The First Report Of Differences In Fibrin Clot Nanostructure and Response To Tissue Plasminogen Activator (TPA) and Unfractionated Heparin (UFH) In Infants Compared To Adults

• Published in: Blood 2013-11, Vol.122 (21), p.459-459
• Main Authors: Ignjatovic, Vera, Pelkmans, Leonie, Bloemen, Saartje, Karlaftis, Vasiliki, Attard, Chantal, Al Dieri, Raed, de Laat, Bas, Monagle, Paul
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood.V122.21.459.459

Age specific differences in the function and concentration of haemostatic proteins are well established and are thought to contribute to the lower incidence of thromboembolism in infants and children compared to adults. We hypothesized that there are age-specific differences in the fibrin clot nanostructure and that these differences impact on fibrinolytic and anticoagulant treatment. To determine the differences in fibrin clot nanostructure and response to tissue Plasminogen Activator (tPA) and Unfractionated Heparin (UFH) in infants compared to adults. Four plasma samples from infants (0.86±0.16 years) and four samples from adults (32.04±15.80 years) were investigated. Thrombin generation (TG) was performed on paper discs in a microplate with 300mmol/L rhodamine substrate (P2Rho), 4mmol/L phospholipids, 5x10-9 mmol/L tissue factor and 16.7 mmol/L CaCl2; with and without additional 50ng/ml tPA, and 0.01IU/ml UFH. Fluorescence signal was recorded with a Fluoroskan Ascent fluorometer, with samples tested in triplicate. The resulting fibrin clots were fixed with 2.5% glutaraldehyde; washed with PBS and fixed with osmium tetroxide OsO4. The clots were dehydrated in ethanol and hexamethyldisilazane and were placed on carbon adhesive tabs. Each clot was coated with gold and studied using Scanning Electron Microscopy (SEM) on a Phenom Pro desktop SEM. The age-specific differences in fibrin fibre thickness and pore size were quantified using the Fibermetric software, with 36 representative images for infants and the same number for adults at each baseline, tPA and UFH, at magnification 10.000, counting 500 fibres per image. We observed significant differences in fibrin clot nanostructure between infants and adults (Fig 1). Results are expressed as median and range. Fibrin fibers were thicker in infants compared to adults (343.3nm, 61.2nm to 997.1nm vs 352.3nm, 26.1nm to 997.5nm, p