Nbeal2 Knockout Mice Are Not Protected Against Hypoxia-Induced Pulmonary Vascular Remodeling and Pulmonary Hypertension.

Inflammation drives the initiation and progression of pulmonary hypertension (PH). Platelets, increasingly recognized as immune cells, are activated and increased in the lungs of patients with PH. Platelet activation leads to the release of α-granule chemokines, many of which are implicated in PH.

A case report of an unprovoked neonatal pulmonary embolism: management strategies and cardiopulmonary complications.

Background: Neonatal pulmonary embolism is a rare occurrence, especially when idiopathic, instead occurring in patients with identifiable risk factors including severe dehydration, presence or history of a central venous line, or identifiable genetic causes. Given the rarity of paediatric and neonatal pulmonary emboli, few guidelines exist to support the clinician in both the initial resuscitation and ongoing management of the critically ill patient with pulmonary emboli.

Case Summary: We present a 5-day-old female with unprovoked massive pulmonary embolism and associated haemodynamic compromise.

Safety and Tolerability of Intravenous Lidocaine Infusions as Opioid Adjunct for Children Hospitalized With Sickle Cell Vaso-Occlusive Pain.

Sickle cell disease (SCD) vaso-occlusive episode (VOE) pain is treated with opioids, and non-opioid adjuvants may reduce pain severity without opioid side effects. We retrospectively investigated the safety and tolerability of intravenous lidocaine infusions as an adjunct to opioids in children and adolescents during VOE hospitalizations. In 2 years, lidocaine was administered in 64.

Association of human leucocyte antigen loci with vaccine-induced immune thrombotic thrombocytopenia: Potential role of the interaction between platelet factor 4-derived peptides and MHC-II.

No risk factors have been identified for vaccine-induced immune thrombotic thrombocytopenia (VITT) so far. The aim of this study was to identify human leucocyte antigen (HLA) alleles potentially associated with VITT susceptibility. Specific HLA class II alleles were detected with significantly higher frequency in VITT patients compared with Italian controls: DPB1*17:01, DQA1*05:01, and DRB1*11:04.

LRRC8 complexes are adenosine nucleotide release channels regulating platelet activation and arterial thrombosis.

Platelet shape and volume changes are early mechanical events contributing to platelet activation and thrombosis. Here, we identify single-nucleotide polymorphisms in Leucine-Rich Repeat Containing 8 (LRRC8) protein subunits that form the Volume-Regulated Anion Channel (VRAC) which are independently associated with altered mean platelet volume. LRRC8A is required for functional VRAC in megakaryocytes (MKs) and regulates platelet volume, adhesion, and agonist-stimulated activation, aggregation, ATP secretion and calcium mobilization.

Deletion of tissue factor pathway inhibitor isoform beta or gamma, but not alpha, improves clotting in hemophilic mice.

Background: Tissue factor pathway inhibitor (TFPI) regulates tissue factor-triggered coagulation. Humans and mice express transcripts encoding for multidistributed (endothelial, platelet, and plasma) 3-Kunitz domain TFPIα and endothelial membrane-anchored 2-Kunitz TFPIβ. Mice express a third transcript, γ, that encodes plasma lipoprotein-associated 2-Kunitz TFPI.

Nanobody activator improves sensitivity of the von Willebrand factor activity assay to multimer size.

Background: The activity of von Willebrand factor (VWF) in facilitating platelet adhesion and aggregation correlates with its multimer size. Traditional ristocetin-dependent functional assays lack sensitivity to multimer sizes. Recently, nanobodies targeting the autoinhibitory module and activating VWF were identified.

Next generation microfluidics: fulfilling the promise of lab-on-a-chip technologies.

Microfluidic lab-on-a-chip technologies enable the analysis and manipulation of small fluid volumes and particles at small scales and the control of fluid flow and transport processes at the microscale, leading to the development of new methods to address a broad range of scientific and medical challenges. Microfluidic and lab-on-a-chip technologies have made a noteworthy impact in basic, preclinical, and clinical research, especially in hematology and vascular biology due to the inherent ability of microfluidics to mimic physiologic flow conditions in blood vessels and capillaries. With the potential to significantly impact translational research and clinical diagnostics, technical issues and incentive mismatches have stymied microfluidics from fulfilling this promise.

D-dimer predicts venous thromboembolism in multiple myeloma: a nested case-control study.

Background: Clinical risk assessment scores, such as IMPEDE VTE, can identify patients with multiple myeloma (MM) at high-risk of venous thromboembolism (VTE). Refinement of these scores, by including 1 or more biomarkers, could improve risk assessment.

Objectives: We sought to determine the association between soluble P-selectin (sP-selectin) and D-dimer with VTE in MM.

N-Acetyl Cysteine Prevents Arterial Thrombosis in a Dose-Dependent Manner In Vitro and in Mice.

Background: Platelet-rich thrombi occlude arteries causing fatal infarcts like heart attacks and strokes. Prevention of thrombi by current antiplatelet agents can cause major bleeding. Instead, we propose using N-acetyl cysteine (NAC) to act against the protein VWF (von Willebrand factor), and not platelets, to prevent arterial thrombi from forming.

Multiomic profiling reveals metabolic alterations mediating aberrant platelet activity and inflammation in myeloproliferative neoplasms.

Platelets from patients with myeloproliferative neoplasms (MPNs) exhibit a hyperreactive phenotype. Here, we found elevated P-selectin exposure and platelet-leukocyte aggregates indicating activation of platelets from essential thrombocythemia (ET) patients. Single-cell RNA-seq analysis of primary samples revealed significant enrichment of transcripts related to platelet activation, mTOR, and oxidative phosphorylation in ET patient platelets.

