or activated protein C. Kinetics of platelet activation, thrombus structure and fibrin formation were assessed by fluorescence microscopy. This work revealed: (1) a priming role of platelet adhesion in thrombus contraction and subsequent fibrin formation; (2) a surface-independent role of tissue factor, independent of the shear rate; (3) a mechanism of tissue factor-enhanced activation of the intrinsic coagulation pathway; (4) a local, suppressive role of the anticoagulant thrombomodulin/protein C pathway under flow. Multiparameter analysis using blood samples from patients with (anti)coagulation disorders indicated characteristic defects in thrombus formation, in cases of factor V, XI or XII deficiency; and in contrast, thrombogenic effects in patients with factor V-Leiden. Taken together, this integrative phenotyping approach of platelet-fibrin thrombus formation has revealed interaction mechanisms of platelet-primed key haemostatic pathways with alterations in patients with (anti)coagulation defects. It can help as an important functional add-on whole-blood phenotyping.
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http://dx.doi.org/10.1038/s41598-020-68438-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7368055PMC
July 2020

Impaired iloprost-induced platelet inhibition and phosphoproteome changes in patients with confirmed pseudohypoparathyroidism type Ia, linked to genetic mutations in GNAS.

Sci Rep 2020 07 9;10(1):11389. Epub 2020 Jul 9.

Department of Biochemistry, CARIM, Maastricht University, PO Box 616, 6200 MD, Maastricht, The Netherlands.

Patients diagnosed with pseudohypoparathyroidism type Ia (PHP Ia) suffer from hormonal resistance and abnormal postural features, in a condition classified as Albright hereditary osteodystrophy (AHO) syndrome. This syndrome is linked to a maternally inherited mutation in the GNAS complex locus, encoding for the GTPase subunit Gsα. Here, we investigated how platelet phenotype and omics analysis can assist in the often difficult diagnosis. By coupling to the IP receptor, Gsα induces platelet inhibition via adenylyl cyclase and cAMP-dependent protein kinase A (PKA). In platelets from seven patients with suspected AHO, one of the largest cohorts examined, we studied the PKA-induced phenotypic changes. Five patients with a confirmed GNAS mutation, displayed impairments in Gsα-dependent VASP phosphorylation, aggregation, and microfluidic thrombus formation. Analysis of the platelet phosphoproteome revealed 2,516 phosphorylation sites, of which 453 were regulated by Gsα-PKA. Common changes in the patients were: (1) a joint panel of upregulated and downregulated phosphopeptides; (2) overall PKA dependency of the upregulated phosphopeptides; (3) links to key platelet function pathways. In one patient with GNAS mutation, diagnosed as non-AHO, the changes in platelet phosphoproteome were reversed. This combined approach thus revealed multiple phenotypic and molecular biomarkers to assist in the diagnosis of suspected PHP Ia.
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http://dx.doi.org/10.1038/s41598-020-68379-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7347634PMC
July 2020

Clonal hematopoietic mutations linked to platelet traits and the risk of thrombosis or bleeding.

Haematologica 2020 08 18;105(8):2020-2031. Epub 2020 Jun 18.

Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht

Platelets are key elements in thrombosis, particularly in atherosclerosis-associated arterial thrombosis (atherothrombosis), and hemostasis. Megakaryocytes in the bone marrow, differentiated from hematopoietic stem cells are generally considered as a uniform source of platelets. However, recent insights into the causes of malignancies, including essential thrombocytosis, indicate that not only inherited but also somatic mutations in hematopoietic cells are linked to quantitative or qualitative platelet abnormalities. In particular cases, these form the basis of thrombo-hemorrhagic complications regularly observed in patient groups. This has led to the concept of clonal hematopoiesis of indeterminate potential (CHIP), defined as somatic mutations caused by clonal expansion of mutant hematopoietic cells without evident disease. This concept also provides clues regarding the importance of platelet function in relation to cardiovascular disease. In this summative review, we present an overview of genes associated with clonal hematopoiesis and altered platelet production and/or functionality, like mutations in We consider how reported CHIP genes can influence the risk of cardiovascular disease, by exploring the consequences for platelet function related to (athero)thrombosis, or the risk of bleeding. More insight into the functional consequences of the CHIP mutations may favor personalized risk assessment, not only with regard to malignancies but also in relation to thrombotic vascular disease.
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http://dx.doi.org/10.3324/haematol.2019.235994DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7395290PMC
August 2020

Thrombo-Inflammation in Cardiovascular Disease: An Expert Consensus Document from the Third Maastricht Consensus Conference on Thrombosis.

Thromb Haemost 2020 Apr 14;120(4):538-564. Epub 2020 Apr 14.

Department of Hematology and Central Hematology Laboratory, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland; Center for Thrombosis and Hemostasis, University Medical Center of the Johannes Gutenberg University, Mainz, Germany; Haemostasis Research Unit, University College London, London, United Kingdom.

