[Show abstract][Hide abstract] ABSTRACT: PURPOSE: Whereas von Willebrand disease is the most common constitutional bleeding disorder, acquired von Willebrand syndrome is rare. METHODS: Retrospective, monocentric descriptive study of consecutive cases of acquired von Willebrand syndrome diagnosed between 2000 and 2012. Diagnostic criteria included: absence of a past history of mucocutaneous bleeding, with low plasma levels of factor VIII (FVIII) and von Willebrand factor (VWF), ristocetine cofactor activity (RCo) and antigen (Ag). RESULTS: Nine men were diagnosed with von Willebrand syndrome. Six of them presented with recent mucocutaneous bleeding. In eight cases, the biological phenotype was a type 2 von Willebrand disease, with decreased VWF:RCo/VWF:Ag ratio. A lymphoproliferative disease with circulating paraprotein was identified in all patients, including one chronic lymphoid leukemia, three Waldenström and one marginal zone lymphomas, four monoclonal gammapathies of unknown significance. Screening for an anti-VWF inhibitor was negative. Symptomatic treatment using infusion of VWF concentrates was administrated in the presence of severe mucocutaneaous bleeding. Five patients received intravenous immunoglobulins with a good response only in patients with G isotype paraprotein. A chemotherapy was initiated if indicated for the underlying disorder. Three of the four patients who achieved remission of the associated lymphoma had a subsequent improvement of plasma VWF levels, while all other patients remained deficient. CONCLUSION: Acquired von Willebrand syndrome is a rare but potentially serious disease. The diagnostic should be suspected in adults with unusual mucocutaneous bleeding, with or without prolonged partial thromboplastin time (PTT), and confirmed with a decreased plasma level of VWF (Ag and RCo). An associated haematological, neoplastic or cardiac valvular disease must be searched.
La Revue de Médecine Interne 06/2013; · 1.07 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Purpose
Whereas von Willebrand disease is the most common constitutional bleeding disorder, acquired von Willebrand syndrome is rare.
Retrospective, monocentric descriptive study of consecutive cases of acquired von Willebrand syndrome diagnosed between 2000 and 2012. Diagnostic criteria included: absence of a past history of mucocutaneous bleeding, with low plasma levels of factor VIII (FVIII) and von Willebrand factor (VWF), ristocetine cofactor activity (RCo) and antigen (Ag).
Nine men were diagnosed with von Willebrand syndrome. Six of them presented with recent mucocutaneous bleeding. In eight cases, the biological phenotype was a type 2 von Willebrand disease, with decreased VWF:RCo/VWF:Ag ratio. A lymphoproliferative disease with circulating paraprotein was identified in all patients, including one chronic lymphoid leukemia, three Waldenström and one marginal zone lymphomas, four monoclonal gammapathies of unknown significance. Screening for an anti-VWF inhibitor was negative. Symptomatic treatment using infusion of VWF concentrates was administrated in the presence of severe mucocutaneaous bleeding. Five patients received intravenous immunoglobulins with a good response only in patients with G isotype paraprotein. A chemotherapy was initiated if indicated for the underlying disorder. Three of the four patients who achieved remission of the associated lymphoma had a subsequent improvement of plasma VWF levels, while all other patients remained deficient.
Acquired von Willebrand syndrome is a rare but potentially serious disease. The diagnostic should be suspected in adults with unusual mucocutaneous bleeding, with or without prolonged partial thromboplastin time (PTT), and confirmed with a decreased plasma level of VWF (Ag and RCo). An associated haematological, neoplastic or cardiac valvular disease must be searched.
La Revue de Médecine Interne 01/2013; 35(3). DOI:10.1016/j.revmed.2013.02.039 · 1.07 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Hereditary factor VII (FVII) deficiency is a rare autosomal recessive disorder. Deleterious mutations that prevent the synthesis of any amount of functional FVII have been associated with life-threatening haemorrhage in neonates. Here we report two infants, of Maghrebian origin, who suffered a fatal spontaneous cerebral haemorrhage. Investigation of the molecular basis for their severe FVII deficiency revealed novel mutations in a homozygous state within the F7 gene promoter: a single nucleotide substitution (c.-65G>C) and a 2bp deletion (c.-60_-59delTT). To determine whether these promoter variants were responsible for the FVII deficiency, computer-assisted sequence analyses were performed. The data predicted a disrupted binding of both HNF4 and COUP-TF transcription factors with each variant. Concordantly, experimental results revealed an altered HNF4-induced transactivation in the promoter mutated variants. The execution of functional tests is critical to ensuring a complete understanding of the effect of any promoter mutant on FVII deficiency. Only then can an accurate molecular diagnosis be made and further genetic counselling and prenatal diagnosis be offered.
