Direct tumoral puncture embolization of onyx before endoscopic endonasal resection of a massive juvenile angiofibroma for a patient with Von Willebrand disease - A case report and review of literature.

INTRODUCTION: Standard treatment of a juvenile angiofibroma (JNA) is surgical resection, usually with an endoscopic endonasal surgery and a preoperative embolization. However, standard intra-arterial embolization may fail to completely devascularize tumors. A novel technique of direct intranasal intratumoral onyx embolization has been described. The aim of this study is to demonstrate the safety and the usefulness of this embolization technique on a pediatric case of JNA and to compare our results to previously reported cases. PRESENTATION OF CASE: A twelve-year-old patient suffering from Von Willebrand disease presented with a voluminous JNA with intracranial extension. Internal carotid artery (ICA) branches partially vascularized the tumor. The patient had two previous incomplete surgical resections, which were preceded by a standard embolization, due to massive perioperative bleeding. DISCUSSION: A direct intratumoral embolization of onyx safely allowed complete tumoral devascularization. Tumoral resection was then completed by an endonasal endoscopic approach. Surgery time was decreased (4,5 h versus 5,5 and 6,5 h) and blood loss were minimized (300 ml versus 1 l and 1,3 l). No complication occurred. Twelve articles previously reported this embolization technique. We present the first reported case of onyx embolization being used for a pediatric patient with a coagulation disorder and a voluminous tumor. CONCLUSION: A direct intratumoral onyx embolization allowed complete resection of a massive JNA, for a patient with Von Willebrand disease. Our data suggest that this technique is safe and may be instrumental for a JNA's resection, even if little vascularization comes from ICA branches.

Mitral regurgitation is associated with similar loss of von Willebrand factor large multimers but lower frequency of anemia compared with aortic stenosis.

Background: Various cardiovascular diseases cause acquired von Willebrand syndrome (AVWS), which is characterized by a decrease in high-molecular-weight (large) von Willebrand factor (VWF) multimers. Mitral regurgitation (MR) has been reported as a cause of AVWS. However, much remains unclear about AVWS associated with MR. Objectives: To evaluate VWF multimers in MR patients and examine their impact on clinical characteristics. Methods: Moderate or severe MR patients (n = 84) were enrolled. VWF parameters such as the VWF large multimer index (VWF-LMI), a quantitative value that represents the amount of VWF large multimers, and clinical data were prospectively analyzed. Results: At baseline, the mean hemoglobin level was 12.9 ± 1.9 g/dL and 58 patients (69.0%) showed loss of VWF large multimers defined as VWF-LMI < 80%. VWF-LMI in patients with degenerative MR was lower than in those with functional MR. VWF-LMI appeared to be restored the day after mitral valve intervention, and the improvement was maintained 1 month after the intervention. Seven patients (8.3%) had a history of bleeding, 6 (7.1%) of whom had gastrointestinal bleeding. Gastrointestinal endoscopy was performed in 23 patients (27.4%) to investigate overt gastrointestinal bleeding, anemia, etc. Angiodysplasia was detected in 2 of the 23 patients (8.7%). Conclusion: Moderate or severe MR is frequently associated with loss of VWF large multimers, and degenerative MR may cause more severe loss compared with functional MR. Mitral valve intervention corrects the loss of VWF large multimers. Gastrointestinal bleeding may be relatively less frequent and hemoglobin level remains stable in MR patients.

Evaluation of an automated von Willebrand factor glycoprotein IbM activity assay compared with 3 alternative von Willebrand factor activity assays.

Background: To overcome deficiencies of the traditional von Willebrand factor (VWF) ristocetin cofactor activity assay (VWF:RCo), several automated assays for VWF platelet-binding activity have been developed. Information on the performance of these assays and their diagnostic utility remains limited. Objectives: To validate the VWF:glycoprotein IbM assay INNOVANCE VWF Ac and compare it with an automated VWF:RCo assay as well as with an automated assay and a manual VWF:Ab assay and to generate reference ranges and analyze reproducibility of the VWF:glycoprotein IbM assay. Methods: Clinical sites enrolled healthy subjects and patients representing the intended use population; VWF activity assays were performed, and results were analyzed. The performance of the INNOVANCE VWF Ac assay was also compared between the BCS XP System and the CS-2500 and CS-5100 analyzers. Results: The INNOVANCE VWF Ac assay correlated well with the VWF:RCo assay and the automated HemosIL VWF:Ab assay, with Pearson coefficients of >.9 and a predicted bias of ≤5.0 IU/dL at VWF levels of 30 IU/dL and ≤5.8 IU/dL at the levels of 50 IU/dL, but correlation and bias were not as good when compared with the REAADS manual VWF:Ab assay. Reference ranges observed for healthy subjects correlated well with previously published findings. Reproducibility of the INNOVANCE VWF Ac assay on the BCS XP System and the CS analyzers was excellent, as was correlation among devices. Conclusion: The characteristics of the INNOVANCE VWF Ac assay regarding comparability with other VWF activity assays, reference ranges, and precision support the use of this assay for evaluation of patients with concern for von Willebrand disease.

