A fully humanized von Willebrand disease type 1 mouse model as unique platform to investigate novel therapeutic options.

Patients suffering from von Willebrand disease (VWD) have reduced quality-of-life despite current treatment options. Moreover, innovation in VWD therapeutic strategies has essentially stalled and available treatments have remained unchanged for decades. Therefore, there is an unmet need to develop new therapeutic strategies for VWD-patients, especially for the large portion of those with VWD-type 1.

Identification of new bioactive molecules in platelet preparation, storage, and transfusion reactions for improved transfusion management.

Platelet concentrates (PCs) intended for transfusion contain bioactive molecules that can be considered Biological Response Modifiers (BRMs), mainly originating from plasma regardless of the preparation process. During storage, NGAL and GDF-15 levels increase in single donor apheresis platelet concentrates (SDA-PC), whereas in buffy coat platelet concentrates (BC-PC), the levels of MIP1α, MCP-3, and HSAA increase, and GDF-15 levels decrease. These molecules, primarily released by leukocytes, may contribute to adverse reactions (ARs) following a PC transfusion.

The effects of an aggressive breast tumor on thrombosis after antithrombin downregulation in a hypercoagulable mouse model.

Background: Despite improvements in therapy, breast cancer still contributes to high mortality rates. Survival of these patients becomes progressively worse upon diagnosis with cancer-associated thrombosis (CAT). Unfortunately, the mechanism causing CAT has remained unclear.

In platelet single donor apheresis, platelet factor 4 levels correlated with donor's age and decreased during storage.

The human population is ageing worldwide. The World Health Organization estimated that the world's population of people aged 60 years and older will increase to at least 30%, coinciding with a growing frequency of cognitive and cardiovascular disease. Recently, in preclinical studies platelet Factor 4 (PF4) was presented as a pro-cognitive factor.

Inhibition of Factor XI: A New Era in the Treatment of Venous Thromboembolism in Cancer Patients?

Direct oral anticoagulants against activated factor X and thrombin were the last milestone in thrombosis treatment. Step by step, they replaced antivitamin K and heparins in most of their therapeutic indications. As effective as the previous anticoagulant, the decreased but persistent risk of bleeding while using direct oral anticoagulants has created space for new therapeutics aiming to provide the same efficacy with better safety.

The efficacy of therapeutic plasma exchange in COVID-19 patients on endothelial tightness is hindered by platelet activation.

Coronavirus disease (COVID)-19 is characterised in particular by vascular inflammation with platelet activation and endothelial dysfunction. During the pandemic, therapeutic plasma exchange (TPE) was used to reduce the cytokine storm in the circulation and delay or prevent ICU admissions. This procedure consists in replacing the inflammatory plasma by fresh frozen plasma from healthy donors and is often used to remove pathogenic molecules from plasma (autoantibodies, immune complexes, toxins, etc.

Bioactive lipids as biomarkers of adverse reactions associated with apheresis platelet concentrate transfusion.

Platelet concentrate (PC) transfusion seeks to provide haemostasis in patients presenting severe central thrombocytopenia or severe bleeding. PCs may induce adverse reactions (AR) that can occasionally be severe (SAR). PCs contain active biomolecules such as cytokines and lipid mediators.

Inflammatory markers and auto-Abs to type I IFNs in COVID-19 convalescent plasma cohort study.

Background: COVID-19 convalescent plasma (CCP) contains neutralising anti-SARS-CoV-2 antibodies that may be useful as COVID-19 passive immunotherapy in patients at risk of developing severe disease. Such plasma from convalescent patients may also have additional immune-modulatory properties when transfused to COVID-19 patients.

Methods: CCP (n = 766) was compared to non-convalescent control plasma (n = 166) for soluble inflammatory markers, ex-vivo inflammatory bioactivity on endothelial cells, neutralising auto-Abs to type I IFNs and reported adverse events in the recipients.

Assessment of breast cancer progression and metastasis during a hypercoagulable state induced by silencing of antithrombin in a xenograft mouse model.

Local coagulation activation has been shown to impact both primary tumor growth and metastasis in mice. It is well known that components of the blood clotting cascade such as tissue factor and thrombin play a role in tumor progression by activating cellular receptors and local formation of fibrin. However, whether venous thromboembolism (VTE) or a hypercoagulable state has a direct impact on cancer progression is unknown.

Immunothrombosis and the Role of Platelets in Venous Thromboembolic Diseases.