Thrombo-inflammation describes the complex interplay between blood coagulation and inflammation that plays a critical role in cardiovascular diseases. The third Maastricht Consensus Conference on Thrombosis assembled basic, translational, and clinical scientists to discuss the origin and potential consequences of thrombo-inflammation in the etiology, diagnostics, and management of patients with cardiovascular disease, including myocardial infarction, stroke, and peripheral artery disease. This article presents a state-of-the-art reflection of expert opinions and consensus recommendations regarding the following topics: (1) challenges of the endothelial cell barrier; (2) circulating cells and thrombo-inflammation, focused on platelets, neutrophils, and neutrophil extracellular traps; (3) procoagulant mechanisms; (4) arterial vascular changes in atherogenesis; attenuating atherosclerosis and ischemia/reperfusion injury; (5) management of patients with arterial vascular disease; and (6) pathogenesis of venous thrombosis and late consequences of venous thromboembolism.
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http://dx.doi.org/10.1055/s-0040-1708035DOI Listing
April 2020

Clinical Applications, Pitfalls, and Uncertainties of Thrombin Generation in the Presence of Platelets.

J Clin Med 2019 Dec 30;9(1). Epub 2019 Dec 30.

Department of Internal Medicine, Laboratory of Clinical Thrombosis and Haemostasis, and Cardiovascular Research Institute Maastricht, Maastricht University Medical Center, 6200 Maastricht, The Netherlands.

Platelet-dependent thrombin generation is a helpful tool to assess ex vivo the interaction between platelets and plasma coagulation factors in the initiation, amplification, and inhibition of thrombin generation (TG). This review article discusses the most relevant available data on the clinical applications of fluorogenic TG, the most widely used TG assay, performed in the presence of platelets, i.e., in platelet-rich plasma. With respect to prothrombotic states, arterial hypertension and obesity were the most prominent cardiovascular conditions linked to increased platelet-dependent TG. In addition, platelet-associated hypercoagulability, assessed by the TG assay, has been shown in individuals with active cancer. In terms of bleeding, platelet-dependent TG has been applied to assess bleeding risk in individuals with hemophilia, von Willebrand disease, and Glanzmann thrombasthenia as well as in subjects with other congenital or acquired coagulation factor deficiencies. In addition to risk prediction, a role of the TG assay has been suggested in monitoring antiplatelet therapy in prothrombotic conditions and replacement therapy in bleeding diathesis. Finally, for the routine clinical use and as a biomarker of disease development and progression, better standardization and clinical validation of platelet-dependent TG are still needed.
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http://dx.doi.org/10.3390/jcm9010092DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7019916PMC
December 2019

Localized endothelial-based control of platelet aggregation and coagulation under flow: A proof-of-principle vessel-on-a-chip study.

J Thromb Haemost 2020 04 20;18(4):931-941. Epub 2020 Feb 20.

Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, The Netherlands.

Background: In the intact vessel wall, endothelial cells form a barrier between the blood and the remaining vascular structures, serving to maintain blood fluidity and preventing platelet activation and fibrin clot formation. The spatiotemporal space of this inhibition is largely unknown.

Objective: To assess the local inhibitory roles of a discontinuous endothelium, we developed a vessel-on-a-chip model, consisting of a microfluidic chamber coated with the thrombogenic collagen and tissue factor (TF), and covered with patches of human endothelial cells. By flow perfusion of human blood and plasma, the heterogeneous formation of platelet aggregates and fibrin clots was monitored by multicolor fluorescence microscopy.

Results: On collagen/TF coatings, a coverage of 40% to 60% of human umbilical vein endothelial cells resulted in a strong overall delay in platelet deposition and fibrin fiber formation under flow. Fibrin formation colocalized with the deposited platelets, and was restricted to regions in between endothelial cells, thus pointing to immediate local suppression of the clotting process. Fibrin kinetics were enhanced by treatment of the cells with heparinase III, partially disrupting the glycocalyx, and to a lesser degree by antagonism of the endothelial thrombomodulin. Co-coating of purified thrombomodulin and collagen had a similar coagulation-suppressing effect as endothelial thrombomodulin.

Conclusions: In this vessel-on-a-chip system with patches of endothelial cells on thrombogenic surfaces, the coagulant activity under flow is regulated by: (a) the residual exposure of trigger (collagen/TF), (b) the endothelial glycocalyx, and (c) to a lesser degree the endothelial thrombomodulin.
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http://dx.doi.org/10.1111/jth.14719DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7187151PMC
April 2020

Whole Blood Based Multiparameter Assessment of Thrombus Formation in Standard Microfluidic Devices to Proxy In Vivo Haemostasis and Thrombosis.

Micromachines (Basel) 2019 Nov 16;10(11). Epub 2019 Nov 16.

Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, 6229 ER Maastricht, The Netherlands.

Microfluidic assays are versatile tests which, using only small amounts of blood, enable high throughput analyses of platelet function in several minutes. In combination with fluorescence microscopy, these flow tests allow real-time visualisation of platelet activation with the possibility of examining combinatorial effects of wall shear rate, coagulation and modulation by endothelial cells. In particular, the ability to use blood and blood cells from healthy subjects or patients makes this technology promising, both for research and (pre)clinical diagnostic purposes. In the present review, we describe how microfluidic devices are used to assess the roles of platelets in thrombosis and haemostasis. We place emphasis on technical aspects and on experimental designs that make the concept of "blood-vessel-component-on-a-chip" an attractive, rapidly developing technology for the study of the complex biological processes of blood coagulability in the presence of flow.
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http://dx.doi.org/10.3390/mi10110787DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6915499PMC
November 2019

Role of Platelet Glycoprotein VI and Tyrosine Kinase Syk in Thrombus Formation on Collagen-Like Surfaces.

