Judith Cosemans

• PhD
• Professor (Full) at Maastricht University

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...

Flow chambers are increasingly used to model thrombus formation in (patho)physiologically inspired geometries and conditions. The flexible design enabled by microfluidics and the variety of commercially available devices makes comparisons between flow chambers challenging [1]. There is also a need to make faithful comparisons between these in vitro...

Coated platelets, formed by collagen and thrombin activation, have been characterized in different ways, i.e. by the formation of a protein coat of α-granular proteins, by exposure of procoagulant phosphatidylserine or by high fibrinogen binding. So far, their functional role has remained unclear. Here, we used a novel transglutaminase probe, Rhod-...

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 f...

Background: -Platelets are central to the process of haemostasis, rapidly aggregating at sites of blood vessel injury and acting as coagulation nidus sites. Upon interaction with sub-endothelial matrix platelets are transformed into balloon-like structures as part of the haemostatic response. It remains unclear, however, how and why platelets gene...

Heart failure with preserved ejection fraction (HFpEF) is characterized by a lack of a specific targeted treatment and a complex, partially unexplored pathophysiology. Common comorbidities associated with HFpEF are hypertension, atrial fibrillation, obesity and diabetes. These comorbidities, combined with advanced age, play a crucial role in the in...

These illustrated capsules have been prepared by some speakers of State-of-the-Art talks and of original investigations, presented at the 5th European Platelet Network (EUPLAN) International Conference, which was held at the Università degli Studi di Milano (Italy) on September 28-30, 2022. The programme featured various state-of-the-art lectures a...

Background: Platelets and neutrophils are the first blood cells accumulating at sites of arterial thrombus formation, and both cell types contribute to the pathology of thrombotic events. We aimed to identify key interaction mechanisms between these cells using microfluidic approaches. Methods: Whole-blood perfusion was performed over a collagen...

Cerebral small vessel disease (cSVD) accounts for 25% of ischemic strokes and is a major cause of cognitive decline. Inflammatory processes, involving immune cells and platelets might drive development and progression of cSVD. The aim of the study was to identify potential novel biomarkers for cSVD, gaining new insights into its pathophysiology. We...

The cAMP-protein kinase A (PKA) pathway in platelets is important for both platelet activation and inactivation. We hypothesize that proteins/processes downstream of the cAMP-PKA pathway that are regulated after platelet activation ánd subsequent inactivation can serve as a “switch” in platelet activation and inhibition. We used a STRING-based prot...

Background Bruton's kinase (Btk) is critical for collagen-triggered platelet signal transduction. The Btk inhibitor ibrutinib has been shown to selectively block platelet adhesion to atherosclerotic plaque material under laminar arterial flow. However, this has not been studied under a shear gradient, which is characteristic for atherothrombosis....

The cause of atherothrombosis is rupture or erosion of atherosclerotic lesions, leading to an increased risk of myocardial infarction or stroke. Here, platelet activation plays a major role, leading to the release of bioactive molecules, for example, chemokines and coagulation factors, and to platelet clot formation. Several antiplatelet therapies...

Introduction Studying arterial thrombus formation by in vitro flow assays is a widely used approach. Incorporating human atherosclerotic plaque material as a thrombogenic surface in these assays represents a method to model the pathophysiological environment of thrombus formation upon plaque disruption. Up until now, achieving a homogeneous coating...

Open in new tabDownload slide Platelet-derived matrix metalloproteinase (MMP)-2 promotes early plaque formation in mice via activation of endothelial protease activated receptor (PAR)-1 and subsequent endothelial activation and monocyte intravasation. MMP-2 is overexpressed on the platelet surface in patients with coronary artery disease (CAD) and...

All irreversible Bruton tyrosine kinase (Btk) inhibitors including ibrutinib and acalabrutinib induce platelet dysfunction and increased bleeding risk. New reversible Btk inhibitors were developed, like MK-1026. The mechanism underlying increased bleeding tendency with Btk inhibitors remains unclear. We investigated the effects of ibrutinib, acalab...

