Imbalance in the vWF - ADAMTS13 axis exists early in acute pancreatitis and predicts persistent organ failure and pancreatic necrosis-a prospective study.

BACKGROUND: The pathophysiology of Acute Pancreatitis (AP) may be complicated by endothelial activation. von Willebrand Factor (vWF)- ADAMTS13 axis is a marker of endothelial activation. The study aimed to investigate the axis in AP, comparing it in patients with and without persistent organ failure (OF), with and without pancreatic necrosis, and correlating it with the standard severity scores (CRP, APACHE II, BISAP, SOFA, and qSOFA) METHODS: vWF-Antigen (vWF:Ag), vWF-Collagen-Binding-Assay (vWF:CBA), and ADAMTS13 activity (ADAMTS13:act) levels were measured within 5 days of symptom onset in consecutive patients (n = 98), who were admitted with a first episode of AP (Dec 2021-May 2023). RESULTS: Of the 98 patients admitted with AP, 78(79.6 %) had no or transient OF; 20(20.4 %) had persistent OF. Age was comparable (43.73 ± 15.36 vs 38.65 ± 13.69) [mean ± SD](years), and males were predominant in both groups (70.5 % vs 80 %). Patientswith persistent OF had higher vWF:CBA(%)[323(279-486.5) vs 199.5(159.1-295.75)] and lower ADAMTS13:act(%)[35.4(23.8-56.85) vs 56.35(44.1-71.9)][median (25th - 75th percentile)](P = 0.001) than those with no or transient OF. Patients with pancreatic necrosis (n = 19) had lower ADAMTS13:act(%)[42.79 ± 18.69] than those without pancreatic necrosis (n = 18) [62.49 ± 22.64] (P < 0.01). ADAMTS13:act had a negative correlation(r = -0.2), whereas vWF:Ag and vWF:CBA had a positive correlation (r = 0.2) with the standard severity scores (P < 0.05). ADAMTS13:act could predict pancreatic necrosis [AUROC-0.737, P < 0.05] and persistent OF [AUROC-0.746, P < 0.001], while vWF:CBA could predict persistent OF [AUROC- 0.73, P < 0.001]. CONCLUSION: vWF-ADAMTS13 axis helps to predict severe disease and is associated with poor outcomes in acute pancreatitis.

Implications of von Willebrand Factor in Inflammatory Bowel Diseases: Beyond Bleeding and Thrombosis.

Inflammatory bowel disease (IBD) displays an increased venous and arterial thrombotic risk despite the common occurrence of intestinal bleeding. While some of the mechanisms leading to these thrombotic complications have been studied, other specific changes in the hemostasis profile of IBD patients have been less explored. One such example relates to von Willebrand factor (VWF) whose plasma levels have been reported to be modulated in IBD. Von Willebrand factor is a plasma glycoprotein crucial for hemostatic functions via roles both in platelet function and coagulation. High plasma VWF is a known risk factor for venous thromboembolism. In addition to its canonical roles in hemostasis, VWF is known to be directly or indirectly involved in other vascular processes such as maintenance of endothelial barrier integrity or proliferation of vascular smooth muscle cells. The purpose of this review is to recapitulate and update the existing data about VWF biology in IBD and to highlight its role both in the existing procoagulant phenotype and in vascular alterations that may occur in IBD.

Inflammatory bowel disease (IBD) displays an increased thrombotic risk. Von Willebrand factor (VWF) is increased in IBD and is a risk factor for venous thromboembolism. This review purposes to recapitulate and update the existing data about VWF biology in IBD.

The effect of ADAMTS13 on graft-versus-host disease.

Allogeneic haematopoietic stem cell transplantation (allo-HSCT) can potentially cure malignant blood disorders and benign conditions such as haemoglobinopathies and immunologic diseases. However, allo-HSCT is associated with significant complications. The most common and debilitating among them is graft-versus-host disease (GVHD). In GVHD, donor-derived T cells mount an alloimmune response against the recipient. The alloimmune response involves several steps, including recognition of recipient antigens, activation and proliferation of T cells in secondary lymphoid organs, and homing into GVHD-targeted organs. Adhesion molecules on T cells and endothelial cells mediate homing of T cells into lymphoid and non-lymphoid tissues. In this study, we showed that Von Willebrand factor (VWF), an adhesion molecule secreted by activated endothelial cells, plays an important role in mouse models of GVHD. We investigated the effect of the VWF-cleaving protease ADAMTS13 on GVHD. We found that ADAMTS13 reduced the severity of GVHD after bone marrow transplantation from C57BL6 donor to BALB/C recipient mice. A recombinant VWF-A2 domain peptide also reduced GVHD in mice. We showed that ADAMTS13 and recombinant VWF-A2 reduced the binding of T cells to endothelial cells and VWF in vitro, and reduced the number of T cells in lymph nodes, Peyer's patches and GVHD-targeted organs in vivo. We identified LFA-1 (αLß2) as the binding site of VWF on T cells. Our results showed that blocking T-cell homing by ADAMTS13 or VWF-A2 peptide reduced the severity of the GVHD after allo-HSCT, a potentially novel method for treating and preventing GVHD.

