PB1195 - Biochemical and structural regulation of the enzymatic degradation of blood clots

Background: Blood clots perform a critical biological function in cessation of bleeding following injury. However, their function is transient and ultimately after performing their physiological function they must be resolved (fibrinolysis), through the cleavage of fibrin(ogen) by a fibrinolytic enzyme. Excessive, early fibrinolysis can lead to bleeding whereas impaired fibrinolysis can result in heart attacks and strokes (thrombosis). The balance of resolution is a critical step in preventing life threatening complications, however it is poorly understood how changes in the fibrin structure influence the biochemical regulation of fibrinolysis.

Aims: In this study, we aim to utilize a combination of mathematical modeling and experiments to probe which structural changes play a dominant role in the degradation of fibrin clots.

Methods: We used turbidimetric experiments to assess the biochemical regulation of intrinsic fibrinolysis and microscopy studies to characterize the microstructure for fibrinolysis in human blood plasma with varying fibrin network structure. Experiments are combined with a 3D stochastic multiscale computational fibrinolysis model to probe the individual influence of changes in network density, pore size, and fiber diameter. One-way ANOVA tests were performed using Prism 9.0 to compare fibrin network density behavior and scenario simulations.

Results: Experimental studies show that increasing fibrinogen concentration leads to changes in fibrin density, pore size, and fiber diameter and ultimately results in impaired fibrinolysis (Figure 1). Analysis of simulations and experiments indicate that the pore size of the fibrin network makes the most significant contribution to the rate of fibrinolysis (Figure 2). We show that this effect is strongly influenced by the ratio of protein:enzyme when compared to absolute enzyme concentration.

Conclusion(s): Our findings suggest that fibrin structure, particularly the pore size of the fibrin work which is altered in pathological conditions, is an important contributor for the development of enzymatic treatments with increased efficacy in treating bleeding and/or thrombosis.