vWF Deficiency Research Articles

Hemostatic potential of recombinant von Willebrand factor and standard or pegylated extended half-life recombinant factor VIII on thrombus formation under high shear flow

BackgroundVon Willebrand factor (VWF) and factor VIII (FVIII) complex play a pivotal role in hemostasis. A deficiency or defect of VWF causes von Willebrand disease (VWD). Recombinant (r)VWF product has proved to be effective for hemostatic treatment of VWD, but limited information is available on their role in moderating thrombus formation under flow condition. We aimed to assess thrombus formation in the presence of rVWF combined with rFVIII or pegylated-extended half-life rFVIII (peg-EHL-rFVIII) in VWD whole blood under high shear flow.MethodsPerfusion chamber experiments under high shear (2,500 s− 1) combined with immunostaining were performed using patient’s whole blood with type 1 VWD, mixed with rVWF (Vonvendi®; 1.6 IU/mL), rFVIII or peg-EHL-rFVIII (Advate® or Adynovate®; 1.0 IU/mL), or both. Similar experiments were also conducted with clinical medical devices (T-TAS®).ResultsThe addition of rFVIII did not augment thrombus formation assessed by surface coverage (SC) and thrombus height (TH), whereas rVWF enhanced these parameters (SC 19.1 ± 1.1% vs. 30.1 ± 4.1%, TH 2.2 ± 0.14 μm vs. 3.6 ± 0.40 μm, respectively). The co-presence of rVWF/rFVIII was comparable to plasma-derived VWF/FVIII (Confact®, VWF:FVIII ratio = 1.6:1.0) for increasing thrombogenicity in SC (32.5 ± 4.3% vs. 38.7 ± 5.5%) and in TH (5.0 ± 0.60 μm vs. 5.5 ± 0.64 μm), respectively. The pre-incubation time with rVWF and rFVIII appeared to have a little effect on the size of thrombus. Peg-EHL-rFVIII mediated thrombus formation to similar extent as rFVIII in the co-presence of rVWF. Similar results were obtained even with T-TAS. Immunostaining demonstrated that rFVIII and peg-EHL-rFVIII were similarly co-localized with rVWF in formed thrombi, indicating that pegylation did not interfere with molecular complexes.ConclusionThe effects of high-level rVWF and peg-EHL-rFVIII on thrombus formation were comparable to conventional therapeutic products in a patient’s whole blood with VWD under high shear flow.

RUPTURED HEMORRHAGIC OVARIAN CYST IN A PATIENT WITH WILLEBRAND DISEASE: A CASE REPORT AND REVIEW OF LITTERATURE

Willebrand Disease (WD) is a familial haemorrhagic disease described in 1926 by Erik von Willebrand, a Finnish physician (1), and is related to a deficiency of Willebrand Factor (VWF) leading to a disorder of primary haemostasis and secondary coagulation. The clinical and biological expression of WD varies according to the form. The common feature is the existence of a constitutional quantitative and/or qualitative VWF deficiency. A classification of the different forms of the disease exists to guide the diagnosis, treatment and genetic information of patients. While isolated biological abnormalities are relatively common with a prevalence of nearly 1%, symptomatic forms of WD are more rare. The prevalence of WM type 3, the most severe form (autosomal recessive), has been estimated at 1 per million population. While autosomal genetic inheritance predicts that both sexes are affected in the same proportion, symptomatic forms are more common in women because of the haemostatic challenge of menstruation, pregnancy and childbirth. Ovarian cysts are fluid-filled sacs that lie on the surface of or within the ovary(2). Roughly 20% of women develop at least one pelvic mass in their lifetime. Therapeutic management is based on surgical haemostasis by total cystectomy and medical haemostasis by exogenous supply of Willebrand factor and finally resuscitation of any state of haemorrhagic shock starting with vascular filling with crystalloids, the introduction of vasoactive amines and finally massive transfusion.We report here the case of a 24 year old female patient, treated for Willebrands disease since birth and who presented to the emergency department with haemorrhagic shock due to a ruptured haemorrhagic ovarian cyst with internal bleeding.

ADAMTS13 Plays a Critical Role in Acetaminophen-Induced Acute Liver Injury in Mice, and Can be a Novel Therapeutic Option

