scholarly journals Thrombin generation in rheumatoid arthritis: Dependence on plasma factor composition

2010 ◽  
Vol 104 (08) ◽  
pp. 224-230 ◽  
Author(s):  
Anetta Undas ◽  
Matthew Gissel ◽  
Beata Kwasny-Krochin ◽  
Piotr Gluszko ◽  
Kenneth Mann ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Tissue Factor ◽  
Cardiovascular Events ◽  
Thrombin Generation ◽  
Protein Composition ◽  
Initiation Phase ◽  
Increased Risk ◽  
Intergroup Comparison ◽  
Plasma Factor ◽  
Thrombin Formation

SummaryGrowing evidence indicates that rheumatoid arthritis (RA) is associated with an increased risk for thromboembolic cardiovascular events. We investigated thrombin generation profiles in RA patients and their dependence on plasma factor/inhibitor composition. Plasma factor (F) compositions (II, V, VII, VIII, IX, X), antithrombin and free tissue factor pathway inhibitor (TFPI) from 46 consecutive RA patients with no cardiovascular events (39 female, 7 male, aged 57 [range, 23–75] years; DAS28 [Disease Activity Score] 5.2 ± 1.1) were compared with those obtained in age- and sex-matched apparently healthy controls. Using each individual’s plasma coagulation protein composition, tissue factor- initiated thrombin generation was assessed both computationally and empirically. RA patients had higher fibrinogen (4.18 [IQR 1.09] vs. 2.56 [0.41] g/l, p<0.0001), FVIII (226 ± 40 vs. 113 ± 15%, p<0.001), PC (107 [16] vs. 100 [14]%, p<0.001), and free TFPI levels (22.3 [2.2] vs. 14.7 [2.1] ng/ml, p<0.001). DAS28, but not age, RA duration, or C-reac- tive protein, was associated with FV, FVIII, FIX, FX, antithrombin, and free TFPI (r from 0.27 to 0.48, p<0.05). Intergroup comparison of computational thrombin generation profiles showed that in RA patients, maximum thrombin levels (p=0.01) and the rate of thrombin formation (p<0.0001) were higher, whereas the initiation phase of thrombin generation (p<0.0001) and the time to maximum thrombin levels (p<0.0001) were longer. Empirical reconstructions of the populations reproduced the thrombin generation profiles generated by the computational model. Simulations of thrombin formation suggest that blood plasma composition, i.e. a marked increase in FVIII, somewhat counterbalanced by free TFPI, contributes to the prothrombotic phenotype in RA patients.

scholarly journals The Role of Factor XI in Thrombin Generation Induced by Low Concentrations of Tissue Factor

2001 ◽  
Vol 85 (06) ◽  
pp. 1060-1065 ◽  
Author(s):  
Irene Keularts ◽  
Ariella Zivelin ◽  
Uri Seligsohn ◽  
H. Coenraad Hemker ◽  
Suzette Béguin
Keyword(s):  
Tissue Factor ◽  
Thrombin Generation ◽  
Contact Activation ◽  
Factor Xi ◽  
Platelet Poor Plasma ◽  
Low Concentrations ◽  
Time Determination ◽  
Thrombin Formation

SummaryThrombin generation has been studied in the plasma of severely factor XI deficient patients under conditions in which contact activation did not play a role. In platelet-rich as well as platelet-poor plasma, thrombin generation was dependent upon the presence of factor XI at tissue factor concentrations of between 1 and 20 pg/ml i.e. ~ 0.01 to 0.20% of the concentration normally present in the thromboplastin time determination. The requirement for factor XI is low; significant thrombin generation was seen at 1% factor XI; at 10%, thrombin formation was nearly normalised. A suspension of normal platelets in severely factor XI deficient plasma did not increase thrombin generation. This implies that there is no significant factor XI activity carried by normal platelets, although the presence of factor XI and factor XI inhibitors in platelets cannot be ruled out.