Weibel-Palade bodies: function and role in thrombotic thrombocytopenic purpura and in diarrhea phase of STEC-hemolytic uremic syndrome.

Vascular endothelial cells are equipped with numerous specialized granules called Weibel-Palade bodies (WPBs). They contain a cocktail of proteins that can be rapidly secreted (3-5 min) into the vascular lumen after an appropriate stimulus such as thrombin. These proteins are ready without synthesis. Von Willebrand factor (VWF) and P-selectin are the main constituents of WPBs. Upon stimulation, release of ultralarge VWF multimers occurs and assembles into VWF strings on the apical side of endothelium. The VWF A1 domain becomes exposed in a shear-dependent manner recruiting and activating platelets. VWF is able to recruit leukocytes via direct leukocyte binding or via the activated platelets promoting NETosis. Ultralarge VWF strings are ultimately cleaved into smaller pieces by the protease ADAMTS-13 preventing excessive platelet adhesion. Under carefully performed flowing conditions and adequate dose of Shiga toxins, the toxin induces the release of ultralarge VWF multimers from cultured endothelial cells. This basic information allows insight into the pathogenesis of thrombotic thrombocytopenic purpura (TTP) and of STEC-HUS in the diarrhea phase. In TTP, ADAMTS-13 activity is deficient and systemic aggregation of platelets will occur after a second trigger. In STEC-HUS, stimulated release of WPB components in the diarrhea phase of the disease can be presumed to be the first hit in the damage of Gb3 positive endothelial cells.

Endothelial biomarkers (Von willebrand factor, BDCA3, urokinase) as predictors of mortality in COVID-19 patients: cohort study.

BACKGROUND: SARS-CoV-2 is a systemic disease that affects endothelial function and leads to coagulation disorders, increasing the risk of mortality. Blood levels of endothelial biomarkers such as Von Willebrand Factor (VWF), Thrombomodulin or Blood Dendritic Cell Antigen-3 (BDCA3), and uUokinase (uPA) increase in patients with severe disease and can be prognostic indicators for mortality. Therefore, the aim of this study was to determine the effect of VWF, BDCA3, and uPA levels on mortality. METHODS: From May 2020 to January 2021, we studied a prospective cohort of hospitalized adult patients with polymerase chain reaction (PCR)-confirmed COVID-19 with a SaO2 ≤ 93% and a PaO2/FiO2 ratio < 300. In-hospital survival was evaluated from admission to death or to a maximum of 60 days of follow-up with Kaplan-Meier survival curves and Cox proportional hazard models as independent predictor measures of endothelial dysfunction. RESULTS: We recruited a total of 165 subjects (73% men) with a median age of 57.3 ± 12.9 years. The most common comorbidities were obesity (39.7%), hypertension (35.4%) and diabetes (30.3%). Endothelial biomarkers were increased in non-survivors compared to survivors. According to the multivariate Cox proportional hazard model, those with an elevated VWF concentration ≥ 4870 pg/ml had a hazard ratio (HR) of 4.06 (95% CI: 1.32-12.5) compared to those with a lower VWF concentration adjusted for age, cerebrovascular events, enoxaparin dose, lactate dehydrogenase (LDH) level, and bilirubin level. uPA and BDCA3 also increased mortality in patients with levels ≥ 460 pg/ml and ≥ 3600 pg/ml, respectively. CONCLUSION: The risk of mortality in those with elevated levels of endothelial biomarkers was observable in this study.

Investigation of von Willebrand factor multimer abnormalities before and after aortic valve replacement using the Hydragel-5 assay.

