Multiscale Modelling Of Vascular Remodeling Induced By Wall Shear Stress

Hemodynamics plays an important role in vascular remodeling.Hemodynamics induced low wall shear stress(WSS)is one of the critical reasons leading to vascular remodeling.There is a lack of research on how to establish a multiscale modelling approach to reveal the vascular remodeling behavior under the interaction between the macro scale of WSS loading and the micro scale of cell evolution.Based on the relationship between low WSS and vascular remodeling,the aim of this study is to establish a multiscale model to reveal the vascular remodeling behavior.In this study,computational fluid dynamics(CFD)method and agent-based model(ABM)were adopted to establish vascular stress analysis model and vascular remodeling model to reveal the vascular remodeling behavior.The first part is to establish a partially coupled multiscale model.On the the macro scale,the CFD method was used to simulate blood flow in the proximal left anterior descending coronary artery and obtain the WSS in cross sections as input of ABM.On the the micro scale,the simulations of smooth muscle cell proliferation/apoptosis and extracellular matrix generation/degradation in cross sections were performed by using ABM.During vascular remodeling procedure,we updated WSS by using the CFD model.The second part is to establish a fully coupled multiscale model.In order to update WSS,we selected multiple cross sections of the blood vessel for ABM.Then,a new 3D blood model was reconstructed by the multiple ABM results.Updated WSS was obtained as input after CFD simulation.The results are as follows: The amount and distribution of smooth muscle cells and extracellular matrix changed with time,and the vessel wall underwent positive and negative remodeling,and finally the vessel wall thickened and the lumen narrowed.The significant wall thickening region was consistent with the low WSS region.There was no evident change of wall thickness in normal WSS region.When the damage index approached to 0,the amount and distribution of smooth muscle cell and extracellular matrix achieved a stable state and the vessel reached the vascular homeostasis.Although the results of each ABM were different,the trend of each simulation result remained coincident.It also showed that random settings during initialization and stochastic events during simulation had little effect on the simulation results.The preliminary conclusion of this study was as follows: with the usage of CFD and ABM,we were able to establish a multiscale modelling approach to reveal the vascular remodeling behavior under different WSS conditions.