Von Willebrand Factor Antigen Research Articles

Platelet Activation Is Upregulated in Cirrhotic Patients with Portal Vein Thrombosis.

Platelet plays a key role in thrombosis formation, especially that the alteration of platelet function may influence the thrombosis development. This study aimed to investigate platelet function alterations in the formation of portal vein thrombosis (PVT) in cirrhosis. Cirrhotic patients admitted to The First Affiliated Hospital of Soochow University between October 2021 and April 2023 were recruited and divided into PVT and non-PVT groups according to radiological results. Clinical parameters and prognosis were also collected and assessed to identify potential risk factors. Flow cytometry was used to detect the expression of CD62p, CD63, monocyte-platelet aggregates (MPAs), neutrophil-platelet aggregates (NPAs), and von Willebrand factor antigen (vWF-Ag) to evaluate platelet activation and adhesion function. A total of 145 subjects were enrolled in our study including 60 cirrhotic PVT patients, 60 cirrhotic non-PVT patients, and 25 healthy volunteers. Multivariate analysis suggested that esophageal gastric varices, splenectomy, and D-dimer were independent risk factors for PVT pathogenesis in cirrhosis. The vWF-Ag expression level was reduced in the PVT group compared with the non-PVT group (p = 0.046) but was not an independent risk factor for PVT formation pathogenesis. The expression of CD41+CD62p+ and CD41+CD63+ platelets in the PVT group was significantly elevated compared with that in the non-PVT group (p < 0.05). There were no significant differences in MPAs and NPAs between the two cirrhotic groups. Subgroup analysis showed that the mean fluorescence intensity (MFI) of CD62p and CD63 was associated with portal hypertension-related complications (p = 0.008, p < 0.001), and CD63 MFI was significantly associated with thrombosis burden (p = 0.019). CD41+CD62p+ and CD41+CD63+ platelets as well as MPAs and NPAs were highly expressed in the splenectomy group compared with those in the nonsplenectomy group in cirrhotic patients (p < 0.05). Positive correlations were found between CD62p MFI and CD63 MFI, MPAs and NPAs (r = 0.642, p < 0.001; r = 0.378, p = 0.003; r = 0.430, p < 0.001). In addition, platelet counts were also correlated with MPAs (r = 0.556, p < 0.001) and NPAs (r = 0.467, p < 0.001). Cirrhotic patients with PVT had higher mortality and were more likely to experience portal hypertension-related complications in the prognostic analysis (p < 0.05). Highly activated platelet function exists in patients with cirrhosis, and platelet activation was elevated during PVT formation, suggesting that activated platelets may participate in the formation of PVT in patients with cirrhosis.

Improving our understanding on the clinical role of plasmin-mediated von Willebrand factor degradation.

Von Willebrand factor (VWF) plays a pivotal role in primary hemostasis. A Disintegrin And Metalloproteinase with a ThromboSpondin type 1 motif, member 13 (ADAMTS13) is primarily responsible for cleaving ultra-large VWF multimers into smaller, less adhesive forms. However, plasmin has also been shown to cleave VWF multimers. This proteolytic cleavage of VWF results in a decreased multimer size and, hence, a lower VWF activity. This review aims to present a comprehensive overview of the involvement of plasmin-mediated VWF proteolysis in (micro)thrombosis. Plasmin-mediated VWF proteolysis has been suggested to play a role in various pathologies involving microthrombosis in combination with an imbalance in VWF antigen levels and ADAMTS13 activity, as well as activation of the fibrinolytic system, but quantitative assays to demonstrate this were lacking. Recently, a VHH-based bioassay was developed designed specifically to quantify plasmin-cleaved VWF (cVWF). The novel ELISA assay holds significant promise for gaining further insights into the clinical relevance of plasmin-mediated VWF proteolysis in several pathologies. Furthermore, local plasmin activation at the site of microthrombosis has been shown to be a promising treatment strategy by degrading VWF-rich microthrombi. Plasmin-mediated proteolysis of VWF is observed during microthrombosis; however, it remains unclear whether it impacts disease severity. A novel ELISA method to detect cVWF will improve our understanding of the clinical role of plasmin-mediated VWF degradation.

The ability of von Willebrand factor antigen in the prediction of poor outcome for patients with first acute ischemic stroke

The ability of von Willebrand factor antigen in the prediction of poor outcome for patients with first acute ischemic stroke

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

BackgroundThe 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. ObjectivesTo develop an assay that can differentiate the platelet-binding activity of VWF multimers. MethodsAn enzyme-linked immunosorbent assay–based assay (VWF nanobody-triggered glycoprotein Ib binding assay [VWF:GPIbNab]) utilizing a VWF-activating nanobody was developed. Recombinant VWF, plasma-derived VWF (pdVWF), and selected gel-filtrated fractions of pdVWF were evaluated for VWF antigen and activity levels. A linear regression model was developed to estimate the specific activity of VWF multimers. ResultsOf the 3 activating nanobodies tested, 6C11 with the lowest activation effect exhibited the highest sensitivity for high-molecular-weight multimers (HMWMs) of VWF. VWF:GPIbNab utilizing 6C11 (VWF:GPIbNab6C11) produced significantly higher activity/antigen ratios for recombinant VWF (>2.0) and HMWM-enriched pdVWF fractions (>2.0) than for pdVWF (∼1.0) or fractions enriched with shorter multimers (<1.0). The differences were much larger than those produced by VWF:GPIbNab utilizing other nanobodies, VWF:GPIbM, VWF:GPIbR, or VWF:CB assays. Linear regression analysis of 5 pdVWF fractions of various multimer sizes produced an estimated specific activity of 2.7 for HMWMs. The analysis attributed >90% of the VWF activity measured by VWF:GPIbNab6C11 to that of HMWMs, which is significantly higher than all other activity assays tested. ConclusionThe VWF:GPIbNab6C11 assay exhibits higher sensitivity to HMWMs than ristocetin-based and collagen-binding assays. Future studies examining the application of this assay in clinical settings and any associated therapeutic benefit of doing so are warranted.

