Search

Introduction: Severe congenital factor V (FV) deficiency is a rare bleeding disorder characterized by very low/undetectable levels of FV. Fresh frozen plasma is the standard treatment for bleeding manifestations. Recently, a novel plasma‐derived FV concentrate has been developed. Aim: To evaluate the “in vitro” ability of the novel FV concentrate to normalize clotting times and generate normal amount of thrombin in plasma collected from patients with severe FV deficiency. Methods: Prothrombin time (PT), activated partial thromboplastin time (aPTT), FV activity and antigen levels and thrombin generation were measured pre‐ and postspiking of plasma samples of 10 patients with increasing doses of FV concentrate (from 0 to 100 IU/dL). Results: Prothrombin time and activated partial thromboplastin time ratios as well as all thrombin generation parameters were fully corrected by the addition of FV concentrate at a final concentration of 25 IU/dL. However, the addition of FV at a concentration of 1‐3 IU/dL was already sufficient to correct peak height and endogenous thrombin potential (but not lag time and time to peak) after activation with 5 pmol/L tissue factor. FV activity and antigen levels showed a linear response to supplementation with the novel FV concentrate. Conclusion: The novel plasma‐derived FV concentrate was effective to correct “in vitro” severe FV deficiency in patients. The optimal FV concentration to fully normalize both global clotting times and thrombin generation parameters using the novel plasma‐derived FV concentrate was 25 IU/dL. [ABSTRACT FROM AUTHOR]

Coagulation factor V ( FV) deficiency is a rare autosomal recessive bleeding disorder. We investigated a patient with severe FV deficiency ( FV:C < 3%) and moderate bleeding symptoms. Thrombin generation experiments showed residual FV expression in the patient's plasma, which was quantified as 0.7 ± 0.3% by a sensitive prothrombinase-based assay. F5 gene sequencing identified a novel missense mutation in exon 4 (c.578G>C, p.Cys193Ser), predicting the abolition of a conserved disulphide bridge, and an apparently synonymous variant in exon 8 (c.1281C>G). The observation that half of the patient's F5 mRNA lacked the last 18 nucleotides of exon 8 prompted us to re-evaluate the c.1281C>G variant for its possible effects on splicing. Bioinformatics sequence analysis predicted that this transversion would activate a cryptic donor splice site and abolish an exonic splicing enhancer. Characterization in a F5 minigene model confirmed that the c.1281C>G variant was responsible for the patient's splicing defect, which could be partially corrected by a mutation-specific morpholino antisense oligonucleotide. The aberrantly spliced F5 mRNA, whose stability was similar to that of the normal mRNA, encoded a putative FV mutant lacking amino acids 427-432. Expression in COS-1 cells indicated that the mutant protein is poorly secreted and not functional. In conclusion, the c.1281C>G mutation, which was predicted to be translationally silent and hence neutral, causes FV deficiency by impairing pre- mRNA splicing. This finding underscores the importance of cDNA analysis for the correct assessment of exonic mutations. [ABSTRACT FROM AUTHOR]

. Severe factor V (FV) deficiency (parahaemophilia) is a rare congenital hemorrhagic disorder characterized by very low or undetectable plasma FV levels and bleeding phenotype ranging from mild to severe. We evaluated whole blood (WB) rotation thromboelastometry (ROTEM) in parahaemophilia patients and the contribution of intraplatelets FV, if any, to clot formation. Standard ROTEM® assays were performed in WB from nine parahaemophilia patients and 50 healthy controls. In addition, platelets poor plasma from one parahaemophilia patient (PPP-Pt) or normal subjects (PPP-N) was reconstituted with washed platelets obtained either from one patient with parahaemophilia (Plts-Pt) or normal subjects (Plts-N) and ROTEM assays were performed in platelets rich plasma (PRP) samples. There was a prolongation of the WB clotting time (CT) in all assays in patients as compared with controls. However, maximum clot firmness (MCF) was similar in patients and controls. ROTEM in PPP-Pt showed both a prolongation of CT and a reduction of MCF as compared with PPP-N. The addition of either Plts-Pt or Plts-N to PPP-Pt resulted in similar increase in MCF and a decrease of CT which was more evident for PPP-Pt + Plts-N than PPP-Pt + Plts-Pt. In contrast, the addition of Plts-Pt or Plts-N to PPP-N had superimposable effects on both CT and MCF. In parahaemophilia patients, WB ROTEM® presents mainly with prolongation of CT and no relevant effect on MCF. Residual intraplatelets FV in parahaemophilia contributes significantly to thrombin generation as shown in artificially reconstituted PRP models. [ABSTRACT FROM AUTHOR]

A letter to the editor in response to an article on platelet factor V levels in moderate to severe congenital factor V deficiency, is presented.