Building the foundation for a community-generated national research blueprint for inherited bleeding disorders: research priorities for mucocutaneous bleeding disorders.

Background: Excessive or abnormal mucocutaneous bleeding (MCB) may impact all aspects of the physical and psychosocial wellbeing of those who live with it (PWMCB). The evidence base for the optimal diagnosis and management of disorders such as inherited platelet disorders, hereditary hemorrhagic telangiectasia (HHT), hypermobility spectrum disorders (HSD), Ehlers-Danlos syndromes (EDS), and von Willebrand disease (VWD) remains thin with enormous potential for targeted research.

Research Design And Methods: National Hemophilia Foundation and American Thrombosis and Hemostasis Network initiated the development of a National Research Blueprint for Inherited Bleeding Disorders with extensive all-stakeholder consultations to identify the priorities of people with inherited bleeding disorders and those who care for them.

What can the plasma proteome tell us about platelets and (vice versa)?

Multi-omics approaches are being used increasingly to study physiological and pathophysiologic processes. Proteomics specifically focuses on the study of proteins as functional elements and key contributors to, and markers of the phenotype, as well as targets for diagnostic and therapeutic approaches. Depending on the condition, the plasma proteome can mirror the platelet proteome, and hence play an important role in elucidating both physiologic and pathologic processes.

A single F153Sβ3 mutation causes constitutive integrin αIIbβ3 activation in a variant form of Glanzmann thrombasthenia.

This report identifies a novel variant form of the inherited bleeding disorder Glanzmann thrombasthenia, exhibiting only mild bleeding in a physically active individual. The platelets cannot aggregate ex vivo with physiologic agonists of activation, although microfluidic analysis with whole blood displays moderate ex vivo platelet adhesion and aggregation consistent with mild bleeding. Immunocytometry shows reduced expression of αIIbβ3 on quiescent platelets that spontaneously bind/store fibrinogen, and activation-dependent antibodies (ligand-induced binding site-319.

Heterogeneity in the half-life of factor VIII concentrate in patients with hemophilia A is due to variability in the clearance of endogenous von Willebrand factor.

Background: Previous studies have reported marked interindividual variation in factor VIII (FVIII) clearance in patients with hemophilia (PWH) and proposed a number of factors that influence this heterogeneity.

Objectives: To investigate the importance of the clearance rates of endogenous von Willebrand factor (VWF) compared with those of other FVIII half-life modifiers in adult PWH.

Methods: The half-life of recombinant FVIII was determined in a cohort of 61 adult PWH.

Peripheral blood mononuclear cell tissue factor (F3 gene) transcript levels and circulating extracellular vesicles are elevated in severe coronavirus 2019 (COVID-19) disease.

Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is associated with excessive coagulation, thrombosis, and mortality.

Objective: To provide insight into mechanisms that contribute to excessive coagulation in coronavirus 2019 (COVID-19) disease.

Patients/methods: Blood from COVID-19 patients was investigated for coagulation-related gene expression and functional activities.

Evaluation for Bleeding Disorders in Suspected Child Abuse.

Bruising or bleeding in a child can raise the concern for child abuse. Assessing whether the findings are the result of trauma and/or whether the child has a bleeding disorder is critical. Many bleeding disorders are rare, and not every child with bruising/bleeding that may raise a concern for abuse requires an evaluation for bleeding disorders.

Germline ETV6 mutation promotes inflammation and disrupts lymphoid development of early hematopoietic progenitors.

Germline mutations in ETV6 are associated with a syndrome of thrombocytopenia and leukemia predisposition, and ETV6 is among the most commonly mutated genes in leukemias, especially childhood B-cell acute lymphoblastic leukemia. However, the mechanisms underlying disease caused by ETV6 dysfunction are poorly understood. To address these gaps in knowledge, using CRISPR/Cas9, we developed a mouse model of the most common recurrent, disease-causing germline mutation in ETV6.

Apolipoprotein A-I, elevated in trauma patients, inhibits platelet activation and decreases clot strength.

Apolipoprotein A-I (ApoA-I) is elevated in the plasma of a subgroup of trauma patients with systemic hyperfibrinolysis. We hypothesize that apoA-I inhibits platelet activation and clot formation. The effects of apoA-I on human platelet activation and clot formation were assessed by whole blood thrombelastography (TEG), platelet aggregometry, P-selectin surface expression, microfluidic adhesion, and Akt phosphorylation.

Enhanced VWF clearance in low VWF pathogenesis: limitations of the VWFpp/VWF:Ag ratio and clinical significance.

Increased von Willebrand factor (VWF) clearance plays a key role in the pathogenesis of type 1 and type 2 von Willebrand disease (VWD). However, the pathological mechanisms involved in patients with mild to moderate reductions in plasma VWF:Ag (range, 30-50 IU/dL; low VWF) remain poorly understood. In this study, we investigated the hypothesis that enhanced VWF clearance may contribute to the pathobiology of low VWF.

Molecular pathogenesis and heterogeneity in type 3 VWD families in U.S. Zimmerman program.

Background: Type 3 von Willebrand Disease (VWD) is a rare and severe form of VWD characterized by the absence of von Willebrand factor (VWF).

Objectives: As part of the Zimmerman Program, we sought to explore the molecular pathogenesis, correlate bleeding phenotype and severity, and determine the inheritance pattern found in type 3 VWD families.

Patients/methods: 62 index cases with a pre-existing diagnosis of type 3 VWD were analyzed.