Simulation Files from Red blood cell dynamics in extravascular biological tissues modelled as canonical disordered porous media

The dynamics of blood flow in the smallest vessels and passages of the human body, where the cellular character of blood becomes prominent, plays a dominant role in the transport and exchange of solutes. Recent studies have revealed that the micro-haemodynamics of a vascular network is underpinned by its interconnected structure, and certain structural alterations such as capillary dilation and blockage can substantially change blood flow patterns. However, for extravascular media with disordered microstructure (e.g. the porous intervillous space in the placenta), it remains unclear how the medium’s structure affects the haemodynamics. Here, we simulate cellular blood flow in simple models of canonical porous media representative of extravascular biological tissue, with corroborative microfluidic experiments performed for validation purposes. For the media considered here, we observe three main effects: first, the relative apparent viscosity of blood increases with the structural disorder of the medium; second, the presence of red blood cells (RBCs) dynamically alters the flow distribution in the medium; third, symmetry breaking introduced by moderate structural disorder can promote more homogeneous distribution of RBCs. Our findings contribute to a better understanding of the cell-scale haemodynamics that mediates the relationship linking the function of certain biological tissues to their microstructure.

人体最小血管与通道内的血流动力学——此时血液的细胞特性愈发显著——在溶质的运输与交换过程中发挥主导作用。近期研究表明，血管网络的微血流动力学由其互联结构所支撑，而诸如毛细血管扩张与阻塞等结构改变，可显著改变血流模式。然而，对于具有无序微结构的血管外介质（例如胎盘中的多孔绒毛间隙），其介质结构如何影响血流动力学，目前仍不明确。本研究针对代表血管外生物组织的典型多孔介质简化模型，模拟了细胞性血流，并通过佐证性微流控实验进行验证。针对本研究涉及的介质，我们观察到三大主要效应：其一，血液的相对表观黏度随介质结构无序程度升高而增大；其二，红细胞（red blood cells, RBCs）的存在会动态改变介质内的流场分布；其三，适度结构无序性引发的对称性破缺，可促进红细胞实现更均匀的分布。本研究结果有助于更深入理解细胞尺度的血流动力学——这类动力学介导了特定生物组织功能与其微结构之间的关联。