Cell-dependent antithrombotic effect of tranexamic acid.

Area of Science:

• Biochemistry
• Hematology
• Pharmacology

Background:

• Tranexamic acid (TXA) is a lysine analog that inhibits fibrinolysis.
• While effective in reducing bleeding mortality, its prophylactic benefits and effects on thrombus formation are context-dependent.
• TXA may have cell-dependent effects beyond antifibrinolysis due to plasmin(ogen)'s interactions with cellular components.

Purpose of the Study:

• To investigate how cellular elements influence TXA's impact on thrombus formation.
• To determine if TXA's antithrombotic effects are cell-dependent.

Main Methods:

• Utilized an *in vivo* murine venous thrombosis model (IVC stenosis) without endothelial injury.
• Assessed thrombin generation in whole blood and platelet-rich plasma to evaluate cell dependence.
• Quantified leukocyte-associated plasminogen activation and measured plasma VWF:Ag and MCP-1 levels.

Main Results:

• TXA significantly reduced venous thrombus initiation by 90% but did not affect existing clot mass.
• TXA decreased thrombin generation in whole blood, but not in platelet-rich plasma, indicating a cellular requirement.
• TXA inhibited leukocyte surface-mediated plasminogen activation and suppressed stenosis-induced MCP-1 increase.

Conclusions:

• TXA is not prothrombotic in venous stasis; it reduces thrombus initiation without impairing primary hemostasis.
• This study demonstrates TXA's cell-dependent modulation of thrombin generation, linked to inhibiting leukocyte-associated plasmin activity.