BACKGROUND: Severe aortic stenosis (sAS) is associated with acquired von Willebrand syndrome (AVWS) by loss of high-molecular-weight multimers (HMWM) of von Willebrand factor (VWF), potentially resulting in perioperative bleeding. Analysis of VWF multimers remains challenging. Recently, the new, rapid Hydragel 5 assay has been developed, using electrophoretic protein separation for dividing VWF-multimers into low (LMWM), intermediate (IMWM), and HMWM, the hemostatically active part of VWF. Here, we evaluated its impact on predicting blood loss in presence of AVWS after surgical aortic valve replacement (SAVR). METHODS: We prospectively examined 52 patients (age: 68 ± 7 years; 54 % male) admitted to SAVR. They were divided in two groups (A: normal VWF, n = 28; B: abnormal VWF, n = 24, defined as VWF-activity/antigen (VWF:Ac/Ag)-ratio < 0.7 and/or HMWM loss). Blood samples and echocardiographic data were collected before, seven days and three months after SAVR. Blood loss and transfusions were recorded. RESULTS: Baseline characteristics and clinical data were similar in both groups. HMWM loss was present in 38.5 % of all patients. HMWM, the VWF:Ac/Ag- and HMWM/(IMWM+LMWM)-ratios were significantly decreased preoperatively in group B but normalized after SAVR. Bleeding, re-thoracotomy and transfusion rates were comparable. HMWM loss was inversely correlated with the peak aortic gradient (Pmax) and positively with the aortic valve area (AVA), while HMWM/(IMWM+LMWM)-ratio negatively correlated with the mean aortic gradient (Pmean). CONCLUSION: HMWM and HMWM/(IMWM+LMWM)-ratio inversely correlate with severity of AS and normalize after SAVR. The Hydragel-5 assay's might be valuable for routine diagnostics to assess bleeding risk and postoperative normalization of AS and VWF abnormalities in SAVR patients.

Type 2N von Willebrand disease: Genotype drives different bleeding phenotypes and treatment needs.

BACKGROUND: Von Willebrand disease type 2N (VWD2N) is usually perceived as a mild bleeding disorder that can be treated by desmopressin (DDAVP). However, VWD2N-patients can be compound heterozygous or homozygous for different variants, p.Arg854Gln (R854Q) being the most frequent causative one. There is limited data about the impact of 2N-variants on VWD2N phenotype and DDAVP-response. OBJECTIVES: To describe the phenotype of VWD2N, including DDAVP-response, according to genotype. PATIENTS/METHODS: VWD2N-patients with a complete genotype/phenotype characterization by the French reference center for VWD, including MCMDM-1VWD bleeding score (BS) were eligible to the study. Results of DDAVP-trial were also collected. RESULTS: A total of 123 VWD2N-patients from the French registry were included in this study. Results were stratified according to the presence (R854QPos, n=114) or absence (R854QNeg, n=9) of at least one R854Q-allele. Three R854QPos-subgroups were further individualized: patients homozygous (R854QHmz, n=55), compound heterozygous for R854Q and a null allele (R854Q/3, n=48) or compound heterozygous for R854Q and another 2N variant (R854Q/2N, n=11). FVIII: C levels were significantly lower in R854QNeg- and R854Q/3-patients compared to R854QHmz-ones (p<0.001 and p<0.0001 respectively). R854QNeg-patients were diagnosed earlier due to bleeding symptoms and had a higher BS than R854QPos-patients (p<0.001). In DDAVP-trial, FVIII:C survival was lower in VWD type 2N than in type 1. R854QPos-patients had a heterogeneous DDAVP-response, which was best predicted by baseline FVIII:C level. CONCLUSION: The heterogeneous genetic background of VWD2N drives different bleeding phenotypes and response patterns to DDAVP, underlining the clinical relevance of DDAVP-trial to identify patients potentially eligible to alternative therapeutic options.

Unravelling the Spectrum of von Willebrand Factor Variants in Quantitative Von Willebrand Disease: Results from a German Cohort Study.

INTRODUCTION: Von Willebrand disease (VWD), the most prevalent hereditary bleeding disorder, results from deficiency of von Willebrand factor (VWF). OBJECTIVES: This large cohort study aims to offer a comprehensive exploration of mutation spectra and laboratory features in quantitative VWF deficiencies, shedding light on genetic underpinnings and genotype-phenotype associations. PATIENTS/METHODS: Our cohort consisted of 221 Caucasian index patients with quantitative VWD, along with 47 individuals whose plasma VWF levels fell within the lower normal boundaries (50-70%). We conducted comprehensive VWF assays and genetic analyses, encompassing VWF gene sequencing, copy number variation investigations, and bioinformatic assessments. RESULTS: Following ISTH-SSC VWF guidelines, 77 index patients characterized as type 1 VWD (VWF:Ag < 30%), 111 as type 1 VWD (VWF:Ag 30-50%), and as 33 type 3 VWD. Mutation detection rates were 88%, 65%, and 92%, respectively. Notably, blood group O overrepresentation was evident in type 1 with VWF:Ag of 30-50%, particularly among mutation-negative patients, suggesting a potential causal role of blood group O. A total of 223 VWF variants, comprising 147 distinct variations, were identified in quantitative VWD patients, of which 57 were novel variants (39%). Additionally, approximately 70% of individuals with VWF levels within the lower normal boundaries (50-70%) displayed VWF variants. CONCLUSION: Our data advances our understanding of the molecular mechanisms underlying quantitative VWD, offering valuable insights for future research and clinical management. Distinct mutation patterns were observed among subgroups, particularly the contrast between type 1 VWD (VWF:Ag <30%) and type 1 (VWF:Ag 30-50%), an area with limited prior investigation.

