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

ABSTRACT: There 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 (ß = 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.

Restraining of glycoprotein VI- and integrin α2ß1-dependent thrombus formation by platelet PECAM1.

The platelet receptors, glycoprotein VI (GPVI) and integrin α2ß1 jointly control collagen-dependent thrombus formation via protein tyrosine kinases. It is unresolved to which extent the ITIM (immunoreceptor tyrosine-based inhibitory motif) receptor PECAM1 and its downstream acting protein tyrosine phosphatase PTPN11 interfere in this process. Here, we hypothesized that integrin α2ß1 has a co-regulatory role in the PECAM1- and PTPN11-dependent restraint of thrombus formation. We investigated platelet activation under flow on collagens with a different GPVI dependency and using integrin α2ß1 blockage. Blood was obtained from healthy subjects and from patients with Noonan syndrome with a gain-of-function mutation of PTPN11 and variable bleeding phenotype. On collagens with decreasing GPVI activity (types I, III, IV), the surface-dependent inhibition of PECAM1 did not alter thrombus parameters using control blood. Blockage of α2ß1 generally reduced thrombus parameters, most effectively on collagen IV. Strikingly, simultaneous inhibition of PECAM1 and α2ß1 led to a restoration of thrombus formation, indicating that the suppressing signaling effect of PECAM1 is masked by the platelet-adhesive receptor α2ß1. Blood from 4 out of 6 Noonan patients showed subnormal thrombus formation on collagen IV. In these patients, effects of α2ß1 blockage were counterbalanced by PECAM1 inhibition to a normal phenotype. In summary, we conclude that the suppression of GPVI-dependent thrombus formation by either PECAM1 or a gain-of-function of PTPN11 can be overruled by α2ß1 engagement.

Peri-operative desmopressin combined with pharmacokinetic-guided factor VIII concentrate in non-severe haemophilia A patients.

INTRODUCTION: Non-severe haemophilia A patient can be treated with desmopressin or factor VIII (FVIII) concentrate. Combining both may reduce factor consumption, but its feasibility and safety has never been investigated. AIM: We assessed the feasibility and safety of combination treatment in nonsevere haemophilia A patients. METHODS: Non-severe, desmopressin responsive, haemophilia A patients were included in one of two studies investigating peri-operative combination treatment. In the single-arm DAVID study intravenous desmopressin (0.3 µg/kg) once-a-day was, after sampling, immediately followed by PK-guided FVIII concentrate, for maximally three consecutive days. The Little DAVID study was a randomized trial in patients undergoing a minor medical procedure, whom received either PK-guided combination treatment (intervention arm) or PK-guided FVIII concentrate only (standard arm) up to 2 days. Dose predictions were considered accurate if the absolute difference between predicted and measured FVIII:C was ≤0.2 IU/mL. RESULTS: In total 32 patients (33 procedures) were included. In the DAVID study (n = 21), of the FVIII:C trough levels 73.7% (14/19) were predicted accurately on day 1 (D1), 76.5% (13/17) on D2. On D0, 61.9% (13/21) of peak FVIII:C levels predictions were accurate. In the Little DAVID study (n = 12), on D0 83.3% (5/6) FVIII:C peak levels for both study arms were predicted accurately. Combination treatment reduced preoperative FVIII concentrate use by 47% versus FVIII monotherapy. Desmopressin side effects were mild and transient. Two bleeds occurred, both despite FVIII:C > 1.00 IU/mL. CONCLUSION: Peri-operative combination treatment with desmopressin and PK-guided FVIII concentrate dosing in nonsevere haemophilia A is feasible, safe and reduces FVIII consumption.

Effectiveness and costs of a stepwise versus an all-in-one approach to diagnose mild bleeding disorders.

