Thromboelastographic study of fibrin clot and molecular basis of maximum clot firmness

Maximum clot firmness (MCF) is the main parameter of thromboelastography (TEG) reflecting the stability of a clot. In this work, we looked for markers that can influence the enhancement of MCF and detec­ted molecular markers and blood clotting parameters that can be involved in such mechanisms. Blood samples of pregnant women with placental disorders were collected in the Kyiv Perinatal Center. TEG was performed on whole blood in EXTEM and INTEM tests. APTT, INR, fibrinogen concentration and platelet aggregation were measured using traditional laboratory approaches. D-dimer was detected in sandwich ELISA using monoclonal antibodies III-3B and II-4D. The relative cross-linking activity of factor XIIIa was measured by the direct quantification of the cross-linked γ-chain of fibrin using Western-Blotting with monoclonal antibody II-4D. D-dimer and fibrinogen concentrations, clotting time in the APTT test, INR and rate of platelet aggregation did not correlate with the MCF. However, we found positive correlations of MCF with factor XIIIa activity: 0.51 and 0.87 for EXTEM and INTEM, respectively. These data indicate that for normal and slightly increased fibrinogen concentrations, fibrin clot firmness will depend mostly on the activity of factor XIIIa. Thus the direct determination of factor XIIIa activity in blood plasma of patients can be relevant for predicting the risk of intravascular coagulation. Evaluation of the content and activity of individual clotting factors or other components of the coagulation system can be useful additions to the TEG diagnostics and should not be neglected.