A noncanonical splicing variant c.875-5 T > G in von Willebrand factor causes in-frame exon skipping and type 2A von Willebrand disease

IntroductionA novel variant involving noncanonical splicing acceptor site (c.875-5 T > G) in propeptide coding region of von Willebrand factor (VWF) was identified in a patient with type 2A von Willebrand disease (VWD), who co-inherited with a null variant (p.Tyr271*) and presented characteristic discrepancy of plasma level of VWF antigen and activity, and a selective reduction of both intermediate-molecular-weight (IMWMs) and high-molecular-weight VWF multimers (HMWMs). Materials and methodsVWF mRNA transcripts obtained from peripheral leukocytes and platelets of the patients were investigated to analyze the consequence of c.875-5 T > G on splicing. The impact of the variant on expression and multimer assembly was further analyzed by in vitro expression studies in AtT-20 cells. The intracellular processing of VWF mutant and the Weibel-Palade bodies (WPBs) formation was evaluated by immunofluorescence staining and electron microscopy. ResultsThe mRNA transcript analysis revealed that c.875-5 T > G variant led to exon 8 skipping and an in-frame deletion of 41 amino acids in the D1 domain of VWF (p.Ser292_Glu333delinsLys), yielding a truncated propeptide. Consistent with the patient's laboratory manifestations, the AtT-20 cells transfected with mutant secreted less VWF, with the VWF antigen level in conditioned medium 47 % of wild-type. A slight retention in the endoplasmic reticulum was observed for the mutant. Almost complete loss of IMWMs and HMWMs in the medium and impaired WPBs formation in the cell, indicating truncated VWF propeptide lost its chaperon-like function for VWF multimerization and tubular storage. ConclusionsThe VWF splicing site variant (c.875-5 T > G) causes propeptide truncation, severely compromising VWF multimer assembly and tubular storage.

Acquired von Willebrand syndrome and post-operative drainage: a comparison of patients with aortic stenosis versus coronary artery disease.

Degenerative aortic stenosis and coronary artery disease are considered to be the most prevalent cardiovascular diseases in industrialized countries. This study aims to determine the change over time in von Willebrand factor antigen, von Willebrand factor activity, and factor VIII and where there is a correlation with total post-operative drainage. The single-center retrospective study included 203 consecutive patients (64.5% male), undergoing coronary artery bypass surgery between March 1, 2019 and June 30, 2020 at the University Clinical Center of Serbia in the Clinic for Cardiac Surgery in Belgrade, Serbia. All patients 18years or older who presented with isolated, hemodynamically significant aortic stenosis were included. The control group consisted of patients who presented with only coronary artery disease. Between patients with only coronary artery disease and patients with coronary artery diseases and aortic stenosis, there was a statistically significant difference between pre-op and 1-month post-op fibrinogen, factor VIII, von Willebrand factor antigen, and von Willebrand factor (p < 0.001), post-op drainage, with overall lower drainage in coronary artery disease patients, and consistent increase in von Willebrand factor antigen, von Willebrand factor activity, and Factor VIII post-operatively in patients with coronary artery diseases and aortic stenosis. This study has shown that there is a correlation between von Willebrand factor antigen, von Willebrand factor activity and total drainage to the level of statistical significance in aortic stenosis patients and in the overall study population.

VWF/ADAMTS13 Ratio as a Potential Predictive Biomarker for Acute Kidney Injury Onset in Cirrhosis.

We investigated the von Willebrand factor to ADAMTS13 ratio (von Willebrand factor [VWF]:Ag/ADAMTS13:AC) as a potential biomarker for the outcomes of acute kidney injury (AKI) in liver cirrhosis (LC). This retrospective cross-sectional study included patients with LC who developed AKI (AKI group: n = 91) and patients with LC who did not develop AKI [non-AKI (NAKI) group, n = 91] as a control group. Plasma levels of the von Willebrand factor antigen (Ag) and ADAMTS13 activity (AC) were measured in patients with AKI or NAKI. Moreover, risk factors for onset of AKI, AKI-associated 90-day mortality, and poor AKI treatment response were identified. The AKI group had a significantly higher VWF:Ag/ADAMTS13:AC than the NAKI group. Values of VWF:Ag/ADAMTS13:AC ≥ 5.7 were identified as risk factors for AKI onset in patients with LC (odds ratio [OR] 2.56; 95% CI 1.26-4.99; p < 0.001). Among patients with AKI, values of VWF:Ag/ADAMTS13:AC ≥ 9.0 were identified as risk factors for 90-day mortality (OR 6.83; 95% CI 2.32-20.10; p < 0.001). Cumulative survival was significantly lower in those with high (≥ 9.0) than in those with low (< 9.0) VWF:Ag/ADAMTS13:AC. Furthermore, values of VWF:Ag/ADAMTS13:AC ≥ 7.4 were identified as risk factors for poor treatment response (OR 4.2; 95% CI 1.39-12.70; p < 0.001). The treatment response rates were significantly higher in those with low (< 7.4) VWF:Ag/ADAMTS13:AC than in those with high (≥ 7.4) VWF:Ag/ADAMTS13:AC. VWF:Ag/ADAMTS13:AC potentially predicts the onset, prognosis, and treatment response of AKI in patients with LC.

Von Willebrand Factor Antigen Levels Predict Poor Outcomes in Patients With Stroke and Cancer: Findings From the Multicenter, Prospective, Observational SCAN Study.

