Pathological Thrombosis Research Articles

Lipid rafts are essential for release of phosphatidylserine-exposing extracellular vesicles from platelets

Platelets protect the vascular system during damage or inflammation, but platelet activation can result in pathological thrombosis. Activated platelets release a variety of extracellular vesicles (EVs). EVs shed from the plasma membrane often expose phosphatidylserine (PS). These EVs are pro-thrombotic and increased in number in many cardiovascular and metabolic diseases. The mechanisms by which PS-exposing EVs are shed from activated platelets are not well characterised. Cholesterol-rich lipid rafts provide a platform for coordinating signalling through receptors and Ca2+ channels in platelets. We show that cholesterol depletion with methyl-β-cyclodextrin or sequestration with filipin prevented the Ca2+-triggered release of PS-exposing EVs. Although calpain activity was required for release of PS-exposing, calpain-dependent cleavage of talin was not affected by cholesterol depletion. P2Y12 and TPα, receptors for ADP and thromboxane A2, respectively, have been reported to be in platelet lipid rafts. However, the P2Y12 antagonist, AR-C69931MX, or the cyclooxygenase inhibitor, aspirin, had no effect on A23187-induced release of PS-exposing EVs. Together, these data show that lipid rafts are required for release of PS-exposing EVs from platelets.

Amicus or Adversary Revisited: Platelets in Acute Lung Injury and Acute Respiratory Distress Syndrome.

Platelets are essential cellular effectors of hemostasis and contribute to disease as circulating effectors of pathologic thrombosis. These are their most widely known biologic activities. Nevertheless, recent observations demonstrate that platelets have a much more intricate repertoire beyond these traditional functions and that they are specialized for contributions to vascular barrier integrity, organ repair, antimicrobial host defense, inflammation, and activities across the immune continuum. Paradoxically, on the basis of clinical investigations and animal models of disease, some of these newly discovered activities of platelets appear to contribute to tissue injury. Studies in the last decade indicate unique interactions of platelets and their precursor, the megakaryocyte, in the lung and implicate platelets as essential effectors in experimental acute lung injury and clinical acute respiratory distress syndrome. Additional discoveries derived from evolving work will be required to precisely define the contributions of platelets to complex subphenotypes of acute lung injury and to determine if these remarkable and versatile blood cells are therapeutic targets in acute respiratory distress syndrome.

Association of Perioperative Red Blood Cell Transfusions With Venous Thromboembolism in a North American Registry

Increasing evidence supports the role of red blood cells (RBCs) in physiological hemostasis and pathologic thrombosis. Red blood cells are commonly transfused in the perioperative period; however, their association with postoperative thrombotic events remains unclear. To examine the association between perioperative RBC transfusions and postoperative venous thromboembolism (VTE) within 30 days of surgery. This analysis used prospectively collected registry data from the American College of Surgery National Surgical Quality Improvement Program (ACS-NSQIP) database, a validated registry of 525 teaching and nonteaching hospitals in North America. Participants included patients in the ACS-NSQIP registry who underwent a surgical procedure from January 1 through December 31, 2014. Data were analyzed from July 1, 2016, through March 15, 2018. Risk-adjusted odds ratios (aORs) were estimated using multivariable logistic regression. The primary outcome was the development of postoperative VTE (deep venous thrombosis [DVT] and pulmonary embolism [PE]) within 30 days of surgery that warranted therapeutic intervention; DVT and PE were also examined separately as secondary outcomes. Subgroup analyses were performed by surgical subtypes. Propensity score matching was performed for sensitivity analyses. Of 750 937 patients (56.8% women; median age, 58 years; interquartile range, 44-69 years), 47 410 (6.3%) received at least 1 perioperative RBC transfusion. Postoperative VTE occurred in 6309 patients (0.8%) (DVT in 4336 [0.6%]; PE in 2514 [0.3%]; both DVT and PE in 541 [0.1%]). Perioperative RBC transfusion was associated with higher odds of VTE (aOR, 2.1; 95% CI, 2.0-2.3), DVT (aOR, 2.2; 95% CI, 2.1-2.4), and PE (aOR, 1.9; 95% CI, 1.7-2.1), independent of various putative risk factors. A significant dose-response effect was observed with increased odds of VTE as the number of intraoperative and/or postoperative RBC transfusion events increased (aOR, 2.1 [95% CI, 2.0-2.3] for 1 event; 3.1 [95% CI, 1.7-5.7] for 2 events; and 4.5 [95% CI, 1.0-19.4] for ≥3 events vs no intraoperative or postoperative RBC transfusion; P < .001 for trend). In subgroup analyses, the association between any perioperative RBC transfusion and postoperative VTE remained statistically significant across all surgical subspecialties analyzed. The association between any perioperative RBC transfusion and the development of postoperative VTE also remained robust after 1:1 propensity score matching (47 142 matched pairs; matched OR, 1.9; 95% CI, 1.8-2.1). The results of this study suggest that perioperative RBC transfusions may be significantly associated with the development of new or progressive postoperative VTE, independent of several putative confounders. These findings, if validated, should reinforce the importance of rigorous perioperative management of blood transfusion practices.