R1205H (Vicenza) causes conformational changes in the VWF-D'D3 domains and enhances VWF binding to clearance receptors LRP1 and SR-A1.

INTRODUCTION: Von Willebrand factor (VWF)-R1205H variant (Vicenza) results in markedly enhanced VWF clearance in humans that has been shown to be largely macrophage-mediated. However, the biological mechanisms underlying this enhanced clearance remain poorly understood. This study aimed to investigate the roles of (i) specific VWF domains and (ii) different macrophage receptors in regulating enhanced VWF-R1205H clearance. METHODS: In vivo clearance of full-length and truncated wild-type (WT)-VWF and VWF with R1205 substitutions was investigated in VWF-/- mice. Plate-binding assays were employed to characterize VWF binding to purified scavenger receptor class A member 1 (SR-A1), low-density lipoprotein receptor-related protein-1 (LRP1) cluster II or cluster IV receptors, and macrophage galactose-type lectin (MGL). RESULTS: In full-length VWF missing the A1 domain (VWF-ΔA1), introduction of R1205H led to significantly enhanced clearance in VWF-/- mice compared to WT-VWF-ΔA1. Importantly, R1205H in a truncated VWF-D'D3 fragment also triggered increased clearance compared to WT-VWF-D'D3. Additional in vivo studies demonstrated that VWF-R1205K (which preserves the positive charge at 1205) exhibited normal clearance, whereas VWF-R1205E (which results in loss of the positive charge) caused significantly enhanced clearance, pinpointing the importance of the positive charge at VWF-R1205. In vitro plate-binding studies confirmed increased VWF-R1205H interaction with SR-A1 compared to WT-VWF. Furthermore, significantly enhanced VWF-R1205H binding to LRP1 cluster IV (p<0.001) and less marked enhanced binding to LRP1 cluster II (p=0.034) was observed. In contrast, VWF-R1205H and WT-VWF demonstrated no difference in binding affinity to MGL. CONCLUSION: Disruption of the positive charge at amino acid 1205 causes conformational changes in the VWF-D'D3 domains, and triggers enhanced LRP1 and SR-A1 mediated clearance.

Real-World Efficacy and Safety of Plasma-Derived Von Willebrand Factor-Containing Factor VIII Concentrates in Patients With Von Willebrand Disease in Italy.

Plasma-derived von Willebrand factor-containing factor VIII concentrates (pd-VWF/FVIII-C) are the mainstay of treatment in von Willebrand disease (VWD). Real-world data on efficacy and safety of these pd-VWF/FVIII-C are required. To retrospectively evaluate the efficacy and safety of pd-VWF/FVIII-C (Fanhdi® and Alphanate®, Grifols) in clinical practice in Italy. A multicentric, observational, retrospective study at 10 Italian centers was conducted. Eligible patients diagnosed with inherited VWD (ISTH criteria) were treated with either Fanhdi® or Alphanate® for bleeding episodes, prevention of surgical bleeding and secondary long-term prophylaxis (SLTP) according to clinical practice with medical records collected from January 2007 to December 2019. Efficacy/safety of pd-VWF/FVIII-C was assessed according to FDA-agreed objective criteria following regulatory procedures. Fifty-seven patients (M/F: 21/36) were enrolled in the study with the following VWD types: VWD1 (n = 29, 52%), VWD2A (n = 10, 18%), VWD2B (n = 7, 12%), VWD2M (n = 2, 4%), VWD2N (n = 1, 2%), VWD2 unclassified (n = 1, 2%), and VWD3 (n = 7, 12%). These pd-VWF/FVIII-C were used to manage 58 bleeding episodes (n = 24 patients), 100 surgeries (n = 47 patients), and 7 SLTP (n = 6 patients). Global clinical efficacy with these pd-VWF/FVIII-C was reported to be excellent/good in 85% of bleeding episodes, 98% of surgeries, and 100% of SLTP. As far as safety, no adverse-drug-related episodes, immunogenic or thrombotic events were reported. This study confirmed that Fanhdi® and Alphanate® were effective and safe in the management of bleeding episodes, the prevention of bleeding during surgeries and for SLTP in Italian patients with inherited VWD.

Review of interventions and effectiveness for heavy menstrual bleeding in women with moderate and severe von Willebrand disease.

