(134c) Regulating Fibrin Formation, Structure, and Mechanical Strength

Blood coagulation proceeds through a number of pathways within the coagulation cascade. These pathways can be initiated via exposure to negatively charged surfaces (intrinsic contact pathway) or through interaction with tissue factor (extrinsic pathway). However, the series of plasma protein reactions that occur to subsequently produce thrombin and fibrin can be drastically affected by a deficiency in zymogen factor XI (FXI), an integral protein in the coagulation cascade, which is activated by FXIIa and thrombin, or in zymogen factor XII, which is the starting point of the intrinsic pathway. Deficiencies in FXI result in prolonged bleeding times, suggesting that FXI plays a crucial role in regulating hemostatic plug formation. The structure of fibrin is integral to the kinetics and stability of thrombus formation, controlling clot strength and susceptibility to lysis. Thus, we used a suite of FXI inhibitors to measure the role of FXI on fibrin by analyzing the kinetics of fibrin formation, quantifying the extent of fibrin gel structure, and measuring the rheological properties of the transient coagulation. We show that FXI plays a key role in regulating the kinetics of fibrin formation and overall fibrin gel structure.