Plasma free tissue factor pathway inhibitor (TFPI) levels and TF-induced thrombin generation ex vivo in men with low testosterone levels

2009 ◽  
Vol 101 (03) ◽  
pp. 471-477 ◽  
Author(s):  
Ingvild Agledahl ◽  
Johan Svartberg ◽  
Bjarne Hansen ◽  
Ellen Brodin
Keyword(s):  
Tissue Factor ◽  
Thrombin Generation ◽  
Tissue Factor Pathway Inhibitor ◽  
Ex Vivo ◽  
Elderly Men ◽  
Lower Plasma ◽  
Testosterone Levels ◽  
Initiation Phase ◽  
Tissue Factor Pathway ◽  
Low Testosterone

SummaryLow testosterone levels in men have been associated with cardiovascular risk factors, some prothrombotic factors, and lately also an increased risk of both cardiovascular disease and all-cause mortality. Experimental studies have shown increased synthesis and release of tissue factor pathway inhibitor (TFPI) by physiological levels of testosterone in endothelial cells. Our hypothesis was that elderly men with low testosterone levels would have lower plasma levels of plasma free TFPI with subsequent increased thrombin generation. Elderly men with low (n=37) and normal (n=41) testosterone levels were recruited from a general population, and tissue factor (TF)-induced thrombin generation ex vivo and plasma free TFPI Ag were measured. Elderly men with low testosterone levels had lower plasma free TFPI Ag (10.9 ± 2.3 ng/ml vs. 12.3 ± 3.0 ng/ml, p=0.027) and shorter initiation phase of TF-induced coagulation assessed by lag-time (5.1 ± 1.0 min vs. 5.7 ± 1.3, p=0.039). The differences between groups remained significant and were strengthened after adjustment for waist circumference and other cardiovascular risk factors. Lag-time increased linearly across quartiles of plasma free TFPI Ag (p<0.001). Multiple regression analysis revealed that total and free testosterone were independent predictors of plasma free TFPI Ag. Our findings suggest that low testosterone levels in elderly men is associated with low plasma free TFPI Ag and subsequent shortened initiation phase of TF-induced coagulation.

Eculizumab Therapy Results in Rapid and Sustained Decreases in Markers of Thrombin Generation and Inflammation in Patients with PNH

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 407-407 ◽  
Author(s):  
Ilene Ceil Weitz ◽  
Michael Ghods ◽  
Leanne Rochanda ◽  
Pedram Prazavi ◽  
Jeffrey Zwicker ◽  
...  
Keyword(s):  
Cell Membrane ◽  
Tissue Factor ◽  
Thrombin Generation ◽  
Treatment Protocol ◽  
Rank Test ◽  
Prior History ◽  
Published Data ◽  
Induction Phase ◽  
Membrane Injury ◽  
Increased Risk