Oral surgery in people with inherited bleeding disorder: A retrospective study.

INTRODUCTION: The objectives were to describe the peri-operative management of people with inherited bleeding disorders in oral surgery and to investigate the association between type of surgery and risk of developing bleeding complications. MATERIALS AND METHODS: This retrospective observational study included patients with haemophilia A or B, von Willebrand disease, Glanzmann thrombasthenia or isolated coagulation factor deficiency such as afibrinogenemia who underwent osseous (third molar extraction, ortho-surgical traction, dental implant placement) or nonosseous oral surgery between 2014 and 2021 at Bordeaux University Hospital (France). Patients and oral surgery characteristics were retrieved from medical records. Odds ratio (OR) and 95% confidence interval (CI) were estimated using logistic regression. RESULTS: Of the 83 patients included, general anaesthesia was performed in 16%. Twelve had a bleeding complication (14.5%) including six after osseous surgery. The most serious complication was the appearance of anti-FVIII inhibitor in a patient with moderate haemophilia A. All bleeding complications were managed by a local treatment and factor injections where indicated. No association was observed between type of surgery (osseous vs. nonosseous) and risk of bleeding complications after controlling for sex, age, disease type and severity, multiple extractions, type of anaesthesia and use of fibrin glue (OR: 3.21, 95% CI: .69-14.88). CONCLUSION: In this study, we have observed that bleeding complications after oral surgery in people with inherited bleeding disorders were moderately frequent and easily managed. However, in this study, we observed a serious complication highlighting the necessity of a thorough benefit-risk balance evaluation during the preoperative planning of the surgical and medical protocol.

Ratio of von Willebrand factor to ADAMTS13 is a useful predictor of esophagogastric varices progression after sustained virologic response in patients with hepatitis C virus-related liver cirrhosis.

AIM: Esophagogastric varices (EGV) are a serious complication of hepatitis C virus (HCV)-related liver cirrhosis (HCV-LC). In most cases, portal hypertension improves after a sustained virologic response (SVR) is achieved with direct-acting antiviral (DAA) treatment; however, in some cases, EGV exacerbation occurs after HCV elimination. We investigated whether von Willebrand factor (VWF) and a disintegrin-like metalloproteinase with thrombospondin type-1 motif 13 (ADAMTS13) can predict EGV progression with HCV-LC after SVR achievement. METHODS: This retrospective study enrolled 47 patients with HCV-LC who achieved an SVR after DAA treatment. Eighteen patients experienced EGV progression after the SVR was achieved (EGV progression group). Twenty-nine patients did not experience EGV progression after the SVR was achieved (non-EGV progression group). Plasma VWF antigen levels and ADAMTS13 activity were measured the day before DAA treatment. RESULTS: The EGV progression group had significantly higher plasma VWF antigen levels (p = 0.00331) and VWF-to-ADAMTS13 ratios (p = 0.000249) than the non-EGV progression group. Multivariate logistic regression models found that a VWF-to-ADAMTS13 ratio >2.3 was the only risk factor for EGV progression after the SVR was achieved (hazard ratio [HR], 18.4; 95% confidence interval [CI], 3.08-109; p = 0.00138). During the observation period, patients with a VWF-to-ADAMTS13 ratio >2.3 had a significantly higher cumulative incidence of EGV progression after SVR achievement than patients with a VWF-to-ADAMTS13 ratio ≤2.3 (HR, 6.4; 95% CI, 1.78-22.96; p = 0.0044). CONCLUSIONS: The VWF-to-ADAMTS13 ratio before DAA treatment for HCV could predict EGV progression after SVR achievement.

