Cheng Xiaopo, Caruso Christina, Lam Wilbur A, Graham Michael D
Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA.
Aflac Cancer and Blood Disorders Center of Children's Healthcare of Atlanta, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30307, USA.
Soft Matter. 2025 Jul 16;21(28):5793-5803. doi: 10.1039/d4sm01519c.
The impacts of cell segregation and margination in blood disorders on microcirculatory hemodynamics within bifurcated vessels are physiologically significant, yet poorly understood. This study presents a comprehensive computational investigation of red blood cell (RBC) suspension dynamics, with a focus on a model of sickle cell disease (SCD) as an example of a disorder associated with subpopulations of aberrant RBCs. The findings reveal how cell margination influences cellular partitioning and distributions as well as vessel wall shear stress (WSS) at vascular bifurcations. Normal RBCs, which migrate toward the channel center, exhibit the Zweifach-Fung effect, preferentially entering high-flow-rate branches. In contrast, sickle cells, which marginate near the vessel wall, demonstrate an -Zweifach-Fung effect, favoring lower-flow-rate branches due to their position within the cell-free layer (CFL). The upstream segregation of cells remains downstream through the bifurcation, where sickle cells accumulate along the outer branch walls. This accumulation of sickle cells increases the frequency of high WSS events direct physical interactions, particularly on the outer side of high-velocity branches, potentially contributing to the vascular damage and endothelial disruption observed in many disorders that affect RBCs. In geometrically asymmetric bifurcations, cells preferentially enter branches with larger radii, underscoring the influence of geometric complexity on microcirculatory blood flow. These findings provide insights into microvascular hemodynamics in SCD and other blood disorders.
血液疾病中细胞分离和边缘化对分叉血管内微循环血流动力学的影响具有重要生理意义，但目前了解甚少。本研究对红细胞（RBC）悬浮动力学进行了全面的计算研究，重点以镰状细胞病（SCD）模型为例，该病是一种与异常RBC亚群相关的疾病。研究结果揭示了细胞边缘化如何影响细胞分配和分布，以及血管分叉处的血管壁剪切应力（WSS）。向通道中心迁移的正常RBC表现出 Zweifach-Fung 效应，优先进入高流速分支。相比之下，在血管壁附近边缘化的镰状细胞表现出 -Zweifach-Fung 效应，由于它们在无细胞层（CFL）中的位置，更倾向于进入低流速分支。细胞的上游分离在分叉处保持在下游，镰状细胞沿着外部分支壁聚集。镰状细胞的这种聚集增加了高WSS事件的频率 直接物理相互作用，特别是在高速分支的外侧，这可能导致在许多影响RBC的疾病中观察到的血管损伤和内皮破坏。在几何不对称的分叉中，细胞优先进入半径较大的分支，突出了几何复杂性对微循环血流的影响。这些发现为SCD和其他血液疾病中的微血管血流动力学提供了见解。