Patients with acute ischemic stroke and active cancer have more severe neurological symptoms, elevated risks of stroke recurrence, and death compared with the general population. We examined whether von Willebrand factor (vWF) antigen levels at stroke onset were associated with the poor outcomes of patients with stroke and cancer. Using data from 90 patients with acute ischemic stroke and active cancer who were registered in the SCAN (Ischemic Stroke in Patients With Cancer and Neoplasia) study, a prospective multicenter, observational study in Japan, we divided patients into 2 groups according to their median vWF antigen levels (high, n=46; or low, n=44). The high-vWF group had a significantly higher initial National Institutes of Health Stroke Scale score (median, 7 [interquartile range, 3-11.25] versus 3 [interquartile range, 1-8.5]; P<0.05) and a significantly higher incidence of cryptogenic stroke (32 [70%] versus 16 [36%]; P<0.01) and venous thromboembolism (7 [15%] versus 0 [0%]; P<0.01), as well as multiple lesions (28 [62%] versus 12 [27%]; P<0.001), than the low-vWF group. We observed no significant difference in the rate of stroke recurrence within 1 year between the groups. However, increased vWF levels were an independent predictor of death within 1 year of stroke onset, after adjusting for potential confounders (odds ratio, 6.77 [95% CI, 1.49-30.78]; P<0.05). Elevated vWF antigen levels were associated with adverse outcomes in patients with cancer-associated stroke and may represent a useful biomarker to guide future therapeutic interventions.

Prognostic performance of non-invasive tests for portal hypertension is comparable to that of hepatic venous pressure gradient

Non-invasive tests to assess the probability of clinically significant portal hypertension (CSPH) - including the ANTICIPATE±NASH models based on liver stiffness measurement and platelet count±BMI, and the von Willebrand factor antigen to platelet count ratio (VITRO) - have fundamentally changed the management of compensated advanced chronic liver disease (cACLD). However, their prognostic utility has not been compared head-to-head to the gold standard for prognostication in cACLD, i.e. the hepatic venous pressure gradient (HVPG). Patients with cACLD (liver stiffness measurement ≥10kPa) who underwent advanced characterization via same-day HVPG/non-invasive test assessment from 2007-2022 were retrospectively included. Long-term follow-up data on hepatic decompensation was recorded. Four hundred and twenty patients with cACLD of varying etiologies, with a CSPH prevalence of 67.6%, were included. The cumulative incidence of hepatic decompensation at 1 and 2 years was 4.7% and 8.0%, respectively. HVPG, VITRO, and ANTICIPATE±NASH-CSPH-probability showed similar time-dependent prognostic value (AUROCs 0.683-0.811at 1 year and 0.699-0.801at 2 years). In competing risk analyses adjusted for MELD score and albumin, HVPG (adjusted subdistribution hazard ratio [aSHR] 1.099 [95% CI 1.054-1.150] per mmHg; p <0.001), or VITRO (aSHR 1.134 [95% CI 1.062-1.211] per unit; p <0.001), or ANTICIPATE±NASH-CSPH-probability (aSHR 1.232 [95% CI 1.094-1.387] per 10%; p <0.001) all predicted first decompensation during follow-up. Previously proposed cut-offs (HVPG ≥10mmHg vs. <10mmHg, VITRO ≥2.5 vs. <2.5, and ANTICIPATE-CSPH probability ≥60% vs. <60%) all accurately discriminated between patients at negligible risk and those at substantial risk of hepatic decompensation. The prognostic performance of ANTICIPATE±NASH-CSPH-probability and VITRO is comparable to that of HVPG, supporting their utility for identifying patients who may benefit from medical therapies to prevent first hepatic decompensation. Non-invasive tests have revolutionized the diagnosis and management of clinically significant portal hypertension in patients with compensated advanced chronic liver disease (cACLD). However, limited data exists regarding the prognostic utility of non-invasive tests in direct comparison to the gold standard for prognostication in cACLD, i.e. the hepatic venous pressure gradient. In our study including 420 patients with cACLD, the ANTICIPATE±NASH model and VITRO yielded similar AUROCs to hepatic venous pressure gradient for hepatic decompensation within 1 to 2 years. Thus, non-invasive tests should be applied and updated in yearly intervals in clinical routine to identify patients at short-term risk, thereby identifying patients who may benefit from treatment aimed at preventing hepatic decompensation.

Von willebrand factor antigen identifies high-risk hepatocellular cancer patients prior to liver resection who might benefit from liver transplantation instead

Von willebrand factor antigen identifies high-risk hepatocellular cancer patients prior to liver resection who might benefit from liver transplantation instead

Type 1 VWD classification revisited: novel insights from combined analysis of the LoVIC and WiN studies

AbstractThere is significant ongoing debate regarding type 1 von Willebrand disease (VWD) defintion. Previous guidelines recommended patients with von Willebrand factor (VWF) levels <30 IU/dL be diagnosed type 1 VWD, whereas patients with significant bleeding and VWF levels from 30 to 50 IU/dL be diagnosed with low VWF. To elucidate the relationship between type 1 VWD and low VWF in the context of age-induced increases in VWF levels, we combined data sets from 2 national cohort studies: 162 patients with low VWF from the Low VWF in Ireland Cohort (LoVIC) and 403 patients with type 1 VWD from the Willebrand in The Netherlands (WiN) studies. In 47% of type 1 VWD participants, VWF levels remained <30 IU/dL despite increasing age. Conversely, VWF levels increased to the low VWF range (30-50 IU/dL) in 30% and normalized (>50 IU/dL) in 23% of type 1 VWD cases. Crucially, absolute VWF antigen (VWF:Ag) levels and increase of VWF:Ag per year overlapped between low VWF and normalized type 1 VWD participants. Moreover, multiple regression analysis demonstrated that VWF:Ag levels in low VWF and normalized type 1 VWD patients would not have been different had they been diagnosed at the same age (β = 0.00; 95% confidence interval, −0.03 to 0.04). Consistently, no difference was found in the prevalence of VWF sequence variants; factor VIII activity/VWF:Ag or VWF propeptide/VWF:Ag ratios; or desmopressin responses between low VWF and normalized type 1 VWD patients. In conclusion, our findings demonstrate that low VWF does not constitute a discrete clinical or pathological entity. Rather, it is part of an age-dependent type 1 VWD evolving phenotype. Collectively, these data have important implications for future VWD classification criteria.

