The remarkable deformability of red blood cells (RBCs) depends on the viscoelasticity of the plasma membrane and cell contents and the surface area to volume (SA:V) ratio; however, it remains unclear which of these factors is the key determinant for passage through small capillaries. We used a microfluidic device to examine the traversal of normal, stiffened, swollen, parasitised and immature RBCs. We show that dramatic stiffening of RBCs had no measurable effect on their ability to traverse small channels. By contrast, a moderate decrease in the SA:V ratio had a marked effect on the equivalent cylinder diameter that is traversable by RBCs of similar cellular viscoelasticity. We developed a finite element model that provides a coherent rationale for the experimental observations, based on the nonlinear mechanical behaviour of the RBC membrane skeleton. We conclude that the SA:V ratio should be given more prominence in studies of RBC pathologies.

中文翻译：

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表面积与体积之比，而不是细胞粘弹性，是红细胞通过小通道的主要决定因素

红细胞 (RBC) 的显着变形能力取决于质膜和细胞内容物的粘弹性以及表面积与体积 (SA:V) 的比值；然而，尚不清楚这些因素中的哪一个是通过小毛细血管的关键决定因素。我们使用微流体装置来检查正常、僵硬、肿胀、寄生和未成熟红细胞的遍历。我们表明，RBC 的急剧硬化对其穿越小通道的能力没有可测量的影响。相比之下，SA:V 比率的适度降低对具有相似细胞粘弹性的 RBC 可通过的等效圆柱直径产生显着影响。我们开发了一个有限元模型，为实验观察提供了连贯的基本原理，基于RBC膜骨架的非线性力学行为。我们得出结论，在红细胞病理学研究中应该更加突出 SA:V 比率。