New anticoagulants, reversal agents, and clinical considerations for perioperative practice.

There are several new anticoagulants on the market that will impact perioperative care, including the use of these anticoagulant drugs in the setting of regional anesthesia. The ideal pharmacological agent would prevent pathological thrombosis and allow for a normal response to vascular injury to limit bleeding. At present, all antithrombotic agents have increased bleeding risk as their main side effect. We describe the different categories of drugs, e.g., antiplatelet, anticoagulant, and thrombolytic, with particular emphasis on the new drugs that have been introduced into the market. These agents can be evaluated by a number of methods including low-, medium-, or high-risk procedures and guidelines and best practice standards that have been published regarding the amount of time to wait after stopping the medication and before performing a procedure, e.g., the American Society of Regional Anesthesia and Pain Medicine recommendations. The present investigation will also describe new reversal agents for anticoagulants and the implications of all these drugs for regional anesthesia.

Do platelets promote cardiac recovery after myocardial infarction: roles beyond occlusive ischemic damage.

Our understanding of platelet function has traditionally focused on their roles in physiological hemostasis and pathological thrombosis, with the latter being causative of vessel occlusion and subsequent ischemic damage to various tissues. In particular, numerous in vivo studies have implicated causative roles for platelets in the pathogenesis of ischemia-reperfusion (I/R) injury to the myocardium. However, platelets clearly have more complex pathophysiological roles, particularly as a result of the heterogeneous nature of biologically active cargo secreted from their granules or contained within released microparticles or exosomes. While some of these released mediators amplify platelet activation and thrombosis through autocrine or paracrine amplification pathways, they can also regulate diverse cellular functions within the localized microenvironment and recruit progenitor cells to the damage site to facilitate repair processes. Notably, there is evidence to support cardioprotective roles for platelet mediators during I/R injury. As such, it is becoming more widely appreciated that platelets fulfill a host of physiological and pathological roles beyond our basic understanding. Therefore, the purpose of this perspective is to consider whether platelets, through their released mediators, can assume a paradoxically beneficial role to promote cardiac recovery after I/R injury.

Maintenance of murine platelet homeostasis by the kinase Csk and phosphatase CD148

AbstractSrc family kinases (SFKs) coordinate the initiating and propagating activation signals in platelets, but it remains unclear how they are regulated. Here, we show that ablation of C-terminal Src kinase (Csk) and receptor-like protein tyrosine-phosphatase CD148 in mice results in a dramatic increase in platelet SFK activity, demonstrating that these proteins are essential regulators of platelet reactivity. Paradoxically, Csk/CD148-deficient mice exhibit reduced in vivo and ex vivo thrombus formation and increased bleeding following injury rather than a prothrombotic phenotype. This is a consequence of multiple negative feedback mechanisms, including downregulation of the immunoreceptor tyrosine-based activation motif (ITAM)– and hemi-ITAM–containing receptors glycoprotein VI (GPVI)-Fc receptor (FcR) γ-chain and CLEC-2, respectively and upregulation of the immunoreceptor tyrosine-based inhibition motif (ITIM)–containing receptor G6b-B and its interaction with the tyrosine phosphatases Shp1 and Shp2. Results from an analog-sensitive Csk mouse model demonstrate the unconventional role of SFKs in activating ITIM signaling. This study establishes Csk and CD148 as critical molecular switches controlling the thrombotic and hemostatic capacity of platelets and reveals cell-intrinsic mechanisms that prevent pathological thrombosis from occurring.