Hemostatic balance between pro- and anticoagulant is maintained during glucocorticoid treatment.

Glucocorticoids are associated with an increased risk of venous thrombosis. Glucocorticoid treatment increases coagulation factor and anticoagulant levels; however, its effect on hemostatic function remains unclear. This study aimed to investigate the changes in comprehensive coagulation profiles after glucocorticoid treatment in noninflammatory diseases to elucidate the direct contribution of glucocorticoids to hemostatic function. Patients diagnosed with primary immune thrombocytopenia requiring glucocorticoid treatment were prospectively enrolled in this study. Changes in coagulation factors and anticoagulants during glucocorticoid treatment and changes in thrombin generation potential were determined in the absence and presence of soluble thrombomodulin (sTM). Seven treatment cases (four for steroid pulse therapy and three for oral glucocorticoid therapy) in six patients with immune thrombocytopenia were examined. After glucocorticoid treatment, activated partial thromboplastin time significantly shortened, and activities of factor VIII, IX, XI, and XII significantly increased, except for von Willebrand factor antigen. Moreover, antithrombin and protein C (PC) activities significantly increased after glucocorticoid treatment. Two major parameters of thrombin generation potential, endogenous thrombin potential (ETP) and peak thrombin (Peak), significantly increased in the absence of sTM after glucocorticoid treatment. However, no significant increases in either parameter were observed in the presence of sTM. ETP-TM and Peak-TM ratios, which represent resistance to the anticoagulant effect of the PC pathway, significantly decreased after glucocorticoid treatment, suggesting that anticoagulant function via the PC pathway is elevated after glucocorticoid treatment. As glucocorticoids increase intrinsic coagulation factor and anticoagulant levels, hemostatic balance between pro- and anticoagulant functions is maintained.

Key Drivers of Coagulation Factor Use in Von Willebrand Disease During Hospitalization: An Overview of the French BERHLINGO Cohort.

Von Willebrand disease (VWD) is the most common inherited bleeding disorder. However, studies of hospitalisation patterns with replacement treatment are scarce. The aim of this study was to investigate the current therapeutic management of VWD and determine the key drivers of coagulation factor uses in patients during hospitalisation. Hopscotch-WILL was a multi-centric retrospective study conducted over a 48-month period in any patients with VWD. The data were collected from the BERHLINGO Research Database and the French Hospital database. A total of 988 patients were included; 153 patients (15%) were hospitalised during 293 stays requiring treatment with von Willebrand factor (VWF) concentrates-pure or in association with Factor VIII (FVIII). Their median basal concentrations of VWF and FVIII were significantly lower than in untreated patients: VWF antigen < 30 IU/dL, VWF activity < 20 IU/dL and FVIII:C < 40 IU/dL. The median (interquartile range) concentrate consumption was similar between highly purified VWF or VWF combined with FVIII (72 [110] vs 57 [89] IU/kg/stay, p = 0.154). The use of VWF was highly heterogeneous by VWD type; type 3 had a particularly high impact on VWF consumption in non-surgical situations. The main admissions were for ear/nose/throat, hepato-gastroenterology, and trauma/orthopaedic conditions, besides gynaecological-obstetric causes in women. The use of VWF concentrates is mostly influenced by low basal levels of VWF and FVIII, but also by VWD type or the cause for hospitalisation. These results could inform future studies of newly released recombinant VWF.

Von Willebrand factor Ristocetin co-factor activity to von Willebrand factor antigen level ratio for diagnosis of acquired von Willebrand syndrome caused by aortic stenosis

BackgroundSevere aortic stenosis (AS) causes acquired von Willebrand syndrome by the excessive shear stress–dependent cleavage of high molecular weight multimers of von Willebrand factor (VWF). While the current standard diagnostic method is so-called VWF multimer analysis that is western blotting under nonreducing conditions, it remains unclear whether a ratio of VWF Ristocetin co-factor activity (VWF:RCo) to VWF antigen levels (VWF:Ag) of <0.7, which can be measured with an automated coagulation analyzer in clinical laboratories and is used for the diagnosis of hereditary von Willebrand disease. ObjectivesTo evaluated whether the VWF:RCo/VWF:Ag is useful for the diagnosis of AS-induced acquired von Willebrand syndrome. MethodsVWF:RCo and VWF:Ag were evaluated with the VWF large multimer index as a reference, which represents the percentage of a patient’s VWF high molecular weight multimer ratio to that of standard plasma in the VWF multimer analysis. ResultsWe analyzed 382 patients with AS having transaortic valve maximal pressure gradients of >30 mmHg, 27 patients with peripheral artery disease, and 46 control patients free of cardiovascular disease with osteoarthritis, diabetes, and so on. We assumed a large multimer index of <80% as loss of VWF large multimers since 59.0% of patients with severe AS had the indices of <80%, while no control patients or patients with peripheral artery disease, except for 2 patients, exhibited the indices of <80%. The VWF:RCo/VWF:Ag ratios, measured using an automated blood coagulation analyzer, were correlated with the indices (rs = 0.470, P < .001). When the ratio of <0.7 was used as a cut-off point, the sensitivity and specificity to VWF large multimer indices of <80% were 0.437 and 0.826, respectively. ConclusionVWF:RCo/VWF:Ag ratios of <0.7 may indicate loss of VWF large multimers with high specificity, but low sensitivity. VWF:RCo/VWF:Ag ratios in patients with AS having a ratio of <0.7 may be useful for monitoring the loss of VWF large multimers during their clinical courses.