Objective: platelets possess not only haemostatic but also inflammatory properties, which combined are thought to play a detrimental role in thromboinflammatory diseases such as acute coronary syndromes and stroke. Phosphodiesterase (PDE) 3 and -5 inhibitors have demonstrated efficacy in secondary prevention of arterial thrombosis, partially media...

The healthy endothelium controls platelet activity through release of prostaglandin I2 (PGI2) and nitric oxide. The loss of this natural brake on platelet activity can cause platelets to become hyperreactive. PGI2 attenuates platelet activation by adenosine diphosphate (ADP) through stimulation of cyclic adenosine monophosphate (cAMP) production an...

In vitro flow‐based assays are widely used to investigate the role of platelets and coagulation in hemostasis and thrombosis. Their main advantage over other assays relies on the fact that they integrate blood flow that regulates many aspects of platelet function, including adhesion, activation, and aggregation. Blood flow is also central in the re...

Hemodynamics play a central role in hemostasis and thrombosis by affecting all aspects linked to platelet functions and coagulation. In vitro flow devices are extensively used in basic research, pharmacological studies, antiplatelet agent screening, and development of diagnostic tools. Because hemodynamic conditions vary tremendously throughout the...

Atherosclerosis is an underlying cause of a broad array of cardiovascular diseases characterized by plaques, arterial wall thickening initiated by hyperlipidemia, pro-inflammatory signals, endothelial dysfunction and the influx of inflammatory cells. By still incompletely characterized mechanisms, these plaques can destabilize or erode, leading to...

While in recent trials the dual pathway inhibition with aspirin plus rivaroxaban has shown to be efficacious in patients with atherosclerotic cardiovascular disease, little is known about the effects of this combination treatment on thrombus formation and vascular remodelling upon vascular damage. The aim of this study was to examine the effects of...

Background and aims Platelets can release extracellular vesicles (EVs) upon stimulation with various agonists. Interestingly, platelets from patients with Glanzmann thrombasthenia have reduced EV release. These platelets lack functional αIIbβ3 integrins, indicating that αIIbβ3 integrin is critical in vesicle release. Integrin activation is central...

Background Genome wide association studies (GWAS) identified SLC44A2 as a novel susceptibility gene for venous thrombosis (VT) and previous work established that SLC44A2 contributed to clot formation upon vascular injury. Objective To further investigate the role of SLC44A2 in VT by utilizing SLC44A2 deficient mice (Slc44a2‐/‐) in two representati...

In spite of current treatment strategies, myocardial infarction and stroke are still major causes of death worldwide. These events are triggered by damage of an atherosclerotic plaque, resulting in occlusive thrombus formation. Mouse studies have significantly contributed to our understanding of the mechanisms of atherogenesis and of thrombosis fol...

The contributions of coagulation factor XI (FXI) and FXII to human clot formation is not fully known. Patients with deficiency in FXI have a variable mild bleeding risk, whereas FXII deficiency is not associated with bleeding. These phenotypes make FXII and FXI attractive target proteins in anticoagulant therapy. Here, we studied the mechanisms of...

Antithrombotic therapies reduce cardiovascular diseases by preventing arterial thrombosis and thromboembolism, but at expense of increased bleeding risks. Arterial thrombosis studies using genetically modified mice have been invaluable for identification of new molecular targets. Because of low sample sizes and heterogeneity in approaches or method...

Tissue factor pathway inhibitor-alpha (TFPI-α) is a Kunitz-type serine protease inhibitor, which suppresses coagulation by inhibiting the tissue factor (TF)/factor VIIa complex as well as factor Xa. In static plasma-phospholipid systems, TFPI-α thus suppresses both factor Xa and thrombin generation. In this article, we used a microfluidics approach...

In patients with dysfunctions of the Ca2+ channel ORAI1, stromal interaction molecule 1 (STIM1) or integrin-regulating kindlin-3 (FERMT3), severe immunodeficiency is frequently linked to abnormal platelet activity. In this paper, we studied in nine rare patients, including relatives, with confirmed genetic mutations of ORAI1, STIM1 or FERMT3, plate...