【Background】 Acetaminophen (APAP) is one of the major causes of drug-induced acute liver injury. It is known that VWF deficiency reduces hepatic platelet accumulation and promotes liver repair in APAP-induced acute liver injury in mice. We hypothesized that VWF-ADAMTS13 axis plays a role in the pathophysiology of APAP-induced acute liver injury. To investigate this hypothesis, we have used a mouse experimental model of APAP-induced hepatic injury. 【Method】 The extent of APAP-induced liver injury was compared between wild-type (WT) and ADAMTS13 gene-deleted (KO) mice (C57BL/6 background). At first, mice were fasted for 24 hours before administration of 300 mg/kg APAP via intraperitoneal injection. Forty-eight hours after APAP administration, Hepatic blood flow was measured as the average of the surface blood flow on the anterior and inferior surfaces of the liver in the right and left lobes using Laser Doppler flowmetry (ALF21N, Advance Co, Tokyo, Japan), followed by sampling of blood and hepatic tissue. Blood cell counts and biochemical analysis including aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were performed. Also, histological analysis and gene expression analysis by quantitative PCR (qPCR) such as interleukin-6 (IL-6), interleukin-1beta (IL1-β), tumor necrosis factor-alfa (TNF-α), Keratinocyte-derived chemokines (KC), monocyte chemoattractant protein-1 (MCP-1), transforming growth factor-beta (TGF-β), alfa-smooth muscle actin (α-SMA) and collagen type I alfa-1 (COL1α1) were conducted using the liver samples. In addition, to confirm whether recombinant ADAMTS13 has a protective effect against APAP-induced liver injury, we administered recombinant ADAMTS13 to WT mice through the retro-orbital cavity 30 min before APAP administration and examined whether the liver injury was reduced. 【Result】 In APAP-challenged KO mice (N=13), serum levels of AST and ALT were significantly elevated compared to WT mice (N=9)（AST; 3115.4 vs 1331.1 IU/L, ALT; 3911.5 vs 1647.8 IU/L）. The area of liver necrosis was increased in KO mice compared to WT mice （area of hepatic necrosis; 58.0 vs 42.9 %）. In addition, inflammation markers other than TNF-α and MCP-1 were not significantly different, but TNF-α and MCP-1 were significantly elevated in KO mice compared to WT mice. Furthermore, hepatic blood flow was decreased in KO mice compared to WT mice（18.3 vs 21.6 ml/hr）, in accordance with the significantly reduced levels of the numbers of platelets in KO mice（269.3 vs 503.2 x109/L）. Surprisingly, the increases of ALT values and the area of hepatic necrosis observed in WT mice were significantly suppressed by recombinant human ADAMTS13 administration. 【Discussion】 We have shown that APAP-induced liver injury is exacerbated by enhanced inflammation in KO mice and clarified that ADAMTS13 plays a critical role in the liver injury induced by APAP. Moreover, we found that recombinant human ADAMTS13 administration reduces APAP-induced hepatic injury. Our results suggest that recombinant human ADAMTS13 can be a novel therapeutic option for APAP poisoning.

Prognostic value of von Willebrand factor in clinical practice

The von Willebrand factor (vWF) is a multimeric plasma glycoprotein, which quantification has important prognostic value. The current literature review demonstrates a relationship between the disease severity and vWF level. For example, von Willebrand disease is characterized by a quantitative/qualitative genetic vWF deficiency resulting in potentially developed massive bleeding, which knowledge can prevent development of formidable complications. We should also not forget about an opportunity of developing acquired Willebrand syndrome most often occurring in response to autoimmune diseases. A marked vWF increase during pregnancy may evidence about developing preeclampsia, whereas in newborns exposed to additional risk factors, it can lead to thrombosis. In cancer patients, a substantially elevated vWF level correlates with low survival, especially in those with ovarian cancer, glioblastomas, esophageal and lung cancer. The emergence of a novel coronavirus infection COVID-19 allowed us to take a fresh look at prognostic value of vWF, because numerous studies show that increased blood plasma vWF:Ag is associated with more adverse outcome in patients with COVID-19. Here, we demonstrate an importance of determining vWF level, because early diagnostics and treatment can improve the outcomes of all such patients.

Acquired von Willebrand syndrome and lymphoid neoplasms: A review of malignancy management, and propositions of practical recommendations.

Acquired von Willebrand syndrome (AWS) is a rare and potentially life-threatening bleeding disorder. AWS is primarily associated with lymphocyte-related disorders (AWS-LRD), such as lymphoma and IgM monoclonal gammopathy of undetermined significance (MGUS), and plasmocyte-related disorders (AWS-PRD), such as non-IgM MGUS and myeloma. Symptomatic treatments are important to control and prevent bleeding, but AWS-LRD and AWS-PRD can only be cured by targeting the responsible clonal cell. No reviews exist on this specific subgroup of AWS. We performed a literature review to help manage these rare cases. Thirty-two AWS-PRD and 43 AWS-LRD cases with data on malignancy treatment were reported in 56 articles from the Medline database. LRDs were exclusively indolent and primarily associated with IgM monoclonal compounds. LRDs and PRDs may be treated because of severe bleeding symptoms, but severe VWF deficiency did not necessarily correlate with severe bleeding. Immunosuppressive drugs in AWS-PRD, including rituximab, provided an overall response rate of AWS (AWS-ORR) of 30% (3/10), including short responses. Anti-myeloma drugs provided an AWS-ORR of 71.4% (20/28), with long-lasting remissions. Bortezomib was the most commonly used drug and provided an AWS-ORR of 66.7% (6/9), including therapeutic associations with other anti-myeloma drugs. Autologous and allogeneic stem cell transplantation was performed in eight and two patients, respectively, and some details on the management of AWS during these procedures were provided. Rituximab in AWS-LRD provided an AWS-ORR of 60% (3/5), and a chemotherapy + rituximab regimen increased the AWS-ORR to above 50%. Bleeding syndrome in AWS-PRD and AWS-LRD generally improved prior to AWS biological improvement. Long term remission of AWS due to lymphoid neoplasms is attainable by treating the underlying clonal cell. Some data and recommendations are provided to help answer difficult questions, including treatment timing, choice of drug, and the timing of evaluations and treatment changes.