Int J Mol Sci 2019 Jun 7;20(11). Epub 2019 Jun 7.

Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, 6229 ER Maastricht, The Netherlands.

Platelet interaction with collagens, via von Willebrand factor, is a potent trigger of shear-dependent thrombus formation mediated by subsequent engagement of the signaling collagen receptor glycoprotein (GP)VI, enforced by integrin αβ. Protein tyrosine kinase Syk is central in the GPVI-induced signaling pathway, leading to elevated cytosolic Ca. We aimed to determine the Syk-mediated thrombogenic activity of several collagen peptides and (fibrillar) type I and III collagens. High-shear perfusion of blood over microspots of these substances resulted in thrombus formation, which was assessed by eight parameters and was indicative of platelet adhesion, activation, aggregation, and contraction, which were affected by the Syk inhibitor PRT-060318. In platelet suspensions, only collagen peptides containing the consensus GPVI-activating sequence (GPO) and Horm-type collagen evoked Syk-dependent Ca rises. In whole blood under flow, Syk inhibition suppressed platelet activation and aggregation parameters for the collagen peptides with or without a (GPO) sequence and for all of the collagens. Prediction models based on a regression analysis indicated a mixed role of GPVI in thrombus formation on fibrillar collagens, which was abolished by Syk inhibition. Together, these findings indicate that GPVI-dependent signaling through Syk supports platelet activation in thrombus formation on collagen-like structures regardless of the presence of a (GPO) sequence.
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http://dx.doi.org/10.3390/ijms20112788DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6600290PMC
June 2019

Platelet biology and functions: new concepts and clinical perspectives.

Nat Rev Cardiol 2019 03;16(3):166-179

Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, The Netherlands.

Platelets - blood cells continuously produced from megakaryocytes mainly in the bone marrow - are implicated not only in haemostasis and arterial thrombosis, but also in other physiological and pathophysiological processes. This Review describes current evidence for the heterogeneity in platelet structure, age, and activation properties, with consequences for a diversity of platelet functions. Signalling processes of platelet populations involved in thrombus formation with ongoing coagulation are well understood. Genetic approaches have provided information on multiple genes related to normal haemostasis, such as those encoding receptors and signalling or secretory proteins, that determine platelet count and/or responsiveness. As highly responsive and secretory cells, platelets can alter the environment through the release of growth factors, chemokines, coagulant factors, RNA species, and extracellular vesicles. Conversely, platelets will also adapt to their environment. In disease states, platelets can be positively primed to reach a pre-activated condition. At the inflamed vessel wall, platelets interact with leukocytes and the coagulation system, interactions mediating thromboinflammation. With current antiplatelet therapies invariably causing bleeding as an undesired adverse effect, novel therapies can be more beneficial if directed against specific platelet responses, populations, interactions, or priming conditions. On the basis of these novel concepts and processes, we discuss several initiatives to target platelets therapeutically.
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http://dx.doi.org/10.1038/s41569-018-0110-0DOI Listing
March 2019

Platelet heterogeneity in activation-induced glycoprotein shedding: functional effects.

Blood Adv 2018 09;2(18):2320-2331

Department of Biochemistry, Cardiovascular Research Institute Maastricht, Maastricht University Medical Centre, Maastricht, The Netherlands.

The platelet receptors glycoprotein Ibα (GPIbα) and GPVI are known to be cleaved by members of a disintegrin and metalloprotease (ADAM) family (ADAM10 and ADAM17), but the mechanisms and consequences of this shedding are not well understood. Our results revealed that (1) glycoprotein shedding is confined to distinct platelet populations showing near-complete shedding, (2) the heterogeneity between (non)shed platelets is independent of agonist type but coincides with exposure of phosphatidylserine (PS), and (3) distinct pathways of shedding are induced by elevated Ca, low Ca protein kinase C (PKC), or apoptotic activation. Furthermore, we found that receptor shedding reduces binding of von Willebrand factor, enhances binding of coagulation factors, and augments fibrin formation. In response to Ca-increasing agents, shedding of GPIbα was abolished by ADAM10/17 inhibition but not by blockage of calpain. Stimulation of PKC induced shedding of only GPIbα, which was annulled by kinase inhibition. The proapoptotic agent ABT-737 induced shedding, which was caspase dependent. In Scott syndrome platelets that are deficient in Ca-dependent PS exposure, shedding occurred normally, indicating that PS exposure is not a prerequisite for ADAM activity. In whole-blood thrombus formation, ADAM-dependent glycoprotein shedding enhanced thrombin generation and fibrin formation. Together, these findings indicate that 2 major activation pathways can evoke ADAM-mediated glycoprotein shedding in distinct platelet populations and that shedding modulates platelet function from less adhesive to more procoagulant.
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http://dx.doi.org/10.1182/bloodadvances.2017011544DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6156892PMC
September 2018

Integrating platelet and coagulation activation in fibrin clot formation.