Abstract Paroxysmal Nocturnal Hemoglobinuria (PNH) is a clonal disorder of the bone marrow resulting from an acquired mutation in the PIG-A gene. The mutation decreases production of the glycosylphosphatidylinositol membrane anchor for a variety of membrane proteins. Loss of cell membrane CD59 and CD55 results in enhanced complement-mediated cell membrane injury. PNH is associated with an increased risk of venous (VTE) and arterial thrombosis. Eculizumab, a monoclonal antibody to complement C5, has received FDA approval for the treatment of PNH. Recent published data demonstrates a 92% reduction in thrombotic events with the use of eculizumab. However, the mechanism for this reduction is unclear. We have enrolled eight PNH patients (pts) in an ongoing IRB-approved study on the effect of eculizumab treatment on markers of thrombin generation and inflammation. Patients were treated by the FDA-approved treatment protocol with blood samples obtained prior to treatment day 1 and prior to each dose on days 8, 15, 22, 29, 43 and 90. Patients receiving anticoagulants and corticosteroids were continued on their baseline medications. Plasma samples were assayed for D-dimers (D-D), thrombin-antithrombin complex (TAT), interleukin 6 (Il-6) by ELISA and tissue factor microparticles (TFMP) by impedance-based flow cytometry. Mean age of pts was 40.8 years (26–70); 6 male pts and 2 females. One patient had a prior history of VTE; 4 pts were receiving anticoagulants (1 full dose low molecular weight heparin (LMWH), 2 prophylactic LMWH, 1 warfarin) and 2 pts were receiving prednisone at the initiation of eculizumab. The effect of eculizumab on markers of hemostatic activation and inflammation was evaluated using Wilcoxon signed-rank test and multilevel models. Results: Pretreatment levels of D-D were significantly elevated in all but two of the patients who were receiving anticoagulants. Pretreatment Il-6 levels were significantly elevated in all but two patients taking prednisone. With eculizumab treatment, there was a statistically significant decrease in LDH (p=0.0001), D-D (p=0.0057), TAT (0.0138) and Il-6 (p=0.0362) during the 4 week induction phase of treatment (days 1–29). TAT levels significantly decreased by day 8 (p=0.008), with little subsequent change to day29 and day 90. All decreases in D-D, TAT, Il-6 and LDH were sustained in the maintenance phase of treatment (days29–90). Plasma TFMP were detectable and significantly increased in all patients prior to treatment. There was a statistically significant decrease in TFMP by day 8 (p=0.0234) and TFMP levels remained below pretreatment levels for the duration of the study (p=0.030). However, there were wide individual variations in TFMP levels over the course of treatment. There were significant Spearman correlations between changes in D-D and TAT (0.521; p&lt;0.0001), in D-D and IL-6 (0.4400; p=0.0007). Changes in LDH did not correlate with changes in D-D, TAT, TFMP or Il-6. Changes in TFMP did not correlate with changes in markers of thrombin generation (TAT or D-D). Conclusion: Eculizumab treatment of patients with PNH results in a rapid decrease in plasma tissue factor microparticles, thrombin generation and inflammation. These changes appear to be independent of eculizumab suppression of RBC hemolysis as characterized by decreases in serum LDH. A direct relationship between plasma TFMP levels and thrombin generation in PNH patients could not be confirmed in this study. Taken together, these data indicate the broader impact of eculizumab treatment to suppress inflammation and prothrombotic activity in patients with PNH.

Recombinant factor VIIa enhances deposition of platelets with congenital or acquired αIIbβ3 deficiency to endothelial cell matrix and collagen under conditions of flow via tissue factor–independent thrombin generation

Blood ◽  
2003 ◽  
Vol 101 (5) ◽  
pp. 1864-1870 ◽  
Author(s):  
Ton Lisman ◽  
Sultana Moschatsis ◽  
Jelle Adelmeijer ◽  
H. Karel Nieuwenhuis ◽  
Philip G. De Groot
Keyword(s):  
Tissue Factor ◽  
Thrombin Generation ◽  
Recombinant Factor Viia ◽  
Factor Viia ◽  
Umbilical Vein ◽  
Novel Approach ◽  
Platelet Deposition ◽  
Platelet Aggregate ◽  
Umbilical Vein Endothelial Cells ◽  
Thrombin Formation

A novel approach to treat bleeding episodes in patients with Glanzmann thrombasthenia (GT) and perhaps also in patients receiving αIIbβ3 inhibitors is the administration of recombinant factor VIIa (rFVIIa). The mechanism of action of rFVIIa in these patients is, however, still unclear. We studied the effect of rFVIIa-mediated thrombin formation on adhesion of αIIbβ3-deficient platelets under flow conditions. Adhesion of αIIbβ3-deficient platelets to the extracellular matrix (ECM) of stimulated human umbilical vein endothelial cells or to collagen type III was studied using a model system with washed platelets and red cells. When αIIbβ3-deficient platelets were perfused over the surface at arterial shear rate for 5 minutes, a low surface coverage was observed (GT platelets, mean ± SEM, 37.5% ± 5.0%; normal platelets preincubated with an RGD-containing peptide, 7.4% ± 2.1%). When rFVIIa, together with factors X and II, was added to the perfusate, platelet deposition significantly increased (GT platelets, mean ± SEM, 67.0% ± 4.3%; normal platelets preincubated with an RGD-containing peptide, 48.2% ± 2.9%). The same effect was observed when normal platelets were pretreated with the commercially available anti-αIIbβ3 drugs abciximab, eptifibatide, or tirofiban. It was shown that tissue factor–independent thrombin generation (presumably induced by binding of rFVIIa to adhered platelets) was responsible for the increase in platelet deposition. In conclusion, defective adhesion of αIIbβ3-deficient platelets to ECM can be restored by tissue factor–independent rFVIIa-mediated thrombin formation. The enhanced generation of platelet procoagulant surface facilitates fibrin formation, so that lack of platelet aggregate formation might be compensated for.