Comprehensive Characterization of Coagulation Parameters in Venous Malformations

Introduction: Localized intravascular coagulopathy (LIC) is a well-recognized, though poorly characterized complication of venous malformations (VM) that can lead to bleeding, thrombosis, and phlebolith formation. While LIC has classically been characterized by elevations in D-dimer and reductions in fibrinogen, no comprehensive studies of coagulation parameters in VM have been performed to date. Since 2021, all patients with VM undergoing evaluation for LIC in the Yale Vascular Malformations Program (VaMP) and the Yale Classical Hematology clinic have been subjected to an extensive set of coagulation tests to fully analyze LIC. Our aim was to use these laboratory test results to comprehensively characterize LIC in this population. Methods: We conducted a retrospective chart review of all VM patients presenting to the Yale VaMP and the Yale Classical Hematology clinic for assessment of LIC from 2021 to 2023. All included patients were evaluated for LIC using the following coagulation parameters: von Willebrand Factor (VWF) antigen, VWF activity, factor VIII (FVIII), alpha-2 antiplasmin (A2AP), plasminogen activator inhibitor-1 (PAI-1), thrombin-antithrombin complex (TAT), D-dimer (DD), fibrinogen, prothrombin time (PT), international normalized ratio (INR), and partial thromboplastin time (PTT). Measurements of VWF antigen, VWF activity, FVIII and A2AP were performed using an ACL TOP system (Instrumentation Laboratory; Bedford, MA, USA), while D-dimer and fibrinogen were measured using a BCS XP System (Siemens; Malvern, PA, USA) at our institution's clinical laboratory. PAI-1 and TAT were processed at national Clinical Laboratory Improvement Amendment-certified reference laboratories using ELISA-based assays. Baseline patient characteristics and coagulation test results were extracted via manual chart review. Data analysis was done using IBM SPSS statistics software and GraphPad Prism 9 software. Categorical variables were described using frequency and percentages, while quantitative variables were described using central tendency and dispersion measures. We performed univariate analysis using the Chi-square test. We also analyzed the coagulation tests using a correlation matrix. Statistical significance was set at p&amp;lt;0.05. This project was approved by our Institutional Review Board. Results: A total of 23 patients with VM were included in the analysis (Table 1). The mean age was 38 ± 16 years; the majority (82.6%) were female. The most common anatomic location was the head and neck (52.2%), while the most frequent extent of tissue involvement was muscle (54.5%), with most patients having a single lesion (59.1%) rather than multiple ones. No patients had venous thromboembolism. Normal DD and high TAT levels were observed in most patients (68.2% and 69.6%, respectively). VWF activity, VWF antigen, FVIII, PAI-1, and fibrinogen all were positively correlated (Figure 1). TAT was positively correlated with PAI-1 and inverselycorrelated withPT and INR. DD was positively correlated only with vWF activity. TAT and DD had a poor correlation; among patients with a normal TAT (n=7), 85.7% had a normal DD, while among patients with a normal DD (n=15), only 40% had a normal TAT. Three out of 4 (75%) patients with skin involvement had a high TAT with normal DD, while 2 out of 3 (66.7%) patients with visceral involvement had both high TAT and DD, although these patternswere not statistically significant (P=0.42 and 0.31, respectively). Among patients with muscle involvement (n=11), 45.5% had a high TAT and normal DD while 36.3% had both high TAT and DD. Conclusions: In this first comprehensive hematologic study of VM, we demonstrate that VM-related LIC is characterized by derangements of multiple coagulation parameters. Due to this, measurements of DD and fibrinogen alone may be inadequate for assessing LIC, and the addition of TAT and multiple other coagulation tests may yield a more complete picture of hemostatic derangements in LIC. A lack of correlation between DD and TAT is unexpected and merits further study. Differences in the depth of the VM tissue involvement and TAT/DD correlation may indicate a progression of coagulopathy related to the extent of VM but require further investigation in a larger study.

Steady-State Von Willebrand Factor Antigen Levels Predict Low Platelet Counts and Risk for Complications in Hospitalizations for Painful Sickle Cell Vaso-Occlusive Episodes

We previously reported that a &amp;gt;20% decline in platelet counts from steady state to presentation predicted severe complications during hospitalization for vaso-occlusive pain crisis (VOC) in 130 adult sickle cell disease (SCD) patients. 1 Sharp platelet decline in acute chest syndrome was reported to be accompanied by large von Willebrand Factor (VWF) aggregates adherent to pulmonary vascular endothelium in SCD. 2 A prospective study of 24 SCD patients found a significant increase of VWF reactivity in VOC admissions relative to steady state, which correlated with low platelet counts and the development of acute chest syndrome. 3 We aimed to investigate the role of steady-state VWF antigen level and ADAMTS13 activity as predictors of platelet count decline and severe complications in VOC admissions. Plasma levels of VWF antigen and ADAMTS13 activity were measured 4 for 56 patients at steady-state outpatient visits (Baseline). VWF antigen was expressed as fold increase or decrease from the concentration in normal pooled plasma of 12.2 ug/ml; ADAMTS13 activity was expressed as fold of the value from normal pooled plasma which was considered 100% activity. Electronic records of VOC admission that occurred &amp;gt;21 days after Baseline were reviewed. Exclusion criteria included non-VOC admissions defined as elective admission for surgery, admission for accident or injury, admission for delivery of an infant, or admission with a pain score &amp;lt;8/10 at presentation. 5 A total of 98 qualifying admissions were identified. Severe complication during the admission was defined as having any of the following: 1) acute chest syndrome, new infiltrate on chest X-ray, or use of ventilator; 2) acute kidney injury; 6 3) acute liver injury; 7 4) thrombotic or hemorrhagic stroke; 5) venous thromboembolism including deep vein thrombosis, atrial thrombosis, and pulmonary embolism; 6) need for transfer to the intensive care unit; 7) need for exchange blood transfusion; 8) death during hospitalization. Platelet counts at presentation to the emergency room (ER) leading to the admissions under study were recorded, as well platelet counts at Baseline. The 56 patients had a median (range) age of 37 (21-66) years; 52% are female, 89% with hemoglobin SS or Sβ 0-thalassemia, and 57% on hydroxyrea (HU). Severe complication occurred in 35 (36%) of the 98 admissions involving 27 (48%) of the patients. Focusing on the first admissions, higher steady-state VWF antigen levels correlated strongly with lower ER platelet counts (ρ= -0.50, P=0.00011, Figure 1A) and higher steady-state ADAMTS13 activity correlated weakly with ER platelet counts (Spearman's ρ= 0.30, P=0.025). The ratio of VWF antigen to ADAMTS13 activity ratio also correlated strongly with lower ER platelet counts (ρ= -0.52, P=0.000052, Figure 1B). In contrast, steady-state VWF antigen level (ρ= -0.17, P=0.23), ADAMTS13 activity (ρ= 0.19, P=0.17), and VWF antigen to ADAMTS13 activity ratio (ρ= -0.23, P=0.098) showed no significant correlation with steady-state platelet counts. The correlations remained by adjusting for age, gender, Hb genotype severity, HU, and treatment of anticoagulant, aspirin, or non-steroidal anti-inflammatory drugs at VOC visits. In analyses restricted to admissions &amp;gt;1 year after Baseline, the correlation between steady-state VWF antigen level and ER platelet counts appeared to persist. Focusing on the 28 first admissions, steady-state VWF antigen level (ρ= -0.50, P=0.0071) and VWF antigen to ADAMTS13 activity ratio (ρ= -0.44, P=0.018) correlated negatively with ER platelet counts. Steady-state ADAMTS13 activity did not correlate with ER platelet counts in admissions that occurred &amp;gt;1 year after Baseline (ρ= 0.16, P=0.43). We further examined the association of steady-state VWF antigen level, ADAMTS13 activity, and their ratio with risk for severe complication in admission. Focusing on the first 56 admissions, which involved 23 complications, steady-state VWF antigen level in the top quartile (1.63) associated with risk for severe complications (OR=6.5, 95% CI 1.4-31, P=0.018, n=56), adjusting for age, gender, Hb genotype severity, and HU. Our observations suggest that steady-state VWF antigen level and the ratio of VWF antigen level to ADAMTS13 activity predict low platelet counts at presentation to VOC admissions, and that steady-state VWF antigen level in SCD patients may be a relatively stable marker for risk of severe VOC complications.