Thrombosis and Haemostasis 05/2012; 108(2):277-83. DOI:10.1160/TH11-09-0638 · 4.98 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Factor (F) X deficiency is a rare inherited autosomal recessive trait. We report on a patient affected by a severe bleeding diathesis. Mutations were sought by F10 sequence analysis. The consequences of the mutation were characterized by measuring thrombin and FXa formation after triggering the clotting cascade with activated partial thromboplastin time (aPTT) reagent or with phospholipid vesicles plus either tissue factor (TF) or FIXabeta, or with the FX activator from Russell's viper venom (RVV-X). The patient was found to be homozygous for a novel FX p.G51V mutation (G11V of the mature protein) within the omega-loop of the gamma-carboxyglutamic-rich domain. FX activity was markedly reduced (FX:C <1%) in prothrombin time and aPTT assays, and was 15% of normal in the RVV-X assay. The antigen level (FX:Ag) was 75%. TF, alone or in combination with recombinant FVIIa, failed to trigger detectable FXa or thrombin activity in the patient's plasma. FIXabeta also failed to trigger measurable FXa or thrombin production, but activation with RVV-X was only 4-fold less effective in the patient's plasma than in normal plasma. Supplementation with normal FX suggested that FX(G11V) and/or FXa(G11V) might slow the clotting cascade by competition. Overall, the patient's phenotype appears to be due to a very low rate of FX(G11V) activation by TF/FVIIa and FVIIIa/FIXa complexes rather than to FXa(G11V) activity within prothrombinase.
Thrombosis Research 02/2009; 124(1):144-8. DOI:10.1016/j.thromres.2008.11.018 · 2.45 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Platelet storage pool disease is a qualitative platelet disorder associated with variable degrees of reduction in the numbers and contents of dense granules (delta-granules). Electron microscopy is the major tool for biological diagnosis. Patients presenting with this platelet disorder generally show a mild bleeding syndrome.
[Show abstract][Hide abstract] ABSTRACT: Polymorphic variants of genes encoding blood coagulation proteins have been extensively studied as risk factors for venous or arterial thrombosis A variation in the 3' untranslated region (UTR) involved in the post-transcriptional regulation of factor VII (FVII) gene has been recently identified, a two adenine insertion/deletion at nucleotide 11293. In this study, we investigated its effect on the risk of thrombosis in the frame of two case-control studies, including patients suffering from peripheral arterial disease (PAD) or venous thromboembolic (VTE) disease. The 3'UTR FVII gene polymorphism was investigated i) in 181 patients who had symptomatic atherosclerotic disease of the lower limbs, ii) in 178 patients who had had at least one episode of objectively diagnosed deep venous thrombosis and iii) in controls matched for age and sex. Plasma FVII antigen (FVII: Ag) levels were lower in the presence of the 3'UTR 2A insertion (68.4 +/- 12.3%, 81.3 +/- 14.5% and 89.5 +/- 13.7% in 2A/2A, 2A/0 and 0/0 subjects respectively, p < 0.0001). No significant relationship was found with VTE disease. In the contrary we observed a lower risk of PAD for the 2A/2A compared to the 0/0 genotype after adjustment for traditional risk factors (hypercholesterolemia, smoking status, diabetes and hypertension), with an OR of 0.24 [95% CI 0.06-0.99]. In conclusion, the 2 adenine insertion in the 3'UTR of FVII gene, related to lower plasma FVII levels, is a genetic variation that may contribute to reduce the risk of PAD.