Von Willebrand Factor: A Central Regulator of Arteriovenous Fistula Maturation Through Smooth Muscle Cell Proliferation and Outward Remodeling.

BackgroundArteriovenous fistula (AVF) maturation failure is a main limitation of vascular access. Maturation is determined by the intricate balance between outward remodeling and intimal hyperplasia, whereby endothelial cell dysfunction, platelet aggregation, and vascular smooth muscle cell (VSMC) proliferation play a crucial role. von Willebrand Factor (vWF) is an endothelial cell–derived protein involved in platelet aggregation and VSMC proliferation. We investigated AVF vascular remodeling in vWF‐deficient mice and vWF expression in failed and matured human AVFs.Methods and ResultsJugular‐carotid AVFs were created in wild‐type and vWF−/− mice. AVF flow was determined longitudinally using ultrasonography, whereupon AVFs were harvested 14 days after surgery. VSMCs were isolated from vena cavae to study the effect of vWF on VSMC proliferation. Patient‐matched samples of the basilic vein were obtained before brachio‐basilic AVF construction and during superficialization or salvage procedure 6 weeks after AVF creation. vWF deficiency reduced VSMC proliferation and macrophage infiltration in the intimal hyperplasia. vWF−/− mice showed reduced outward remodeling (1.5‐fold, P=0.002) and intimal hyperplasia (10.2‐fold, P<0.0001). AVF flow in wild‐type mice was incremental over 2 weeks, whereas flow in vWF−/− mice did not increase, resulting in a two‐fold lower flow at 14 days compared with wild‐type mice (P=0.016). Outward remodeling in matured patient AVFs coincided with increased local vWF expression in the media of the venous outflow tract. Absence of vWF in the intimal layer correlated with an increase in the intima‐media ratio.ConclusionsvWF enhances AVF maturation because its positive effect on outward remodeling outweighs its stimulating effect on intimal hyperplasia.

The Cardioprotective Potential of von Willebrand Disease in Ischemic Heart Disease.

von Willebrand factor (vWF) aids coagulation at sites of vessel injury. Elevated vWF levels have been associated with an increased risk of ischemic heart disease (IHD); however, it is unclear whether vWF deficiency, seen in patients with von Willebrand disease (vWD), protects people against IHD. We determined and compared the prevalence and risk of IHD in patients with versus without vWD by using data from the National Inpatient Sample (2009-2014), excluding patients younger than 18 and older than 75 years. The primary outcome was the odds ratio (OR) of IHD in patients with versus without vWD. Secondary outcomes were major medical comorbidities and demographic characteristics in patients with vWD. Of 224,475,443 weighted hospital-discharge samples, we identified 82,809 patients with a vWD diagnosis. The odds of IHD were lower in patients with vWD than in those without (OR=0.54; 95% CI, 0.52-0.56). After multivariable logistic regression analysis and adjustment for age, sex, and typical IHD risk factors (hypertension, smoking, diabetes, hyperlipidemia, chronic kidney disease, obesity, and family history of IHD), the likelihood of IHD remained lower in patients with vWD than in patients without (OR=0.65; 95% CI, 0.63-0.67). Our study shows that vWF deficiency, as seen in patients with vWD, is associated with a decreased prevalence of IHD. Further investigation may confirm these findings.

Single-cell transcriptional analysis of human endothelial colony-forming cells from patients with low VWF levels

Abstractvon Willebrand factor (VWF) plays a key role in normal hemostasis, and deficiencies of VWF lead to clinically significant bleeding. We sought to identify novel modifiers of VWF levels in endothelial colony-forming cells (ECFCs) using single-cell RNA sequencing (scRNA-seq). ECFCs were isolated from patients with low VWF levels (plasma VWF antigen levels between 30 and 50 IU/dL) and from healthy controls. Human umbilical vein endothelial cells were used as an additional control cell line. Cells were characterized for their Weibel Palade body (WPB) content and VWF release. scRNA-seq of all cell lines was performed to evaluate for gene expression heterogeneity and for candidate modifiers of VWF regulation. Candidate modifiers identified by scRNA-seq were further characterized with small-interfering RNA (siRNA) experiments to evaluate for effects on VWF. We observed that ECFCs derived from patients with low VWF demonstrated alterations in baseline WPB metrics and exhibit impaired VWF release. scRNA-seq analyses of these endothelial cells revealed overall decreased VWF transcription, mosaicism of VWF expression, and genes that are differentially expressed in low VWF ECFCs and control endothelial cells (control ECs). An siRNA screen of potential VWF modifiers provided further evidence of regulatory candidates, and 1 such candidate, FLI1, alters the transcriptional activity of VWF. In conclusion, ECFCs from individuals with low VWF demonstrate alterations in their baseline VWF packaging and release compared with control ECs. scRNA-seq revealed alterations in VWF transcription, and siRNA screening identified multiple candidate regulators of VWF.

