Plasmin-cleaved von Willebrand factor as a biomarker for microvascular thrombosis.

von Willebrand factor (VWF) is an essential contributor to microvascular thrombosis. Physiological cleavage by ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) limits its prothrombotic properties, explaining why ADAMTS13 deficiency leads to attacks of microthrombosis in patients with thrombotic thrombocytopenic purpura (TTP). We previously reported that plasminogen activation takes place during TTP attacks in these patients.

Small-Molecule Cyclophilin Inhibitors Potently Reduce Platelet Procoagulant Activity.

Procoagulant platelets are associated with an increased risk for thrombosis. Procoagulant platelet formation is mediated via Cyclophilin D (CypD) mediated opening of the mitochondrial permeability transition pore. Inhibiting CypD activity could therefore be an interesting approach to limiting thrombosis.

Metallated phthalocyanines and their hydrophilic derivatives for multi-targeted oncological photodynamic therapy.

Background And Aim: A photosensitizer (PS) delivery and comprehensive tumor targeting platform was developed that is centered on the photosensitization of key pharmacological targets in solid tumors (cancer cells, tumor vascular endothelium, and cellular and non-cellular components of the tumor microenvironment) before photodynamic therapy (PDT). Interstitially targeted liposomes (ITLs) encapsulating zinc phthalocyanine (ZnPC) and aluminum phthalocyanine (AlPC) were formulated for passive targeting of the tumor microenvironment. In previous work it was established that the PEGylated ITLs were taken up by cultured cholangiocarcinoma cells.

VhH anti-thrombomodulin clone 1 inhibits TAFI activation and enhances fibrinolysis in human whole blood under flow.

Background: Thrombomodulin on endothelial cells can form a complex with thrombin. This complex has both anticoagulant properties, by activating protein C, and clot-protective properties, by activating thrombin-activatable fibrinolysis inhibitor (TAFI). Activated TAFI (TAFIa) inhibits plasmin-mediated fibrinolysis.

Microlyse: a thrombolytic agent that targets VWF for clearance of microvascular thrombosis.

Thrombotic microangiopathies are hallmarked by attacks of disseminated microvascular thrombosis. In thrombotic thrombocytopenic purpura (TTP), this is caused by a rise in thrombogenic ultra-large von Willebrand factor (VWF) multimers because of ADAMTS13 deficiency. We previously reported that systemic plasminogen activation is therapeutic in a TTP mouse model.

Targeted SERPIN (TaSER): A dual-action antithrombotic agent that targets platelets for SERPIN delivery.

Background: Occlusive thrombi are not homogeneous in composition. The core of a thrombus is rich in activated platelets and fibrin while the outer shell contains resting platelets. This core is inaccessible to plasma proteins.

Thrombotic Events in COVID-19 Are Associated With a Lower Use of Prophylactic Anticoagulation Before Hospitalization and Followed by Decreases in Platelet Reactivity.

Coronavirus disease of 2019 (COVID-19) is associated with a prothrombotic state and a high incidence of thrombotic event(s) (TE). To study platelet reactivity in hospitalized COVID-19 patients and determine a possible association with the clinical outcomes thrombosis and all-cause mortality. Seventy nine hospitalized COVID-19 patients were enrolled in this retrospective cohort study and provided blood samples in which platelet reactivity in response to stimulation with ADP and TRAP-6 was determined using flow cytometry.

Normoxic Tumour Extracellular Vesicles Modulate the Response of Hypoxic Cancer and Stromal Cells to Doxorubicin In Vitro.

Extracellular vesicles (EV) secreted in the tumour microenvironment (TME) are emerging as major antagonists of anticancer therapies by orchestrating the therapeutic outcome through altering the behaviour of recipient cells. Recent evidence suggested that chemotherapeutic drugs could be responsible for the EV-mediated tumour-stroma crosstalk associated with cancer cell drug resistance. Here, we investigated the capacity of tumour EV (TEV) secreted by normoxic and hypoxic (1% oxygen) C26 cancer cells after doxorubicin (DOX) treatment to alter the response of naïve C26 cells and RAW 264.

