Time-dependent deformations in bone cells exposed to fluid flow in vitro: investigating the role of cellular deformation in fluid flow-induced signaling
Time-dependent deformations in bone cells exposed to fluid flow in vitro: investigating the role of cellular deformation in fluid flow-induced signaling
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DOI：
10.1016/j.jbiomech.2007.04.003
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发表时间：
2007-01-01
影响因子：
2.4
通讯作者：
Jacobs, Christopher R.
中科院分区：
文献类型：
--
作者：
Kwon, Ronald Y.;Jacobs, Christopher R.
大量实验表明，流体流动是体外骨细胞的有效刺激物，这表明流体流动是骨机械传导中的重要物理信号。在流体流动实验中，骨细胞暴露于时间依赖性（例如，振荡或脉冲）和时间无关（例如，稳定）流动剖面。有趣的是，骨细胞的信号响应显示依赖于加载频率和/或速率，这被假定是由于粘弹性行为。因此，本研究的目的是研究骨细胞暴露于体外流体流动的时间依赖性变形。具体而言，我们的目标是表征骨细胞暴露于0.5至2.0 Hz的振荡流和稳定流的机械响应，因为这些流量曲线先前已被证明在体外诱导不同的形态和生化反应。通过跟踪不同尺寸的细胞结合硫酸盐和胶原蛋白涂层荧光珠，我们量化了暴露于1.0 Pa振荡流的骨细胞中的归一化峰值变形（峰值位移通过所有频率下观察到的最大峰值位移进行归一化）和相位滞后频率为0.5-2.0 Hz。相位滞后很小（3-10度），并且与频率有关，而归一化峰值位移则以弱的频率幂律（类似于f（-0.2））下降。在稳定流动期间，细胞表现出几乎瞬时的变形，然后蠕变。我们的研究结果表明，虽然大量的粘性变形可能会发生在稳定的流动（相比，振荡流在类似1赫兹），骨细胞的行为主要是弹性体时，暴露于流动频率与习惯性负载。(c)2007爱思唯尔有限公司保留所有权利。
Numerous experiments have shown fluid flow to be a potent stimulator of bone cells in vitro, suggesting that fluid flow is an important physical signal in bone mechanotransduction. In fluid flow experiments, bone cells are exposed to both time-dependent (e.g., oscillating or pulsing) and time-independent (e.g., steady) flow profiles. Interestingly, the signaling response of bone cells shows dependence on loading frequency and/or rate that has been postulated to be due to viscoelastic behavior. Thus, the objective of this study was to investigate the time-dependent deformations of bone cells exposed to fluid flow in vitro. Specifically, our goal was to characterize the mechanical response of bone cells exposed to oscillatory flow from 0.5 to 2.0 Hz and steady flow, since these flow profiles have previously been shown to induce different morphological and biochemical responses in vitro. By tracking cell-bound sulfate and collagen coated fluorescent beads of varying sizes, we quantified the normalized peak deformation (peak displacement normalized by the maximum peak displacement observed for all frequencies) and phase lag in bone cells exposed to 1.0 Pa oscillating flow at frequencies of 0.5-2.0 Hz. The phase lag was small (3-10 degrees) and frequency dependent, while the normalized peak displacements decreased as a weak power law of frequency (similar to f(-0.2)). During steady flow, the cells exhibited a nearly instantaneous deformation, followed by creep. Our results suggest that while substantial viscous deformation may occur during steady flow (compared to oscillating flow at similar to 1 Hz), bone cells behave primarily as elastic bodies when exposed to flow at frequencies associated with habitual loading. (c) 2007 Elsevier Ltd. All rights reserved.