Thrombogenicity of Microparticles Derived from Vascular Cells.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 382-382
Author(s):  
Hirotaka Isobe ◽  
Thomas Perkmann ◽  
Olga Oskolkova ◽  
Valeri Bochkov ◽  
Bernd R. Binder
Keyword(s):  
Tissue Factor ◽  
Thrombin Generation ◽  
Cell Activation ◽  
Smooth Muscles ◽  
Calcium Ionophore ◽  
Vascular Cells ◽  
Independent Manner ◽  
Thrombin Formation

Abstract Microparticles (MPs) are released from cells during processes such as apoptosis or during cell activation. These MPs contain phospholipids, proteins and even nucleic acids derived from their parent cells. They are found circulating in plasma but also in tissues such as atherosclerotic plaques. It is thought that MPs contain and transfer tissue factor and can thereby induce blood clotting. In this study we analyzed clot promoting properties of MPs generated from vascular cells in vitro. MPs were generated from endothelial cells (EC), smooth muscles cells (SMC), monocytes (U937), erythrocytes (RBC) or platelets (Pl) by inducing apoptosis or by calcium ionophore activation; they were subsequently isolated by differential centrifugation. Thrombogenicity of the MPs was evaluated using a thrombin generation assay (Technothrombin® TGA) and MP free plasma as substrate. MPs displayed a different thrombin generating potential depending on the parent cells. MPs derived from RBCs (~400nM peak thrombin/105 MPs/ml plasma), ECs (~300nM), SMCs (~300nM) and Pls (~300nM) were more thrombogenic than MPs derived from U937 (~200 nM). In addition EC, SMC and U937 MPs all expressed tissue factor but EC MPs induced thrombin generation in a tissue factor and FVII independent manner. EC MPs even expressed active tissue factor pathway inhibitor and functionally inhibited tissue factor dependent thrombin generation. Since the higher thrombin generation induced by MPs derived from EC as compared U937 derived MPs could not be explained by a different activity of tissue factor, we were interested whether lipids contained in the microparticles could account for the differences in thrombin generation. We therefore analyzed thrombin generation induced by lipids isolated from MPs and parent cells and could show that lipids from EC MPs and SMC MPs exhibited higher thrombin generation than those from U937 MPs. Upon analysis of lipids by thin layer chromatography and mass spectrometry we found that in general microparticles are enriched in cholesterol, sphingomyeline and phosphatidylserine over the parent cells and that EC and SMC MPs were enriched in negatively charged phospholipids (different species of phosphatidylserine and phosphatiylglycerol) as compared to MPs derived from U937 cells. When thrombogenicity was, however, evaluated in vivo by injecting MPs into mice it was found that the highest capability to induce thrombin-antithrombin (TAT) complexes had MPs derived from SMCs; also U937 MPs induced an increase in TAT levels, while EC MPs – although more thrombogenic than U937 MPs in vitro – did not induce TAT complex formation by themselves but were only synergistic in vivo. From these data we conclude that thrombin formation in vivo depends on the initiation of the tissue factor FVII pathway, while the extent of thrombin formation is dependent on negatively charged phospholipids contained to a higher extent in MPs derived e.g. from ECs.

