Polyphosphate enhances fibrin clot structure

Abstract

Polyphosphate, a linear polymer of inorganic phosphate, is present in platelet dense granules and is secreted on platelet activation. We recently reported that polyphosphate is a potent hemostatic regulator, serving to activate the contact pathway of blood clotting and accelerate factor V activation. Because polyphosphate did not alter thrombin clotting times, it appeared to exert all its procoagulant actions upstream of thrombin. We now report that polyphosphate enhances fibrin clot structure in a calciumdependent manner. Fibrin clots formed in the presence of polyphosphate had up to 3-fold higher turbidity, had higher masslength ratios, and exhibited thicker fibers in scanning electron micrographs. The ability of polyphosphate to enhance fibrin clot turbidity was independent of factor XIIIa activity. When plasmin or a combination of plasminogen and tissue plasminogen activators were included in clotting reactions, fibrin clots formed in the presence of polyphosphate exhibited prolonged clot lysis times. Release of polyphosphate from activated platelets or infectious microorganisms may play an important role in modulating fibrin clot structure and increasing its resistance to fibrinolysis. Polyphosphate may also be useful in enhancing the structure of surgical fibrin sealants. (Blood. 2008;112: 2810-2816) IntroductionA fibrin clot is the final product of the blood clotting cascade. Thrombin catalyzes release of fibrinopeptide A from fibrinogen to create fibrin monomers, which then aggregate to protofibrils. Proteolytic release of fibrinopeptide B by thrombin permits lateral protofibril aggregation, resulting in a three-dimensional fibrin gel. Factor XIIIa, a transglutaminase activated by thrombin, covalently crosslinks these fibers to increase the strength and elasticity of the resulting clot. 1 Variables known to influence fibrin clot structure include fibrinogen and thrombin concentrations, 1 pH, 2,3 ionic strength, 3 chloride ion concentration, 2 and presence of calcium ions. 4 A variety of molecules are reported to affect fibrin clot structure, including homocysteine, 5 decorin core protein, 6 heparins, 7,8 dextran, 9 and hydroxyethylstarch. 10 In this study, we demonstrate that inorganic polyphosphate (polyP) strongly modulates fibrin clot structure.polyP is a negatively charged, linear polymer of phosphate units linked by high-energy phosphoanhydride bonds. polyP has a wide biologic distribution, 11 but its functions have been studied most extensively in prokaryotes and unicellular eukaryotes, in which high levels of polyP accumulate in organelles known as acidocalcisomes. In such organisms, polyP plays essential roles in stress responses and virulence. 12 Although polyP has been studied less extensively in mammalian cells, 13 it has been reported to induce apoptosis in plasma cells, 14 promote calcification in osteoblasts, 15 and block metastasis of melanoma cells in a mouse model. 16 It has also been proposed to serve as a regulatory factor in proliferative signaling pathways. 17 Dense granules of human...

Nucleic acid scavengers inhibit thrombosis without increasing bleeding

“…Polyphosphates have been shown to accelerate factor XI activation by thrombin and factor Xa (11). Polyphosphates can also inhibit the activity of tissue factor pathway inhibitor (TFPI) and accelerate the activity of thrombin-activatable fibrinolysis inhibitor (TAFI) (12,13). In the blood of hemophilia A and B patients and Hermansky-Pudlak syndrome patients, polyphosphates significantly reduce the clotting times (14).…”

Use of 2-octyl cyanoacrylate adhesive in rat liver induced lesion

“…It also has sealing and bactericide properties 12 . Its bactericide properties are of major importance, since the second main cause of death by liver traumatism is represented by intra or extra-abdominal sepsis, seconded only by hemorrhage 5 Cyanoacrylate adhesive was applied to the liver diaphragmatic surface of the adhesive group (AG) according to the manufacturer (Dermabond ® , Ethicon) recommendations, obtaining satisfactory haemostatic activity. The need for compression and site cleansing for adequate bonding polymerization must be highlighted 13 .…”

“…Liver lesions can be treated in several manners depending on their severity varying from simple stitching, drainage, regradas and widening resections, or even transplant. In spite of hospital improved infrastructure, aseptic means, material, technical and anatomical know-how, mortality rate is still elevated for subjects with lever lesions, though such organ is protected by the costal gradil 4,5 .…”

Les polyphosphates

“…En corollaire, les polyP de longueur de chaîne supé-rieure à 45 unités phosphate (polyP 45 ) modulent la coagulation et la fibrinolyse (lyse du réseau de fibrine, Figure 2) dans du plasma dépourvu de plaquettes, car ils activent la voie intrinsèque, dite phase contact, de la coagulation (voir ci-dessous et Figure 1), potentialisent l'activation du Facteur V 1 de coagulation ( Figure 2) [4], et solidifient la structure du caillot de fibrine [5]. Enfin, une étude collaborative internationale vient d'être publiée dans la revue Cell, démontrant que les polyP sécrétés par les plaquettes activées sont des modula- B.…”