Extracorporeal membrane oxygenation seems to induce impairment of primary hemostasis pathology as measured by a Multiplate analyzer: An observational retrospective study.

Extracorporeal membrane oxygenation (ECMO) support is often associated with bleeding complications caused by secondary or primary hemostasis pathology. However, there are limited data investigating primary hemostasis using Multiplate aggregometry with specific diagnostics tests for vWF (von Willebrand factor) deficiency. The aim of this study was to find out whether short-term ECMO produces the pathology of primary hemostasis that is detected by Multiplate aggregometry and to investigate the pathology of vWF. In this study, blood samples of 20 patients undergoing lung transplantations with short-term perioperative ECMO support were analyzed. The multimeric structure, the levels of von Willebrand factor antigen (vWF), ristocetin cofactor (RCo), collagen-binding protein (CB), and the results of multiple electrode aggregometry RISTO (ristocetin), ADP (adenosine diphosphate), ASPI (Aspirin®; arachidonic acid), and TRAP (thrombin receptor activating peptide) tests were compared to the samples obtained before and after ECMO support. The Multiplate ADP and RISTO tests showed the presence of significant pathology in primary hemostasis after surgery (p<0.05), suggesting the presence of acquired platelet dysfunction. Although the RISTO tests suggest the presence of acquired vWF deficiency, laboratory tests for vWF antigen and RCo and CB tests showed an increase in this case. The multimeric structure of vWF did not show clinically significant deterioration. Multiple aggregometry ADP, ASPI, and TRAP tests seem to be able to detect primary hemostasis pathology (platelets aggregation and adhesion pathology) that is present during short-term perioperative ECMO support in lung transplantation procedures. Interestingly, RISTO tests seem to be more suitable for the diagnosis of platelet dysfunction than the diagnosis of acquired vWF deficiency in this situation.

Anemia-Induced Bleeding in Patients with Platelet Disorders.

Anemia is not only a consequence of bleeding, but also a modifiable risk factor for bleeding in patients with thrombocytopenia or platelet function defects. In this review we outline the mechanism of anemia-induced bleeding in patients with platelet disorders, which involves a disturbance in normal red blood cell (RBC) rheology and reduced platelet margination to the endothelial surface due to a decrease in RBC mass, leading to impaired primary hemostasis and bleeding. Biologically, anemia reduces the mass of RBCs in the central column of flowing blood through a vessel resulting in fewer platelets coming into contact with the endothelial surface at the periphery of the flowing blood column. Thus, anemia results in impaired primary hemostasis. Von Willebrand factor (vWF) is another component of primary hemostasis and vWF deficiency, especially a deficiency of the highest vWF multimers, can also manifest with bleeding when concomitant anemia occurs. Clinically, patients at greatest risk for anemia-induced bleeding include patients with hematological malignancies in whom anemia and thrombocytopenia occur as a result of the underlying disease or the myelotoxic effects of treatment; patients with renal insufficiency with uremic thrombocytopathy and hypoproliferative anemia; and patients with inherited or acquired bleeding disorders affecting primary hemostasis (eg, Bernard-Soulier syndrome, von Willebrand disease) with chronic blood loss and iron deficiency anemia. Underlying abnormalities of any components of primary hemostasis plus concomitant anemia may result in major bleeding disorders; therefore, correction of remediable abnormalities-most notably, correction of the anemia- would be expected to have important clinical benefit. In this review we discuss how the correction of the anemia may lead to improvement of bleeding outcomes in patients with a primary hemostatic defect, supported by evidence from animal models, clinical trials and clinical experience.

Endothelial Colony Forming Cells from Individuals with Low VWF Levels Demonstrate Impairment in Stimulated VWF Release