Tissue Factor: An Essential Mediator of Hemostasis and Trigger of Thrombosis.

Tissue factor (TF) is the high-affinity receptor and cofactor for factor (F)VII/VIIa. The TF-FVIIa complex is the primary initiator of blood coagulation and plays an essential role in hemostasis. TF is expressed on perivascular cells and epithelial cells at organ and body surfaces where it forms a hemostatic barrier. TF also provides additional hemostatic protection to vital organs, such as the brain, lung, and heart. Under pathological conditions, TF can trigger both arterial and venous thrombosis. For instance, atherosclerotic plaques contain high levels of TF on macrophage foam cells and microvesicles that drives thrombus formation after plaque rupture. In sepsis, inducible TF expression on monocytes leads to disseminated intravascular coagulation. In cancer patients, tumors release TF-positive microvesicles into the circulation that may contribute to venous thrombosis. TF also has nonhemostatic roles. For instance, TF-dependent activation of the coagulation cascade generates coagulation proteases, such as FVIIa, FXa, and thrombin, which induce signaling in a variety of cells by cleavage of protease-activated receptors. This review will focus on the roles of TF in protective hemostasis and pathological thrombosis.

Translational Implications of Platelets as Vascular First Responders.

Platelets play a vital role in normal hemostasis to stem blood loss at sites of vascular injury by tethering and adhering to sites of injury, recruiting other platelets and blood cells to the developing clot, releasing vasoactive small molecules and proteins, and assembling and activating plasma coagulation proteins in a tightly regulated temporal and spatial manner. In synchrony with specific end products of coagulation, primarily cross-linked fibrin, a stable thrombus quickly forms. Far beyond physiological hemostasis and pathological thrombosis, emerging evidence supports platelets playing a pivotal role in vascular homeostasis, inflammation, cellular repair, regeneration, and wide range of autocrine and paracrine functions. In essence, platelets play both structural and functional roles as reporters, messengers, and active transporters surveying the vasculature for cues of environmental or developmental stimuli and participating as first responders.1 In this review, we will provide a contemporary perspective of platelet physiology, including fundamental, translational, and clinical constructs that apply directly to human health and disease.

Platelet and von Willebrand factor interactions at the vessel wall.

The process of platelet thrombus formation contributes to the haemostatic response that prevents excessive blood loss after tissue injury, but may become a life-threatening disease mechanism by causing the acute thrombotic occlusion of atherosclerotic arteries. The participation of platelets in the formation of thrombi is centered on their adhesive properties and the ability to respond to stimuli with rapid activation. Platelet adhesion and activation are multifaceted and modulated by different environmental conditions, suggesting that it should be possible to obtain a selective pharmacological inhibition of the pathways more relevant to athero-thrombosis than to haemostasis. In particular, progress in understanding the structure and function of von Willebrand factor and the mechanisms that underlie its interactions with vascular surfaces and platelets can elucidate important differentiating aspects of normal haemostasis and pathological arterial thrombosis.