Impact of Anticoagulant Function By the Addition of Heparinoid in Vitro in the Plasmas from Patients with Hemophilia and Von Willebrand Disease

Background: Heparinoid (Hirudoid ®) is a local anticoagulant preparation as skin application that relieves pain and inflammation with addition to promoting healing in superficial thrombophlebitis and bruising. Heparinoid is mainly composed of chondroitin sulfate and has high moisturizing ability due to the large number of hydrophilic group. Thus, it is used as topical treatments for sebum deficiency in Japan. Since heparinoid has a structure similar to heparin, the package insert states the contraindication for hemorrhagic diseases such as hemophilia and von Willebrand disease (VWD) in Japan. Hemophilia A and B (HA/HB) are inherited bleeding disorders caused by a defect in factor (F) VIII and FIX coagulant protein, respectively. Based on its activity levels, the clinical severity is classified as severe (&amp;lt;1 IU/dL), moderate (1-5 IU/dL), and mild (&amp;gt;5-40 IU/dL). VWD is the common congenital bleeding disorders and is caused by a deficiency of von Willebrand factor (VWF). VWD is classified into partial deficiency (type 1), qualitative deficiency (type 2), and complete quantitative deficiency (type 3) of VWF, based on the VWF antigen (VWF:Ag) and ristocetin cofactor activity (VWF:RCo) level. In the clinical practice, there are cases of hemorrhagic patients using heparinoid at the discretion of their families. However, the influence of heparinoid on coagulant function in human subjects remains to be investigated, and it is unclear if the patients with hemophilia and VWD can use heparinoid safely. Aim: To examine the impact of anticoagulant function of heparinoid in vitro in the plasmas from patients with hemophilia and VWD. Methods: The maximum blood concentration from absorbed heparinoid was estimated to be 2.5 µg/mL, based on the previous report, when heparinoid was applied to the skin as stated in package insert. Heparinoid (0-6.5 µg/mL) or unfractionated heparin (0-0.6 IU/mL) were added to normal plasma (NP), followed by measuring activated partial thromboplastin time (aPTT) by one-stage clotting assay. A modified clot waveform analysis (CWA) using an aPTT reagent were performed on the CS-2400™ (Sysmex), followed by measuring clotting time (CT) and adjusted maximum coagulation velocity (Ad|min1|). Heparinoid was also added to the patients' plasmas with HA, HB, or VWD, followed by CWA assessment. The CT and Ad|min1| of 20 healthy individuals were 31.1±0.1 sec and 6.90±0.05 (median±SEM). Results: aPTT and CT values in NP by the spike of heparinoid were prolonged and Ad|min1| was decreased dose-dependently. The addition of 2.5 µg/mL heparinoid showed that aPTT (34.3 sec; 1.2-fold of control (no heparinoid)), CT (36.3 sec; 1.2-fold of control), and Ad|min1| (9.5; 0.96-fold of control) were comparable to the effect of ~0.2 IU/mL heparin, suggesting that heparinoid exhibited slight anticoagulant effect for NP. To examine the effect of heparinoid on HA/HB plasmas, recombinant (r) FVIII or rFIX (0-50 IU/dL) were added to FVIII- or FIX-deficient plasmas (3 lots each) together with heparinoid (0-6.3 µg/mL), respectively. The addition of heparinoid had prolonged the CT and decreased the Ad|min1| at each concentration of FVIII and FIX dose-dependently. The addition of 2.5 µg/mL heparinoid showed modest anticoagulant effect for HA and HB at each concentration of FVIII and FIX (CT; 1.3- and 1.5-fold of control, Ad|min1|; 0.82- and 0.87-fold of control). Next, the effect of heparinoid on the plasma from one VWD patient each with type 1 (VWF:Ag/VWF:RCo 28 IU/dL/26 IU/dL), type 2 (20 IU/dL/9 IU/dL), and type 3 (&amp;lt;2 IU/dL/&amp;lt;3 IU/dL) was assessed. The addition of 2.5 µg/mL heparinoid showed slight anticoagulant effect for each type of VWD (CT; ~1.3-fold of control, Ad|min1|; ~0.91-fold of control). Conclusion: The presence of heparinoid demonstrated mild anticoagulant effect in vitro in the plasmas of patients with hemophilia and VWD. It might be possible to apply the heparinoid-contained product as skin treatment for these patients.