BackgroundVon Willebrand factor (VWF) is an essential hemostatic protein and deficiencies of VWF predispose to mucocutaneous bleeding (MCB) such as seen in von Willebrand disease (VWD). VWD type 1 is characterized by incomplete penetrance and variable expressivity even in individuals and families with the same mutation in VWF . In addition to those patients with VWD type 1, there is a large subset of individuals that have VWF levels below 50 IU/dL, who suffer from MCB but do not meet the full criteria for VWD (VWF levels less than 30 IU/dL). The mechanisms for low VWF levels in these patients are poorly understood but are thought to be due to decreased synthesis and/or decreased secretion, increased clearance, or altered proteolysis. Endothelial colony forming cells (ECFCs, also known as blood outgrowth endothelial cells or endothelial progenitor cells) are a source of donor-specific endothelial cells and have demonstrated defects in VWF release and packaging in VWD. ECFCs have been previously studied in patients with VWD, but have not been evaluated in individuals with low VWF levels.Hypothesis/ObjectiveWe hypothesize that the study of ECFCs from individuals with low VWF levels will reveal deficiencies of abnormal VWF release and shed light on the mechanisms of low VWF.MethodsECFC Derivation: Patients with low VWF levels and MCB (30-50 IU/dL) were enrolled in a IRB-approved study and whole blood was collected into sodium heparin vacutainers, layered on Ficoll and centrifuged to isolate the mononuclear cell layer, which is then plated in a twelve-well collagen coated plate. After extended incubation, the presence of phenotypically ECFCs was confirmed by visual morphology and by single stain flow cytometry with appropriate (positive/negative) staining for the endothelial cells markers CD146, CD105, CD31 and negative non-endothelial cell markers CD34, CD90, CD133, and CD45.Stimulated Release of VWF from ECFC: ECFCs were plated in 12 well tissue culture plates. For stimulated release, the cells were exposed to 1mL serum-free media ± phorbol-12-myristate-13-acetate (PMA) (50ng/mL) for 1 hour. The conditioned media samples were then collected and assayed via the VWF:Ag ELISA.Enzyme-Linked ImmunoSorbant Assay (VWF:Ag ELISA): A 96-well plate was be coated with anti-VWF antibodies and after blocking and incubation with respective samples VWF levels were determined anti-VWF primary and HRP-linked secondary antibodies; values were compared to a standard curve and normalized to cell surface area. Results are analyzed via ANOVA with correction for multiple comparisons.ResultsECFC Derivation: A total of seven ECFC lines were created, 5 from individuals with MCB and VWF levels between 30-50 IU/dL (4:1 female: male ratio, age range 11-54 years) and 2 from healthy controls (2 female, age range 22-39 years, control ECFC 1, control ECFC 2) without symptoms of MCB.VWF release from patient derived endothelial cells: When treated with 0ng/mL of PMA, Low VWF derived ECFCs showed no demonstrable differences in VWF release into the conditioned media (Figure A). However, when treated with 50ng/mL of PMA, there is a noticeable trend of increased VWF release in the HUVEC and Control 1 and 2 ECFCs in comparison to the Low VWF ECFCs 1-5, although the results were not statistically significant (Figure B). When respective cohorts are grouped, the low VWF cohort demonstrates a statistically significant decrease in VWF at 50ng/mL as compared to HUVEC (p=0.0001) or control ECFC (p=0.0147) (Figure C).ConclusionsWe have demonstrated the ability to derive ECFCs from patients with Low VWF levels and MCB. Patient derived ECFCs from individuals with Low VWF levels demonstrate impairments in VWF release when stimulated with PMA and as a group, those individuals with low VWF levels demonstrate a significant decrease in VWF release. This decrease in stimulated VWF release is seen with several different individual patient samples and suggests that individuals with low VWF levels may have defects in VWF synthesis and or release that correspond to their lower plasma levels of VWF. [Display omitted] DisclosuresNg:Shire: Consultancy; CSL Behring Heimburger Award: Research Funding.

Increased VWF and Decreased ADAMTS-13 in COVID-19: Creating a Milieu for (Micro)Thrombosis.

von Willebrand factor (VWF) is a large adhesive multimeric protein involved in hemostasis. The larger the size (or number of VWF multimers), the greater the functionality of the protein. A deficiency or defect of VWF can lead to von Willebrand disease (VWD) and cause bleeding. Conversely, an increase in VWF may create an environment that promotes thrombosis. ADAMS-13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13), sometimes called VWF-cleaving protease, is primarily responsible for controlling the size of VWF. The most severe deficiency (<10% of normal levels) of ADAMTS-13 arises in thrombotic thrombocytopenic purpura, a condition characterized by the presence of ultralarge VWF and clinically resulting in enhanced risk of thrombosis. However, ADAMTS-13 deficiency may result from other pathological processes. Of relevance is the recent finding that COVID-19 (coronavirus disease 2019) is associated with both increased levels and activity of VWF as well as generally decreased (or occasionally normal) activity levels of ADAMTS-13. Thus, in COVID-19 there is an alteration in the VWF/ADAMTS-13 axis, most often described by increased VWF/ADAMTS-13 ratio (or reduced ADAMTS-13/VWF ratio). COVID-19 is also associated with high prothrombotic risk. Thus, the imbalance of VWF and ADAMTS-13 in COVID-19 may be providing a milieu that promotes (micro)thrombosis, in a clinical picture resembling a secondary thrombotic microangiopathy in some patients. This review therefore assesses the literature on VWF, ADAMTS-13, and COVID-19. Whenever reported in COVID-19, VWF has always been identified as raised (compared with normal reference ranges or control populations). Reports have included VWF level (i.e., VWF antigen) and in some cases one or more VWF "activity" (e.g., collagen binding; platelet glycoprotein Ib [GPIb] binding, using ristocetin cofactor or more modern versions including VWF:GPIbR [recombinant] and VWF:GPIbM [mutant]). Whenever reported, ADAMTS-13 has been reported as "normal" or reduced; however, it should be recognized that "normal" levels may still identify a relative reduction in individual cases. Some reports also discuss the raised VWF/ADAMTS-13 (or reduced ADAMTS-13/VWF) ratio, but very few provide actual numerical data.