The diagnostic work-up of patients referred to the haematologist for bleeding evaluation is performed in a stepwise way: bleeding history and results of screening laboratory tests guide further diagnostic evaluation. This can be ineffective, time-consuming and burdensome for patients. To improve this strategy, the initial laboratory investigation can be extended. In a model-based approach, effectiveness and costs of a conventional stepwise versus a newly proposed all-in-one diagnostic approach for bleeding evaluation were evaluated and compared, using data from an observational patient cohort study, including adult patients referred for bleeding evaluation. In the all-in-one approach, specialized platelet function tests, coagulation factors, and fibrinolysis tests were included in the initial investigation. Final diagnosis, hospital resource use and costs and patient burden were compared. A total of 150 patients were included. Compared to the stepwise approach, in the all-in-one approach, 19 additional patients reached a diagnosis and patient burden was lower, but total costs per patient were higher [€359, 95% bootstrapped confidence interval (BCI) 283-518, p = 0.001]. For bleeding evaluation of patients referred to the haematologist, an all-in-one diagnostic approach has a higher diagnostic yield and reduces patient burden, at a higher cost. This raises the question what costs justify the diagnosis of a bleeding disorder and a less burdensome diagnostic strategy.

Transition readiness among adolescents and young adults with haemophilia in the Netherlands: Nationwide questionnaire study.

INTRODUCTION: Care for adolescents with haemophilia is transferred from paediatric to adult care around the age of 18 years. Transition programs help to prepare adolescents for this transfer and prevent declining treatment adherence. Evaluating transition readiness may identify areas for improvement. OBJECTIVE: Assess transition readiness among Dutch adolescents and young adults with haemophilia, determine factors associated with transition readiness, and identify areas of improvement in transition programs. METHODS: All Dutch adolescents and young adults aged 12-25 years with haemophilia were invited to participate in a nationwide questionnaire study. Transition readiness was assessed using multiple-choice questions and was defined as being ready or almost ready for transition. Potential factors associated with transition readiness were investigated, including: socio-demographic and disease-related factors, treatment adherence, health-related quality of life, and self-efficacy. RESULTS: Data of 45 adolescents and 84 young adults with haemophilia (47% with severe haemophilia) were analyzed. Transition readiness increased with age, from 39% in 12-14 year-olds to 63% in 15-17 year-olds. Nearly all post-transition young adults (92%, 77/84) reported they were ready for transition. Transition readiness was associated with treatment adherence, as median VERITAS-Pro treatment adherence scores were worse in patients who were not ready (17, IQR 9-29), compared to those ready for transition (11, IQR 9-16). Potential improvements were identified: getting better acquainted with the adult treatment team prior to transition and information on managing healthcare costs. CONCLUSIONS: Nearly all post-transition young adults reported they were ready for transition. Improvements were identified regarding team acquaintance and preparation for managing healthcare costs.

Nationwide study of eculizumab in paroxysmal nocturnal hemoglobinuria: Evaluation of treatment indications and outcomes.

Eculizumab is an effective treatment for paroxysmal nocturnal hemoglobinuria (PNH). However, considering the risk of life-threatening meningococcal disease, life-long duration and costs, there are strict criteria for initiation of therapy. To evaluate the application and real-world effectiveness of eculizumab in the Netherlands, a multicenter retrospective cohort study was conducted: indications and treatment outcomes were collected for 105 Dutch PNH patients. In all patients, eculizumab was initiated conforming to indications as formulated in the Dutch PNH guideline. According to recently published response criteria, 23.4% of the patients had reached a complete hematological response, 53.2% a good or partial response, and 23.4% a minor response after 12 months of therapy. In the majority of patients the response remained stable during long-term follow-up. The degree and relevance of extravascular hemolysis significantly differed between response groups (p = 0.002). Improvements of EORTC-QLQc30 and FACIT-fatigue scores were observed, however patients reported lower scores than the general population. A detailed evaluation of 18 pregnancies during eculizumab showed no maternal or fetal deaths, and no thromboembolic events during pregnancy. This study demonstrates that the majority of patients benefit from eculizumab when adhering to the indications as formulated in the Dutch PNH guideline. However, novel therapies are needed to further improve real-world outcomes, such as hematological responses and quality of life.

Multiparameter platelet function analysis of bleeding patients with a prolonged platelet function analyser closure time.

