Fibrin polymerizes into a fibrous mesh that provides mechanical stability to blood clots. Ultimately, this mesh needs to be dissolved, in a process called fibrinolysis, to allow normal blood flow. Mesh structure and lysis depend on fibrinogen and thrombin concentrations; however, quantitative relationships of these dependencies are lacking. This study aims to investigate the effects of fibrinogen and thrombin concentrations on the structural properties of fibrin clots, including fiber density, pore size, fractal dimension, and fiber diameter. Additionally, we seek to derive mathematical relationships that describe how these structural properties influence clot lysis time, providing insights into the relative contributions of fibrinogen and thrombin to clot formation and their implications for thrombosis, hemostasis, and lysis. We used confocal and electron microscopy to quantitatively analyze the relationship between structural properties of plasma clots—fiber density, pore size, fractal dimension, fiber diameter—and fibrinogen and thrombin concentrations; we used a lysis assay to determine lysis time for all clot conditions. We found that higher concentrations of fibrinogen and thrombin led to clots with increased fiber density, reduced pore size, and greater fractal dimension (branching). Fiber diameter was observed to increase with increasing fibrinogen and decreasing thrombin. From these observations, power-law equations were derived to describe the relationship between clot structural properties, lysis time, and the concentrations of fibrinogen and thrombin. The equations revealed that fibrinogen concentration has a more pronounced effect on clot structure than thrombin concentration. These findings hold significant implications for understanding clot formation and their relevance in the context of thrombosis, hemostasis, and lysis.
Nameny et al. (Sun,) studied this question.