Invited commentary

In this translational study, Dr Dansdill and the group from Loyola show that the synthetic organic compound vepoloxamer (P-188) can potentiate the effects of heparin and tissue plasminogen activator in a rat model. This is a triblock, organic, synthetic, and amphipathic molecule that improves the rheology of blood. It has been studied in the sickle cell population with no reports of bleeding complications. To date, the use of anticoagulants to prevent thromboembolism and recurrent thrombosis in the arterial and venous circulation has been plagued by a very real and problematic attendant risk of bleeding. Whereas the advent of the direct oral anticoagulants has provided a breakthrough in convenience for the patient, the true “Holy Grail” of anticoagulant therapy is to establish a way to prevent pathologic thrombosis with minimal or no bleeding risk. Major bleeding rates for low-molecular-weight heparin approximate 2%, and even for the direct oral anticoagulants, major and clinically nonmajor bleeding may be as high as 8% to 10%.1Crowther M.A. Warkentin T.E. Bleeding risk and the management of bleeding complications in patients undergoing anticoagulant therapy: focus on new anticoagulant agents.Blood. 2008; 111: 4871-4879Crossref PubMed Scopus (225) Google Scholar, 2Yeh C.H. Gross P.L. Weitz J.I. Evolving use of new oral anticoagulants for treatment of venous thromboembolism.Blood. 2014; 124: 1020-1028Crossref PubMed Scopus (101) Google Scholar As such, this work represents a priority issue in anticoagulation pharmacology. If vepoloxamer allows a lower dose of heparin to be used and potentiation of tissue plasminogen activator, then the use of such a compound could have significant clinical impact and benefit. Importantly, this medication has been shown to be safe in phase I and II trials (albeit for different indications) and thus represents a tangible and realistic translation of bench research. Although this work is interesting and potentially important, areas that need to be clarified include the dose of heparin that was used and how it relates to clinical dosage (the amount of heparin in the current study seems to be low compared with what is clinically used in patients although previously used in other rat studies) and the establishment of parameters by which to monitor the effect of the drug with standard tests. Nonetheless, the data are provocative and the concept an important one. We should all applaud the efforts to look at improving the safety of patients by decreasing dosages of anticoagulants and fibrinolytic agents while maintaining therapeutic efficacy. The opinions or views expressed in this commentary are those of the authors and do not necessarily reflect the opinions or recommendations of the Journal of Vascular Surgery or the Society for Vascular Surgery. Synthetic, organic compound vepoloxamer (P-188) potentiates tissue plasminogen activatorJournal of Vascular SurgeryVol. 67Issue 1PreviewPoloxamer-188 is a synthetic, organic compound that acts by binding hydrophobic pockets on damaged lipid bilayers in the circulation. P-188 reduces blood viscosity and confers anti-inflammatory and cytoprotective effects. Vepoloxamer (Mast Therapeutics, San Diego, Calif) is a purified version of this compound that has limited side effects. The aim of this study was to investigate drug interactions between vepoloxamer and heparin and tissue plasminogen activator (tPA). Full-Text PDF Open Archive

Neutrophil Extracellular Traps in Plasma from Dogs with Immune-mediated Hemolytic Anemia.

BackgroundNeutrophil extracellular traps (NETs) are part of the innate immune response and are essential in local pathogen control, but are associated with pathological inflammation, organ damage, autoimmunity, and thrombosis. Immune‐mediated hemolytic anemia (IMHA) is a pro‐inflammatory, prothrombotic disease associated with high mortality.Hypothesis/ObjectivesNeutrophil extracellular traps (NETs) are a feature of the inflammatory process in dogs with IMHA. The objective of the study was to evaluate plasma from dogs with IMHA for the presence of 2 indirect markers and 1 direct marker of NETs.AnimalsHealthy client‐owned dogs (56) and hospitalized dogs with IMHA (n = 35).MethodsProspective study. Plasma samples for all dogs were evaluated for cell‐free DNA using a fluorescence assay, histone‐DNA (hisDNA) complex using an ELISA, and citrullinated histone H3 (specific for NETosis) using Western blot. Reference intervals were generated using plasma from healthy dogs.ResultsIn dogs with IMHA, cell‐free DNA concentration was above the reference interval in 17% of samples with a median (range) of 1.0 μg/mL (0.1–17.3), and hisDNA concentration was above the reference interval in 94% of samples with a median (range) of 30.7 × pooled normal plasma (PNP; 0.6–372.1). Western blot for citrullinated histone H3 identified detectable bands in 84% samples from dogs with IMHA.Conclusions and Clinical ImportanceThe assay for cell‐free DNA detected evidence of NETs in fewer dogs than did the other approaches. Excessive NETs appears to be a feature of IMHA in dogs and contributions to the prothrombotic state deserve further study.

Novel Antithrombotic Drugs on the Horizon: The Ultimate Promise to Prevent Clotting While Avoiding Bleeding.