Patients referred for evaluation of bleeding symptoms occasionally have a prolonged platelet function analyser (PFA) closure time, without evidence for von Willebrand disease or impaired platelet aggregation. The aim of this study was to establish a shear-dependent platelet function defect in these patients. Patients were included based on high bleeding score and prior PFA prolongation. Common tests of von Willebrand factor (VWF) and platelet function and exome sequencing were performed. Microfluidic analysis of shear-dependent collagen-induced whole-blood thrombus formation was performed. In 14 PFA-only patients, compared to healthy volunteers, microfluidic tests showed significantly lower platelet adhesion and thrombus formation parameters. This was accompanied by lower integrin activation, phosphatidylserine exposure and P-selectin expression. Principal components analysis indicated VWF as primary explaining variable of PFA prolongation, whereas conventional platelet aggregation primarily explained the reduced thrombus parameters under shear. In five patients with severe microfluidic abnormalities, conventional platelet aggregation was in the lowest range of normal. No causal variants in Mendelian genes known to cause bleeding or platelet disorders were identified. Multiparameter assessment of whole-blood thrombus formation under shear indicates single or combined effects of low-normal VWF and low-normal platelet aggregation in these patients, suggesting a shear-dependent platelet function defect, not detected by static conventional haemostatic tests.

Nonredundant Roles of Platelet Glycoprotein VI and Integrin αIIbß3 in Fibrin-Mediated Microthrombus Formation.

OBJECTIVE: Fibrin is considered to strengthen thrombus formation via integrin αIIbß3, but recent findings indicate that fibrin can also act as ligand for platelet glycoprotein VI. Approach and Results: To investigate the thrombus-forming potential of fibrin and the roles of platelet receptors herein, we generated a range of immobilized fibrin surfaces, some of which were cross-linked with factor XIIIa and contained VWF-BP (von Willebrand factor-binding peptide). Multicolor microfluidics assays with whole-blood flowed at high shear rate (1000 s-1) indicated that the fibrin surfaces, regardless of the presence of factor XIIIa or VWF-BP, supported platelet adhesion and activation (P-selectin expression), but only microthrombi were formed consisting of bilayers of platelets. Fibrinogen surfaces produced similar microthrombi. Markedly, tiggering of coagulation with tissue factor or blocking of thrombin no more than moderately affected the fibrin-induced microthrombus formation. Absence of αIIbß3 in Glanzmann thrombasthenia annulled platelet adhesion. Blocking of glycoprotein VI with Fab 9O12 substantially, but incompletely reduced platelet secretion, Ca2+ signaling and aggregation, while inhibition of Syk further reduced these responses. In platelet suspension, glycoprotein VI blockage or Syk inhibition prevented fibrin-induced platelet aggregation. Microthrombi on fibrin surfaces triggered only minimal thrombin generation, in spite of thrombin binding to the fibrin fibers. CONCLUSIONS: Together, these results indicate that fibrin fibers, regardless of their way of formation, act as a consolidating surface in microthrombus formation via nonredundant roles of platelet glycoprotein VI and integrin αIIbß3 through signaling via Syk and low-level Ca2+ rises.

Comparative analysis of thrombin generation platforms for patients with coagulation factor deficiencies: A comprehensive assessment.

INTRODUCTION: Thrombin generation assays (TGAs) assess the overall functionality of the hemostatic system and thereby provide a reflection of the hemostatic capacity of patients with disorders in this system. Currently, four (semi-)automated TGA platforms are available: the Calibrated Automated Thrombogram, Nijmegen Hemostasis Assay, ST Genesia and Ceveron s100. In this study, we compared their performance for detecting patients with congenital single coagulation factor deficiencies. MATERIALS AND METHODS: Pooled patient samples, healthy control samples and normal pooled plasma were tested on all four platforms, using the available reagents that vary in tissue factor and phospholipid concentrations. The TGA parameters selected for analysis were peak height and thrombin potential. Results were normalized by using the calculated mean of healthy controls and a correction for between-run variation. Outcomes were presented as relative values, with the mean of healthy controls standardized to 100 %. RESULTS: Across all platforms and reagents used, thrombin potentials and peak heights of samples with coagulation factor deficiencies were lower than those of healthy controls. Reagents designed for bleeding tendencies yielded the lowest values on all platforms (relative median peak height 19-32 %, relative median thrombin potential 19-45 %). Samples representing more severe coagulation factor deficiencies generally exhibited lower relative peak heights and thrombin potentials. CONCLUSIONS: Thrombin generation assays prove effective in differentiating single coagulation factor deficient samples from healthy controls, with modest discrepancies observed between the platforms. Reagents designed for assessing bleeding tendencies, featuring the lowest tissue factor and phospholipid concentrations, emerged as the most suitable option for detecting coagulation factor deficiencies.

