Recktenwald Steffen M, Graessel Katharina, Maurer Felix M, John Thomas, Gekle Stephan, Wagner Christian
Dynamics of Fluids, Department of Experimental Physics, Saarland University, Saarbrücken, Germany.
Biofluid Simulation and Modeling, Department of Physics, University of Bayreuth, Bayreuth, Germany.
Biophys J. 2022 Jan 4;121(1):23-36. doi: 10.1016/j.bpj.2021.12.009. Epub 2021 Dec 9.
The dynamics of single red blood cells (RBCs) determine microvascular blood flow by adapting their shape to the flow conditions in the narrow vessels. In this study, we explore the dynamics and shape transitions of RBCs on the cellular scale under confined and unsteady flow conditions using a combination of microfluidic experiments and numerical simulations. Tracking RBCs in a comoving frame in time-dependent flows reveals that the mean transition time from the symmetric croissant to the off-centered, nonsymmetric slipper shape is significantly faster than the opposite shape transition, which exhibits pronounced cell rotations. Complementary simulations indicate that these dynamics depend on the orientation of the RBC membrane in the channel during the time-dependent flow. Moreover, we show how the tank-treading movement of slipper-shaped RBCs in combination with the narrow channel leads to oscillations of the cell's center of mass. The frequency of these oscillations depends on the cell velocity, the viscosity of the surrounding fluid, and the cytosol viscosity. These results provide a potential framework to identify and study pathological changes in RBC properties.
单个红细胞（RBC）的动力学特性通过使其形状适应狭窄血管中的流动条件来决定微血管中的血流。在本研究中，我们结合微流控实验和数值模拟，在受限和非稳态流动条件下，从细胞尺度探索红细胞的动力学特性和形状转变。在随时间变化的流动中，在一个共同移动的坐标系中追踪红细胞，结果显示从对称新月形到偏心、非对称拖鞋形的平均转变时间明显快于相反的形状转变，后者表现出明显的细胞旋转。补充模拟表明，这些动力学特性取决于随时间变化的流动过程中红细胞膜在通道中的取向。此外，我们展示了拖鞋形红细胞的坦克履带式运动与狭窄通道相结合如何导致细胞质心的振荡。这些振荡的频率取决于细胞速度、周围流体的粘度和细胞质粘度。这些结果为识别和研究红细胞特性的病理变化提供了一个潜在的框架。