In this issue of the Journal of Thrombosis and Haemostasis, Branchford et al. [1] present novel data on the role of Mer tyrosine kinase in platelet function and thrombosis. Mer forms, together with Axl and Tyro3, the TAM receptor family of Growth arrest-specific (Gas6) receptors. The vitamin-K dependent protein Gas6 is regarded as a platelet primer...

Traditionally, in vitro flow chamber experiments and in vivo arterial thrombosis studies have been proven to be of vital importance to elucidate the mechanisms of platelet thrombus formation after vessel wall injury. In recent years, it has become clear that platelets also act as modulators of inflammatory processes, such as atherosclerosis. A key...

Platelet activation and blood coagulation are reciprocal processes, both contributing to hemostasis and thrombosis in an interactive way. Exposed collagen, von Willebrand factor (VWF), and other components of the subendothelial matrix initiate platelet adhesion, whereas exposed tissue factor simultaneously triggers the coagulation cascade. During t...

The Scott syndrome is a very rare and likely under-diagnosed bleeding disorder associated with mutations in the gene encoding anoctamin-6. Platelets from Scott patients are impaired in various Ca2+-dependent responses, including phosphatidylserine exposure, integrin closure, intracellular protein cleavage and cytoskeleton-dependent morphological ch...

Scott syndrome is a rare bleeding disorder, characterized by altered Ca(2+)-dependent platelet signaling with defective phosphatidylserine (PS) exposure and microparticle formation, and is linked to mutations in the ANO6 gene, encoding anoctamin (Ano)6. We investigated how the complex platelet phenotype of this syndrome is linked to defective expre...

The potential relevance of murine atherothrombosis models for understanding human disease has been debated in the past. Despite this, in the last decade, many thrombosis studies with atherogenic Apoe(-/-) mice have been performed, which provide novel insight into the molecular mechanisms by which platelet and coagulation processes accomplish acute...

Objective: To investigate the roles and signaling pathways of CD40L and CD40 in platelet activation and thrombus formation under atherothrombotic conditions. Approach and Results: Mouse platelets lacking CD40L (Cd40lg -/- Apoe -/- ) showed diminished αIIbβ3 activation and α-granule secretion in response to collagen receptor (GPVI) stimulation, whil...

To investigate the roles and signaling pathways of CD40L and CD40 in platelet-platelet interactions and thrombus formation under conditions relevant for atherothrombosis. Platelets from mice prone to atherosclerosis lacking CD40L (Cd40lg(-/-)Apoe(-/-)) showed diminished αIIbβ3 activation and α-granule secretion in response to glycoprotein VI stimul...

Rationale: Besides their essential role in hemostasis, platelets also have functions in inflammation. In platelets, junctional adhesion molecule (JAM)-A was previously identified as an inhibitor of integrin αIIbβ3-mediated outside-in signaling and its genetic knockdown resulted in hyperreactivity. Objective: This gain-of-function was specificall...

Objective Rheumatoid arthritis, and to a lesser extent ankylosing spondylitis and psoriatic arthritis, associates with increased morbidity and mortality due to cardiovascular complications. We hypothesized that the increased risk of cardiovascular disease is reflected by changes in blood parameters that are compatible with a prothrombotic propensit...

Thrombus formation by adhering and aggregating blood platelets is fundamental to hemostasis and is a prerequisite for vascular occlusion in pathological thrombosis. The parallel-plate flow chamber technique has been extensively used to measure platelet adhesion and activation in vitro at arterial or venous flow conditions. Here, we describe the use...

Assays measuring platelet aggregation (thrombus formation) at arterial shear rate mostly use collagen as only platelet-adhesive surface. Here we report about have developed a multi-surface and multi-parameter flow assay to characterize thrombus formation in whole blood from healthy subjects and patients with platelet function deficiencies. A syste...