Predictive performance of pharmacokinetic-guided prophylactic dosing of factor concentrates in hemophilia A and B.

Background: Pharmacokinetic (PK)-guided dosing is used to individualize factor (F)VIII and FIX replacement therapy. Objectives: This study investigates the reliability and feasibility of PK-guided prophylactic dosing of factor concentrates in hemophilia A and B. Methods: In this multicenter, prospective cohort study, people of all ages with hemophilia received prophylactic treatment with factor concentrates based on individual PK parameters. During follow-up, at least 4 measured FVIII/FIX levels per patient were compared with corresponding predicted levels obtained by Bayesian forecasting. Predictive performance was defined as adequate when ≥80% of measured FVIII/FIX levels were within ±25% of prediction (relative error). Additionally, mean absolute error and mean error were calculated. In post hoc analyses, predictive performance was assessed allowing maximum absolute errors of 1 (trough), 5 (mid), and 15 (peak) IU/dL. Five-point scale questionnaires addressed feasibility of PK guidance. Results: We included 50 patients (median age, 19 years; range: 2-72 years). Median follow-up was 36 weeks. Seventy-one percent of levels (58% trough, 83% mid, and 80% peak) were within ±25% of prediction. Mean absolute errors were 0.8 (trough), 2.0 (mid), and 8.6 (peak) IU/dL. In post hoc analyses, 81% (trough), 96% (mid), and 82% (peak) of levels were within set limits. Patients reported low burden and high satisfaction. Conclusion: PK-guided dosing was reliable according to post hoc analyses, based on low absolute errors that were regarded as clinically irrelevant in most cases. The predefined predictive performance was achieved in mid and peak factor levels but not in trough factor levels due to measurement inaccuracy. PK guidance also seemed feasible.

Sensitive Measurement of Clinically Relevant Factor VIII Levels in Thrombin Generation Assays Requires Presence of Factor XIa.

BACKGROUND: Hemophilia A (HA) is characterized by decreased or absent factor VIII (FVIII) activity. Current FVIII assays are based on clotting time and thus only provide information about the initiation of coagulation. In contrast, thrombin generation assays (TGAs) can be used to measure the full coagulation spectrum of initiation, propagation, and termination that provide information on the whole course of thrombin generation and inhibition. However, the commercially available TG kits lack sensitivity for measurements of hemophilia plasma within lower FVIII ranges, which is essential for explaining differences in bleeding phenotypes in hemophiliacs at clinically low levels of FVIII. AIMS: Optimization of the TGA for measurements of low FVIII levels in severe HA patients. METHODS: TGA measurements were performed in severe HA pooled plasma (n = 10). Investigations of several preanalytical and analytical variables of the assay were performed in a stepwise process and adjusted based on sensitivity toward intrinsic coagulation activation. RESULTS: TGA initiated by tissue factor (TF) alone at varying concentrations was unable to significantly differentiate between FVIII levels below 20%. In contrast, TGA activation with low concentrations of TF in presence of FXIa appeared to be highly sensitive for FVIII changes both in high and low ranges. In addition, a representative TGA curve at trough levels could only be produced using the dual TF/FXIa TGA. CONCLUSION: We propose a critical optimization for the setup of the TGA for measurements in severe HA plasma. The dual TF/FXIa TGA shows increased sensitivity, especially in lower FVIII ranges, which allows for better individual characterization at baseline, prediction of interventions, and follow-up.

Colorectal cancer screening in patients with inherited bleeding disorders: high cancer detection rate in hemophilia patients.