Background & Aims: Understanding factors responsible for the increased bleeding tendency in acute-on-chronic liver failure (ACLF) would improve the management of these complications. We investigated coagulation alterations in ACLF and assessed whether they were predictive of bleeding., Methods: Cirrhosis patients with ACLF (cases) and acute decompensation (AD, controls) were prospectively recruited and underwent an extensive haemostatic assessment including standard tests, pro and anticoagulant factors, thrombomodulin-modified thrombin generation (TG) and thromboelastometry (ROTEM ® ). In study part 1 (case-control), we compared coagulation in ACLF vs AD. In study part 2 (prospective), all patients were followed for bleeding, and predictors of outcome were assessed., Results: Ninety-one patients were included (51 with ACLF, 40 with AD). Infections and ascites/renal dysfunction were the most common precipitating and decompensating events. Platelet count was lower while INR and activated partial thrombin time were longer in ACLF cohort vs AD. Regarding clotting factors, fibrinogen and factor VIII were comparable between groups while protein C and antithrombin were significantly reduced in ACLF. Endogenous thrombin potential by TG was comparable between groups. Clotting formation time and clot stability by ROTEM ® were significantly lower in ACLF, indicative of a more hypocoagulable state. No haemostasis alteration could discriminate between patients who had bleeding complications during hospitalization and those who did not., Conclusion: We found coagulation changes in ACLF to largely overlap with that of AD and evidence of preserved coagulation capacity in both groups. ROTEM alterations were indicative of a more pronounced hypocoagulable state in ACLF; however, no correlation was found between such alterations and bleeding., (© 2021 The Authors. Liver International published by John Wiley & Sons Ltd.)

Background In this prospective cohort study, we aimed to evaluate the efficacy and safety of direct oral anticoagulants (DOACs) versus heparin/vitamin K antagonists for the treatment of venous thromboembolism (VTE) in patients with inherited thrombophilia. Methods and Results We enrolled consecutive patients with acute VTE and inherited thrombophilia treated with DOACs (cases) or heparin/vitamin K antagonists (controls), matched for age, sex, ethnicity, and thrombophilia type. End points were VTE recurrence and bleeding complications; residual vein thrombosis and post-thrombotic syndrome; VTE recurrence after anticoagulant discontinuation. Two hundred fifty-five cases (age 52.4±17.3 years, Female 44.3%, severe thrombophilia 33.1%) and 322 controls (age 49.7±18.1 years, Female 50.3%, severe thrombophilia 35.1%) were included. The cumulative incidence of VTE recurrence during anticoagulation was 1.09% in cases versus 1.83%, adjusted hazard ratio (HR) 0.67 (95% CI, 0.16-2.77). The cumulative incidence of bleeding was 10.2% in cases versus 4.97%, HR 2.24 (95% CI 1.10-4.58). No major bleedings occurred in cases (versus 3 in controls). No significant differences regarding residual vein thrombosis and post-thrombotic syndrome. After anticoagulant discontinuation, DOACs yielded a significantly lower 2-year VTE recurrence risk versus traditional anticoagulants (HR, 0.61 [95% CI, 0.47-0.82]). Conclusions DOACs and heparin/vitamin K antagonists showed a similar efficacy in treating VTE in patients with thrombophilia. Although major bleeding episodes were recorded solely with heparin/vitamin K antagonists, we noted an overall increased bleeding rate with DOACs. The use of DOACs was associated with a lower 2-year risk of VTE recurrence after anticoagulant discontinuation.