Diseases associated with arterial thrombosis or venous thrombosis are leading causes of mortality and morbidity globally. Since the 1930s, anti thrombotic therapy has been the cornerstone of medical therapy for thrombotic diseases. However, the success of anti thrombotic therapy has come at the cost of one of the most dreaded iatrogenic complications— bleeding. Recently, new evidence has emerged on potentially important differences between thrombosis and hemostasis, thereby raising the possibility of developing new anti thrombotic drugs that do not cause bleeding. All currently used antithrombotic drugs in the clinic are associated with an inherent risk of bleeding. For example, the risk of serious major bleeding with a non–vitamin K antagonist oral anticoagulant is ≈2% to 3%, with the risk of intracranial hemorrhage of ≈0.3 to 0.5% per annum.1 Likewise nonmajor bleeding with aspirin approximates 2%, and the rates of major and life-threatening bleeding rises significantly in those over 75 years of age to >2% per year.2 Thus, a significant proportion of patients at high risk of thrombotic disease are vulnerable to bleeding complications and often miss out on potentially beneficial antithrombotic therapy. Importantly, aside from the mortality and morbidity directly linked to the index bleeding event, there is a large body of evidence demonstrating that hemorrhagic complications are associated with adverse clinical outcomes.3 Despite the introduction of new anticoagulants, such as the non–vitamin K antagonist oral anticoagulants and newer antiplatelet drugs, we have reached a tipping point with regard to the achievable balance between antithrombotic potency and bleeding risk with current antithrombotic approaches. Therefore, there remains an unmet clinical need for new antithrombotic approaches that maintain efficacy while preserving hemostasis. Recently, major progress has been achieved in our understanding of the factors that may differentially regulate pathological thrombosis from hemostasis based on the introduction of intravital microscopy, …

Selective factor VIII activation by the tissue factor–factor VIIa–factor Xa complex

Safe and effective antithrombotic therapy requires understanding of mechanisms that contribute to pathological thrombosis but have a lesser impact on hemostasis. We found that the extrinsic tissue factor (TF) coagulation initiation complex can selectively activate the antihemophilic cofactor, FVIII, triggering the hemostatic intrinsic coagulation pathway independently of thrombin feedback loops. In a mouse model with a relatively mild thrombogenic lesion, TF-dependent FVIII activation sets the threshold for thrombus formation through contact phase-generated FIXa. In vitro, FXa stably associated with TF-FVIIa activates FVIII, but not FV. Moreover, nascent FXa product of TF-FVIIa can transiently escape the slow kinetics of Kunitz-type inhibition by TF pathway inhibitor and preferentially activates FVIII over FV. Thus, TF synergistically primes FIXa-dependent thrombin generation independently of cofactor activation by thrombin. Accordingly, FVIIa mutants deficient in direct TF-dependent thrombin generation, but preserving FVIIIa generation by nascent FXa, can support intrinsic pathway coagulation. In ex vivo flowing blood, a TF-FVIIa mutant complex with impaired free FXa generation but activating both FVIII and FIX supports efficient FVIII-dependent thrombus formation. Thus, a previously unrecognized TF-initiated pathway directly yielding FVIIIa-FIXa intrinsic tenase complex may be prohemostatic before further coagulation amplification by thrombin-dependent feedback loops enhances the risk of thrombosis.

Different adhesion behaviors of platelets depending on shear stress around stenotic channels

Platelet adhesion, activation, and aggregation play important roles in pathological thrombosis and the progression of atherosclerosis. In our previous study, it was observed that the probability of platelet adhesion increased under high-hematocrit conditions. The present study aimed to investigate how the interactions between hemodynamic properties and platelet adhesion around stenosed channels varied according to the hematocrit level. After passing through the narrow stenotic channels with different stenotic widths (100, 50, and 10 μm), the platelets were activated, and then these platelets were adhered on the downstream of the stenosis. Flow information, such as the velocity field and shear rate around the stenotic channels, was estimated by using particle image velocimetry (PIV) measurements and simulations. By using a Y-shaped device, the viscosity variations according to the shear rate could be measured for samples with different hematocrit levels (0, 30, and 50%). Based on the estimated flow and viscosity information, the distribution of shear stress around the stenotic channels was estimated. Due to the high shear stress in the 10-μm-wide stenosis, significant adhesion of platelets with a 3D circulating motion was observed at the posterior end of the stenosis. In the 50-μm-wide stenosis, the degree of platelet adhesion varied according to the hematocrit levels; the area of the adhered platelets increased as the hematocrit of the sample increased. Thus, in relatively high-viscosity conditions, frequent particle collision can contribute to the promotion of platelet activation and adhesion, even when the shear rate is relatively low. This study provides a better understanding of the effect of the hematocrit level on the adhesion of platelets after they pass through a stenosis.

Novel targets for anticoagulants lacking bleeding risk.