Objective: Atherothrombosis is the main cause of myocardial infarction and ischemic stroke. Although the extrinsic (tissue factor-factor VIIa [FVIIa]) pathway is considered as a major trigger of coagulation in atherothrombosis, the role of the intrinsic coagulation pathway via coagulation FXII herein is unknown. Here, we studied the roles of the e...

The coagulation process is activated by tight control mechanisms, in which platelets play prominent and unique roles. In thrombosis and hemostasis, activated platelets regulate the coagulation system in various ways: by exposing a phosphatidylserine surface for thrombin formation, by supporting fibrin formation, and by regulating the retraction of...

Platelets abundantly express the membrane receptor CD36 and store its ligand thrombospondin-1 (TSP1) in the α-granules. We investigated whether released TSP1 can support platelet adhesion and thrombus formation via interaction with CD36. Mouse platelets deficient in CD36 showed reduced adhesion to TSP1 and subsequent phosphatidylserine expression....

Platelet activation is essential for primary hemostasis and acute thrombotic vascular occlusions. On activation, platelets release their prothrombotic granules and expose phosphatidylserines, thus fostering thrombin generation and thrombus formation. In other cell types, both degranulation and phosphatidylserine exposure are modified by sphingomyel...

Injury of an arterial vessel wall acutely triggers a multifaceted process of thrombus formation, which is dictated by the high-shear flow conditions in the artery. In this overview, we describe how the classical concept of arterial thrombus formation and vascular occlusion, driven by platelet activation and fibrin formation, can be extended and fin...

Background: Inactivation of integrin αIIbβ3 reverses platelet aggregate formation upon coagulation. Results and conclusion: Platelets from patient (Scott) and mouse (Capn1(-/-) and Ppif(-/-)) blood reveal a dual mechanism of αIIbβ3 inactivation: by calpain-2 cleavage of integrin-associated proteins and by cyclophilin D/TMEM16F-dependent phosphol...

Multimeric glycoprotein von Willebrand factor (VWF) exhibits a unique triplet structure of individual oligomers, resulting from ADAMTS-13 (a disintegrin and metalloproteinase with thrombospondin type 1 motifs 13) cleavage. The faster and slower migrating triplet bands of a given VWF multimer have one shorter or longer N-terminal peptide sequence, r...

Introduction: Consumption of n-3 polyunsaturated fatty acids (PUFA) and antioxidant polyphenols is considered to decline the risk of cardiovascular disease. Materials and methods: To provide an explanation for this cardioprotective effect, we performed an intervention study with proatherogenic Apoe(-/-) mice which were fed during eight weeks wit...

Platelets in a thrombus interact with (anti)coagulation factors and support blood coagulation. In the concept of cell-based control of coagulation, three different roles of platelets can be distinguished: control of thrombin generation, support of fibrin formation, and regulation of fibrin clot retraction. Here, we postulate that different populati...

Cardiovascular disease is a major cause of mortality globally and is subject to ongoing research to improve clinical treatment. It is established that activation of platelets and coagulation are central to thrombosis, yet at different extents in the arterial and venous system. In vitro perfusion chamber technology has contributed significant knowle...

Custom-made and commercial parallel-plate flow chambers are widely used for studies of platelet activation and thrombus formation in whole blood at defined shear rates. When used in a reproducible way, such flow chamber devices give valuable information on the thrombogenic potential of human, mouse, or rat blood. This article aims to provide a prac...

Platelets tightly regulate haemostasis and arterial thrombosis. Protein kinase C (PKC) is involved in most platelet responses implicated in thrombus formation. Recent pharmacological and mouse gene knockout approaches show that the conventional PKC isoforms and the novel PKC isoforms contribute in distinct ways to these platelet responses. We hypot...

Platelets abundantly express glycoprotein CD36 with thrombospondin-1 (TSP1) and oxidized low-density lipoprotein (oxLDL) as proposed ligands. How these agents promote platelet activation is still poorly understood. Both TSP1 and oxLDL caused limited activation of platelets in suspension. However, immobilized TSP1 and oxLDL, but not LDL, strongly su...