Res Pract Thromb Haemost 2018 Jul 20;2(3):450-460. Epub 2018 May 20.

Department of Biochemistry Cardiovascular Research Institute Maastricht (CARIM) Maastricht University Maastricht The Netherlands.

Platelets interact with the coagulation system in a multitude of ways, not only during the phases of thrombus formation, but also in specific areas within a formed thrombus. This review discusses current concepts of platelet control of thrombin generation, fibrin formation and structure, and anticoagulation. Indicated are how combined signalling via the platelet receptors for collagen (glycoprotein VI) and thrombin induces the secretion of (anti)coagulation factors, as well as surface exposure of phosphatidylserine, thereby catalysing thrombin generation. This procoagulant platelet response is also facilitated by the adhesive complexes glycoprotein Ib-V-IX and integrin αβ. In the buildup of a platelet-fibrin thrombus, the extrinsic, tissue factor-driven coagulation pathway is predominant in early stages, while the intrinsic, factor XII pathway seems to promote at later time points. Already early generation of thrombin enforces platelet responses and stimulates intra-thrombus heterogeneity with patches of loosely aggregated, contracted, and phosphatidylserine-exposing platelets. Fibrin actively formed on the surface of activated platelets supports thrombus growth, but also captures thrombin. The fibrin distribution in a thrombus appears to rely on the local procoagulant trigger and the blood flow rate. Clinical studies support the importance of the platelet-coagulation interplay, by showing beneficial effects of combination therapy in the secondary prevention of cardiovascular disease.
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http://dx.doi.org/10.1002/rth2.12107DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6046596PMC
July 2018

The coagulation system in atherothrombosis: Implications for new therapeutic strategies.

Res Pract Thromb Haemost 2018 Apr 19;2(2):188-198. Epub 2018 Feb 19.

Department of Internal Medicine Maastricht University Medical Center+ (MUMC+) Maastricht The Netherlands.

Clinical manifestations of atherosclerotic disease include coronary artery disease (CAD), peripheral artery disease (PAD), and stroke. Although the role of platelets is well established, evidence is now accumulating on the contribution of coagulation proteins to the processes of atherosclerosis and atherothrombosis. Coagulation proteins not only play a role in fibrin formation and platelet activation, but also mediate various biological and pathophysiologic processes through activation of protease-activated-receptors (PARs). Thus far, secondary prevention in patients with CAD/PAD has been the domain of antiplatelet therapy, however, residual atherothrombotic risks remain substantial. Therefore, combining antiplatelet and anticoagulant therapy has gained more attention. Recently, net clinical benefit of combining aspirin with low-dose rivaroxaban in patients with stable atherosclerotic disease has been demonstrated. In this review, based on the State of the Art lecture "Clotting factors and atherothrombosis" presented at the ISTH Congress 2017, we highlight the role of coagulation proteins in the pathophysiology of atherothrombosis, and specifically focus on therapeutic strategies to decrease atherothrombotic events by optimization of vascular protection.
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http://dx.doi.org/10.1002/rth2.12080DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6055505PMC
April 2018

Impaired mitochondrial activity explains platelet dysfunction in thrombocytopenic cancer patients undergoing chemotherapy.

Haematologica 2018 09 7;103(9):1557-1567. Epub 2018 Jun 7.

Department of Biochemistry, Cardiovascular Research Institute Maastricht, Maastricht University Medical Centre, the Netherlands

Severe thrombocytopenia (≤50×10 platelets/L) due to hematological malignancy and intensive chemotherapy is associated with an increased risk of clinically significant bleeding. Since the bleeding risk is not linked to the platelet count only, other hemostatic factors must be involved. We studied platelet function in 77 patients with acute leukemia, multiple myeloma or malignant lymphoma, who experienced chemotherapy-induced thrombocytopenia. Platelets from all patients - independent of disease or treatment type - were to a variable extent compromised in Ca flux, integrin a β activation and P-selectin expression when stimulated with a panelof agonists. The patients' platelets were also impaired in spreading on fibrinogen. Whereas the Ca store content was unaffected, the patients' platelets showed ongoing phosphatidylserine exposure, which was not due to apoptotic caspase activity. Interestingly, mitochondrial function was markedly reduced in platelets from a representative subset of patients, as evidenced by a low mitochondrial membrane potential (<0.001) and low oxygen consumption (<0.05), while the mitochondrial content was normal. Moreover, the mitochondrial impairments coincided with elevated levels of reactive oxygen species (Spearman's rho=-0.459, =0.012). Markedly, the impairment of platelet function only appeared after two days of chemotherapy, suggesting origination in the megakaryocytes. In patients with bone marrow recovery, platelet function improved. In conclusion, our findings disclose defective receptor signaling related to impaired mitochondrial bioenergetics, independent of apoptosis, in platelets from cancer patients treated with chemotherapy, explaining the low hemostatic potential of these patients.
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http://dx.doi.org/10.3324/haematol.2017.185165DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6119160PMC
September 2018

Platelet populations and priming in hematological diseases.

