Blood exposure to supraphysiological shear stress within mechanical circulatory support is suspected of reducing red blood cell (RBC) deformability and being primal in the pathogenesis of several secondary complications. No prior works have explored RBC dynamics with the resolution required to determine shear elastic modulus, and/or cell capillary velocity, following exposure to mechanical stresses. Healthy RBCs were exposed to 0, 5, 50, and 100 Pa in a Couette shearing system. For comparison, blood was also exposed to heat treatment—a method that predictably increases RBC rigidity. Shear modulus assessment required aspiration of single RBCs through narrow micropipettes at known suction force. Cell transit velocities were measured within microchannels in regions of fully developed flow. Supraphysiological shear stress increased the elastic shear modulus by 39% and 69% following exposure to 50 and 100Pa, respectively. Cell transit velocity, however, did not change following shear, with concurrent decreases in cell volume likely nullifying increased shear modulus‐friction interactions. Differences observed were consistent with our internal control (heat treatment), supporting that cell mechanics are significantly impaired following supraphysiological‐sublethal shear exposure. Given mechanical circulatory support operates at shear stresses consistent with the present study, it is plausible that these devices induce fundamental impairment to the material properties of RBCs.

中文翻译：

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亚致死机械剪切应力会增加红细胞的弹性剪切模量，但不会改变毛细血管传输速度。

血液在机​​械循环支持中暴露于超生理剪切应力被怀疑会降低红细胞 (RBC) 的变形能力，并且在几种继发性并发症的发病机制中起主要作用。在暴露于机械应力后，没有先前的工作探索具有确定剪切弹性模量和/或细胞毛细血管速度所需的分辨率的 RBC 动力学。健康的红细胞在库埃特剪切系统中暴露于 0、5、50 和 100 Pa。相比之下，血液也接受了热处理——一种可以预见增加红细胞硬度的方法。剪切模量评估需要通过狭窄的微量移液管以已知的吸力吸入单个 RBC。在完全发展的流动区域中的微通道内测量细胞传输速度。在暴露于 50 和 100Pa 后，超生理剪切应力分别使弹性剪切模量增加了 39% 和 69%。然而，细胞传输速度在剪切后没有改变，同时细胞体积的减少可能抵消了增加的剪切模量-摩擦相互作用。观察到的差异与我们的内部控制（热处理）一致，支持超生理-亚致死剪切暴露后细胞力学显着受损。鉴于机械循环支持在与本研究一致的剪切应力下运行，这些设备对红细胞的材料特性造成根本性损害是合理的。随着细胞体积的同时减少，可能会抵消增加的剪切模量-摩擦相互作用。观察到的差异与我们的内部控制（热处理）一致，支持超生理-亚致死剪切暴露后细胞力学显着受损。鉴于机械循环支持在与本研究一致的剪切应力下运行，这些设备对红细胞的材料特性造成根本性损害是合理的。随着细胞体积的同时减少，可能会抵消增加的剪切模量-摩擦相互作用。观察到的差异与我们的内部控制（热处理）一致，支持超生理-亚致死剪切暴露后细胞力学显着受损。鉴于机械循环支持在与本研究一致的剪切应力下运行，这些设备对红细胞的材料特性造成根本性损害是合理的。