Modeling and simulation of interstitial fluid flow around an osteocyte in a lacuno-canalicular network
Modeling and simulation of interstitial fluid flow around an osteocyte in a lacuno-canalicular network
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DOI：
10.1063/5.0085299
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发表时间：
2022-04
影响因子：
4.6
通讯作者：
Luoding Zhu;J. Barber;Robert Zigon;S. Na;H. Yokota
中科院分区：
文献类型：
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作者：
Luoding Zhu;J. Barber;Robert Zigon;S. Na;H. Yokota
实验表明，外部机械载荷在骨的发育和重建过程中起着重要作用。事实上，最近的研究已经提供了证据表明，骨细胞可以感觉到这种负荷，并通过释放启动骨降解或生长的生化信号(机械转导，MT)来做出反应。关于MT的许多方面仍不清楚，特别是在细胞水平上。由于骨基质的极度坚硬和骨细胞生存的微环境的复杂性，体内研究很困难；相比之下，建模和模拟是可行的方法。虽然已经进行了许多计算研究，但复杂的几何形状可能涉及60多个不规则的小管，通常被简化为选定的几个直管或通道。此外，通常不考虑细胞外基质(PCM)。为了更好地理解这些经常被忽视的方面的影响，我们使用格子Boltzmann方程来模拟二维腔道网络中骨细胞的流体流动。我们重点研究了骨小管的数量/几何形状以及PCM对骨细胞表面的流体壁切应力(WSS)和法向应力(WNS)的影响。我们考虑16、32和小管，分别为16和32个小管使用一个随机生成的几何图形，并为小管使用三个随机生成的几何图形。我们还考虑了0%、5%、10%、20%和40%的细胞周围基质密度。对WSS和WNS分布以及速度场的数值结果进行了可视化、比较和分析。我们的主要结果如下：(1)如果模型包括细胞周围基质(PCM)，流体流动在骨细胞表面产生的力明显更大；(2)在没有PCM的情况下，尽管小管的数量和几何形状对这些应力的总体变化和分布有一定的量化影响，但骨细胞表面上的平均应力大小并没有显著改变；(3)骨细胞表面上的无量纲化应力(无量纲化后的应力)尺度近似为雷诺数的倒数和小管中PCM密度的倒数，减小了尺度定律适用的雷诺数值范围。
Experiments have shown that external mechanical loading plays an important role in bone development and remodeling. In fact, recent research has provided evidence that osteocytes can sense such loading and respond by releasing biochemical signals (mechanotransduction, MT) that initiate bone degradation or growth. Many aspects on MT remain unclear, especially at the cellular level. Because of the extreme hardness of the bone matrix and complexity of the microenvironment that an osteocyte lives in, in vivo studies are difficult; in contrast, modeling and simulation are viable approaches. Although many computational studies have been carried out, the complex geometry that can involve 60+ irregular canaliculi is often simplified to a select few straight tubes or channels. In addition, the pericellular matrix (PCM) is usually not considered. To better understand the effects of these frequently neglected aspects, we use the lattice Boltzmann equations to model the fluid flow over an osteocyte in a lacuno-canalicular network in two dimensions. We focus on the influences of the number/geometry of the canaliculi and the effects of the PCM on the fluid wall shear stress (WSS) and normal stress (WNS) on an osteocyte surface. We consider 16, 32, and 64 canaliculi using one randomly generated geometry for each of the 16 and 32 canaliculi cases and three geometries for the 64 canaliculi case. We also consider 0%, 5%, 10%, 20%, and 40% pericellular matrix density. Numerical results on the WSS and WNS distributions and on the velocity field are visualized, compared, and analyzed. Our major results are as follows: (1) the fluid flow generates significantly greater force on the surface of the osteocyte if the model includes the pericellular matrix (PCM); (2) in the absence of PCM, the average magnitudes of the stresses on the osteocyte surface are not significantly altered by the number and geometry of the canaliculi despite some quantitative influence of the latter on overall variation and distribution of those stresses; and (3) the dimensionless stress (stress after non-dimensionalization) on the osteocyte surface scales approximately as the reciprocal of the Reynolds number and increasing PCM density in the canaliculi reduces the range of Reynolds number values for which the scaling law holds.