BACKGROUND: The population-based colorectal cancer (CRC) screening program in individuals aged 55 to 75 years in the Netherlands uses fecal immunochemical testing (FIT), to detect hemoglobin in feces, followed by colonoscopy in individuals with a positive FIT. OBJECTIVES: The objectives of this study are to assess the false-positive rate, detection rate, and positive predictive value of FIT for CRC and advanced adenoma (AA) in patients with Von Willebrand disease (VWD) or hemophilia. METHODS: We performed a multicenter, nationwide cross-sectional study embedded in 2 nationwide studies on VWD and hemophilia in the Netherlands. RESULTS: In total, 493 patients with hemophilia (n = 329) or VWD (n = 164) were included, of whom 351 patients participated in the CRC screening program (71.2%). FIT positivity and false-positive rate in patients with hemophilia and VWD were significantly higher than those in the general population (14.8% vs. 4.3%, p < .001 and 10.3% vs. 2.3%, p <.001, respectively). In patients with hemophilia, the detection rate of CRC/AA was significantly higher than that in the general male population (4.5% vs. 1.8%, p = .02), and the positive predictive value of FIT for CRC/AA was comparable (32.3% vs. 39.7%, n.s.). In patients with VWD, the detection rate was similar to that of the general population (0.8% vs. 1.4%, n.s.), whereas the positive predictive value was significantly lower than that in the general population (6.3% vs. 36.8%, p = .02). CONCLUSION: This study indicates that despite a high false-positive rate of FIT in patients with inherited bleeding disorders, the detection rate of CRC and/or AA in hemophilia patients is high. FIT performs different in patients with hemophilia or VWD compared with the general population.

Desmopressin in nonsevere hemophilia A: patient perspectives on use and efficacy.

Background: Desmopressin increases plasma factor VIII and von Willebrand factor levels in persons with nonsevere hemophilia A. Patients' perspectives on desmopressin are relevant to increase and optimize its suboptimal use. However, patients' views on desmopressin are not reported. Objectives: To evaluate the perspectives of persons with nonsevere hemophilia A on desmopressin use, barriers for its use, side effects, and their knowledge about desmopressin's efficacy and side effects. Methods: Persons with nonsevere hemophilia A were included in a cross-sectional, national, multicenter study. Questionnaires were filled out by adult patients and children aged ≥12 years themselves. Caretakers filled out questionnaires for children aged <12 years. Results: In total, 706 persons with nonsevere hemophilia A were included (544 mild, 162 moderate, [age range, 0-88 years]). Of 508 patients, 234 (50%) patients reported previous desmopressin use. Desmopressin was considered as at least moderately effective in 171 of 187 (90%) patients. Intranasal administration was the modality of choice for 138 of 182 (76%) patients. Flushing was the most reported side effect in 54 of 206 (26%) adults and 7 of 22 (32%) children. The most frequently reported advantage and disadvantage were the convenience of intranasal, out-of-hospital administration by 56% (126/227) and side effects in 18% (41/227), respectively. Patients' self-perceived knowledge was unsatisfactory or unknown in 28% (63/225). Conclusion: Overall, desmopressin was most often used intranasally and considered effective, with flushing as the most common side effect. The most mentioned advantage was the convenience of intranasal administration and disadvantage was side effects. More information and education on desmopressin could answer unmet needs in patients with current or future desmopressin treatment.

GPVI expression is linked to platelet size, age, and reactivity.

Platelets within one individual display heterogeneity in reactivity, size, age, and expression of surface receptors. To investigate the combined intraindividual contribution of platelet size, platelet age, and receptor expression levels on the reactivity of platelets, we studied fractions of large and small platelets from healthy donors separated by using differential centrifugation. Size-separated platelet fractions were perfused over a collagen-coated surface to assess thrombus formation. Multicolor flow cytometry was used to characterize resting and stimulated platelet subpopulations, and platelet age was determined based on RNA and HLA-I labeling. Signal transduction was analyzed by measuring consecutive phosphorylation of serine/threonine-protein kinase Akt. Compared with small platelets, large platelets adhered faster to collagen under flow and formed larger thrombi. Among the large platelets, a highly reactive juvenile platelet subpopulation was identified with high glycoprotein VI (GPVI) expression. Elevated GPVI expression correlated with high HLA-I expression, RNA content, and increased platelet reactivity. There was a stronger difference in Akt phosphorylation and activation upon collagen stimulation between juvenile and older platelets than between large and small platelets. GPVI expression and platelet reactivity decreased throughout platelet storage at 22°C and was better maintained throughout cold storage at 4°C. We further detected higher GPVI expression in platelets of patients with immune thrombocytopenia. Our findings show that high GPVI expression is a feature of highly reactive juvenile platelets, which are predominantly found among the large platelet population, explaining the better performance of large platelets during thrombus formation. These data are important for studies of thrombus formation, platelet storage, and immune thrombocytopenia.