Background & Aims: The eradication of Hepatitis C (HCV) infection by direct-acting antiviral (DAAs) agents has been linked to an amelioration of liver synthesis and regression of fibrosis. Although changes in number and type of circulating microvesicles (MVs) have been reported in cirrhosis, conclusive data on the effect of DAAs treatment on MVs profile in HCV cirrhotic patients remain scarce., Methods: We measured the levels of endothelial, platelet and hepatocyte MVs, as well as MVs-expressing versican core protein (VCAN+) in patients with HCV-related cirrhosis at baseline, end of treatment (EOT), at 12, 24 and 48 weeks (W) after EOT by new generation flow cytometry., Results: Fifty-eight patients were enrolled (86% Child's A). MVs were increased at EOT vs baseline, though only platelet MVs revealed a statistically significant difference (P < .01). MV levels did not change significantly after EOT notwithstanding a steady downward trend towards baseline levels. Conversely, VCAN + MVs dropped significantly at EOT (P < .001) and remained low throughout the follow-up. Hepatocyte MVs significantly correlated with liver stiffness (r = .40, P = .0021). Eight composite outcomes occurred during the 1-year follow-up: three portal vein thromboses (PVTs), two hepatocellular carcinomas (HCCs) and three liver decompensation. Child's B, the presence of F2 oesophageal varices (OR for interaction 19.2 [95% CI 1.45-253.7], P = .023) and platelet MVs (OR 1.026 [95% CI 1.00-1.05, P = .023) correlated significantly with clinical outcomes., Conclusions: VCAN + MVs appear to mirror the profibrotic status of the cirrhotic disease; hepatocyte MVs correlate with liver stiffness and increased platelet MV levels could be associated with a worse clinical outcome., (© 2019 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background & Aims: The long-term impact of sustained virological response (SVR) after direct-acting antivirals (DAAs) on the hypercoagulability associated with HCV cirrhosis is unknown. We longitudinally evaluated the effect of DAAs treatment on cirrhotic coagulopathy., Methods: Pro- and anticoagulant factor levels and thrombin generation were assessed in patients with HCV-related cirrhosis at baseline, end of therapy (EOT), at 12, 24 and 48 weeks (W) after EOT., Results: Fifty-eight patients were enrolled (86% Child's A). SVR was 100%. Median factor VIII activity significantly decreased at EOT, 12 weeks and 24 weeks compared with baseline, whereas protein C significantly increased at 24 weeks and 48 weeks. Cirrhotic patients showed a slight but sustained increase in endogenous thrombin potential (ETP) with a statistically significant difference at EOT, 12 weeks, 24 weeks and 48 weeks compared with baseline. Conversely, thrombomodulin-modified ETP was elevated before treatment and decreased over time to normal levels at 24 weeks and 48 weeks. The ETP ratio decreased slowly at EOT and 12 weeks, and was significantly decreased at 24 weeks and 48 weeks compared with baseline (P < .001 for both comparisons), being not statistically different from ETP ratio measured in healthy controls. Child's B patients showed a significantly higher ETP ratio compared to Child's A at baseline and did not show any significant improvement in ETP ratio through 12 weeks. Two Child's B patients developed PVT with an incidence rate of 1.1% p-yrs (95%CI, 0.18 to 3.58)., Conclusions: DAAs therapy in HCV-related cirrhotic patients is associated with significant changes in thrombin generation suggesting a reversal of hypercoagulability particularly in Child's A patients., (© 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Although human megakaryocytes can synthesize factor V (FV), platelet FV derives largely from endocytosis of plasma FV. Recently, it has been shown that plasma transfusions can replenish the platelet FV pool in parahaemophilic patients. Here we corroborate this finding by showing FV endocytosis by ex vivo differentiated megakaryocytes derived from patients with inherited parahaemophilia. Mononuclear stem cells isolated from peripheral blood of healthy subjects and of three patients with severe parahaemophilia were cultured in the presence of thrombopoietin and interleukin-3 and differentiated into CD41-positive polynucleated megakaryocytes. Exogenous purified FV was added to the culture medium to evaluate FV endocytosis. Immunofluorescence staining revealed abundant FV expression in megakaryocytes derived from healthy donors, but no FV expression in those derived from patients with severe parahaemophilia. However, after the addition of purified FV to the culture medium, megakaryocytes from parahaemophilia patients became positive upon FV immunostaining, suggesting endocytosis of exogenous FV. Endocytosed FV retained factor Xa-co-factor activity as assessed by a prothrombin time-based functional test in megakaryocyte lysates. Addition of exogenous FV to culture medium can restore the FV content of megakaryocytes derived from patients with severe FV defects. This rescue mechanism can have important clinical implications in the management of parahaemophilia patients., (© 2016 John Wiley & Sons Ltd.)