Magnetic resonance imaging-guided focused ultrasound thalamotomy for essential tremor in a patient with von Willebrand disease: perioperative optimization for patients with coagulopathies. Illustrative case.

BACKGROUND: Essential tremor (ET) is one of the most common movement disorders worldwide. In medically refractory ET, deep brain stimulation (DBS) of the ventral intermediate nucleus of the thalamus is the current standard of care. However, DBS carries an inherent 2% to 3% risk of hemorrhage, a risk that can be much higher in patients with concomitant coagulopathy. Magnetic resonance imaging-guided focused ultrasound (MRgFUS) thalamotomy is a surgical alternative that is highly effective in treating ET, with no reports of intracranial hemorrhage to date. OBSERVATIONS: This is the first documented case of successful MRgFUS thalamotomy in a patient with von Willebrand disease (VWD). A 60-year-old left-handed male had medically refractory ET, VWD type 2B, and a family history of clinically significant hemorrhage after DBS. He underwent right-sided MRgFUS thalamotomy and received a perioperative course of VONVENDI (recombinant von Willebrand factor) to ensure appropriate hemostasis. Postprocedure imaging confirmed a focal lesion in the right thalamus without evidence of hemorrhage. The patient reported 90% improvement of his left-hand tremor and significant improvement in his quality of life without obvious side effects. LESSONS: MRgFUS thalamotomy with peri- and postoperative hematological management is a promising alternative to DBS for patients with underlying coagulopathies.

Von Willebrand's disease in breast surgery: case report.

Von Willebrand disease is an inherited disorder characterized by deficiency of von Willebrand factor, which contributes to platelet adhesion to the endothelium. Patients with coagulation disorders present a challenge at the time of surgery due to the high risk of presenting heavy bleeding within the procedure or postoperative hematomas. We present a case of a 56-year-old woman with Type 1 von Willebrand's disease who was scheduled for breast explantation with autologous reconstruction, due to the presence of long-standing breast implants. The case was satisfactorily managed by a multidisciplinary team formed by plastic surgery, hematology, and anesthesiology, individualizing the management for the patient's case, obtaining good results and a safe procedure.

Daytime plasma cortisol and cortisol response to dexamethasone suppression are associated with a prothrombotic state in hypertension.

Background and aims: A prothrombotic state was demonstrated in patients with Cushing's syndrome and is involved in the development and progression of cardiovascular and renal damage in hypertensive patients. This study was designed to examine the relationships between cortisol secretion and the hemostatic and fibrinolytic systems in hypertension. Methods: In 149 middle-aged, nondiabetic, essential hypertensive patients free of cardiovascular and renal complications, we measured hemostatic markers that express the spontaneous activation of the coagulation and fibrinolytic systems and assessed daily cortisol levels (8 AM, 3 PM, 12 AM; area under the curve, AUC-cortisol) together with the cortisol response to dexamethasone overnight suppression (DST-cortisol). Results: Plasma levels of D-dimer (D-dim), prothrombin fragment 1 + 2 (F1 + 2), and von Willebrand factor (vWF) were progressively and significantly higher across tertiles of AUC-cortisol and DST-cortisol, whereas no differences were observed in fibrinogen, tissue plasminogen activator, plasminogen activator inhibitor-1, antithrombin III, protein C, and protein S. D-dim, F1 + 2, and vWF were significantly and directly correlated with age and both AUC-cortisol and DST-cortisol. Multivariate regression analysis showed that both AUC-cortisol and DST-cortisol were related to plasma D-dim, F1 + 2, and vWF independently of age, body mass index, blood pressure, and renal function. Conclusion: Greater daily cortisol profile and cortisol response to overnight suppression are independently associated with a prothrombotic state in hypertensive patients and might contribute to the development of organ damage and higher risk of cardiovascular complications.

Diversification of von Willebrand Factor A and Chitin-Binding Domains in Pif/BMSPs Among Mollusks.

Pif is a shell matrix protein (SMP) identified in the nacreous layer of Pinctada fucata (Pfu) comprised two proteins, Pif97 and Pif 80. Pif97 contains a von Willebrand factor A (VWA) and chitin-binding domains, whereas Pif80 can bind calcium carbonate crystals. The VWA domain is conserved in the SMPs of various mollusk species; however, their phylogenetic relationship remains obscure. Furthermore, although the VWA domain participates in protein-protein interactions, its role in shell formation has not been established. Accordingly, in the current study, we investigate the phylogenetic relationship between PfuPif and other VWA domain-containing proteins in major mollusk species. The shell-related proteins containing VWA domains formed a large clade (the Pif/BMSP family) and were classified into eight subfamilies with unique sequential features, expression patterns, and taxa diversity. Furthermore, a pull-down assay using recombinant proteins containing the VWA domain of PfuPif 97 revealed that the VWA domain interacts with five nacreous layer-related SMPs of P. fucata, including Pif 80 and nacrein. Collectively, these results suggest that the VWA domain is important in the formation of organic complexes and participates in shell mineralisation.