Design of a Prospective Study on Pharmacokinetic-Guided Dosing of Prophylactic Factor Replacement in Hemophilia A and B (OPTI-CLOT TARGET Study).

In resource-rich countries, almost all severe hemophilia patients receive prophylactic replacement therapy with factor concentrates to prevent spontaneous bleeding in joints and muscles to decrease the development of arthropathy and risk of long-term disability. Pharmacokinetic (PK)-guided dosing can be applied to individualize factor replacement therapy, as interindividual differences in PK parameters influence factor VIII (FVIII) and FIX activity levels. PK-guided dosing may therefore lead to more optimal safeguarding of FVIII/FIX levels during prophylaxis and on demand treatment. The OPTI-CLOT TARGET study is a multicenter, nonrandomized, prospective cohort study that aims to investigate the reliability and feasibility of PK-guided prophylactic dosing of factor concentrates in hemophilia-A and -B patients in daily clinical practice. At least 50 patients of all ages on prophylactic treatment using standard half-life (SHL) and extended half-life (EHL) factor concentrates will be included during 9 months and will receive PK-guided treatment. As primary endpoint, a minimum of four FVIII/FIX levels will be compared with FVIII/FIX levels as predicted by Bayesian forecasting. Secondary endpoints are the association of FVIII and FIX levels with bleeding episodes and physical activity, expectations and experiences, economic analyses, and optimization of population PK models. This study will lead to more insight in the reliability and feasibility of PK-guided dosing in hemophilia patients. Moreover, it will contribute to personalization of treatment by greater knowledge of dosing regimens needed to prevent and treat bleeding in the individual patient and provide evidence to more clearly associate factor activity levels with bleeding risk.

Assessment of need for hemostatic evaluation in patients taking valproic acid: A retrospective cross-sectional study.

INTRODUCTION: Valproic acid (VPA) is a frequently prescribed anti-epileptic drug. Since its introduction side effects on hemostasis are reported. However, studies show conflicting results, and the clinical relevance is questioned. We aimed to determine the coagulopathies induced by VPA in patients who undergo high-risk surgery. The study results warrant attention to this issue, which might contribute to reducing bleeding complications in future patients. METHODS: Between January 2012 and August 2020, 73 consecutive patients using VPA were retrospectively included. Extensive laboratory hemostatic assessment (including platelet function tests) was performed before elective high-risk surgery. Patient characteristics, details of VPA treatment, and laboratory results were extracted from medical records. RESULTS: 46.6% of the patients using VPA (n = 73) showed coagulopathy. Mainly, platelet function disorder was found (36.4%). Thrombocytopenia was seen in 9.6% of the patients. Data suggested that the incidence of coagulopathies was almost twice as high in children as compared to adults and hypofibrinogenemia was only demonstrated in children. No association was found between the incidence of coagulopathies and VPA dosage (mg/kg/day). CONCLUSION: A considerable number of patients using VPA were diagnosed with coagulopathy, especially platelet function disorder. Further prospective studies are needed to confirm the need for comprehensive laboratory testing before elective high-risk surgery in these patients.

Multiparameter microfluidics assay of thrombus formation reveals increased sensitivity to contraction and antiplatelet agents at physiological temperature.

INTRODUCTION: Current developments to assess qualitative and quantitative platelet traits in flowed whole-blood are based on microfluidic devices that mostly operate at room temperature. However, operation at physiological temperature (37 °C) may increase the assay's sensitivity, and facilitates the comparison to other platelet function tests of the diagnostic laboratory. MATERIALS AND METHODS: We adapted the conventional microspot-based microfluidic device with a simple thermo-coupled pre-heating module. Automated analysis of microscopic images assisted in obtaining five time-dependent parameters of thrombus formation over collagen microspots (shear rate 1000 s-1). These modifications allowed rapid testing of control and patient blood samples at physiological temperature. RESULTS AND CONCLUSION: The higher temperature enhanced platelet adhesion and aggregation as well as late thrombus characteristics such as size and contraction, when compared to room temperature. Moreover, assessment at 37 °C indicated a time-dependent impairment of the thrombus parameters in blood from patients taking common antiplatelet medication, i.e. aspirin and/or clopidogrel. This pointed to increased contribution of the autocrine platelet agonists thromboxane A2 and ADP in the buildup of contracted thrombi under flow. Overall, this study underlined the advantage of multiparameter assessment of microfluidic thrombus formation in detecting an acquired platelet dysfunction, when operating at physiological temperature. This work may bring microfluidics tests closer to the diagnostic laboratory.