Arterial and venous thromboembolic diseases are associated with significant morbidity and mortality and present a major medical burden. Currently used anticoagulants for the prevention or treatment of thromboembolic events including heparins, vitamin K-antagonists and inhibitors of thrombin or factor Xa target enzymes of the coagulation cascade that are critical for fibrin formation. However, fibrin is also necessary for hemostatic mechanisms to terminate blood loss at injury sites. As a result currently used anticoagulants substantially raise the risk of bleeding and are associated with an increase in potentially life-threatening hemorrhage, partially offsetting the benefits of reduced thrombosis. Within the last decade, experimental and preclinical data have revealed the existence of coagulation mechanisms that principally differ in thrombosis and haemostasis. Some coagulation proteins including, XI and XII have a differential role in haemostasis and thrombosis. Targeting these proteins may provide an opportunity to prevent thromboembolic disease without causing bleeding. This review summarizes recent studies on selective targeting of coagulation proteins that may allow prevention and treatment of thrombosis without causing bleeding. These novel approaches present a possibility for selective interference with fibrin formation in pathologic thrombosis that may lead to a new generation of safe anticoagulant drugs.

Importance of Endogenous Fibrinolysis in Platelet Thrombus Formation.

The processes of thrombosis and coagulation are finely regulated by endogenous fibrinolysis maintaining healthy equilibrium. When the balance is altered in favour of platelet activation and/or coagulation, or if endogenous fibrinolysis becomes less efficient, pathological thrombosis can occur. Arterial thrombosis remains a major cause of morbidity and mortality in the world despite advances in medical therapies. The role endogenous fibrinolysis in the pathogenesis of arterial thrombosis has gained increasing attention in recent years as it presents novel ways to prevent and treat existing diseases. In this review article, we discuss the role of endogenous fibrinolysis in platelet thrombus formation, methods of measurement of fibrinolytic activity, its role in predicting cardiovascular diseases and clinical outcomes and future directions.

Possibilities of Ultrasound in Diagnosis of Kidney Cancer at the Stage of Surgery

Despite the availability of a large number of state programs for the re-equipment of state medical institutions, ultrasonic research, due to the relative simplicity of the organization of the research process and the decisiveness, still remains relevant for the examination of patients and, in particular, kidney cancer. In recent years, a number of new ultrasound techniques have emerged – three-dimensional reconstruction of ultrasound imaging, tissue harmonic technology and echocontrast with intravenous contrast agents. Due to the continuous improvement of the capabilities of ultrasound scanners and ultrasound imaging techniques, a review of the significance of ultrasound in the diagnosis and differential diagnosis of renal cell carcinoma (RCC).The purpose:to evaluate the diagnostic possibilities of ultrasound in patients with kidney tumors at the preoperative stage.Materials and methods.136 patients with kidney tumors aged 21 to 73 years were examined and treated in A.V. Vishnevsky Institute of Surgery in the period from 2012 to 2017. The study slightly dominated by men – 65.4%. All patients underwent a complex clinical and laboratory examination, which included the analysis of complaints, data of anamnesis, clinical examination, laboratory data, as well as a wide range of instrumental studies (ultrasound, MSCT and MRI). Each of the study methods was evaluated according to three criteria (localization, prevalence, presence of vein thrombosis), which are key to assessing the feasibility of surgical intervention and subsequent tactics of surgery. Evaluation of the informative value of each of the radiation methods of the study (ultrasound, MSCT, MRI) was carried out on the basis of the following criteria: sensitivity, specificity and overall accuracy of the method. All patients underwent surgical operations in various volumes, the formations were morphologically verified as RCC. As a “control” for each of the parameters used the protocol of subsequent surgery. The effectiveness of ultrasound is significantly comparable with CT and MRI in assessing such preoperative parameters as tumor localization in the kidney, the prevalence of the pathological process and thrombosis of the inferior vena cava and the main trunk of the renal vein. In the evaluation of thrombosis of segmental renal veins, ultrasound is also comparable to other methods of investigation, but these data can not be considered statistically reliable (due to the small number of observations) and their confirmation requires further study. Conclusion.In the conditions of a specialized surgical hospital focused on the diagnosis and treatment of kidney cancer, ultrasound can be comparable to CT and MRI in its effectiveness, providing the surgeon with pre-operative information sufficient for planning surgical intervention.

Effect of Progesterone and Synthetic Progestins on Whole Blood Clot Formation and Erythrocyte Structure.