Blood Rev 2017 11 22;31(6):389-399. Epub 2017 Jul 22.

Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, PO Box 616, 6200 MD Maastricht, The Netherlands. Electronic address:

In healthy subjects and patients with hematological diseases, platelet populations can be distinguished with different response spectra in hemostatic and vascular processes. These populations partly overlap, and are less distinct than those of leukocytes. The platelet heterogeneity is linked to structural properties, and is enforced by inequalities in the environment. Contributing factors are variability between megakaryocytes, platelet ageing, and positive or negative priming of platelets during their time in circulation. Within a hemostatic plug or thrombus, platelet heterogeneity is enhanced by unequal exposure to agonists, with populations of contracted platelets in the thrombus core, discoid platelets at the thrombus surface, patches of ballooned and procoagulant platelets forming thrombin, and coated platelets binding fibrin. Several pathophysiological hematological conditions can positively or negatively prime the responsiveness of platelet populations. As a consequence, in vivo and in vitro markers of platelet activation can differ in thrombotic and hematological disorders.
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http://dx.doi.org/10.1016/j.blre.2017.07.004DOI Listing
November 2017

Determinants of agreement between proposed therapeutic windows of platelet function tests in vulnerable patients.

Eur Heart J Cardiovasc Pharmacother 2017 01 7;3(1):11-17. Epub 2016 Sep 7.

Department of Biochemistry, Cardiovascular Research Institute Maastricht, Maastricht University, PO Box 616, 6200 MD Maastricht, The Netherlands.

Aims: Therapeutic windows for residual platelet reactivity in patients with coronary artery disease on P2Y12 inhibitors were proposed in a consensus document. We aimed to explore the level of agreement between windows for different platelet function tests (PFTs) used to classify patients in low, optimal, and high on-treatment platelet reactivity categories, and to identify variables contributing to the level of agreement.

Methods And Results: In this explorative clinical study, the VerifyNow P2Y12, Multiplate adenosine diphosphate (ADP), and light transmission aggregometry (LTA) 20 μmol/L ADP were performed simultaneously in 145 consecutive vulnerable patients. Measurements were performed within 6 months of percutaneous intervention. Patients were considered vulnerable if they had ≥2 risk factors for bleeding or ischaemic events. Window-agreement between PFT pairs was slight to moderate. Multiplate-VerifyNow agreed in 72 patients (50%), κ = 0.41; VerifyNow-LTA agreed in 76 patients (52%), κ = 0.36; and LTA-Multiplate agreed in 64 patients (44%), κ = 0.20. Several variables including the type of P2Y12 inhibitor, aspirin, haemoglobin level, platelet count, age, and previous stroke significantly influenced agreement between PFTs.

Conclusions: Our results suggest that the PFTs, with accompanying therapeutic windows, are not interchangeable when determining the response to antiplatelet therapy in vulnerable coronary artery disease patients on P2Y12 inhibitors. Hence, the type of PFT can directly affect the treatment strategy, which may be especially relevant for patients with multiple factors influencing individual PFTs and thereby test agreement.
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http://dx.doi.org/10.1093/ehjcvp/pvw026DOI Listing
January 2017

Hemostatic Therapy Using Tranexamic Acid and Coagulation Factor Concentrates in a Model of Traumatic Liver Injury.

Anesth Analg 2016 07;123(1):38-48

From the *Department of Anaesthesiology, RWTH Aachen University Hospital, Aachen, Germany; †Institute for Laboratory Animal Science, RWTH Aachen University Hospital, Aachen, Germany; ‡Laboratory for Clinical Thrombosis and Haemostasis, Department of Biochemistry, Cardiovascular Research Institute Maastricht, Maastricht University Medical Center, Maastricht, The Netherlands; and §Department of Pathology, RWTH Aachen University Hospital, Aachen, Germany.

Background: The potential clinical benefits of targeted therapy with coagulation factor concentrates (e.g., fibrinogen) and antifibrinolytic agents (e.g., tranexamic acid [TXA]) for the treatment of trauma-induced coagulopathy are increasingly recognized. We hypothesized that human fibrinogen concentrate (FC) and prothrombin complex concentrate (PCC), administered as combined therapy with TXA, would provide additive effects for reducing blood loss in an animal trauma model.

Methods: Thirty-six pigs were subjected to 2 consecutive blunt liver injuries, resulting in severe hemorrhagic shock and coagulopathy. Intervention comprised saline (control group); TXA (15 mg kg, TXA group); TXA and FC (90 mg kg, TXA-FC); or TXA, FC, and PCC (20 U kg, TXA-FC-PCC). Blood loss, thromboelastometry (ROTEM), measures of thrombin generation, platelet activation, and global coagulation variables were monitored for 4 hours. Tissue sections were examined to determine the occurrence of thromboembolic events.