INTRODUCTION: Women with VWD have an increased risk of gynaecological complications due to haemostatic challenges of menstruation. AIM: Review gynecological bleeding symptoms and their management in women with moderate-severe VWD. MATERIALS AND METHODS: Retrospective cohort analysis of prospectively collected data for women with moderate and severe VWD attending a joint multidisciplinary clinic between January 2010 and December 2020. Data was collected from electronic patient records on response to treatment options using PBAC, quality of life (QoL) assessment using SF-36 scores, haemoglobin and ferritin in comparison to pre-treatment values. RESULTS: Of the 67 women managed in the clinic; all reported heavy menstrual bleeding (HMB). Combination therapy with concurrent hormonal agents and tranexamic acid was required in 80% of women. There was an overall 64% improvement in PBAC scores in the first year, reflecting on QoL with 35% improvement in SF-36 score and correction of anaemia in 21% of cases. The cumulative effect of continued treatment culminated in greater reduction of blood loss, with an overall 71% improvement in PBAC scores by 5 years. One in 10 women required surgical treatment for a gynaecological pathology. Non-compliance was the cause of excessive unscheduled bleeding in 50% of adolescents. After 3 years, one in five women experienced a relapse of symptom, of whom 46% became perimenopausal and 54% discontinued hormonal treatments due to concerns about fertility, hair loss and weight gain. CONCLUSION: Management of HMB requires careful monitoring and follow-up by MDT with close collaboration between the gynaecology team and HTC. Control of HMB often requires a combination therapy.

von Willebrand factor antigen, von Willebrand factor propeptide and ADAMTS13 activity in TIA or ischaemic stroke patients changing antiplatelet therapy.

Data are limited on the impact of commencing antiplatelet therapy on von Willebrand Factor Antigen (VWF:Ag) or von Willebrand Factor propeptide (VWFpp) levels and ADAMTS13 activity, and their relationship with platelet reactivity following TIA/ischaemic stroke. In this pilot, observational study, VWF:Ag and VWFpp levels and ADAMTS13 activity were quantified in 48 patients ≤4 weeks of TIA/ischaemic stroke (baseline), and 14 days (14d) and 90 days (90d) after commencing aspirin, clopidogrel or aspirin+dipyridamole. Platelet reactivity was assessed at moderately-high shear stress (PFA-100® Collagen-Epinephrine / Collagen-ADP / INNOVANCE PFA P2Y assays), and low shear stress (VerifyNow® Aspirin / P2Y12, and Multiplate® Aspirin / ADP assays). VWF:Ag levels decreased and VWFpp/VWF:Ag ratio increased between baseline and 14d and 90d in the overall population (P ≤ 0.03). In the clopidogrel subgroup, VWF:Ag levels decreased and VWFpp/VWF:Ag ratio increased between baseline and 14d and 90d (P ≤ 0.01), with an increase in ADAMTS13 activity between baseline vs. 90d (P ≤ 0.03). In the aspirin+dipyridamole subgroup, there was an inverse relationship between VWF:Ag and VWFpp levels with both PFA-100 C-ADP and INNOVANCE PFA P2Y closure times (CTs) at baseline (P ≤ 0.02), with PFA-100 C-ADP, INNOVANCE PFA P2Y and C-EPI CTs at 14d (P ≤ 0.05), and between VWF:Ag levels and PFA-100 INNOVANCE PFA P2Y CTs at 90d (P = 0.03). There was a positive relationship between ADAMTS13 activity and PFA-100 C-ADP CTs at baseline (R2 = 0.254; P = 0.04). Commencing/altering antiplatelet therapy, mainly attributed to commencing clopidogrel in this study, was associated with decreasing endothelial activation following TIA/ischaemic stroke. These data enhance our understanding of the impact of VWF:Ag and VWFpp especially on ex-vivo platelet reactivity status at high shear stress after TIA/ischaemic stroke.

Hemostatic management of von Willebrand disease during childbirth with a plasma-derived von Willebrand factor/factor VIII concentrate.

BACKGROUND: Females with von Willebrand disease (VWD) do not show the same increases in von Willebrand factor and factor (F)VIII levels during pregnancy as females without VWD and are at higher risk of excessive bleeding associated with childbirth. Data on hemostatic management for childbirth in VWD patients are limited. OBJECTIVES: To evaluate the dosing, efficacy, and safety of plasma-derived von Willebrand factor/FVIII (wilate) for prevention of excessive bleeding associated with childbirth in females with any type of VWD. METHODS: Data for females with VWD who received wilate for hemostatic coverage for childbirth during 2 prospective clinical studies were analyzed. RESULTS: Ten females with VWD and a mean age at enrolment of 29.6 years were treated with wilate to prevent excessive bleeding associated with childbirth. Two patients had type 1, 4 had type 2 (2 2A, 1 2B, and 1 2M), and 4 had type 3 VWD. Of the 10 deliveries, 5 were by cesarean section. Patients received a mean of 9.5 infusions of wilate over 6.8 exposure days, with a mean total dose of 234 IU/kg per delivery and 25 IU/kg per infusion. Hemostatic management for all deliveries was rated excellent or good, with no excessive bleeding during delivery and no postpartum bleeding during the period of wilate treatment in any patient. Two patients experienced 8 possible or probable treatment-related adverse events; all were mild or moderate and resolved. No thromboembolic events were observed. CONCLUSION: The results of this case series indicate that wilate provided effective hemostatic cover for childbirth in females with VWD during delivery and postpartum.