Donor fecal microbiota transplantation ameliorates intestinal graft-versus-host disease in allogeneic hematopoietic cell transplant recipients.

Disruption of the intestinal microbiota occurs frequently in allogeneic hematopoietic cell transplantation (allo-HCT) recipients and predisposes them to development of graft-versus-host disease (GvHD). In a prospective, single-center, single-arm study, we investigated the effect of donor fecal microbiota transplantation (FMT) on symptoms of steroid-refractory or steroid-dependent, acute or late-onset acute intestinal GvHD in 15 individuals who had undergone allo-HCT. Study participants received a fecal suspension from an unrelated healthy donor via nasoduodenal infusion. Donor FMT was well tolerated, and infection-related adverse events did not seem to be related to the FMT procedure. In 10 of 15 study participants, a complete clinical response was observed within 1 month after FMT, without additional interventions to alleviate GvHD symptoms. This response was accompanied by an increase in gut microbial α-diversity, a partial engraftment of donor bacterial species, and increased abundance of butyrate-producing bacteria, including Clostridiales and Blautia species. In 6 of the 10 responding donor FMT recipients, immunosuppressant drug therapy was successfully tapered. Durable remission of steroid-refractory or steroid-dependent GvHD after donor FMT was associated with improved survival at 24 weeks after donor FMT. This study highlights the potential of donor FMT as a treatment for steroid-refractory or steroid-dependent GvHD, but larger clinical trials are needed to confirm the safety and efficacy of this procedure.

Fibrinolysis in patients with chemotherapy-induced thrombocytopenia and the effect of platelet transfusion.

Essentials Bleeding in chemotherapy induced thrombocytopenia (CIT) might be influenced by hyperfibrinolysis. t-PA-thromboelastography is a fast and reliable assay for hyperfibrinolysis in CIT patients. Clots of CIT patients are more susceptible to t-PA induced lysis compared to healthy individuals. Besides platelets, other factors are likely to influence clot lysis in CIT patients. BACKGROUND: Bleeding events in chemotherapy-induced thrombocytopenic (CIT) patients with similar platelet counts might be influenced by changes in clot lysis potential. OBJECTIVES: To investigate, in an observational study, thromboelastographic lysis parameters, alterations in clot strength and susceptibility to clot lysis in CIT patients. To identify factors associated with fibrinolytic profiles, and to evaluate the effects of platelet transfusions. METHODS: Independent determinants of tissue-type plasminogen activator (t-PA)-ROTEM lysis parameters were identified with multivariable linear regression. Clot formation, strength and lysis parameters were compared with the results of healthy individuals. Characteristics of CIT patients with and without hyperfibrinolytic profiles were compared. t-PA-ROTEM results before, 1 hour after and 24 hours after platelet transfusion were compared. RESULTS: A total of 72 consecutive CIT patients were included. t-PA-ROTEM lysis parameters correlated with changes in fibrinolytic proteins. Clot formation time was longer, maximum clot firmness was weaker and lysis times were shorter than in healthy individuals. CIT patients had low plasminogen activator inhibitor-1 and thrombin-activatable fibrinolysis inhibitor levels, and 40% showed hyperfibrinolytic profiles. Platelet transfusions resulted in less hyperfibrinolytic profiles in many, but not all CIT patients. Patients without hyperfibrinolytic profiles had higher fibrinogen, factor VIII and α2 -antiplasmin levels. CONCLUSIONS: t-PA-ROTEM can be used as a fast and reliable assay to detect hyperfibrinolytic profiles in CIT patients. CIT patients have weaker clots, which are more susceptible to clot lysis, than healthy individuals. Besides platelets, other factors are likely to influence clot susceptibility to fibrinolysis in CIT patients. The impact of a hyperfibrinolytic t-PA-ROTEM profile on bleeding remains to be investigated.