Navigating the challenges: a case report on managing a complicated postpartum course in type 3 von Willebrand disease with alloantibodies.

Background: Von Willebrand disease (VWD) type 3 is characterized by a complete deficiency of von Willebrand factor (VWF), resulting in a severe bleeding phenotype. Treatment often requires administration of VWF concentrates/factor (F)VIII. However, the development of alloantibodies is a rare complication, resulting in ineffective recovery and allergic reactions. Emicizumab, a bispecific antibody mimicking FVIII function, has emerged as a potential alternative, with promising results reported in several case reports. Key Clinical Question: Description of multiple approaches to control highly severe postpartum hemorrhage in type 3 VWD with alloantibodies, including off-label use of emicizumab. Clinical Approach: Here we present a 28-year-old patient with type 3 VWD and alloantibodies, known to have arthropathy of the right elbow. Previous immune tolerance induction was unsuccessful. Despite receiving negative pregnancy advice during preconception counseling, the patient became pregnant. Delivery was induced at 38 4/7 weeks with prostaglandin, and recombinant FVIIa (rFVIIa) was administered every 2 hours. Despite administration of rFVIIa, bleeding persisted, requiring manual placental removal and insertion of a Bakri balloon. Since bleeding persisted, plasma-derived VWF was administered with an initial excellent recovery and successful embolization of the uterine artery. Twelve days postpartum, she developed endometritis and recurrent vaginal bleeding treated with antibiotics, rFVIIa every 2 hours, and multiple erythrocyte transfusions. Plasma-derived VWF was administered but was complicated by anaphylaxis and no recovery. Due to persistent vaginal bleeding, reembolization of uterine arteries was performed and off-label emicizumab was initiated. Twenty-nine days postpartum, she developed septic shock requiring an abdominal hysterectomy, again complicated by severe bleeding necessitating direct intraabdominal packing after rFVIIa. A computed tomography scan 9 days postsurgery revealed thrombosis in the left iliac vein and asymptomatic pulmonary embolisms. rFVIIa was stopped and prophylactic low-molecular-weight heparin was started. The patient was discharged 2 months after delivery on low-dose low-molecular-weight heparin, emicizumab, and antibiotics for an intra-abdominal abscess. During 2.5 years of emicizumab prophylaxis, she has had no rebleeding in her arthropathic right elbow. Conclusion: The current case emphasizes the postpartum clinical challenges of patients with type 3 VWD and alloantibodies. It underscores the potential role of emicizumab in maintaining hemostatic control.

Orthognathic Surgery in Patients With Von Willebrand's Disease: A Report of Four Cases and Literature Review.

Von Willebrand's disease (VWD), characterized by quantitatively or qualitatively abnormal von Willebrand factor (VWF), is the most common inherited bleeding disorder. There is limited evidence of treatment using orthognathic surgery in patients with VWD. This report focuses on four patients with VWD who underwent orthognathic surgery and received Factor VIII/VWF concentrates (Confact F) preoperatively. One patient with type 3 (severe) VWD underwent delayed extubation owing to laryngeal edema and exhibited epistaxis thereafter. No perioperative complications were observed in any of the other patients. Two of the four patients were diagnosed with VWD during preoperative screening. Most young adults do not experience general anesthesia and, therefore, may not have undergone blood tests at a hospital. Thus, preoperative screening and adoption of a multidisciplinary approach to orthognathic surgery is important in patients with bleeding disorders such as VWD. Close communication between anesthetists, surgeons, and hematologists is essential to ensure effective management during the perioperative period.

Removal of endothelial surface-associated von villebrand factor suppresses accelerate datherosclerosis after myocardial infarction.

