(437a) Mechanical Strain Decreases the Rate of Fibrin Gel Degradation by Plasmin

Fibrin is a major component of blood clots and is formed by polymerization of fibrinogen. From a bio-materials standpoint, fibrin is of great interest because it can withstand strains of 200% and serves as an excellent tissue engineering scaffold. The mechanical properties of fibrin gels are likewise of fundamental medical importance: it is highly desirable to dissolve fibrin networks in the context of thrombosis, but mechanically robust clot formation is essential during wound healing. Fibrin networks are subject to strain both in vivo and in engineered biomaterials. However, very little is known about how mechanical stress may affect fibrinolysis by plasmin, the major enzyme responsible for clot dissolution.  Here we describe micro-scale measurements that quantify the effect of mechanical strain on fibrin clot dissolution by plasmin. We find that 170% strain results in a dramatic, ~8-fold decrease in fibrinolysis rates. A poroelastic model of the fibrin network can account for the decrease in proteolysis rate that we observe.  Our data and resulting model suggest that mechanical strain may be an important regulator of fibrinolysis in vivo.