Multi-Scale Simulation Study of the Effect of Fiber Alignment and Bending and Stress–Strain Relation on Fibrin Networks

Structural and mechanical properties of fibrin networks are essential factors determining growth and stability of blood clots. Changes of a blood clot structure and its mechanical properties can occur dynamically in blood flow, during clot contraction or vasospasm. Predicting these alterations using multi-scale modeling is important not only for getting better understanding of clot deformation under various (patho-) physiological conditions but also for designing new fibrin-based biomaterials. A discrete worm-like-chain model of a fibrin network calibrated using confocal microscopy data, is used in this thesis to study how microscopic behavior of individual fibers affects macroscopic behavior of the whole network. The novelty of the approach is in combining study of the mechanical properties of individual fibers and fibrin network, such as rigidity, bending, stiffness and elasticity, with the study of the structural properties of the network, such as fiber degree distribution, length distribution and density. In particular, model simulations demonstrate that the surface shape of the entire network and its stress–strain behavior dramatically depend on the alignment of

individual fibers and their stress–strain response. Simulation results agree well with the data obtained in recent fibrin gel stretching experiments and suggest a novel micro- scale mechanism of the fibrin network mechanics and blot clot deformation under action of the tensile force based on alignment and bending of individual fibers.