Efficacy of a 1:1 ratio VWF/FVIII concentrate in patients with von Willebrand disease.

INTRODUCTION: Patients with von Willebrand disease (VWD) require administration of von Willebrand factor (VWF) concentrates peri-operatively. Concerns about FVIII accumulation after repetitive injections of a 1:1 ratio VWF/FVIII clotting factor concentrate (CFC) led this study to explore the recovery and FVIII accumulation over time. METHODS: This monocentre study examined patients with VWD receiving perioperative 1:1 ratio CFC infusions. CFC dosing was based on body weight and endogenous VWF/FVIII activity. FVIII and VWF activity was monitored at T0 (baseline), T1 (15 min postinfusion), and trough levels at T2-T6 (24-120 h). RESULTS: We included 125 patients, undergoing 125 procedures (63 major surgeries, 62 minor), with a median of two CFC infusions (IQR 1-3). With a mean administered dose of 35.7 IU/kg CFC, recovery rates of FVIII and VWF were 2.6 IU/dL per IU/kg and 2.4 IU/dL per IU/kg, respectively. Mean FVIII levels at T0 were 62 (SD 51.9), T1: 164 (SD 80.4), T2: 155 (SD 62.8), T3: 162 (SD 59.8), T4: 124 (SD 78.4), and T5: 120 (SD 65.3) IU/dL. Mean VWF activity levels at T0 were 29 (SD 25.0), T1: 133 (SD 43.7), T2: 92 (SD 37.2), and T3: 86 (SD 37.5) IU/dL. Subgroup analysis in 47 patients with more than three infusions, showed no accumulation of mean FVIII levels. CONCLUSION: This perioperative study demonstrated excellent FVIII and VWF recovery of a 1:1 ratio VWF product in patients with VWD. Stable FVIII and VWF activity levels were observed after repeated infusions, without accumulation. Most major surgeries required only three CFC infusions.

Exploring nonreplacement therapies' impact on hemophilia and other rare bleeding disorders.

The management of hemophilia, von Willebrand disease (VWD), and rare coagulation disorders traditionally relied on replacement therapies, such as factor concentrates, to address clotting factor deficiencies. However, in recent years, the emergence of nonreplacement therapies has shown promise as an adjunctive approach, especially in hemophilia, and also for patients with VWD and rare bleeding disorders. This review article offers an overview of nonreplacement therapies, such as FVIII-mimicking agents and drugs aimed at rebalancing hemostasis by inhibiting natural anticoagulants, particularly in the management of hemophilia. The utilization of nonreplacement therapies in VWD and rare bleeding disorders has recently attracted attention, as evidenced by presentations at the International Society on Thrombosis and Haemostasis 2023 Congress. Nonreplacement therapies provide alternative methods for preventing bleeding episodes and enhancing patients' quality of life, as many of them are administered subcutaneously and allow longer infusion intervals, resulting in improved quality of life and comfort for patients.

Exposure-Response Relationship between VWF/FVIII Activity and Spontaneous Bleeding Events Following Recombinant VWF Prophylaxis in Severe VWD.

Background Recombinant von Willebrand factor (rVWF, vonicog alfa, Takeda Pharmaceuticals USA) is indicated in adults diagnosed with von Willebrand disease (VWD). In this study, the exposure-response (ER) relationship between VWF activity (VWF:RCo) or factor VIII activity (FVIII:C) and spontaneous bleeding events (BEs) was evaluated in adults with severe VWD receiving rVWF prophylaxis for up to 1 year. Methods This secondary analysis included 23 patients receiving rVWF prophylaxis in the open-label, phase 3 prophylaxis trial (NCT02973087). Population pharmacokinetic (PK) and PK/pharmacodynamic (PD) models were used to characterize VWF activity and endogenous FVIII:C, and PK/PD simulations were linked to spontaneous BEs to develop an ER model. Results None of the five patients with VWD types 1 or 2A/B experienced spontaneous BEs. Five of 18 patients with VWD type 3 experienced ≥1 spontaneous BEs. An ER relationship was observed whereby higher VWF:RCo levels were associated with a numerically lower spontaneous BE risk ( p < 0.10). This relationship was independent of patients' pretrial VWF treatment. A statistically significant ER relationship was observed after accounting for relevant data (average ± standard error exposure estimate for VWF:RCo over 24 hours prior to the spontaneous BE: -0.043 ± 0.021, p = 0.041). The model-generated hazard ratio for a 10 IU/dL increment in the average exposure of VWF:RCo 24 hours before a spontaneous BE was 0.651 (95% confidence interval: 0.431-0.982). Conclusions This ER analysis suggests a causal association between VWF:RCo and spontaneous BEs, with an increase of VWF:RCo exposure leading to a decrease in spontaneous BE risk.