Thrombosis and Haemostasis 11/2007; 98(4):733-7. DOI:10.1160/TH07-02-0103 · 4.98 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The presence of gene lesions in blood coagulation factor X (FX) was investigated in eight FX-deficient patients with severe bleeding symptoms, originating from five unrelated Algerian families (FX coagulant activity <1%, FX antigen ranging from 2% to 16%). A missense mutation (p.Phe31Ser) in the Gla domain was found in homozygous form for all patients but one, who is a compound heterozygote for the Phe31Ser mutation and for a non-sense mutation, Tyr130Term in EGF-2 domain. The haplotypes of FX alleles were determined by the following allelic variants located in the promoter: g.1323_1330delTTGTGA (A1/A2), g.1449T>C, g.1451C>A, upstream to exon 3: g.17257C>T and downstream to exon 3: g.17396A>C. The A1-C-A-T-C haplotype was found on each allele bearing the Phe31Ser mutation in the eight FX deficient patients contrasting with its low frequency (8%) in a control Algerian population (in which the Phe31Ser substitution was absent). The patients came from the same geographical area of Algeria (5/8 are certainly from Kabyle origin) and the haplotype analysis suggests a founder effect. Transient expression study reveals that, for the mutant FX-Phe31Ser, FX antigen level was 60% in conditioned media and 140% in cell lysates compared with the wild type FX. The partial retention and intracellular accumulation of the mutant FX might be due to impaired folding and/or conformational changes, and the discrepancies observed between the FX antigen level in COS-7 cell supernatant (60%) and in the patients plasma (2-16%) to an in vivo increased clearance of the secreted unstable FX mutant.
European Journal Of Haematology 05/2007; 78(5):405-9. DOI:10.1111/j.1600-0609.2007.00836.x · 2.07 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We have investigated the effect on human platelet aggregation of native dermatan sulfate (DS) and three oversulfated DS derivatives with different sulfur contents, and compared it with that of unfractionated heparin. An inhibitory effect on collagen-induced platelet aggregation was observed only with unfractionated heparin at high concentrations, whereas no inhibitory effect was observed when arachidonic acid was used. Heparin was the most potent inhibitor of the thrombin-induced platelet aggregation in platelet-rich plasma (PRP), whereas the oversulfated DS had a higher potency than the native DS. All these glycosaminoglycans (GAGs) also inhibited thrombin-induced aggregation of washed platelets in the presence of antithrombin (AT) or heparin cofactor II (HCII) but not in their absence. Heparin was by far the most potent inhibitor of washed platelet aggregation in the presence of AT, whereas the inhibitory effects of the DS (native or oversulfated) were lower but dependent on the sulfur content. In the presence of HCII, DSb, a slightly oversulfated DS, had the highest inhibitory effect, whereas heparin and DSd, the most oversulfated derivative, had lower potencies in this case. These data suggest that the inhibition of thrombin-induced platelet aggregation by the oversulfated DS derivatives is related to their ability to potentiate thrombin inactivation by AT or HCII. Hence, the oversulfated DS derivatives may not have an effect per se on the inhibition of platelet aggregation. They may constitute a new class of anticoagulants with enhanced anticoagulant effects in comparison with the native DS, but with only minor side-effects of bleeding in comparison with heparin.
Thrombosis Research 02/2007; 120(4):615-21. DOI:10.1016/j.thromres.2006.10.023 · 2.45 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Splice site selection is a key element of pre-mRNA splicing. Although it is known to involve specific recognition of short consensus sequences by the splicing machinery, the mechanisms by which 5' splice sites are accurately identified remain controversial and incompletely resolved. The human F7 gene contains in its seventh intron (IVS7) a 37-bp VNTR minisatellite whose first element spans the exon7-IVS7 boundary. As a consequence, the IVS7 authentic donor splice site is followed by several cryptic splice sites identical in sequence, referred to as 5' pseudo-sites, which normally remain silent. This region, therefore, provides a remarkable model to decipher the mechanism underlying 5' splice site selection in mammals. We previously suggested a model for splice site selection that, in the presence of consecutive splice consensus sequences, would stimulate exclusively the selection of the most upstream 5' splice site, rather than repressing the 3' following pseudo-sites. In the present study, we provide experimental support to this hypothesis by using a mutational approach involving a panel of 50 mutant and wild-type F7 constructs expressed in various cell types. We demonstrate that the F7 IVS7 5' pseudo-sites are functional, but do not compete with the authentic donor splice site. Moreover, we show that the selection of the 5' splice site follows a scanning-type mechanism, precluding competition with other functional 5' pseudo-sites available on immediate sequence context downstream of the activated one. In addition, 5' pseudo-sites with an increased complementarity to U1snRNA up to 91% do not compete with the identified scanning mechanism. Altogether, these findings, which unveil a cell type-independent 5'-3'-oriented scanning process for accurate recognition of the authentic 5' splice site, reconciliate apparently contradictory observations by establishing a hierarchy of competitiveness among the determinants involved in 5' splice site selection.
