Modifications of flow measurement to determine fibrin gel permeability and the preliminary use in research and clinical materials

Abstract

Our earlier investigations employing a flow measurement have yielded intriguing findings as to what governs the fibrin network porosity. To make the method suitable for use by more groups with various laboratory conditions, sample materials or study purposes, we simplified the essential equipment and thereby minimized the sample volume to 250 microl in comparison with the need for 3000 microl in the previous method. To assess whether the fibrin gel permeability depends on changes in thrombin generation potential and/or fibrinogen clotting property, different concentrations of thrombin with or without frozen-thawed platelets, serving as phospholipids, were used. The platelets and 0.05 IU/ml thrombin were added to plasma samples from patients with previous myocardial infarction. The fibrin gel permeability, expressed as Darcy constant (Ks), was decreased compared with that in controls, supporting findings about high risk of thromboembolism in this disease due to increases of thrombin activity and fibrinogen function. When 0.4 IU/ml thrombin was used in samples provided by 10 healthy individuals treated with acetysalicylic acid, Ks levels were increased during versus before therapy. Since almost no thrombin generation was found in the samples with the higher dose of exogenous thrombin, we considered that modifications in fibrinogen clotting property by acetysalicylic acid rendered the fibrin network more permeable. In summary, as the reproducibility remains satisfactory (coefficient of variation < 10%) despite aforementioned modifications in the equipment and reagents, any interested laboratory ought to be able to repeat the method. Assays of fibrin permeability in such a simple way may help to determine the fibrin clot stability in pathological/pharmacological studies, and probably serve as a tool to estimate thromboembolism risk in clinical materials, such as patients with cardiovascular diseases.

Is a decrease of microparticles related to improvement of hemostasis after FVIII injection in hemophilia A patients treated on demand?

“…The latter results have been used in a larger study previously published [12,13]. Comparison was also made with fibrin gel structure (unpublished data, manuscript in preparation), which was determined according to previously published procedures [17]. Ks represents the coefficient of permeability and it is inversely related to fibrin gel porosity (i.e.…”

Platelet Activity, Coagulation, and Fibrinolysis During Exercise in Healthy Males

“…The fibrin gels were prepared by adding 45 L of a modified gel-initiating cocktail consisting of 5 pM rTF, 4 mol/L PPL, and 20 mmol/L CaCl 2 , to 200 L plasma, 10 followed by incubation overnight at room temperature to mature. Permeability (porosity) of the gel was measured by the volume of a buffer percolated through the gel under different hydrostatic pressures.…”

“…Permeability (porosity) of the gel was measured by the volume of a buffer percolated through the gel under different hydrostatic pressures. 10 …”

“…Furthermore, as exercise enhances fibrinolysis, it is of considerable interest to investigate how exercise influences the fibrin gel network, being the final outcome of coagulation, using a permeability assay. 10 Platelet activation has a pivotal role in arterial thrombosis. Thrombin is the primary activator of platelets at the site of thrombus formation and a major driving force in thrombus growth.…”

Permeability calculations in three-dimensional isotropic and oriented fiber networks

“…[6][7][8][9][10] The most common measure used to characterize such flows is the hydraulic permeability k, which for an isotropic medium is defined by Darcy's law as 11…”