Effect of a treat-to-target intervention of cardiovascular risk factors on subclinical and clinical atherosclerosis in rheumatoid arthritis: a randomised clinical trial

2019 ◽  
pp. annrheumdis-2018-214075 ◽  
Author(s):  
Benjamin Burggraaf ◽  
Deborah F van Breukelen-van der Stoep ◽  
Marijke A de Vries ◽  
Boudewijn Klop ◽  
Anho H Liem ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Risk Factors ◽  
Usual Care ◽  
Cardiovascular Events ◽  
Target Group ◽  
Secondary Outcome ◽  
Treat To Target ◽  
Cvd Risk Factors ◽  
Cvd Risk ◽  
Increased Risk

BackgroundPatients with rheumatoid arthritis (RA) have an increased risk for cardiovascular disease (CVD). No long-term intervention trials on CVD risk factors have been published, and a debate on the efficacy of controlling traditional risk factors in RA is ongoing. We aimed to evaluate a treat-to-target approach versus usual care regarding traditional CVD risk factors in patients with RA.MethodsIn this open-label, randomised controlled trial, patients with RA aged <70 years without prior CVD or diabetes mellitus were randomised 1:1 to either a treat-to-target approach or usual care of traditional CVD risk factors. The primary outcome was defined as change in carotid intima media thickness (cIMT) over 5 years, and the secondary outcome was a composite of first occurrence of fatal and non-fatal cardiovascular events.ResultsA total of 320 patients (mean age 52.4 years; 69.7% female) with RA underwent randomisation and 219 patients (68.4%) completed 5 years of follow-up. The mean cIMT progression was significantly reduced in the treat-to-target group compared with usual care (0.023 [95% CI 0.011 to 0.036] mm vs 0.045 [95% CI 0.030 to 0.059] mm; p=0.028). Cardiovascular events occurred in 2 (1.3%) of the patients in the treat-to-target group vs 7 (4.7%) in those receiving usual care (p=0.048 by log-rank test).ConclusionThis study provides evidence on the benefit of a treat-to-target approach of traditional CVD risk factors for primary prevention in patients with well-treated RA.Trial registration numberNTR3873.

scholarly journals An In Vitro Analysis of the Combination of Hemophilia A and Factor VLEIDEN

Blood ◽  
1997 ◽  
Vol 90 (8) ◽  
pp. 3067-3072 ◽  
Author(s):  
Cornelis van ‘t Veer ◽  
Neal J. Golden ◽  
Michael Kalafatis ◽  
Paolo Simioni ◽  
Rogier M. Bertina ◽  
...  
Keyword(s):  
Factor Viii ◽  
Tissue Factor ◽  
Thrombin Generation ◽  
Hemophilia A ◽  
Factor Viia ◽  
Factor V ◽  
Severe Hemophilia ◽  
Factor Viii Activity ◽  
Thrombin Formation

Abstract The classification of factor VIII deficiency, generally used based on plasma levels of factor VIII, consists of severe (<1% normal factor VIII activity), moderate (1% to 4% factor VIII activity), or mild (5% to 25% factor VIII activity). A recent communication described four individuals bearing identical factor VIII mutations. This resulted in a severe bleeding disorder in two patients who carried a normal factor V gene, whereas the two patients who did not display severe hemophilia were heterozygous for the factor VLEIDEN mutation, which leads to the substitution of Arg506 → Gln mutation in the factor V molecule. Based on the factor VIII level measured using factor VIII–deficient plasma, these two patients were classified as mild/moderate hemophiliacs. We studied the condition of moderate to severe hemophilia A combined with the factor VLEIDEN mutation in vitro in a reconstituted model of the tissue factor pathway to thrombin. In the model, thrombin generation was initiated by relipidated tissue factor and factor VIIa in the presence of the coagulation factors X, IX, II, V, and VIII and the inhibitors tissue factor pathway inhibitor, antithrombin-III, and protein C. At 5 pmol/L initiating factor VIIa⋅tissue factor, a 10-fold higher peak level of thrombin formation (350 nmol/L), was observed in the system in the presence of plasma levels of factor VIII compared with reactions without factor VIII. Significant increase in thrombin formation was observed at factor VIII concentrations less than 42 pmol/L (∼6% of the normal factor VIII plasma concentration). In reactions without factor VIII, in which thrombin generation was downregulated by the addition of protein C and thrombomodulin, an increase of thrombin formation was observed with the factor VLEIDEN mutation. The level of increase in thrombin generation in the hemophilia A situation was found to be dependent on the factor VLEIDEN concentration. When the factor VLEIDEN concentration was varied from 50% to 150% of the normal plasma concentration, the increase in thrombin generation ranged from threefold to sevenfold. The data suggested that the analysis of the factor V genotype should be accompanied by a quantitative analysis of the plasma factor VLEIDEN level to understand the effect of factor VLEIDEN in hemophilia A patients. The presented data support the hypothesis that the factor VLEIDEN mutation can increase thrombin formation in severe hemophilia A.