BACKGROUND: Thromboinflammation involving platelet adhesion to endothelial surface-associated von Willebrand factor (VWF) has been implicated in the accelerated progression of non-culprit plaques after MI. The aim of this study was to use arterial endothelial molecular imaging to mechanistically evaluate endothelial-associated VWF as a therapeutic target for reducing remote plaque activation after myocardial infarction (MI). METHODS: Hyperlipidemic mice deficient for the low-density lipoprotein receptor and Apobec-1 underwent closed-chest MI and were treated chronically with either: (i) recombinant ADAMTS13 which is responsible for proteolytic removal of VWF from the endothelial surface, (ii) N-acetylcysteine (NAC) which removes VWF by disulfide bond reduction, (iii) function-blocking anti-factor XI (FXI) antibody, or (iv) no therapy. Non-ischemic controls were also studied. At day 3 and 21, ultrasound molecular imaging was performed with probes targeted to endothelial-associated VWF A1-domain, platelet GPIbα, P-selectin and vascular cell adhesion molecule-1 (VCAM-1) at lesion-prone sites of the aorta. Histology was performed at day 21. RESULTS: Aortic signal for P-selectin, VCAM-1, VWF, and platelet-GPIbα were all increased several-fold (p < 0.01) in post-MI mice versus sham-treated animals at day 3 and 21. Treatment with NAC and ADAMTS13 significantly attenuated the post-MI increase for all four molecular targets by > 50% (p < 0.05 vs. non-treated at day 3 and 21). On aortic root histology, mice undergoing MI versus controls had 2-4 fold greater plaque size and macrophage content (p < 0.05), approximately 20-fold greater platelet adhesion (p < 0.05), and increased staining for markers of platelet transforming growth factor-ß1 signaling. Accelerated plaque growth and inflammatory activation was almost entirely prevented by ADAMTS13 and NAC. Inhibition of FXI had no significant effect on molecular imaging signal or plaque morphology. CONCLUSIONS: Plaque inflammatory activation in remote arteries after MI is strongly influenced by VWF-mediated platelet adhesion to the endothelium. These findings support investigation into new secondary preventive therapies for reducing non-culprit artery events after MI.

Deciphering the triad of endothelial glycocalyx, von Willebrand Factor, and P-selectin in inflammation-induced coagulation.

This review examines the endothelial glycocalyx's role in inflammation and explores its involvement in coagulation. The glycocalyx, composed of proteins and glycosaminoglycans, interacts with von Willebrand Factor and could play a crucial role in anchoring it to the endothelium. In inflammatory conditions, glycocalyx degradation may leave P-selectin as the only attachment point for von Willebrand Factor, potentially leading to uncontrolled release of ultralong von Willebrand Factor in the bulk flow in a shear stress-dependent manner. Identifying specific glycocalyx glycosaminoglycan interactions with von Willebrand Factor and P-selectin can offer insights into unexplored coagulation mechanisms.

Retrospective chart review of GI bleeding in people with von Willebrand disease.

INTRODUCTION: Gastrointestinal (GI) bleeding events (BEs) in von Willebrand disease (VWD) are difficult to diagnose and often recurrent. Limited data from clinical trials has led to lack of consensus on treatment options. AIM: Describe current treatments and outcomes for GI BEs in people with VWD. METHODS: This retrospective, observational, multicentre chart review study was conducted from January 2018 through December 2019 and included patients with inherited VWD with ≥1 GI BE in the preceding 5 years. Baseline characteristics, number and aetiology of BEs, associated GI-specific morbidities/lesions, treatment and outcomes were analysed descriptively. RESULTS: Sixty bleeds were reported in 20 patients with type 1 (20%), type 2 (50%) and type 3 (30%) VWD. During the 5-year study period, 31 (52%) BEs had one identified or suspected cause; multiple causes were reported in 11 (18%). Most GI BEs (72%) were treated with a combination of von Willebrand factor (VWF), antifibrinolytics and/or other haemostatic or non-haemostatic treatments. Time to resolution did not differ by VWF treatment use; however, BEs treated with non-VWF treatments tended to resolve later. In patients with GI-specific morbidities/lesions, 84% resolved with first-line treatment; time to resolution tended to be longer than in patients without such morbidities/lesions. Thirteen BEs occurred in patients receiving prophylaxis and 47 in patients receiving on-demand treatment; 18 BEs resulted in a switch to prophylaxis after bleed resolution. CONCLUSIONS: This study confirms the unmet need for the management of recurrent GI BEs in people with VWD and the need for prospective data, especially on prophylaxis.