Hemoglobin concentration and body mass index are determinants of plasma von Willebrand factor and factor VIII levels.

BACKGROUND: Von Willebrand Disease (VWD) is the most common inherited bleeding disorder. VWD is characterized by an abnormal quantity or quality of von Willebrand Factor (VWF). Anemia is often found at presentation for a bleeding disorder evaluation due to chronic blood loss. OBJECTIVES/HYPOTHESIS: We hypothesized that anemia is associated with elevations in both VWF and factor VIII (FVIII) over baseline. We also hypothesized that obesity would be associated with increased levels of VWF. METHODS: We conducted a single-center review of the electronic health record for patients that had proximal von Willebrand profiles and Hb data. RESULTS: We identified 4552 unique subjects with VWF studies and a CBC within 24 h. We found that decreasing hemoglobin inversely correlated with VWF antigen, VWF ristocetin cofactor activity, and FVIII activity. We also found that obesity and Black race were independently associated with increased VWF antigen, activity, and FVIII activity. Hb, race, and body mass index (BMI) continued to be determinants of VWF and FVIII levels in multivariable analysis. CONCLUSION: Our study demonstrates that anemia, race, and BMI were found to be associated with elevation of VWF antigen, VWF activity, and FVIII levels. As many individuals with anemia present for evaluation for a bleeding disorder, these variables need to be considered. KEY POINTS: - Anemia was found to be associated with elevation of VWF antigen, VWF activity and FVIII levels. - Testing von Willebrand factor at times of anemia may mask a diagnosis of von Willebrand Disease.

Isaridin E Protects against Sepsis by Inhibiting Von Willebrand Factor-Induced Endothelial Hyperpermeability and Platelet-Endothelium Interaction.

Endothelial hyperpermeability is pivotal in sepsis-associated multi-organ dysfunction. Increased von Willebrand factor (vWF) plasma levels, stemming from activated platelets and endothelium injury during sepsis, can bind to integrin αvß3, exacerbating endothelial permeability. Hence, targeting this pathway presents a potential therapeutic avenue for sepsis. Recently, we identified isaridin E (ISE), a marine-derived fungal cyclohexadepsipeptide, as a promising antiplatelet and antithrombotic agent with a low bleeding risk. ISE's influence on septic mortality and sepsis-induced lung injury in a mouse model of sepsis, induced by caecal ligation and puncture, is investigated in this study. ISE dose-dependently improved survival rates, mitigating lung injury, thrombocytopenia, pulmonary endothelial permeability, and vascular inflammation in the mouse model. ISE markedly curtailed vWF release from activated platelets in septic mice by suppressing vesicle-associated membrane protein 8 and soluble N-ethylmaleide-sensitive factor attachment protein 23 overexpression. Moreover, ISE inhibited healthy human platelet adhesion to cultured lipopolysaccharide (LPS)-stimulated human umbilical vein endothelial cells (HUVECs), thereby significantly decreasing vWF secretion and endothelial hyperpermeability. Using cilengitide, a selective integrin αvß3 inhibitor, it was found that ISE can improve endothelial hyperpermeability by inhibiting vWF binding to αvß3. Activation of the integrin αvß3-FAK/Src pathway likely underlies vWF-induced endothelial dysfunction in sepsis. In conclusion, ISE protects against sepsis by inhibiting endothelial hyperpermeability and platelet-endothelium interactions.

Laparoscopic liver resection for a patient of hepatocellular carcinoma with von Willebrand disease: a case report.