Abstract 13941: The Prevalence of Cardiovascular Disease in Patients With Von Willebrand Disease; A Potential Therapeutic Target

Introduction: Von Willebrand factor (vWF) plays an important role in the coagulation process at the site of vascular injury. It is unclear whether vWF deficiency is protective against cardiovascular disease (CVD) since investigations are limited in this entity. Hypothesis: Our study assessed the hypothesis that the prevalence of CVD is less in patients with than without Von Willebrand disease (vWD). Methods: We queried the National Inpatient Sample (NIS) from 2009-2014. Entire data was used with exclusion of patients below 18 and over 75-year-old. We defined cardiovascular disease as any event of myocardial infarction or a diagnosis of ischemic heart disease using the International Classification of Disease, 9th edition (ICD-9). The primary outcome of interest was to compare the odds ratio of CVD in patients with and without vWD. Results: A total of 224,475,443 weighted hospital discharge samples were identified. Of these, 82,809 carried a diagnosis of vWD. The odds of CVD were less common in vWD patients (OR 0.54; 95% CI 0.52 - 0.56) (table 1). After multivariate logistic regression analysis, with adjustment for age, gender and the most common CVD risk factors including hypertension, smoking, diabetes, hyperlipidemia, family history of CVD, chronic kidney disease and obesity the likelihood of CVD remained lower in vWD patients (OR 0.65; 95% CI 0.63-0.67) (table 2). Conclusions: Our study, the first to involve a large cohort of patients, demonstrated that vWF deficiency is associated with decreased prevalence of CVD. Hence, vWF could potentially be a therapeutic target in CVD management. More investigations are needed for confirmation of these findings and to determine causation.

Shear stress induced activation of von Willebrand factor may predispose to gastrointestinal bleeding in syndrome of Heyde

Abstract Introduction Von Willebrand factor (vWF) changes conformation from globular to fibrillar in the range of shear rates above 5000 s-1. High shear rates, observed in severe aortic stenosis, create conditions for activation of vWF, which opens up access for platelets and coagulation factors to the previously hidden domains of the molecule. At the same time, vWF undergoes increased degradation by metalloproteinase ADAMTS13. Proteolytic cleavage of vWF leads to deficiency of hemostatically active high molecular weight multimers (HMWM) of vWF, while its mass concentration remains unaltered. This results in the development of acquired von Willebrand disease type 2A (vWD) and concomitant gastrointestinal bleeding. The combination of acquired vWD 2A and gastrointestinal bleeding, developed due to severe aortic stenosis, is called Heyde's syndrome. The correlation of shear stress activation of vWF and gastrointestinal bleeding in patients with Heyde's syndrome remains poorly studied. The aim of the study was to measure vWF-mediated platelet adhesion to fibrinogen-coated surfaces under shear rates higher than 5000 s-1 in whole blood samples of healthy volunteers and patients with Heyde's syndrome. Methods A microfluidic system simulating blood flow in vessels was used to assess platelet adhesion. Platelet adhesion was measured by an increase in the intensity of laser radiation scattered from a fibrinogen-coated surface during a 15 minutes circulation of whole blood samples through a flow chamber under shear rates higher than 5000 s-1. Platelets in whole blood samples were activated with 5 μM ADP prior to measurement. The study included 5 patients with Heyde's syndrome 55–80 years old. The control group included 6 healthy volunteers 25–55 years old. vWF-mediated platelet adhesion was detected by blocking platelet-vWF binding with anti-GPIb monoclonal antibody (mAb). Fibrinogen-mediated platelet adhesion was detected by blocking platelet GPIIb/IIIa receptors with mAb. Result The inhibition of GPIb vWF-receptor reduced platelet adhesion by 7.6±3.5% (p&amp;lt;0.05) in patients with Heyde's syndrome, and by 16.5±3.3% (p&amp;lt;0.05) in healthy volunteers. The inhibition of GPIIb/IIIa fibrinogen receptor reduced platelet adhesion by 96±7% (p&amp;lt;0.05) in patients with Heyde's syndrome, and by 80.2±6.6% (p&amp;lt;0.05) in healthy volunteers. Conclusion Significantly reduced contribution of vWF to platelet adhesion under shear rates higher than 5000 s-1 may indicate a decrease in hemostatically active HMWM of vWF. Shear stress activation of vWF in the range of high shear rates and its subsequent inactivation by ADAMTS13 may lead to functional vWF deficiency and the development of gastrointestinal bleeding in Heyde's syndrome. Funding Acknowledgement Type of funding source: Foundation. Main funding source(s): The Russian Science Foundation

Shear Stress-Induced Activation of von Willebrand Factor and Cardiovascular Pathology.