Venous thromboembolism (VTE) is the third leading cardiovascular cause of death and is conventionally treated with anticoagulants that directly antagonize coagulation. However, recent data have demonstrated that also platelets play a crucial role in VTE pathophysiology. In the current review, we outline how platelets are involved during all stages of experimental venous thrombosis.

Lipidomic analysis of differently prepared platelet concentrates in additive solution during storage.

Background: Structural and biochemical changes in stored platelets are influenced by collection and processing methods. Lesions may appear during platelet concentrate storage, some of which may be involved in adverse transfusion reactions. The preparation and storage of platelet concentrates (PC) may modify and even damage the lipid mediator content.

Anticoagulants: A Short History, Their Mechanism of Action, Pharmacology, and Indications.

Anticoagulant drugs antagonize coagulation and are used to prevent or cure (recurrent) venous thromboembolism (VTE). Drugs to prevent clotting have been used for more than a century, and, nowadays, physicians possess a broad panel of multiple anticoagulants to meet the individual needs of a patient. Within this review, we aimed to revise the history of the different anticoagulants that are currently prescribed in the clinic.

Inflammatory profile of convalescent plasma to treat COVID: Impact of amotosalen/UVA pathogen reduction technology.

Blood products in therapeutic transfusion are now commonly acknowledged to contain biologically active constituents during the processes of preparation. In the midst of a worldwide COVID-19 pandemic, preliminary evidence suggests that convalescent plasma may lessen the severity of COVID-19 if administered early in the disease, particularly in patients with profound B-cell lymphopenia and prolonged COVID-19 symptoms. This study examined the influence of photochemical Pathogen Reduction Treatment (PRT) using amotosalen-HCl and UVA light in comparison with untreated control convalescent plasma (n= 72 - paired samples) - cFFP, regarding soluble inflammatory factors: sCD40L, IFN-alpha, IFN-beta, IFN-gamma, IL-1 beta, IL-6, IL-8, IL-10, IL-18, TNF-alpha and inflammatory bioactivity on endothelial cells.

Pulmonary Embolism in the Cancer Associated Thrombosis Landscape.

In cancer patients, pulmonary embolism (PE) is the second leading cause of death after the cancer itself, most likely because of difficulties in diagnosing the disease due to its nonclassical presentation. The risk of PE recurrence and possibly the case-fatality rate depends on whether the patient presents a symptomatic PE, an unsuspected PE, a subsegmental PE, or a catheter-related PE. Choosing the best therapeutic option is challenging and should consider the risk of both the recurrence of thrombosis and the occurrence of bleeding.

Factor XI Inhibition for the Prevention of Venous Thromboembolism: An Update on Current Evidence and Future perspectives.

During the past decade, emergence of direct oral anticoagulants (DOACs) has drastically improved the prevention of thrombosis. However, several unmet needs prevail in the field of thrombosis prevention, even in the DOACs' era. The use of DOACs is still constrained and the drugs cannot be administered in every clinical scenario, such as an increased anticoagulant-associated bleeding risk, particularly in some specific populations (cancer - notably those with gastrointestinal or genitourinary cancer - and frail patients), the impossibility to be used in certain patients (eg, end-stage kidney failure during hemodialysis, pregnancy and breastfeeding), and their lack of efficacy in certain clinical scenarios (eg, mechanical heart valves, triple-positive antiphospholipid syndrome).

Identification of the factor XII contact activation site enables sensitive coagulation diagnostics.

Contact activation refers to the process of surface-induced activation of factor XII (FXII), which initiates blood coagulation and is captured by the activated partial thromboplastin time (aPTT) assay. Here, we show the mechanism and diagnostic implications of FXII contact activation. Screening of recombinant FXII mutants identified a continuous stretch of residues Gln317-Ser339 that was essential for FXII surface binding and activation, thrombin generation and coagulation.

NADPH Oxidases Are Required for Full Platelet Activation In Vitro and Thrombosis In Vivo but Dispensable for Plasma Coagulation and Hemostasis.

Objective: Using 3KO (triple NOX [NADPH oxidase] knockout) mice (ie, NOX1/NOX2/NOX4), we aimed to clarify the role of this family of enzymes in the regulation of platelets in vitro and hemostasis in vivo. Approach and Results: 3KO mice displayed significantly reduced platelet superoxide radical generation, which was associated with impaired platelet aggregation, adhesion, and thrombus formation in response to the key agonists collagen and thrombin. A comparison with single-gene knockouts suggested that the phenotype of 3KO platelets is the combination of the effects of the genetic deletion of NOX1 and NOX2, while NOX4 does not show any significant function in platelet regulation.