Retrospectively diagnosed autoimmune VWF deficiency in a patient with repeated hemorrhagic events after two common colds.

Autoimmune von Willebrand factor (VWF) deficiency (AiVWFD) caused by anti-VWF autoantibodies is a rare bleeding disorder, whereas "non-immune" acquired von Willebrand syndrome (AVWS) caused by other etiologies is more common. Therefore, only 40 patients with AiVWFD have been identified in Japan through an ongoing nationwide survey on autoimmune coagulation factor deficiencies. This may be due to the inability to efficiently detect anti-VWF antibodies, as anti-VWF antibody testing is not routine. An 80-year-old Japanese woman developed AVWS and experienced bleeding after two separate common colds. She took the same cold medicine each time and recovered spontaneously after discontinuation of the medicine. Severe VWF deficiency normalized each time. Initial immunological tests did not detect anti-VWF autoantibodies, and thus a diagnosis of "non-immune" AVWS of unknown origin was made. However, after 6 years, new ELISA assays using purified VWF proteins detected free anti-VWF autoantibodies, which led to a retrospective diagnosis of AiVWFD. It is probable that the cold medicine (and/or cold virus infection) induced the autoantibodies, as the recurrence and normalization of the same coagulation abnormality and the clinical course (including drug administration and discontinuation) were completely synchronized. If AiVWFD is suspected, highly sensitive autoantibody tests should be performed.

Impact of extracorporeal membrane oxygenation treatments on acquired von Willebrand syndrome in patients with out-of-hospital cardiac arrest: a retrospective observational study.

BACKGROUND: Von Willebrand factor (vWF) plays a crucial role in hemostasis, acting as a key factor for platelet adhesion/aggregation and as a transport protein for coagulation factor VIII. vWF is secreted as a giant multimer, and it undergoes shear stress-dependent cleavage by a specific metalloproteinase in plasma. Among vWF multimers, high-molecular-weight (large) multimers are essential for hemostasis. Acquired von Willebrand syndrome, linked to various conditions, is a hemostatic disorder due to reduced vWF activity. Extracorporeal membrane oxygenation (ECMO), utilized recently for out-of-hospital cardiac arrest patients, generates high shear stress inside the pump. This stress may induce a conformational change in vWF, enhancing cleavage by a specific metalloproteinase and thereby reducing vWF activity. However, no study has investigated the effects of ECMO on vWF-related factors in patients receiving or not receiving ECMO. This study aimed to elucidate the relationship between ECMO treatment and acquired von Willebrand syndrome-related factors in patients with out-of-hospital cardiac arrest. METHODS: This study included patients with cardiogenic out-of-hospital cardiac arrest admitted to our hospital. The patients were categorized into two groups (ECMO and non-ECMO) based on the presence or absence of ECMO treatment. Plasma samples were collected from patients admitted to the emergency department (days 0-4). The vWF antigen (vWF: Ag), vWF ristocetin cofactor activity (vWF: RCo), and factor VIII activity were measured. Additionally, a large multimer of vWF was evaluated through vWF multimer analysis, utilizing western blotting to probe vWF under non-reducing conditions. RESULTS: The ECMO and non-ECMO groups included 10 and 22 patients, respectively. The median ECMO treatment in the ECMO group was 64.6 h. No differences in vWF: Ag or factor VIII activity were observed between the two groups during the observation period. However, the ECMO group exhibited a decrease in large vWF multimers and vWF: RCo during ECMO. Strong correlations were observed between vWF: RCo and vWF: Ag in both groups, although the relationships were significantly different between the two groups. CONCLUSIONS: ECMO treatment in patients with out-of-hospital cardiac arrest resulted in the loss of large vWF multimers and decreased vWF activity. Hence, decreased vWF activity should be considered as a cause of bleeding during ECMO management.

Relationship between thrombus vWF and NETs with clinical severity and peripheral blood immunocytes' indicators in patients with acute ischemic stroke.