The von Willebrand factor (vWF) is a plasma protein that mediates platelet adhesion and leukocyte recruitment to vascular injury sites and carries coagulation factor VIII, a building block of the intrinsic pathway of coagulation. The presence of ultra-large multimers of vWF in the bloodstream is associated with spontaneous thrombosis, whereas its deficiency leads to bleeding. In cardiovascular pathology, the progression of the heart valve disease results in vWF deficiency and cryptogenic gastrointestinal bleeding. The association between higher plasma levels of vWF and thrombotic complications of coronary artery disease was described. Of note, it is not the plasma levels that are crucial for vWF hemostatic activity, but vWF activation, triggered by a rise in shear rates. vWF becomes highly reactive with platelets upon unfolding into a stretched conformation, at shear rates above the critical value (more than 5000 s−1), which might occur at sites of arterial stenosis and injury. The activation of vWF and its counterbalance by ADAMTS-13, the vWF-cleaving protease, might contribute to complications of cardiovascular diseases. In this review, we discuss vWF involvement in complications of cardiovascular diseases and possible diagnostic and treatment approaches.

Association between von Willebrand disease and angiodysplasia

Von Willebrand factor (vWf) is a fundamental multimeric plasma glycoprotein in the coagulation process. Its function is to mediate platelet adhesion and to stabilize circulating factor VIII. A functional or quantitative alteration of vWf gives rise to von Willebrand disease (vWD). The association between vWD and angiodysplasia was described in 1967, but it was only until 2011 that Starke et al demonstrated the in vitro and in vivo role of vWf in angiogenesis. Congenital or acquired vWf deficiency, especially of high molecular weight multimeters, not only favors bleeding, but also contributes to increased angiogenesis in these patients. The treatment should be focused both on the control of the acute episode of gastrointestinal bleeding, with vWf replacement therapy and local endoscopic treatment, as well as on the prevention of the progression of angiodysplasia and future bleeding. There are different published therapeutic approaches using vWf replacement that are not effective in all patients. Recently, angiogenesis inhibitor medications have been used.

Bleeding Time in Different Blood Groups and Genders In Hawija Technical Institute Students

In medicine, blood groups play an active role. A noticeable relationship is observed linking ABO with the Wilbrand factor and vWF deficiency which results in hemorrhagic disorders, while increased levels are a risk factor for blood clotting. Previous investigations found that individuals in group O have long hemorrhageand blood clotting time. The aim of the current study is to evaluate the bleeding time relationship with the different blood groups and sex also. This cross-sectional study includes 95 students aged between 18 and 20 years. Permission has been takenfrom the students participated in this study before the bleeding time (the method of filter paper for Duke) was determined.The obtained results showed a longer time of bleeding among the AB group. Moreover, the bleeding time is longer in women than men. For more results, it is necessary to involve a larger research group.

Does Outcome/Survival of Patients With Myelodysplastic Syndromes Should Be Predicted by Reduced Levels of ADAMTS-13? Results From a Pilot Study

IntroductionVon Willebrand factor (vWF) cleaving protease ADAMTS-13 has a key role for maintaining normal size of vWF. A deficiency or dysfunction of vWF cleaving protease is associated with ultra large vWF multimers and thrombotic microangiopathy. Patients with cancers have reduced levels of vWF cleaving protease. In this pilot study, we have evaluated whether or not deficiencies of ADAMTS-13 were present in myelodysplastic syndromes (MDS). Moreover, we assessed if a reduction in basal levels of ADAMTS-13 may play a role in the prognosis of MDS. Patients and MethodsWe measured and compared the levels of vWF cleaving protease ADAMTS-13 in 100 patients with MDS and 35 healthy controls. Patients were divided into 2 groups according to the International Prognostic Scoring System: group I consisting of 44 patients with low-risk MDS and group II of 56 patients with high-risk MDS. Patients with high-risk and low-risk MDS presented significantly lower levels of ADAMTS-13 than controls (P < .001 and P = .0177, respectively). High-risk patients had significantly lower levels of ADAMTS-13 when compared with the low-risk group (P < .001). ResultsWe found that reduced levels of ADAMTS-13 have a relationship with overall survival (P < .001). Statistical analysis showed that ADAMTS-13 correlates with cytogenetics (P < .001) and a tendency of slight correlation with platelet count and basal levels of ADAMTS-13 (R, 0.35; P value, 0.001). Moreover, we found that levels of ADAMTS-13 have correlation with response to treatment (P < .001). ConclusionsADAMTS-13 in MDS might represent a surrogate marker of prognosis, response to therapy, or disease progression. Further studies are needed.