Combined oral contraceptive (COC) use is a risk factor for venous thrombosis (VT) and related to the specific type of progestin used. VT is accompanied by inflammation and pathophysiological clot formation, that includes aberrant erythrocytes and fibrin(ogen) interactions. In this paper, we aim to determine the influence of progesterone and different synthetic progestins found in COCs on the viscoelasticity of whole blood clots, as well as erythrocyte morphology and membrane ultrastructure, in an in vitro laboratory study. Thromboelastography (TEG), light microscopy, and scanning electron microscopy were our chosen methods. Our results point out that progestins influence the rate of whole blood clot formation. Alterations to erythrocyte morphology and membrane ultrastructure suggest the presence of eryptosis. We also note increased rouleaux formation, erythrocyte aggregation, and spontaneous fibrin formation in whole blood which may explain the increased risk of VT associated with COC use. Although not all COC users will experience a thrombotic event, individuals with a thrombotic predisposition, due to inflammatory or hematological illness, should be closely monitored to prevent pathological thrombosis.

Abstract 344: Comparative Metabolomic Profiling of Thrombotic Myocardial Infarction Reveals a Metabolic Signature Distinct From Non-Thrombotic Myocardial Infarction and Stable Coronary Artery Disease in Human Participants

Background: Current non-invasive diagnostics for acute myocardial infarction (MI) identify myocardial necrosis rather than the primary cause and therapeutic target—plaque disruption and resultant thrombosis. Aim: The aim of this study is to identify change specific to plaque disruption and pathological thrombosis. Methods: We quantified 1,032 plasma metabolites by mass spectrometry in 11 thrombotic MI, 12 non-thrombotic MI and 15 stable CAD subjects at two acute phase [time of catheterization (T0), six hours (T6)] and one quiescent (&gt;3 months follow-up) time points. A statistical classifier was constructed utilizing (T0) abundances of a parsimonious set of metabolites that demonstrated a significant change between quiescent phase and the acute phase that was distinct from any change seen in non-thrombotic MI or stable CAD subjects. Classifier performance as estimated by 10-fold cross-validation was suggestive of high sensitivity and specificity for differentiating thrombotic from non-thrombotic MI and stable CAD subjects. Results: Nineteen metabolites (Table 1) with an intra-subject fold change from time of acute thrombotic MI presentation to the quiescent state were distinct from any change measured in both the non-thrombotic MI and stable CAD subjects undergoing cardiac catheterization over the same time course (false discovery rate &lt;5%). Conclusions: We have identified a candidate metabolic signature that differentiates acute thrombotic MI from quiescent state and from acute non-thrombotic MI and stable CAD. Further validation of these metabolites is warranted given their potential as diagnostic biomarkers and novel therapeutic targets for the prevention or treatment of acute MI.

Identification of a plasma metabolomic signature of thrombotic myocardial infarction that is distinct from non-thrombotic myocardial infarction and stable coronary artery disease.

AimsCurrent non-invasive diagnostics for acute myocardial infarction (MI) identify myocardial necrosis rather than the primary cause and therapeutic target—plaque disruption and resultant thrombosis. The aim of this study was to identify changes specific to plaque disruption and pathological thrombosis that are distinct from acute myocardial necrosis.Methods and resultsWe quantified 1,032 plasma metabolites by mass spectrometry in 11 thrombotic MI, 12 non-thrombotic MI, and 15 stable coronary artery disease (CAD) subjects at two acute phase (time of catheterization [T0], six hours [T6]) and one quiescent (>3 months follow-up) time points. A statistical classifier was constructed utilizing baseline (T0) abundances of a parsimonious set of 17 qualifying metabolites. Qualifying metabolites were those that demonstrated a significant change between the quiescent phase and the acute phase and that were distinct from any change seen in non-thrombotic MI or stable CAD subjects. Classifier performance as estimated by 10-fold cross-validation was suggestive of high sensitivity and specificity for differentiating thrombotic from non-thrombotic MI and stable CAD subjects at presentation.Nineteen metabolites demonstrated an intra-subject change from time of acute thrombotic MI presentation to the quiescent state that was distinct from any change measured in both the non-thrombotic MI and stable CAD subjects undergoing cardiac catheterization over the same time course (false discovery rate <5%).ConclusionsWe have identified a candidate metabolic signature that differentiates acute thrombotic MI from quiescent state after MI, from acute non-thrombotic MI, and from stable CAD. Further validation of these metabolites is warranted given their potential as diagnostic biomarkers and novel therapeutic targets for the prevention or treatment of acute MI.