Results: Total blood loss was similar in the TXA-FC and TXA-FC-PCC groups (mean ± SD: 1012 ± 86 mL and 1037 ± 118 mL, respectively; P = 1.000). These values were both lower (P < 0.001) than the TXA group (1579 ± 306 mL). Blood loss in all 3 intervention groups was lower (P < 0.001) than in the control group (2376 ± 478 mL). After trauma and resuscitation, but before study intervention, plasma fibrinogen levels were severely depleted (median for the whole study population: 66 mg dL; interquartile range: 51-108 mg dL) and clot strength was decreased (EXTEM whole-blood maximum clot firmness [MCF]: 53 ± 5 mm). Compared with controls, TXA inhibited fibrinolysis and stabilized MCF and clotting time. The addition of FC restored and stabilized hemostasis to a greater extent than TXA alone; the addition of PCC had no statistically significant impact on blood loss, clot strength (MCF), or clotting time, but it increased thrombin generation. There were no significant differences among the study groups regarding platelet activation. No thrombi or microthrombi were observed in any group at necropsy.

Conclusions: The early use of TXA and FC reduced blood loss and improved coagulation measurements in a porcine model of blunt liver injury and hemorrhagic shock. FC, administered in addition to TXA, was highly effective in reducing blood loss. The lack of statistically significant reduction in blood loss when PCC was added to TXA and FC may be attributable to the absence of thrombin generation impairment in this model.
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http://dx.doi.org/10.1213/ANE.0000000000001379DOI Listing
July 2016

Platelet Control of Fibrin Distribution and Microelasticity in Thrombus Formation Under Flow.

Arterioscler Thromb Vasc Biol 2016 Apr 4;36(4):692-9. Epub 2016 Feb 4.

From the Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, The Netherlands (F.S., C.C.F.M.J.B., R.V., T.G.M., J.M.E.M.C., J.W.M.H., P.E.J.v.d.M.); Research and Development, Optics11, Amsterdam, The Netherlands (N.R., K.O.v.d.L., E.J.B.); Arthur Bloom Haemophilia Centre, Cardiff Institute of Infection & Immunity, School of Medicine, Cardiff University, Cardiff, United Kingdom (P.W.C.); and Central Diagnostic Laboratory (Y.M.C.H.), Departments of Anaesthesiology (M.D.L.) and Internal Medicine (Y.M.C.H.), Maastricht University Medical Center, Maastricht, The Netherlands.

Objective: Platelet- and fibrin-dependent thrombus formation is regulated by blood flow and exposure of collagen and tissue factor. However, interactions between these blood-borne and vascular components are not well understood.

Approach And Results: Here, we developed a method to assess whole-blood thrombus formation on microspots with defined amounts of collagen and tissue factor, allowing determination of the mechanical properties and intrathrombus composition. Confining the collagen content resulted in diminished platelet deposition and fibrin formation at high shear flow conditions, but this effect was compensated by a larger thrombus size and increased accumulation of fibrin in the luminal regions of the thrombi at the expense of the base regions. These thrombi were more dependent on tissue factor-triggered thrombin generation. Microforce nanoindentation analysis revealed a significantly increased microelasticity of thrombi with luminal-oriented fibrin. At a low shear rate, fibrin fibers tended to luminally cover the thrombi, again resulting in a higher microelasticity. Studies with blood from patients with distinct hemostatic insufficiencies indicated an impairment in the formation of a platelet-fibrin thrombus in the cases of dilutional coagulopathy, thrombocytopenia, Scott syndrome, and hemophilia B.

Conclusions: Taken together, our data indicate that (1) thrombin increases the platelet thrombus volume; (2) tissue factor drives the formation of fibrin outside of the platelet thrombus; (3) limitation of platelet adhesion redirects fibrin from bottom to top of the thrombus; (4) a lower shear rate promotes thrombus coverage with fibrin; (5) the fibrin distribution pattern determines thrombus microelasticity; and (6) the thrombus-forming process is reduced in patients with diverse hemostatic defects.
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http://dx.doi.org/10.1161/ATVBAHA.115.306537DOI Listing
April 2016

Coated platelets function in platelet-dependent fibrin formation via integrin αIIbβ3 and transglutaminase factor XIII.

Haematologica 2016 Apr 31;101(4):427-36. Epub 2015 Dec 31.

Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, The Netherlands

Coated platelets, formed by collagen and thrombin activation, have been characterized in different ways: i) by the formation of a protein coat of α-granular proteins; ii) by exposure of procoagulant phosphatidylserine; or iii) by high fibrinogen binding. Yet, their functional role has remained unclear. Here we used a novel transglutaminase probe, Rhod-A14, to identify a subpopulation of platelets with a cross-linked protein coat, and compared this with other platelet subpopulations using a panel of functional assays. Platelet stimulation with convulxin/thrombin resulted in initial integrin α(IIb)β3 activation, the appearance of a platelet population with high fibrinogen binding, (independently of active integrins, but dependent on the presence of thrombin) followed by phosphatidylserine exposure and binding of coagulation factors Va and Xa. A subpopulation of phosphatidylserine-exposing platelets bound Rhod-A14 both in suspension and in thrombi generated on a collagen surface. In suspension, high fibrinogen and Rhod-A14 binding were antagonized by combined inhibition of transglutaminase activity and integrin α(IIb)β3 Markedly, in thrombi from mice deficient in transglutaminase factor XIII, platelet-driven fibrin formation and Rhod-A14 binding were abolished by blockage of integrin α(IIb)β3. Vice versa, star-like fibrin formation from platelets of a patient with deficiency in α(IIb)β3(Glanzmann thrombasthenia) was abolished upon blockage of transglutaminase activity. We conclude that coated platelets, with initial α(IIb)β3 activation and high fibrinogen binding, form a subpopulation of phosphatidylserine-exposing platelets, and function in platelet-dependent star-like fibrin fiber formation via transglutaminase factor XIII and integrin α(IIb)β3.
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http://dx.doi.org/10.3324/haematol.2015.131441DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5004391PMC
April 2016