Congenital FVIII/IX or VWF Deficiency Does Confer a Lower Rate of Myocardial Infarction-Related Mortality Despite Decreased Cardiovascular Interventions

Introduction: Patients with common inherited bleeding disorders (IBDs) including hemophilia and von Willebrand disease (VWD) are at risk of coronary artery disease (CAD) as they age, albeit lower than the general population. Intuitively, these patients would appear to have a higher mortality rate given an increased risk of hemorrhagic complications and/or possibly cardiovascular complications from undertreatment with antithrombotic agents and/or procedures. Methods: Data from National Hospital Discharge Survey (NHDS) from 2001-2010 were analyzed using diagnosis codes (ICD 9) to identify patients with hemophilia, VWD and myocardial infarction (MI). Demographics and discharge information were compared amongst patients who had an MI with and without these coagulopathies, using chi-squared tests, Fisher's exact tests, and linear regressions. All tests were adjusted for survey design with sampling weights. Yearly rates of MI were compared between patients with and without these coagulopathies. All analyses were performed in STATA 12.0. Results: During the years 2001-2010, about 0.2 million patients (weighted data) were discharged with IBD i.e. hemophilia and VWD. Among them, the incidence of MI was 0.26% in hemophilia and 1.61% in VWD patients. Hemophilia patients were more likely to be men (76.9% vs 56.2%) and Caucasians (66% vs 65%) while VWD patients were more likely to be younger (67 vs 69 years), women (52% vs 44%) and Caucasians (66% vs 65%) compared to the normal population (all p-values &lt;0.001). Compared to non-bleeding disorder patients, the patients with VWD and hemophilia had shorter duration of hospital stay and lower in-hospital mortality compared to normal population. Furthermore, VWD patients were less likely to undergo coronary artery bypass graft (CABG) (2.0% vs 30.4%), coronary angiogram (14.5% vs 29.5%) and systemic thrombolysis (0.0% vs 1.1%) for the treatment of MI whereas patients with hemophilia are less likely to undergo CABG (11.1% vs 30.4%) but more likely to undergo coronary angiogram (41.2% vs 29.5%) (all p-values &lt;0.001). They are also less likely to undergo systemic thrombolysis (0.0% vs 1.1%) but the difference was not statistically significant (p-value 0.121). On the other hand, hemophilia patients with MI had a higher prevalence of the following complications: cardiogenic shock (26% vs 2.3%), pneumonia (32.9% vs 8.2%), respiratory failure (25.9% vs 9%) and intubation (25.9% vs 7%) compared to MI patients without hemophilia (all p-values &lt;0.001). While VWD patients with MI had comparatively better outcomes in terms of lower risk of cardiogenic shock (0.0% vs 2.3%), pneumonia (0.8% vs 8.2%), respiratory failure (0.0% vs 9%), and GI bleeding (0.0 vs 1.6%) compared to MI patients without VWD (all p-values &lt;0.001), they did have increased prevalence of acute kidney injury (50.1% vs 9.0%, p-value &lt;0.001). Conclusion: Although patients with coagulopathic disorders are historically thought to have a lower risk of MI, they can be at an increased risk of complications. But, nonetheless, they have a lower risk of in-hospital mortality which may be due to the putative protective effect of lower levels of FVIII/IX or VWF. These patients, in general, are less likely to receive therapeutic interventions. Further prospective study is needed in order to confirm and better understand the discordance of a lower in-patient mortality in inherited bleeding disorder patients despite a decrease in some cardiac interventions and an increase in some non-cardiac complications Disclosures No relevant conflicts of interest to declare.

Blood inflammatory and endothelial markers in women with von Willebrand disease.

IntroductionVWD-affected females often experience menorrhagia. Periodical fluctuations of the sex steroids during the menstrual cycle cause changes both in the coagulation and immune system. The aim of the current study was to assess the changes in selected inflammatory and endothelial markers in women with VWD during two phases of the menstrual cycle (follicular and luteal) and to compare it with corresponding data from healthy controls.Materials and methodsThe study group included 12 VWD-affected females with regular menstrual cycle, with none of them being prescribed hormone treatment. They were not pregnant or breastfeeding. The control group consisted of 102 healthy females, matched for age and BMI.ResultsWithin the VWD group, endostatin was higher during the follicular phase, compared to the luteal phase, although the difference was not significant (p = 0.062). sICAM-1 and IL-6 were higher in VWD-affected females, compared to the controls, sVCAM-1, cathepsin S and sP-selectin were lower (p<0.003 for all cases). The pattern was constant throughout the menstrual cycle.ConclusionsHigher levels of endostatin during early follicular phase could potentially predispose women with VWD to the development of heavy menstrual bleeding, due to antiangiogenic properties and ability to suppress several coagulation factors. Lower p-selectin levels in VWD group, compared to controls, may also contribute to the bleeding tendency. Changes in other proteins, involved in angiogenesis are hypothetically related to the formation of angiodysplasia—common complication of VWF deficiency. The latter statement requires confirmation in larger studies.