scholarly journals Blood coagulation dynamics in haemostasis

2009 ◽  
Vol 29 (01) ◽  
pp. 7-16 ◽  
Author(s):  
T. Orfeo ◽  
S. Butenas ◽  
A. Undas ◽  
K. Brummel-Ziedins ◽  
K. G. Mann
Keyword(s):  
Tissue Factor ◽  
Epidemiologic Studies ◽  
Initiation Phase ◽  
Anticoagulation Agents ◽  
Plasma Factor ◽  
Tissue Factor Pathway ◽  
Sufficient Magnitude ◽  
Subsequent Propagation ◽  
Perforating Injury

SummaryOur studies involve computational simulations, a reconstructed plasma/platelet proteome, whole blood in vitro and blood exuding from microvascular wounds. All studies indicate that in normal haemostasis, the binding of tissue factor (TF) with plasma factor (F) VIIa (extrinsic FXase complex) results in the initiation phase of the procoagulant response. This phase is negatively regulated by tissue factor pathway inhibitor (TFPI) in combination with antithrombin (AT) and the protein C (PC) pathway. The synergy between these inhibitors provides a threshold-limited reaction in which a stimulus of sufficient magnitude must be provided for continuation of the reaction. With sufficient stimulus, the FXa produced activates some prothrombin. This initial thrombin activates the procofactors and platelets required for presentation of the intrinsic FXase (FVIIIa- FIXa) and prothrombinase (FVa-FXa) complexes which drive the subsequent propagation phase; continuous downregulation of which is provided by AT and the thrombinthrombomodulin- PC complex. FXa generation during the propagation phase is largely (>90%) provided by the intrinsic FXase complex. TF is required for the initiation phase of the reaction but becomes non-essential once the propagation phase has been achieved. The propagation phase catalysts (FVIIIa-FIXa and FVa-FXa) continue to drive the reaction as blood is resupplied to the wound site by flow. Ultimately, the control of the reaction is governed by the pro- and anticoagulant dynamics and the supply of blood reactants to the site of a perforating injury. Our systems have been utilized to examine the qualities of hypothetical and novel antihaemorrhagic and anticoagulation agents and in epidemiologic studies of venous and arterial thrombosis and haemorrhagic pathology.

Oestradiol-responsive miR-365a-3p interacts with tissue factor 3’-UTR to modulate tissue factor-initiated thrombin generation

2021 ◽  
Author(s):  
Jiayin Tian ◽  
Murray J Adams ◽  
Jasmine Wee Ting Tay ◽  
Ian James ◽  
Suzanne Powell ◽  
...  
Keyword(s):  
Tissue Factor ◽  
Thrombin Generation ◽  
Direct Interaction ◽  
Protein S ◽  
Coagulation Factors ◽  
Luciferase Reporter ◽  
Protein Levels ◽  
Thrombin Generation Assay ◽  
Increased Risk ◽  
Reporter Assays