Platelets are highly specialized blood cells critically involved in hemostasis and thrombosis. Members of the protein kinase C (PKC) family have established roles in regulating platelet function and thrombosis, but the molecular mechanisms are not clearly understood. In particular, the conventional PKC isoform, PKCα, is a major regulator of platele...

Introduction: Platelets express high levels of CD36 known as glycoprotein IV. Thrombospondin-1 (TSP1) and oxidized low density lipoprotein (oxLDL) are proposed ligands of CD36, but how their interaction with this receptor influences platelet function is still poorly understood. Methods and Results: Immobilized TSP1 and oxLDL, but not native LDL, p...

Introduction. Flowing platelets rapidly interact with collagens and other matrix components of the damaged vessel wall. Using a microarray of matrix-derived proteins, we determined the requirements of platelet receptor interactions for thrombus formation. Methods. Arrays of matrix proteins were microspotted using a Microgrid robot. Spots (binding i...

The glycoprotein CD36, also known as glycoprotein IIIb/IV or FAT, is expressed on the surface of platelets, monocytes, microvascular endothelial cell, smooth muscle cells, cardiomyocytes and other cells of the cardiovascular system. In spite of its abundant presence, CD36 has remained for long a mysterious protein with a poorly understood role. In...

A microscopic method was developed to study the role of platelets in fibrin formation. Perfusion of adhered platelets with plasma under coagulating conditions at a low shear rate (250(-1)) resulted in the assembly of a star-like fibrin network at the platelet surface. The focal fibrin formation on platelets was preceded by rises in cytosolic Ca(2+)...

 Interaction of murine Gas6 with the platelet Gas6 receptors Tyro3, Axl and Mer (TAM) plays an important role in arterial thrombus formation. However, a role for Gas6 in human platelet activation has been questioned.  To determine the role of Gas6 in human and murine platelet activation and thrombus formation.  Gas6 levels appeared to be 20-fold hi...

Arterial thrombosis, a major cause of myocardial infarction and stroke, is initiated by activation of blood platelets by subendothelial collagen. The protein kinase C (PKC) family centrally regulates platelet activation, and it is becoming clear that the individual PKC isoforms play distinct roles, some of which oppose each other. Here, for the fir...

Thrombus formation and fibrin deposition on collagen under shear. Human whole blood was co-perfused with CaCl2/TF over collagen for 15 minutes at a shear rate of 200 s-1, 500 s-1, or 1000 s-1. Experiments were performed in the presence of vehicle or hirudin (2.9 μmol/L). A, Photo micrographs of platelet adhesion and fibrin formation. B, Following p...

The generation of thrombin is a critical process in the formation of venous thrombi. In isolated plasma under static conditions, phosphatidylserine (PS)-exposing platelets support coagulation factor activation and thrombin generation; however, their role in supporting coagulation factor binding under shear conditions remains unclear. We sought to d...

In most models of experimental thrombosis, healthy blood vessels are damaged. This results in the formation of a platelet thrombus that is stabilized by ADP signaling via P2Y(12) receptors. However, such models do not predict involvement of P2Y(12) in the clinically relevant situation of thrombosis upon rupture of atherosclerotic plaques. We invest...

Vascular injury leads to formation of a structured thrombus as a consequence of platelet activation and aggregation, thrombin and fibrin formation, and trapping of leukocytes and red cells. This review summarises current evidence for heterogeneity of platelet responses and functions in the thrombus-forming process. Environmental factors contribute...

Platelets are activated by adhesion to vascular collagen via the immunoglobulin receptor, glycoprotein VI (GPVI). This causes potent signaling toward activation of phospholipase Cgamma2, which bears similarity to the signaling pathway evoked by T- and B-cell receptors. Phosphoinositide 3-kinase (PI3K) plays an important role in collagen-induced pla...

