Mesoscopic Protofibril Aggregation Model for Numerical Analysis of Fibrin Clot Formation

A fibrin clot is main component of thrombus. The formation of the fibrin clot consists of several multi-scale processes. Fibrinogen, which is a plasma protein, is activated by thrombin and polymerized into a filament, the so-called protofibril. The protofibrils aggregate and form network structures called as fibrin clots. According to previous studies, the network structure varies depending on aggregation conditions, e.g., concentrations of fibrinogen and solvent flow, and alters the mechanical and chemical characteristics of the fibrin clot. However, the formation mechanisms of various network structures have not been understood in detail yet because of the spatiotemporal multi-scale of the formation process. In this study, we develop a numerical mesoscopic protofibril aggregation model to describe the fibrin clot formation from the mechanical point of view. We model protofibril as discrete elements consisting of material points bounded by linear springs. Each material point follows an overdamped Langevin equation. Our model can demonstrate the network structure observed in experiments. Additionally, we discuss the relationship between the characteristics of the network structure and each model parameter, to clarify why the various network structures appear in experiments.