Ciasca G, Papi M, Di Claudio S, Chiarpotto M, Palmieri V, Maulucci G, Nocca G, Rossi C, De Spirito M
Instituto di Fisica, Università Cattolica del Sacro Cuore, Largo F. Vito 1, 00168, Roma, Italy.
Nanoscale. 2015 Oct 28;7(40):17030-7. doi: 10.1039/c5nr03145a.
In order to pass through the microcirculation, red blood cells (RBCs) need to undergo extensive deformations and to recover the original shape. This extreme deformability is altered by various pathological conditions. On the other hand, an altered RBC deformability can have major effects on blood flow and can lead to pathological implications. The study of the viscoelastic response of red blood cells to mechanical stimuli is crucial to fully understand deformability changes under pathological conditions. However, the typical erythrocyte biconcave shape hints to a complex and intrinsically heterogeneous mechanical response that must be investigated by using probes at the nanoscale level. In this work, the local viscoelastic behaviour of healthy and pathological red blood cells was probed by Atomic Force Microscopy (AFM). Our results clearly show that the RBC stiffness is not spatially homogeneous, suggesting a strong correlation with the erythrocyte biconcave shape. Moreover, our nanoscale mapping highlights the key role played by viscous forces, demonstrating that RBCs do not behave as pure elastic bodies. The fundamental role played by viscous forces is further strengthened by the comparison between healthy and pathological (diabetes mellitus) RBCs. It is well known that pathological RBCs are usually stiffer than the healthy ones. Our measures unveil a more complex scenario according to which the difference between normal and pathological red blood cells does not merely lie in their stiffness but also in a different dynamical response to external stimuli that is governed by viscous forces.
为了通过微循环，红细胞（RBCs）需要经历广泛的变形并恢复原始形状。这种极端的可变形性会因各种病理状况而改变。另一方面，红细胞可变形性的改变会对血流产生重大影响，并可能导致病理后果。研究红细胞对机械刺激的粘弹性反应对于全面理解病理状况下的可变形性变化至关重要。然而，典型的红细胞双凹形状暗示了一种复杂且本质上异质的机械反应，必须通过在纳米尺度水平上使用探针来进行研究。在这项工作中，通过原子力显微镜（AFM）探测了健康和病理红细胞的局部粘弹性行为。我们的结果清楚地表明，红细胞的硬度在空间上并非均匀一致，这表明与红细胞双凹形状存在强烈关联。此外，我们的纳米尺度映射突出了粘性力所起的关键作用，表明红细胞并非表现为纯弹性体。通过对健康和病理（糖尿病）红细胞的比较，进一步强化了粘性力所起的基本作用。众所周知，病理红细胞通常比健康红细胞更硬。我们的测量揭示了一个更复杂的情况，即正常和病理红细胞之间的差异不仅在于它们的硬度，还在于对由粘性力控制的外部刺激的不同动态反应。
