Microstructure-based computational study of nonlinear mechanics of fibrin networks (original) (raw)

Structural and mechanical properties of fibrin networks, which are essential factors determining growth and stability of blood clots, can dynamically undergo fast changes due to blood flow shear, clot contraction, or vasospasms. Predicting these alterations using computational modeling is important for understanding mechanisms governing clot deformation under various (patho-)physiological conditions and designing new fibrin-based bio-materials. In this work, a discrete worm-like-chain model (WLC) of a fibrin network is introduced to study how the macroscale behavior of the network, including macro-scale structural changes and force-strain response of the fibrin clot, emerge from the micro-scale characteristics of the network. The model was calibrated using confocal microscopy data on single fiber stretching and the simulation results will be shown to be in good agreement with the data obtained in the fibrin gel stretching experiments. Additionally, simulations demonstrate how structural metrics, such as length and orientation of individual fibers, change when stretching forces are applied to the network and how network's stress-strain response depends on these metrics. Lastly, the addition of a modeling component representing bending of single fibers, allowed us to study impacts of shear stress and compression on the network and how its stress-strain profile under these conditions depends on bending stiffness and other properties of the network. The suggested micro-scale mechanisms based on alignment and bending of fibers, tested in simulations, are used to make predictions about the behavior of the fibrin network under patient specific conditions.