Background: High oestradiol (E2) levels are linked to an increased risk of venous thromboembolism, however, the underlying molecular mechanism(s) remain poorly understood. We previously identified an E2-responsive microRNA (miR), miR-494-3p that downregulates protein S expression, and posited additional coagulation factors, such as tissue factor, may be regulated in a similar manner via miRs. Objectives: To evaluate the coagulation capacity of cohorts with high physiological E2, and to further characterise novel E2-responsive miR and miR regulation on tissue factor in E2-related hypercoagulability. Methods: Ceveron® Alpha thrombin generation assay (TGA) was used to assess plasma coagulation profile of three cohorts. The effect of physiological levels of E2, 10 nM on miR expression in HuH-7 cells was compared using NanoString nCounter® and validated with independent assays. The effect of tissue factor interacting miR was confirmed by dual-luciferase reporter assays, immunoblotting, flow cytometry, biochemistry assays and TGA. Results: Plasma samples from pregnant women and women on the contraceptive pill were confirmed to be hypercoagulable (compared with sex-matched controls). At equivalent and high physiological levels of E2, miR-365a-3p displayed concordant E2-down-regulation in two independent miR quantification platforms, and tissue factor mRNA (F3) was up-regulated by E2 treatment. Direct interaction between miR-365a-3p and F3-3’UTR was confirmed and overexpression of miR-365a-3p led to a decrease of 1) tissue factor mRNA transcripts, 2) protein levels, 3) activity and 4) tissue factor-initiated thrombin generation. Conclusion: miR-365a-3p is a novel tissue factor regulator. High E2 concentrations induces a hypercoagulable state via a miR-network specific for coagulation factors.

Comparison of the Use of TFPI Inhibition and Plasma Dilution to Increase the Sensitivity of Thrombin Generation Assay to Measure the Procoagulant Activity of Microvesicles

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 4392-4392
Author(s):  
Damien DG Gheldof ◽  
François Mullier ◽  
Bernard Chatelain ◽  
jean-Michel Dogne ◽  
Christian Chatelain
Keyword(s):  
Venous Thromboembolism ◽  
Tissue Factor ◽  
Thrombin Generation ◽  
Conflicts Of Interest ◽  
Surrogate Marker ◽  
Predictive Biomarker ◽  
Procoagulant Activity ◽  
Assay Sensitivity ◽  
Thrombin Generation Assay ◽  
Increased Risk

Abstract Abstract 4392 Introduction: Patients with cancer have a 7- to 10- fold increased risk of developing venous thromboembolism. Circulating microvesicles (MVs) could be a predictive biomarker for venous thromboembolism in cancer. Thrombin generation assay is a useful technique to detect procoagulant activity of MVs. However, thrombin generation assay suffers from a lack of sensitivity due to the presence of Tissue Factor Pathway Inhibitor (TFPI) in plasma. Aims: To improve the sensitivity of thrombin generation assay to tissue factor (TF) by limiting the interference of TFPI. Methods: Serial dilutions of MDA-MB231 cells were incubated for 45 min at 37°C to generate MVs. Samples were then centrifuged and supernatants which contain MVs were used for thrombin generation assay. Normal pooled plasma was incubated with inhibitor of TFPI or was diluted twice to decrease plasma level of TFPI. Lagtime was used as a surrogate marker of thrombin generation assay to detect procoagulant activity of MVs. Results: i) Inhibition of TFPI decreased twice the cell concentration needed for a significant reduction of lagtime and decreased 2.4-fold the intra-assay variability. ii) Plasma dilution had no impact on the thrombin generation assay sensitivity when thrombin generation assay was triggered by MVs derived from MDA-MB-231. Conclusions: Thrombin generation is a very sensitive method to study the procoagulant activity of TF-MVs. The sensitivity can be increased by inhibition of TFPI with specific monoclonal antibody against its Kunitz Domain I. A twice plasma dilution is an interesting alternative to study the procoagulant activity of MVs by thrombin generation assay with a good sensitivity, especially when low plasma quantities are available. Disclosures: No relevant conflicts of interest to declare.

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