Platelet-Associated Matrix Metalloproteinases Regulate Thrombus Formation and Exert Local Collagenolytic Activity.

Arterioscler Thromb Vasc Biol 2015 Dec 15;35(12):2554-61. Epub 2015 Oct 15.

From the Department of Biochemistry (T.G.M., M.A.H.F., R.M.W.K., M.T.J.v.d.B., F.S., P.E.J.v.d.M., J.M.E.M.C.) and Synapse BV (R.M.W.K.), Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, The Netherlands; School of Physiology and Pharmacology (M.T.J.v.d.B.) and School of Clinical Sciences (J.L.J.), University of Bristol, Bristol, United Kingdom; Neural Circuit Development and Regeneration Research Group, Department of Biology, KU Leuven, Leuven, Belgium (L.D.G., L.M.); Department of Haematology, University of Cambridge, Cambridge, United Kingdom (C.B., C.G.); and National Health Service Blood and Transplant, Cambridge Biomedical Campus, Cambridge, United Kingdom (C.B., C.G.).

Objective: Platelets are increasingly implicated in processes beyond hemostasis and thrombosis, such as vascular remodeling. Members of the matrix metalloproteinase (MMP) family not only remodel the extracellular matrix but also modulate platelet function. Here, we made a systematic comparison of the roles of MMP family members in acute thrombus formation under flow conditions and assessed platelet-dependent collagenolytic activity over time.

Approach And Results: Pharmacological inhibition of MMP-1 or MMP-2 (human) or deficiency in MMP-2 (mouse) suppressed collagen-dependent platelet activation and thrombus formation under flow, whereas MMP-9 inhibition/deficiency stimulated these processes. The absence of MMP-3 was without effect. Interestingly, MMP-14 inhibition led to the formation of larger thrombi, which occurred independently of its capacity to activate MMP-2. Platelet thrombi exerted local collagenolytic activity capable of cleaving immobilized dye-quenched collagen and fibrillar collagen fibers within hours, with loss of the majority of the platelet adhesive properties of collagen as a consequence. This collagenolytic activity was redundantly mediated by platelet-associated MMP-1, MMP-2, MMP-9, and MMP-14 but occurred independently of platelet α-granule release (Nbeal2(-/-) mice). The latter was in line with subcellular localization experiments, which indicated a granular distribution of MMP-1 and MMP-2 in platelets, distinct from α-granules. Whereas MMP-9 protein could not be detected inside platelets, activated platelets did bind plasma-derived MMP-9 to their plasma membrane. Overall, platelet MMP activity was predominantly membrane-associated and influenced by platelet activation status.

Conclusions: Platelet-associated MMP-1, MMP-2, MMP-9, and MMP-14 differentially modulate acute thrombus formation and at later time points limit thrombus formation by exerting collagenolytic activity.
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http://dx.doi.org/10.1161/ATVBAHA.115.306153DOI Listing
December 2015

Theme 1: Pathogenesis of venous thromboembolism (and post-thrombotic syndrome).

Thromb Res 2015 Sep;136 Suppl 1:S3-7

Leiden University Medical Centre, Department of Thrombosis and Hemostasis, Einthoven Laboratory for Experimental Vascular Medicine, Leiden, The Netherlands.

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http://dx.doi.org/10.1016/j.thromres.2015.07.034DOI Listing
September 2015

Maastricht Consensus Conference on Thrombosis (MCCT): A roadmap for future research, February 11-13, 2015, Maastricht, The Netherlands.

Thromb Res 2015 Sep;136 Suppl 1:S1-2

Maastricht University Medical Center, Cardiovascular Center, Maastricht, the Netherlands; Cardiovascular Research Institute Maastricht (CARIM), Maastricht, the Netherlands; Department of Vascular Surgery, Maastricht, the Netherlands.

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http://dx.doi.org/10.1016/j.thromres.2015.07.033DOI Listing
September 2015

Assessment of bleeding risk in patients with coronary artery disease on dual antiplatelet therapy. A systematic review.

Thromb Haemost 2016 Jan 13;115(1):7-24. Epub 2015 Aug 13.