In vivo mouse models have indicated that the intrinsic coagulation pathway, initiated by factor XII, contributes to thrombus formation in response to major vascular damage. Here, we show that fibrillar type I collagen provoked a dose-dependent shortening of the clotting time of human plasma via activation of factor XII. This activation was mediated...

Platelets are central players in atherothrombosis development in coronary artery disease. The PKC family provides important intracellular mechanisms for regulating platelet activity, and platelets express several members of this family, including the classical isoforms PKCalpha and PKCbeta and novel isoforms PKCdelta and PKCtheta. Here, we used a g...

Background. ADP stabilizes thrombi via P2Y12 signaling to integrin IIb3. This was also shown in collagen-dependent thrombosis models in healthy mice. We studied the role of ADP in thrombus formation on atherosclerotic plaques in vivo. The mechanism was revealed via whole blood perfusion over collagen or plaque material. Methods. Plaque rupture a...

In the classical concept of platelet integrin activation, it is considered that unidirectional conformational changes of alpha(IIb)beta(3) and alpha(2)beta(1) regulate the adhesiveness of platelets for fibrin(ogen) and collagen, respectively. Here, we summarize recent evidence that these conformational changes: (i) can also occur in the reverse dir...

Blood coagulation and platelet activation are mutually dependent processes, but contribute differently to venous and arterial thrombosis. We investigated the interplay of these processes in vivo in a mouse model of arteriolar and venular thrombus formation. Thrombus formation was studied by intravital (fluorescence) microscopy after topical applica...

PKCtheta is a novel protein kinase C isozyme, predominately expressed in T cells and platelets. PKCtheta(-/-) T cells exhibit reduced activation and PKCtheta(-/-) mice are resistant to autoimmune disease, making PKCtheta an attractive therapeutic target for immune modulation. Collagen is a major agonist for platelets, operating through an immunorec...

During thrombus formation, thrombin, which is abundantly present at sites of vascular injury, activates platelets in part via autocrine-produced ADP. We investigated the signaling pathways by which thrombin and ADP in synergy induced platelet Ca2+ elevation and procoagulant activity, and we monitored the consequences for the coagulation process. Ev...

Platelets stably interact with collagen via glycoprotein (GP)VI and alpha2beta1integrin. With alpha2-null mice, we investigated the role of alpha2beta1 in thrombus formation and stability in vivo and in vitro. Using a FeCl(3)-induced thrombosis model, in arteries from alpha2-null mice smaller thrombi were formed with more embolization compared to v...

Platelets stably interact with collagen via glycoprotein (GP)VI and alpha 2 beta l integrin.With alpha 2-null mice, we investigated the role of alpha 2 beta l in thrombus formation and stability in vivo and in vitro. Using a FeCl3-incluced thrombosis model, in arteries from alpha 2-null mice smaller thrombi were formed with more embolization compar...

Protein kinase C (PKC) isoforms regulate many platelet responses in a still incompletely understood manner. Here we investigated the roles of PKC in the platelet reactions implicated in thrombus formation as follows: secretion aggregate formation and coagulation-stimulating activity, using inhibitors with proven activity in plasma. In human and mou...

Protein kinase C (PKC) isoforms regulate many platelet responses in a still incompletely understood manner. Here we investigated the roles of PKC in the platelet reactions implicated in thrombus formation as follows: secretion aggregate formation and coagulation-stimulating activity, using inhibitors with proven activity in plasma. In human and mou...

Platelet integrins alpha2beta1 and alphaIIbbeta3 play critical roles in platelet adhesion and thrombus formation after vascular injury. On resting platelets, both integrins are in a low-affinity state. However, agonist stimulation results in conformational changes that enable ligand binding that can be detected with conformation dependent monoclona...

Signaling from collagen and G protein-coupled receptors leads to platelet adhesion and subsequent thrombus formation. Paracrine agonists such as ADP, thromboxane, and Gas6 are required for platelet aggregate formation. We hypothesized that thrombi are intrinsically unstable structures and that their stabilization requires persistent paracrine activ...