Endothelial Cell Targeting by cRGD-Functionalized Polymeric Nanoparticles under Static and Flow Conditions.

Since αβ integrin is a key component of angiogenesis in health and disease, Arg-Gly-Asp (RGD) peptide-functionalized nanocarriers have been investigated as vehicles for targeted delivery of drugs to the αβ integrin-overexpressing neovasculature of tumors. In this work, PEGylated nanoparticles (NPs) based on poly(lactic-co-glycolic acid) (PLGA) functionalized with cyclic-RGD (cRGD), were evaluated as nanocarriers for the targeting of angiogenic endothelium. For this purpose, NPs (~300 nm) functionalized with cRGD with different surface densities were prepared by maleimide-thiol chemistry and their interactions with human umbilical vein endothelial cells (HUVECs) were evaluated under different conditions using flow cytometry and microscopy.

Influenza-induced thrombocytopenia is dependent on the subtype and sialoglycan receptor and increases with virus pathogenicity.

Thrombocytopenia is a common complication of influenza virus infection, and its severity predicts the clinical outcome of critically ill patients. The underlying cause(s) remain incompletely understood. In this study, in patients with an influenza A/H1N1 virus infection, viral load and platelet count correlated inversely during the acute infection phase.

Heparin Forms Polymers with Cell-free DNA Which Elongate Under Shear in Flowing Blood.

Heparin is a widely used anticoagulant which inhibits factor Xa and thrombin through potentiation of antithrombin. We recently identified that the nucleic acid stain SYTOX reacts with platelet polyphosphate due to molecular similarities, some of which are shared by heparin. We attempted to study heparin in flowing blood by live-cell fluorescence microscopy, using SYTOX for heparin visualisation.

Platelet function is disturbed by the angiogenesis inhibitors sunitinib and sorafenib, but unaffected by bevacizumab.

Introduction: At the clinical introduction of antiangiogenic agents as anticancer agents, no major toxicities were expected as merely just endothelial cells (ECs) in tumors would be affected. However, several (serious) toxicities became apparent, of which underlying mechanisms are largely unknown. We investigated to what extent sunitinib (multitargeted antiangiogenic tyrosine kinase inhibitor (TKI)), sorafenib (TKI) and bevacizumab [specific antibody against vascular endothelial growth factor (VEGF)] may impair platelet function, which might explain treatment-related bleedings.

Preeclampsia and coronary plaque erosion: Manifestations of endothelial dysfunction resulting in cardiovascular events in women.

Atherosclerosis is the major underlying pathology of cardiovascular disease (CVD). The risk for CVD is increased in women with a history of preeclampsia. Multiple studies have indicated that accelerated atherosclerosis underlies this increased CVD risk.

Live-cell Imaging of Platelet Degranulation and Secretion Under Flow.

Blood platelets are essential players in hemostasis, the formation of thrombi to seal vascular breaches. They are also involved in thrombosis, the formation of thrombi that occlude the vasculature and injure organs, with life-threatening consequences. This motivates scientific research on platelet function and the development of methods to track cell-biological processes as they occur under flow conditions.

Polyphosphate nanoparticles on the platelet surface trigger contact system activation.

Polyphosphate is an inorganic polymer that can potentiate several interactions in the blood coagulation system. Blood platelets contain polyphosphate, and the secretion of platelet-derived polyphosphate has been associated with increased thrombus formation and activation of coagulation factor XII. However, the small polymer size of secreted platelet polyphosphate limits its capacity to activate factor XII in vitro.

Interaction of Extracellular Vesicles with Endothelial Cells Under Physiological Flow Conditions.

In the last few years it has become clear that, in addition to soluble molecules such as growth factors and cytokines, cells use extracellular vesicles (EVs) for intercellular communication. For example, EVs derived from cancer cells interact with endothelial cells, thereby affecting angiogenesis and metastasis, two essential processes in tumor progression. In most experiments, the interaction of EVs with target cells is investigated under static conditions.

In Vitro Hemocompatibility Testing of Dyneema Purity Fibers in Blood Contact.