Minka Vries, CARIM, Universiteitssingel 50, 6229 ER Maastricht, P. O. Box 616, 6200 MD Maastricht, The Netherlands, Tel.: +31 433881542, Fax: +31 43884159, E-mail:

Patients with coronary artery disease are usually treated with dual antiplatelet therapy (DAPT) after percutaneous coronary intervention. Patients on DAPT are at risk of both ischaemic and bleeding events. Although side-lined for a long time, real-life studies have shown that both the incidence and the associated morbidity and mortality of out-of-hospital bleeding are high. This indicates that prevention of (post-interventional) bleeding is as important as prevention of ischaemia. For this purpose it is crucial to reliably identify patients with a high bleeding risk. In order to postulate an algorithm, which could help identifying these patients, we performed a systematic review to determine the value of previously proposed prognostic modalities for bleeding. We searched and appraised the following tools: platelet function tests, genetic tests, bleeding scores and questionnaires and haemostatic tests. Most studies indicated that low on-treatment platelet reactivity (LTPR), as measured by several platelet function tests, and the carriage of CYP2C19*17 allele were independent risk factors for bleeding. A bleeding score also proved to be helpful in identifying patients at risk. No studies on haemostatic tests were retrieved. Several patient characteristics were also identified as independent predictors of bleeding, such as older age, female sex and renal failure. Combining these risk factors we propose an algorithm that would hypothetically facilitate identification of those patients at highest risk, warranting prevention measures for bleeding. This could be a starting point for further research concerning the topic.
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http://dx.doi.org/10.1160/TH15-04-0355DOI Listing
January 2016

Gradual increase in thrombogenicity of juvenile platelets formed upon offset of prasugrel medication.

Haematologica 2015 Sep 25;100(9):1131-8. Epub 2015 Jun 25.

Department of Biochemistry, Cardiovascular Research Institute Maastricht, Maastricht University Medical Centre, The Netherlands

In patients with acute coronary syndrome, dual antiplatelet therapy with aspirin and a P2Y12 inhibitor like prasugrel is prescribed for one year. Here, we investigated how the hemostatic function of platelets recovers after discontinuation of prasugrel treatment. Therefore, 16 patients who suffered from ST-elevation myocardial infarction were investigated. Patients were treated with aspirin (100 mg/day, long-term) and stopped taking prasugrel (10 mg/day) after one year. Blood was collected at the last day of prasugrel intake and at 1, 2, 5, 12 and 30 days later. Platelet function in response to ADP was normalized between five and 30 days after treatment cessation and in vitro addition of the reversible P2Y12 receptor antagonist ticagrelor fully suppressed the regained activation response. Discontinuation of prasugrel resulted in the formation of an emerging subpopulation of ADP-responsive platelets, exhibiting high expression of active integrin αIIbβ3. Two different mRNA probes, thiazole orange and the novel 5'Cy5-oligo-dT probe revealed that this subpopulation consisted of juvenile platelets, which progressively contributed to platelet aggregation and thrombus formation under flow. During offset, juvenile platelets were overall more reactive than older platelets. Interestingly, the responsiveness of both juvenile and older platelets increased in time, pointing towards a residual inhibitory effect of prasugrel on the megakaryocyte level. In conclusion, the gradual increase in thrombogenicity after cessation of prasugrel treatment is due to the increased activity of juvenile platelets.
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http://dx.doi.org/10.3324/haematol.2014.122457DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4800712PMC
September 2015

Effects of Fibrinogen Concentrate on Thrombin Generation, Thromboelastometry Parameters, and Laboratory Coagulation Testing in a 24-Hour Porcine Trauma Model.

Clin Appl Thromb Hemost 2016 Nov 6;22(8):749-759. Epub 2015 May 6.

Department of Anaesthesiology, RWTH Aachen University Hospital, Aachen, Germany

Introduction: In a 24-hour porcine model of liver injury, we showed that fibrinogen supplementation does not downregulate endogenous fibrinogen synthesis. Here we report data from the same study showing the impact of fibrinogen on coagulation variables.

Materials And Methods: Coagulopathy was induced in 20 German land race pigs by hemodilution and blunt liver injury. Animals randomly received fibrinogen concentrate (100 mg/kg) or saline. Coagulation parameters were assessed and thromboelastometry (ROTEM) was performed.

Results: Fibrinogen concentrate significantly reduced the prolongations of EXTEM clotting time, EXTEM clot formation time, and prothrombin time induced by hemodilution and liver injury. A decrease in clot strength was also ameliorated. Endogenous thrombin potential was significantly higher in the fibrinogen group than in the control group, 20 minutes (353 ± 24 vs 289 ± 22 nmol/L·min; P < .05) and 100 minutes (315 ± 40 vs 263 ± 38 nmol/L·min; P < .05) after the start of infusion. However, no significant between-group differences were seen in other thrombin generation parameters or in d-dimer or thrombin-antithrombin levels. Fibrinogen-platelet binding was reduced following liver injury, with no significant differences between groups. No significant between-group differences were observed in any parameter at ∼12 and ∼24 hours.

Conclusion: This study suggests that, in trauma, fibrinogen supplementation may shorten some measurements of the speed of coagulation initiation and produce a short-lived increase in endogenous thrombin potential, potentially through increased clotting substrate availability. Approximately 12 and 24 hours after starting fibrinogen concentrate/saline infusion, all parameters measured in this study were comparable in the 2 study groups.
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http://dx.doi.org/10.1177/1076029615584662DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5056597PMC
November 2016
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