[Show abstract][Hide abstract] ABSTRACT: DSS1 and DSS2 are two oversulfated dermatan sulfate derivatives with sulfur contents of 7.8% and 11.5%, respectively. DSS1 and DSS2 both enhanced the rate at which antithrombin (AT) inactivates thrombin according to a concentration dependent manner. The analysis of the experimental data, using our previously described kinetic model [Biomaterials1997, 18, 203] (i) suggested that both DSS1 and DSS2 catalyzed the thrombin-AT reaction according to a mechanism in which the oversulfated derivative quickly formed with AT a complex, which was more reactive towards thrombin than the free inhibitor and (ii) allowed us to determine the dissociation constants of the polysaccharide-inhibitor complexes, which were (1.15 +/- 0.74) x 10(-7) and (7.17 +/- 0.65) x 10(-9) M, and the catalyzed reaction rate constants, which were (2.29 +/- 0.15) x 10(8) and (8.71 +/- 0.08) x 10(8) M(-1) min(-1), for DSS1 and DSS2, respectively. These data suggested that the oversulfation confers an affinity for AT to dermatan sulfate and that the higher the sulfur content the higher the affinity for AT. They also suggested that the reactivities of the polysaccharide-AT complexes formed towards the protease increased with the sulfur content.
Carbohydrate Research 05/2006; 341(5):672-6. DOI:10.1016/j.carres.2005.11.026 · 1.93 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We describe here five F7 mutations found in four patients without bleeding history, despite constitutional coagulation Factor VII (FVII) deficiency. All five mutations are missense and affect the catalytic domain of FVII (A191T, A191V, T239P, R224Q and M298I). The A191V and T239P mutations are novel and were found in homozygous patients with no clinical bleeding tendency. The patient diagnosed with the A191V mutation had a phenotype corresponding to a moderate type 1 FVII deficiency (FVII:C 4%, FVII:Ag 5%). The T239P mutation was found in a patient with mild type 2 FVII deficiency (FVII:C 25%, FVII:Ag 95%). Novel mutations are both in close vicinity to the charge-stabilizing system of FVII. Modeling studies allow understanding in part the molecular basis for the loss of function.
Thrombosis Research 02/2005; 116(2):115-20. DOI:10.1016/j.thromres.2004.11.005 · 2.45 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In a patient with lethal factor VII (FVII) deficiency, 2 homozygous nucleotide substitutions were identified in the F7 gene: a IVS7+2T>G transversion involving the IVS7 donor splice site, followed by a mutation at nucleotide 10588 that would result in a missense variation (Arg224Gln). The mutated splice site, located within the first repeat of a minisatellite, is followed by a variable number of pseudo-sites, normally silent. To investigate the consequences of this mutation on F7 splicing, we designed normal and mutant minigenes, spanning exons 5 to 8. In cells transfected with the mutant construct, no normal splicing occurred. Only spliced transcripts including the first minisatellite repeat were observed, resulting from the activation of the most proximal wild-type pseudo-site, which would generate a truncated protein (stop codon upstream of nucleotide 10588). These findings, which suggest the existence of a mechanism selecting one single splice site among multiple cryptic sites, explain the patient's phenotype.
[Show abstract][Hide abstract] ABSTRACT: Fucosylated chondroitin sulfate (FucCS), a glycosaminoglycan obtained from sea cucumber, has the same structure as mammalian chondroitin sulfate, but some of the glucuronic acid residues display sulfated fucose branches. This new polysaccharide has a more favorable effect than heparin on vascular cell growth. It inhibits smooth muscle cell proliferation as heparin, and it has a potent enhancing effect on endothelial cell proliferation and migration in the presence of heparin-binding growth factors. We now extend our studies to the effect of this glycosaminoglycan on endothelial cells to an in vitro angiogenesis model on Matrigel. FucCS, in the presence of fibroblast growth factor-2 (FGF-2), strongly increases the capacity of endothelial cells to form vascular tubes on Matrigel with a well-organized capillary-like network and typical closed structures. Comparison between the activity of native and chemically modified chondroitin sulfate from sea cucumber reveals that the sulfated fucose branches are the structural motif for the proangiogenic activity. Heparin does not induce angiogenesis in this experimental model. We also have evidence for the proposition that endothelial cell proliferation is not the sole event involved in the in vitro FGF-2-induced angiogenesis. It implies a variety of other modifications of the endothelial cells and of their interaction with the extracellular matrix, such as integrin expression and actin cytoskeleton reorganization. Finally, the proangiogenic effect of FucCS, concomitant with its capacity to prevent venous and arterial thrombosis, in animal models makes this new glycosaminoglycan a promising molecule with possible beneficial effects in pathological conditions affecting blood vessels such as the neovascularization of ischemic areas.