Pre-Operative Coagulation Test Results Do Not Correlate with Self-Bleeding Assessment Tool (Self-BAT) Scores

Background: Elective surgical procedures are planned hemostatic challenges and laboratory coagulation testing is often the typical approach to pre-operative hemostatic assessments. This is unfortunate as the prothrombin time [PT] and activated partial thromboplastin time [aPTT] are of suboptimal predictive value for surgical bleeding risk and are have limited screening ability for inherited bleeding disorders. To the contrary, personal and family history of bleeding are important predictors of inherited bleeding disorders, and thus also likely predictive of perioperative bleeding risk. Quantitative bleeding assessment tools (BATs) have been developed to standardize the patient bleeding history, and a patient self-administered BAT (Self-BAT) has been validated for the diagnosis of type 1 von Willebrand disease. As part of a large, multicentre prospective cohort study to assess the accuracy of the Self-BAT in predicting peri-operative bleeding, we aimed to determine the correlation between results of coagulation assays and the Self-BAT score in patients undergoing elective surgery. Methods: We enrolled adult patients with no previously identified bleeding disorder who were undergoing general elective surgery between 2017 to 2018. We excluded patients with any prior history of therapeutic dose antithrombotic use, and those undergoing cardiac, vascular, emergency, ophthalmologic, or dental surgeries. Bloodwork was drawn at the pre-operative visit, and included aPTT, PT, von Willebrand factor (VWF) antigen, VWF GP1b (ristocetin calibrated) activity, factor VIII activity, platelet function assay (PFA)-100 closure times. The pre-operative Self-BAT and all laboratory tests were analyzed at the same site . We used Spearman's correlation coefficient to determine the relationship between results of laboratory testing and the Self-BAT scores. An abnormal Self-BAT score was defined as ≥6 for women and ≥4 for men. R v4.3.1 was used to perform the analysis. Results: A total of 368 were enrolled in the study, the mean age was 56 years old (standard deviation: 14.4) and 64.3% were women. A total of 12 individuals (3.3%) had a first degree relative with a bleeding disorder. The most common planned procedure was orthopedic (61%), followed by neurosurgery (14.4%), and general surgery (8.2%). The median Self-BAT score for women was 2 (interquartile range [IQR]: 1-4.3) and 1 (IQR: 0-2) for men. Of the 236 women and 131 men, 42 (17.8%) and 17 (13%) had abnormal Self-bat score. We found no significant correlations between the aPTT PT, Factor VIII, VWF panel nor PFA-100 and the Self-BAT score (Table 1). There was also no correlation found for sex stratified analyses. Conclusions: Our findings confirm that unselected ‘routine’ and specialized coagulation test results do not correlate with an individual's bleeding history. Thus, indiscriminate testing should not be used as surrogate screening tests for bleeding disorders in the pre-operative setting. Specialized coagulation testing should be reserved for when a hemostatic defect is suspected based on a positive personal or family bleeding history. We look forward to the results of the primary objective of the larger cohort study; enrollment is more than half completed to determine if the Self-BAT score itself is an accurate predictor of peri-operative bleeding.

The Utility of a Coagulation Laboratory Profile in Addition to Clinical Risk Factors for Thrombosis Risk Evaluation in Patients with Myeloproliferative Neoplasms: A Pilot Study

Background: Patients (pts) with myeloproliferative neoplasms (MPN) have a significantly increased risk of arterial and venous thrombotic events (TEs), while some pts may paradoxically suffer from bleeding manifestations. Thrombosis risk evaluation in polycythemia vera (PV) and essential thrombocythemia (ET) has important implications for patient management, however, the currently used risk stratification models are extremely limited. Methods: We designed a pilot study to assess the utility of an expanded coagulation laboratory profile in addition to other clinical variables for thrombosis and bleeding risk evaluation in a heterogenous MPN patient population. Our laboratory profile included PT, aPTT, fibrinogen, D-dimer, von-Willebrand Factor (vWF) antigen and activity testing, platelet (PLT) aggregation studies and thrombin generation assay (TGA, ST-Genesia, Stago, France), along with CBC and comprehensive biochemistry studies. Blood was drawn from pts visiting the hematology clinics or day care at Hadassah Medical Center. Clinical and demographic data were collected retrospectively from electronic medical records. The study was approved by the local IRB committee. Results:74 pts were included in the study; the mean age was 59.7 years and 51% were women. Sixty percent had a diagnosis of PV, 20% had ET, 17.6% had myelofibrosis (MF) and 2.7% had MPN unclassifiable. 78% of the pts harbored a JAK2V617F mutation, 8% and 2.7% harbored CALR and MPL mutations, respectively, and 11% were negative to all three MPN driver mutations. 63% of the pts had at least one cardiovascular risk factor, most commonly hypertension (HTN) and dyslipidemia. Most of the pts were treated with antiplatelet agents (62%), anticoagulants (16%) and/or cytoreductive agents (58%). Of 74 pts, 31% had a history of TEs (20% arterial, 11% venous), 22% reported suffering from microvascular symptoms, and 20% had experienced bleeding. The high rate of bleeding manifestations in our study population suggests an underestimation of the bleeding burden in MPN, as proposed by our group previously [Rottenstreich, Eur J Intern Med 2017]. Other patient characteristics were overall comparable to MPN patient populations in other studies (Table 1). In multivariate analyses, history of TEs was significantly associated with older age, type 2 diabetes mellitus (DM2), HTN and dyslipidemia, but not with gender, MPN subtype, driver mutation status or smoking. Pts with history of TEs had significantly lower hematocrit and prolonged PT/INR, associated with a higher rate of treatment with cytoreduction and anticoagulation, respectively, in these pts. Interestingly, pts with TEs had significantly higher vWF antigen levels (p=0.007), which were independent of age, blood counts and treatments, a finding not previously reported in MPN. No association was observed between TEs and PLT or WBC counts, D-dimer levels and vWF activity (Table 2), however, vWF activity was decreased in pts with higher PLT counts. TGA was of key interest in this study. In 62 pts not receiving anticoagulation, we observed an association between prolonged lag time (suggesting decreased coagulability) and older age, male gender and (near significant trend) JAK2V617 negative status, but did not find a correlation to TEs, blood counts and other variables. PLT aggregation indices were not associated with TEs, bleeding history or blood counts. In multivariate logistic regression analyses, history of DM2 and HTN, and vWF antigen levels, showed the strongest association to TEs, which was independent of age, blood counts and all other variables. A risk-model incorporating these variables showed a sensitivity of 77% and specificity of 92% for history of TEs in our study population. Conclusions: Despite being limited by a small and heterogenous study population and retrospective data collection; these findings support the utility of a coagulation laboratory profile in the evaluation of thrombosis and bleeding risk in MPN. The potential of TGA in risk evaluation in MPN is intriguing but merits further research. The multivariate risk-model incorporating history of DM2 and HTN along with vWF antigen levels merits validation in larger studies. Based on this pilot, a prospective study following over 250 pts with PV and ET (excluding overt MF) was initiated. This study will include NGS mutational profiling and JAK2V617F allele burden testing and omit the use of PLT aggregation studies.