OBJECTIVE: To investigate the association between von Willebrand factor (vWF) and neutrophil extracellular traps (NETs) in thrombus with clinical severity and peripheral blood immunocytes' indicators in patients with early-stage acute ischemic stroke (AIS). METHODS: A retrospective study was conducted using the clinical data of 66 patients with AIS who underwent endovascular mechanical thrombectomy and had their thrombus samples collected. The concentrations of vWF and NETs in the thrombus samples were quantitatively assessed. Peripheral blood samples taken in the early stages of the disease were analyzed for total white blood cell counts (WBC), ratios of neutrophils (NEU%), lymphocytes (LYM%), eosinophils (EOS%), and monocytes (MONO%). The severity of clinical symptoms in these patients was evaluated using the modified Rankin Scale (mRS), Essen Stroke Risk Score (ESRS), Barthel Index (BI), and National Institute of Health Stroke Scale (NIHSS). RESULTS: Higher vWF levels in thrombus were associated with lower NIHSS scores, while higher NETs levels were associated with higher initial NIHSS scores. In the early stages of AIS, WBC count and vWF levels were negatively correlated, as well as NEU%. LYM% was positively correlated with vWF level; however, it was negatively correlated with NETs. EOS% was positively correlated with vWF levels. CONCLUSION: In the early stages of AIS, a higher peripheral WBC count and NEU%, combined with decreased EOS% and LYM%, were significantly correlated with a lower vWF level in the thrombus, potentially indicating more severe symptoms. Consequently, the timely administration of vWF-targeted medications is recommended for such patients. Reduced LYM% is indicative of elevated NETs levels and correlated with more severe clinical symptoms. Therefore, the prompt initiation of NETs-targeted medication is warranted for these patients.

Early diagnosis of persons with von Willebrand disease using a machine learning algorithm and real-world data.

BACKGROUND: Von Willebrand disease (VWD) is underdiagnosed, often delaying treatment. VWD claims coding is limited and includes no severity qualifiers; improved identification methods for VWD are needed. The aim of this study is to identify and characterize undiagnosed symptomatic persons with VWD in the US from medical insurance claims using predictive machine learning (ML) models. RESEARCH DESIGN AND METHODS: Diagnosed and potentially undiagnosed VWD cohorts were defined using Komodo longitudinal US claims data (January 2015-March 2020). ML models were built using key characteristics predictive of VWD diagnosis from the diagnosed cohort. Two ML models predicted VWD diagnosis with the highest accuracy in females (random forest; 84%) and males (gradient boosting machine; 85%). Undiagnosed persons suspected to have VWD were identified using an 80% cutoff probability; profiles of key characteristics were constructed. RESULTS: The trained ML models were applied to the undiagnosed cohort (28,463 females; 20,439 males) with suspected VWD. Fifty-two percent of undiagnosed females had heavy menstrual bleeding, a key pre-diagnosis symptom. Undiagnosed males tended to have more frequent medical procedures, hospitalizations, and emergency room visits compared with undiagnosed females. CONCLUSIONS: ML algorithms successfully identified potentially undiagnosed symptomatic people with VWD, although many may remain undiagnosed and undertreated. External validation of the algorithms is recommended.

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

BACKGROUND: The activity of von Willebrand factor (VWF) in facilitating platelet adhesion and aggregation correlates with its multimer size. Traditional ristocetin-dependent functional assays lack sensitivity to multimer sizes. Recently, nanobodies targeting the autoinhibitory module and activating VWF were identified. OBJECTIVES: To develop an assay that can differentiate the platelet-binding activity of VWF multimers. METHODS: A novel enzyme-linked immunosorbent assay (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. RESULTS: Of 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. CONCLUSION: The 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.

Platelet Biorheology and Mechanobiology in Thrombosis and Hemostasis: Perspectives from Multiscale Computation.

Thrombosis is the pathological clot formation under abnormal hemodynamic conditions, which can result in vascular obstruction, causing ischemic strokes and myocardial infarction. Thrombus growth under moderate to low shear (<1000 s-1) relies on platelet activation and coagulation. Thrombosis at elevated high shear rates (>10,000 s-1) is predominantly driven by unactivated platelet binding and aggregating mediated by von Willebrand factor (VWF), while platelet activation and coagulation are secondary in supporting and reinforcing the thrombus. Given the molecular and cellular level information it can access, multiscale computational modeling informed by biology can provide new pathophysiological mechanisms that are otherwise not accessible experimentally, holding promise for novel first-principle-based therapeutics. In this review, we summarize the key aspects of platelet biorheology and mechanobiology, focusing on the molecular and cellular scale events and how they build up to thrombosis through platelet adhesion and aggregation in the presence or absence of platelet activation. In particular, we highlight recent advancements in multiscale modeling of platelet biorheology and mechanobiology and how they can lead to the better prediction and quantification of thrombus formation, exemplifying the exciting paradigm of digital medicine.