Effects of tissue factor, thrombomodulin and elevated clotting factor levels on thrombin generation in the calibrated automated thrombogram

Abstract

SummaryElevated procoagulant levels have been correlated with increased thrombin generation in vitro and with increased venous thromboembolism (VTE) risk in epidemiological studies. Thrombin generation tests are increasingly being employed as a high throughput method to provide a global measure of procoagulant activity in plasma samples. The objective of this study was to distinguish the effects of assay conditions [tissue factor (TF), thrombomodulin, platelets/lipids] and factor levels on thrombin generation parameters, and determine the conditions and parameters with the highest sensitivity and specificity for detecting elevated factor levels. Thrombin generation was measured using calibrated automated thrombography (CAT) in corn trypsin inhibitor (CTI)-treated plateletfree plasma (PFP) and platelet-rich plasma (PRP). Statistical analysis was performed using logarithms of observed values with analysis of variance that accounted for experiment and treatment. The relative sensitivity of lag time (LT), time to peak (TTP), peak height and endogenous thrombin potential (ETP) to elevated factors XI, IX, VIII, X, and prothrombin was as follows: PFP initiated with 1 pM TF > PFP initiated with 5 pM TF > PRP initiated with 1 pM TF. For all conditions, inclusion of thrombomodulin prolonged the LT and decreased the peak and ETP; however, addition of thrombomodulin did not increase the ability of CAT to detect elevated levels of individual procoagulant factors. In conclusion, CAT conditions differentially affected the sensitivity of thrombin generation to elevated factor levels. Monitoring the peak height and/or ETP following initiation of clotting in PFP with 1 pM TF was most likely to detect hypercoagulability due to increased procoagulant factor levels.

Diet Modulates Endogenous Thrombin Generation, A Biological Estimate of Thrombosis Risk, Independently of the Metabolic Status

“…39 In the present study, switching to healthy diet was followed by a decrease in coagulation factors, mainly FII and FVII. However, because of the small variations observed and the lack of correlation between coagulation factors and ETP, it is doubtful that changes in coagulation factors could account for changes in ETP, 40 corroborating our data in rats. Stepwise regression analysis underlined the independent effect of changes in the percentage of energy intake provided by proteins and by circulating DHA levels on ETP.…”

Characterization of the thrombin generation potential of leukemic and solid tumor cells by calibrated automated thrombography

“…In plasma studies, endogenous thrombin potential is considered one of the most important parameters of the thrombin generation curve, 17 although some studies have also highlighted the importance of peak height. 18 In cell studies, however, it has not been established which is the more important parameter and, therefore, the entire thrombin generation curve profile should be taken into consideration. For example, despite the fact that H69 and MCF-7 cells produce similar amounts of thrombin (endogenous thrombin potential), the kinetic profiles of the two curves are different.…”

“…During this step, known as the propagation phase, 10 TF becomes less important, because the reaction is mainly driven by the FVIIa/FXa and FVa/FXa complexes. 18,24 To further understand to what extent tumor cell TF contributes to thrombin generation, two different strategies were used: (i) inhibiting cell-associated TF with a specific anti-TF antibody, and (ii) performing the assay in FVIIdeficient plasma. In both cases, the thrombin generation NB4 K562 HEL H69 MCF7 NB4 K562 HEL H69 MCF7 NB4 K562 HEL H69 MCF7 NB4 K562 HEL H69 MCF7 NB4 K562 HEL H69 MCF7 NB4 K562 HEL H69 MCF7 NB4 K562 HEL H69 MCF7 NB4 K562 HEL © F e r r a t a S t o r t i F o u n d a t i o n capacity of all cell lines was significantly reduced, and the decrease was proportional to cell TF content.…”

Prothrombin Complex Concentrates for Bleeding in the Perioperative Setting

“…In vitro assays such as the calibrated automated thrombogram (CAT®; Thrombinoscope, Inc., Parsippany, NJ) provide a sensitive blood assay for thrombin generation. [23][24][25] CAT is not yet FDAapproved for clinical use and, thus, is limited to research. This assay promises clinically relevant insight into the management of hemostasis and thrombosis by risk-stratifying patients according to the ability of thrombin generation during various clinical scenarios.…”