The Effect of Voxelotor on Erythrocyte Deformability, Neutrophil Phenotype and Endothelial Activation

Introduction Sickle cell disease (SCD) is characterized by chronic intravascular hemolysis, caused by polymerization of abnormal sickle hemoglobin. The ongoing intravascular hemolysis leads to release of cell-free heme and iron, resulting in widespread oxidative damage, inflammation, neutrophil activation, endothelial activation and hypercoagulability, all contributing to vaso-occlusive events and end organ damage. Voxelotor, a small molecule reversibly binding to hemoglobin S (HbS) increases its oxygen affinity, thereby decreasing HbS polymerization and sickling, resulting in decreased hemolysis. The decrease in erythrocyte sickling might lead to improved erythrocyte deformability and decreased adhesion, while reductions in cell-free heme and labile plasma iron levels might result in decreased neutrophil activation, adhesion and aging and decreased endothelial activation. The aim of this study is to assess the effects of voxelotor on erythrocyte deformability, neutrophil activation, adhesion and aging and endothelial activation. Methods SCD patients (HbSS and HbSβ 0-thalassemia), with hemoglobin (Hb) ≤ 10.5 g/dL were treated with voxelotor 1500 mg in a single arm interventional study. Blood was collected at baseline and after 3 months of treatment. Erythrocyte deformability was assessed by ektacytometry (Lorrca, RR mechatronics), measuring elongation index (EI) and point of sickling (PoS). EI max and EI min indicate the highest and lowest erythrocyte deformability upon oxygenation and deoxygenation respectively. PoS is the oxygen tension at which 5% reduction of the EI max is observed. Antigen expression of neutrophil markers for activation, adhesion and aging were assessed with flow cytometry. Reactive oxygen species (ROS) production of neutrophils was measured by Amplex Red Assay (Molecular probes), measuring hydrogen peroxide (H 2O 2) production under unstimulated and stimulated (zymosan, streptozotocin (STZ), factor-n-formyl-MET-LEU-Phe (fMLP), Phorbol myristate acetate (PMA)) and platelet-activating factor-fMLP (PAF-fMLP)). Endothelial activation was assessed by measuring von Willebrand Factor antigen (vWF-Ag) using enzyme-linked immunosorbent assay (ELISA) (Glostrup). Prothrombin fragment 1+2 (F 1+2), thrombin-antithrombin complexes (TAT) and D-dimer were measured using ELISA. Data are presented as median with interquartile range (IQR), unless stated otherwise. A P value of &amp;lt;0.05 was considered significant. Results 15 SCD patients (11 HbSS, 4 HbSβ 0-thalassemia), 5 female, median age 35 years (IQR 27-46)) completed 3-month follow-up. Hb levels increased significantly after 3 months of treatment (from 7.4 (6.9 - 8.1) g/dL to 9.7 (7.9 - 11.0) g/dL, p=0.002), corresponding to significant decreases in LDH and bilirubin levels and reticulocyte counts as markers of hemolysis (p&amp;lt;0.05). PoS decreased significantly after 3 months (from 20.1 (17.5 - 26.1) mmHg to 16.1 (10.3 - 18.1) mmHg, p=0.006). Both EI max and EI min increased after 3 months of treatment (from 0.33 (0.24 - 0.42) to 0.38 (0.28 - 0.48), p=0.029 and from 0.13 (0.07 - 0.26) to 0.21 (0.16 - 0.41), p=0.007 respectively). Markers of neutrophil activation, adhesion and aging were generally lower after 3 months of treatment, though the differences were not statistically significant (Figure 1 A-C). Neutrophil ROS production in both unstimulated and stimulated condition remained unchanged (Figure 1D). After 3 months of treatment vWF-Ag significantly decreased (from 252 (187 - 284) % to 183 (153-205) %, p = 0.033). No changes were observed in markers of coagulation activation (F 1+2 and TAT, and D-dimer). Conclusion Voxelotor significantly improved erythrocyte deformability as suggested by decreased PoS and increased EI max and EI min, potentially leading to improved rheological properties. While markers of neutrophil activation seem to decrease, the differences are not statistically significant, possibly due to the relatively small sample size. A reduction in vWF-Ag was observed possibly reflecting diminished endothelial activation, due to a decrease in intravascular hemolysis.