BACKGROUND: The safety of laparoscopic hepatectomy for inherited coagulation disorders is unclear; however, the safety of open hepatectomy has been reported in several studies. Herein, we report the first case of a laparoscopic hepatectomy for a patient with von Willebrand Disease (VWD). CASE PRESENTATION: A 76-year-old male with a history of chronic hepatitis C and VWD type 2B was advised surgical resection of a 4 cm hepatocellular carcinoma in segment 7 of the liver. The patient was diagnosed with VWD in his 40 s due to gastrointestinal bleeding caused by gastric erosion. The von Willebrand factor (VWF) ristocetin cofactor activity was 30%, and VWF large multimer deficiency and increased ristocetin-induced platelet agglutination were observed. The preoperative platelet count was reduced to 3.5 × 104/µL; however, preoperative imaging findings had no evidence of liver cirrhosis, such as any collateral formations and splenomegaly. The indocyanine green retention rate at 15 min was 10%, and his Child-Pugh score was 5 (classification A). Perioperatively, VWF/factor VIII was administered in accordance with our institutional protocol. A laparoscopic partial hepatectomy of the right posterior segment was performed. The most bleeding during surgery occurred during the mobilization of the right lobe of the liver due to inflammatory adhesion between the retroperitoneum and the tumor. Bleeding during parenchymal transection was controlable. The duration of hepatic inflow occlusion was 65 min. The surgical duration was 349 min, and the estimated blood loss was 2150 ml. Four units of red blood cells and fresh frozen plasma were transfused at the initiation of parenchymal transection, and 10 units of platelets were transfused at the end of the parenchymal transection. On postoperative day 1, the transection surface drainage fluid became hemorrhagic, and emergency contrast-enhanced computed tomography showed extravasation in the greater omentum. Percutaneous transcatheter arterial embolization of the omental branch of the right gastroepiploic artery was performed. No further postoperative interventions were required. The patient was discharged on postoperative day 14. CONCLUSION: The indications for laparoscopic hepatectomy in patients with VWD should be carefully considered, and an open approach may still be the standard approach for patients with VWD.

Procoagulant phenotype of virus-infected pericytes is associated with portal thrombosis and intrapulmonary vascular dilations in fatal COVID-19.

BACKGROUND & AIMS: Mechanisms and clinical impact of portal microthrombosis featuring severe COVID-19 are unknown. Intrapulmonary vascular dilation (IPVD)-related hypoxia has been described in severe liver diseases. We hypothesized that portal microthrombosis is associated with IPVD and fatal respiratory failure in COVID-19. METHODS: Ninety-three patients who died from COVID-19, were analysed for portal microvascular damage (histology), IPVD (histology and chest-computed tomography, CT), and hypoxemia (arterial blood gas). Seventeen patients who died from COVID-19-unrelated pneumonia served as controls. Vascular lesions and microthrombi were phenotyped for endothelial (vWF) and pericyte (αSMA/PDGFR-ß) markers, tissue factor (TF), viral spike-protein and nucleoprotein (SP, NP), fibrinogen, platelets (CD41a). Viral particles in vascular cells were assessed by transmission electron microscopy (TEM). Cultured pericytes were infected with SARS-CoV-2 to measure TF expression and tubulisation of human pulmonary microvascular endothelial cells (HPMEC) was assessed upon vWF treatment. RESULTS: IPVD was present in 16/66 COVID-19 patients with both liver and lung histology, with a younger age (62 vs 78yo), longer illness (25 vs 14 days), worsening hypoxemia (PaO2/FiO2 from 209 to 89), and more ventilatory support (63 vs 22%) compared to COVID-19/Non-IPVD. IPVD, absent in controls, were confirmed by chest-CT. COVID-19/IPVD liver histology showed portal microthrombosis in >82.5% of portal areas, with a thicker wall of αSMA/PDGFR-ß+/ SP+/NP+ pericytes compared with COVID-19/Non-IPVD. Thrombosed portal venules correlated with αSMA+ area, whereas infected SP+/NP+ pericytes expressed TF. SARS-CoV-2 viral particles were observed in portal pericytes. In-vitro SARS-CoV-2 infection of pericytes up-regulated TF and induced endothelial cells to overexpress vWF, which expanded HPMEC tubules. CONCLUSIONS: SARS-CoV-2 infection of liver pericytes elicits a local procoagulant response associated with extensive portal microthrombosis, IPVD and worsening respiratory failure in fatal COVID-19. IMPACT AND IMPLICATIONS: Vascular involvement of the liver represents a serious complication of COVID-19 infection that must be considered in the work-up of patients with long-lasting and progressively worsening respiratory failure, as it may associate with the development of intrapulmonary vascular dilations. This clinical picture is associated with a pro-coagulant phenotype of portal venule pericytes, which is induced by SARS-CoV-2 infection of pericytes. Both observations provide a model that may apply, at least in part, to other vascular disorders of the liver, featuring obliterative portal venopathy, similarly characterized at the clinical level by development of hypoxemia and at the histological level, by phlebosclerosis and reduced caliber of the portal vein branches in the absence of cirrhosis. Moreover, our findings bring light to an as yet overlooked player of thrombosis pathophysiology, i.e. pericytes, which may provide novel therapeutic tools to halt prothrombotic mechanisms.