Molecular Cancer Research 01/2003; 1(2):96-102. · 4.38 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The molecular basis of severe type I factor (F)VII deficiency was investigated in two Algerian patients. One patient, a 13-year-old-girl who has suffered from severe bleeding since birth, was homozygous for a 7-bp deletion (nt 7774-7780) and a 251-bp insertion (nt 7773-7781) of mitochondrial origin, in IVS 4 acceptor splice site. The other patient, an infant who died from massive intracranial haemorrhage, was homozygous for a transversion in the IVS 7 donor splice site (T9726+2-->G) and a missense mutation in exon 8 (G10588-->A; Arg224-->Gln). In both cases, the deleterious mutations are probably the splice site junction abnormalities impairing mRNA processing. These three lesions have not yet been reported.
British Journal of Haematology 04/2002; 117(1):168-71. DOI:10.1046/j.1365-2141.2002.03397.x · 4.71 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A polysaccharide extracted from the sea cucumber body wall has the same backbone structure as the mammalian chondroitin sulfate, but some of the glucuronic acid residues display sulfated fucose branches. These branches confer high anticoagulant activity to the polysaccharide. Since the sea cucumber chondroitin sulfate has analogy in structure with mammalian glycosaminoglycans and sulfated fucans from brown algae, we compared its anticoagulant action with that of heparin and of a homopolymeric sulfated fucan with approximately the same level of sulfation as the sulfated fucose branches found in the sea cucumber polysaccharide. These various compounds differ not only in their anticoagulant potencies but also in the mechanisms of thrombin inhibition. Fucosylated chondroitin sulfate, like heparin, requires antithrombin or heparin cofactor II for thrombin inhibition. Sulfated fucans from brown algae have an antithrombin effect mediated by antithrombin and heparin cofactor II, plus a direct antithrombin effect more pronounced for some fractions. But even in the case of these two polysaccharides, we observed some differences. In contrast with heparin, total inhibition of thrombin in the presence of antithrombin is not achieved with fucosylated chondroitin sulfate, possibly reflecting a less specific interaction. Fucosylated chondroitin sulfate is able to inhibit thrombin generation after stimulation by both contact-activated and thromboplastin-activated systems. It delayed only the contact-induced thrombin generation, as expected for an anticoagulant without direct thrombin inhibition. Overall, the specific spatial array of the sulfated fucose branches in the fucosylated chondroitin sulfate not only confer high anticoagulant activity to the polysaccharide but also determine differences in the way it inhibits thrombin.