Objective: Heart valve and vascular prosthesis implantation is a common procedure for patients with heart valve stenosis or regurgitation and dilated or obstructive vascular disease. Drawbacks of conventional valve prostheses are the requirement for anticoagulant drugs, moderate durability, and suboptimal resistance to fatigue and tear. Dyneema Purity fibers are made from ultra-high-molecular-weight polyethylene filaments and are very thin, flexible, and fatigue and abrasion resistant and have high strength.

Quantitative proteomics analysis reveals similar release profiles following specific PAR-1 or PAR-4 stimulation of platelets.

Aims: Platelets are a natural source of growth factors, cytokines and chemokines, that regulate angiogenesis and inflammation. It has been suggested that differential release of pro- and anti-angiogenic growth factors from platelet α-granules by protease-activated receptors (PAR) 1 and 4 may be important for the regulation of angiogenesis. We aimed to compare the releasates of unstimulated platelets with PAR-1- and PAR-4-stimulated platelets.

Plasmin cleavage of von Willebrand factor as an emergency bypass for ADAMTS13 deficiency in thrombotic microangiopathy.

Background: Von Willebrand factor (VWF) multimer size is controlled through continuous proteolysis by ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type I motif, member 13). This prevents spontaneous platelet agglutination and microvascular obstructions. ADAMTS13 deficiency is associated with thrombotic thrombocytopenic purpura, in which life-threatening episodes of microangiopathy damage kidneys, heart, and brain.

Chronic dysfunction of the endothelium is associated with mortality in acute coronary syndrome patients.

Introduction: Platelet activation and endothelium dysfunction are determinants of atherothrombosis in acute coronary syndrome (ACS) patients. The aim of this study was to investigate the relationship between platelet and endothelial cell activation markers and mortality in patients presenting with ACS.

Materials And Methods: Plasma levels of RANTES, Neutrophil Activating Protein-2 (NAP-2), Thrombospondin-1 (TSP-1), Von Willebrand Factor (VWF), Von Willebrand Factor Propeptide (VWF:pp) and Osteoprotegerin (OPG) were measured in a cohort study of 339 consecutive ACS patients who underwent percutaneous coronary interevention (PCI).

Plasma concentration of von Willebrand factor predicts mortality in patients on chronic renal replacement therapy.

Background: Traditional cardiovascular risk factors do not explain the high incidence of cardiovascular mortality and morbidity in patients with end-stage renal disease. A prothrombotic state could accelerate the process of vascular disease in these patients.

Methods: In this study, four platelet activation markers (NAP-2, P-selectin, GP1b and RANTES) and two endothelial cell activation markers (von Willebrand factor and its propeptide) were measured in 671 haemodialysis patients and 275 patients on continuous ambulatory peritoneal dialysis (PD).

High-throughput genotyping with infrared fluorescence allele specific hybridization (iFLASH): a simple, reliable and low-cost alternative.

Objectives: To develop and validate a novel genotyping approach, named infrared Fluorescence Allele Specific Hybridization (iFLASH), which combines the principles of allele specific oligonucleotide (ASO) hybridization with the advanced possibilities of infrared imaging.

Design And Methods: As an example, we genotyped the 55L > M and the 192Q > R common genetic variants of the paraoxonase-1 gene in 92 DNA samples using the iFLASH technique, and validated the outcomes with the restriction fragment length polymorphism (RFLP) and TAQman genotyping assays.

Results: There was a 100 percent agreement in genotype outcome among the three methods.

Variation at the paraoxonase gene locus contributes to carotid arterial wall thickness in subjects with familial hypercholesterolemia.

Objectives: Paraoxonase (PON1) is a potent enzyme, physically associated with the high-density lipoprotein particle. PON1 may protect against cardiovascular disease (CVD), since it is capable of hydrolyzing oxidized LDL-cholesterol, thereby negating the detrimental effects of this lipoprotein on the arterial wall.

Design And Methods: In 187 patients with familial hypercholesterolemia, we studied the seven most common single nucleotide polymorphisms (SNPs) in both the coding and promoter sequences of PON1 (L55M, Q192R, T-107C, C-126G, G-162A, G-824A, and C-907G) in terms of PON1 activity and intima media thickness (IMT) of the carotid arterial wall, a validated surrogate marker for CVD.