Xenotropic and polytropic retrovirus receptor 1 regulates procoagulant platelet polyphosphate.

Polyphosphate is a procoagulant inorganic polymer of linear-linked orthophosphate residues. Multiple investigations have established the importance of platelet polyphosphate in blood coagulation; however, the mechanistic details of polyphosphate homeostasis in mammalian species remain largely undefined. In this study, xenotropic and polytropic retrovirus receptor 1 (XPR1) regulated polyphosphate in platelets and was implicated in thrombosis in vivo.

Use of "C9/11 Mismatch" Control siRNA Reveals Sequence-Related Off-Target Effect on Coagulation of an siRNA Targeting Mouse Coagulation Factor XII.

Recently, our group reported that a small interfering RNA (siRNA) targeting coagulation factor XII (si) leads to an unexpected prothrombotic response in a mouse model where venous thrombosis follows inhibition of endogenous anticoagulants. In this study, we aimed to clarify this unexpected response by evaluating the effects of this si (here, si-A) on plasma coagulation through thrombin generation (TG). Besides a routine negative control siRNA (siNEG), we included extra siRNA controls: one siRNA similar to si except for positions 9-11 of the siRNA that are replaced with its complementary base pairs (si-A), and a second siRNA against (si-B).

Mouse venous thrombosis upon silencing of anticoagulants depends on tissue factor and platelets, not FXII or neutrophils.

Tissue factor, coagulation factor XII, platelets, and neutrophils are implicated as important players in the pathophysiology of (experimental) venous thrombosis (VT). Their role became evident in mouse models in which surgical handlings were required to provoke VT. Combined inhibition of the natural anticoagulants antithrombin () and protein C () using small interfering RNA without additional triggers also results in a venous thrombotic phenotype in mice, most notably with vessel occlusion in large veins of the head.

Predilection of Low Protein C-induced Spontaneous Atherothrombosis for the Right Coronary Sinus in Apolipoprotein E deficient mice.

Silencing of anticoagulant protein C using RNA interference (siProc) evokes low incident but spontaneous atherothrombosis in the aortic root of apolipoprotein E-deficient (Apoe) mice. The aims of the current study were (1) to analyze if plaque characteristics or circulating factors could be linked to atherothrombosis susceptibility, (2) to increase the incidence of atherothrombosis by transiently increasing blood pressure, and (3) to direct atherothrombosis to an additional predefined vascular site by applying a semi-constrictive collar around the carotid artery. siProc-driven spontaneous atherothrombosis in the aortic root of Apoe mice was reproduced and occurred at an incidence of 23% (9 out of 39 mice), while the incidence of collar-induced atherothrombosis in the carotid artery was 2.

Atherothrombosis and Thromboembolism: Position Paper from the Second Maastricht Consensus Conference on Thrombosis.

Atherothrombosis is a leading cause of cardiovascular mortality and long-term morbidity. Platelets and coagulation proteases, interacting with circulating cells and in different vascular beds, modify several complex pathologies including atherosclerosis. In the second Maastricht Consensus Conference on Thrombosis, this theme was addressed by diverse scientists from bench to bedside.

Silencing of Anticoagulant Protein C Evokes Low-Incident but Spontaneous Atherothrombosis in Apolipoprotein E-Deficient Mice-Brief Report.

Objective: Murine atherosclerosis models do not spontaneously develop atherothrombotic complications. We investigated whether disruption of natural anticoagulation allows preexisting atherosclerotic plaques to progress toward an atherothrombotic phenotype.

Approach And Results: On lowering of plasma protein C levels with small interfering RNA (si) in 8-week Western-type diet-fed atherosclerotic apolipoprotein E-deficient mice, 1 out of 4 mice displayed a large, organized, and fibrin- and leukocyte-rich thrombus on top of an advanced atherosclerotic plaque located in the aortic root.

Oligonucleotides targeting coagulation factor mRNAs: use in thrombosis and hemophilia research and therapy.

Small interfering (si) RNAs and antisense oligonucleotides (ASOs; here for simplicity reasons, both referred to as oligonucleotides) are small synthetic RNA or DNA molecules with a sequence complementary to a (pre)mRNA. Although the basic mechanisms of action between siRNAs and ASO are distinct, a sequence-specific interaction of the both oligonucleotides with the target (pre)mRNA alters the target's fate, which includes highly effective sequence-specific blockade of translation and consequently depletion of the corresponding protein. For a number of years, these oligonucleotides have been used as a tool in biological research to study gene function in vitro.