Thrombosis Research 05/2001; 102(2):167-76. DOI:10.1016/S0049-3848(01)00230-4 · 2.45 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Fucosylated chondroitin sulfate is a glycosaminoglycan extracted from the sea cucumber Ludwigothurea grisea. This polysaccharide has the same structure as a mammalian chondroitin sulfate but some of the glucuronic acid residues display sulfated fucose branches. Anticoagulant and antithrombotic properties of fucosylated chondroitin sulfate have already been described. In order to further investigate its potential therapeutic use as an antithrombotic agent, we studied its effect on vascular smooth muscle cell (SMC) proliferation and endothelial cell proliferation, migration and Tissue Factor Pathway Inhibitor (TFPI) release. The experiments were performed on SMC from rat thoracic aorta and on human umbilical vein endothelial cell (HUVEC) in culture with or without added fibroblast growth factors (FGF-1 and FGF-2). Our results showed that: (i) fucosylated chondroitin sulfate had a strong inhibitory effect on SMC proliferation (IC50 =10 +/- 5 microg/ml) and (ii) no effect on HUVEC proliferation and migration assays, in the absence of exogenous FGF, while heparin had inhibitory effects; (iii) fucosylated chondroitin sulfate (10 microg/ml) enhanced FGF-1 and FGF-2 induced HUVEC proliferation by 45% (145.4 +/- 7.2%) and 27% (126.9 +/- 4.2%), respectively; (iv) on FGF-induced HUVEC migration, fucosylated chondroitin sulfate (10 microg/ml) had a strong enhancing effect with FGF-1, +122% (222.2 +/- 15.8%), three times higher than that of heparin, and a lower enhancing effect with FGF-2, +43% (142.7 +/- 4.6%), whereas heparin had no effect; (v) fucosylated chondroitin sulfate stimulated TFPI release, mainly on the free form. +98% (198.2 +/- 25%). In addition, the structural features of the polysaccharide associated with its biological activity were resolved using chemically modified fucosylated chondroitin sulfates. Sulfated fucose branches groups are essential to the potentiating effect of the polysaccharide on HUVEC proliferation and migration. Surprisingly, removal of fucose branches from the fucosylated chondroitin sulfate did not abolish TFPI release. Finally, partial reduction of the glucuronic acid carboxyl groups limited the potentiating effect on HUVEC proliferation and migration but did not affect TFPI release. In conclusion, this fucosylated chondroitin sulfate from invertebrate origin reveals useful properties for an antithrombotic agent: inhibition of SMC proliferation, enhancement of endothelium wound repair and TFPI release. These properties on vascular cells, associated with a low bleeding tendency and an antithrombotic activity, strongly suggest its potential use as a new therapeutic agent in arterial thrombosis and restenosis, with a more favorable effect than heparin.
Thrombosis and Haemostasis 09/2000; 84(2):332-7. · 4.98 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Fucoidan is a sulfated polysaccharide extracted from brown seaweeds. It has anticoagulant and antithrombotic properties and inhibits, as well as heparin, vascular smooth muscle cell growth. In this study, we investigated, in the presence of serum and human recombinant growth factors, the effects of fucoidan and heparin on the growth and migration of human umbilical vein endothelial cells (HUVEC) in culture. We found that fucoidan stimulated fetal bovine serum-induced HUVEC proliferation, whereas heparin inhibited it. In the presence of fibroblast growth factor-1 (FGF-1), both fucoidan and heparin potentiated HUVEC growth. In contrast, fucoidan and heparin inhibited HUVEC proliferation induced by FGF-2, but did not influence the mitogenic activity of vascular endothelial growth factor (VEGF). In the in vitro migration assay from a denuded area of confluent cells, the two sulfated polysaccharides markedly enhanced the migration of endothelial cells in the presence of FGF-1. Finally, a weak inhibitory effect on cell migration was found only with the two polysaccharides at high concentrations (> or = 100 micro/ml) in presence of serum or combined with FGF-2. All together, the results indicated that heparin and fucoidan can be used as tools to further investigate the cellular mechanisms regulating the proliferation and migration of human vascular cells. Moreover, the data already suggest a potential role of fucoidan as a new therapeutic agent of vegetal origin in the vascular endothelium wound repair.
European Journal of Cell Biology 01/1999; 77(4):352-9. DOI:10.1016/S0171-9335(98)80094-0 · 3.83 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Fucoidan, a sulfated polysaccharide extracted from brown seaweeds, has antithrombotic properties, the mechanism of which is not yet completely understood. Tissue factor pathway inhibitor (TFPI), which regulates the tissue factor-dependent pathway of blood coagulation, is released from the endothelium by heparin, a mechanism contributing to its antithrombotic activity. In this study, we demonstrated that fucoidan, as heparin, induces TFPI release from cultured human umbilical vein endothelial cells (HUVEC). The TFPI accumulation in the HUVEC supernatants depends on the incubation time and polysaccharide concentration. After 30 to 60 minutes of incubation, TFPI concentration (total antigen level) was twice higher in the presence of both polysaccharides than in their absence. After one hour of incubation, in the presence of increasing concentrations of each polysaccharide, an optimal stimulation was observed for 0.5 microg/ml of fucoidan and 5 microg/ml of heparin, as evidenced by a raise of the basal TFPI level: a 2-fold increase for the total antigen and a 3-fold increase for the free antigen. These data suggest that TFPI released from vascular endothelial cells may contribute to the antithrombotic effect of fucoidan.
Thrombosis and Haemostasis 11/1998; 80(4):692-5. · 4.98 Impact Factor