Analysis of the mechanical behavior of chondrocytes in unconfined compression tests for cyclic loading
Analysis of the mechanical behavior of chondrocytes in unconfined compression tests for cyclic loading
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DOI：
10.1016/j.jbiomech.2005.01.007
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发表时间：
2006-01-01
影响因子：
2.4
通讯作者：
Herzog, W
中科院分区：
文献类型：
--
作者：
Wu, JZ;Herzog, W
实验证据表明软骨细胞的生物合成活性与机械环境有关。例如，过度的、重复的负载被发现会诱导细胞死亡、形态和细胞损伤，如退行性关节疾病中所见，而循环的、类似生理的负载被发现会触发骨关节炎人类关节软骨细胞的形态和超微结构方面的部分恢复。据信机械刺激通过细胞变形影响生物合成活性。然而，软骨细胞在循环载荷条件下的原位变形尚未在实验或理论上进行过研究。本研究的目的是使用有限元模型模拟无侧限压缩试验中软骨细胞对循环载荷的机械响应。软骨细胞和细胞外基质的材料特性被认为是双相的。在两个频率（0.02 和 0.1 Hz）和两个振幅（0.1 和 0.2 MPa）的静态和循环载荷条件下，预测了软骨内三个位置（即表面、中心和底部）软骨细胞形状和体积变化的时间历程。我们的结果表明，在循环加载过程中，软骨内不同深度的细胞变形不同，并且细胞变形的深度依赖性受到循环加载幅度的影响。发现 0.02 Hz 循环载荷下的单元变形与 0.1 Hz 循环载荷下的变形相似。我们从模拟结果中得出结论，在均匀的软骨层中，细胞变形是位置相关的，并且进一步受到载荷大小的影响。在生理条件下，由于软骨基质的各向异性、深度依赖性不均匀性和拉压非线性，细胞的机械环境更加复杂。因此，推测软骨细胞对循环负荷的生物合成反应取决于细胞位置和负荷大小是可行的。由爱思唯尔有限公司出版
Experimental evidence indicates that the biosynthetic activity of chondrocytes is associated with the mechanical environment. For example, excessive, repetitive loading has been found to induce cell death, morphological and cellular damage, as seen in degenerative joint disease, while cyclic, physiological-like loading has been found to trigger a partial recovery of morphological and ultrastructural aspects in ostcoarthritic human articular chondrocytes. Mechanical stimuli are believed to influence the biosynthetic activity via the deformation of cells. However, the in situ deformation of chondrocytes for cyclic loading conditions has not been investigated experimentally or theoretically. The purpose of the present study was to simulate the mechanical response of chondrocytes to cyclic loading in unconfined compression tests using a finite element model. The material properties of chondrocytes and extracellular matrix were considered to be biphasic. The time-histories of the shape and volume variations of chondrocytes at three locations (i.e., surface, center, and bottom) within the cartilage were predicted for static and cyclic loading conditions at two frequencies (0.02 and 0.1 Hz) and two amplitudes (0.1 and 0.2 MPa). Our results show that cells at different depths within the cartilage deform differently during cyclic loading, and that the depth dependence of cell deformation is influenced by the amplitude of the cyclic loading. Cell deformations under cyclic loading of 0.02 Hz were found to be similar to those at 0.1 Hz. We conclude from the simulation results that, in homogeneous cartilage layers, cell deformations are location-dependent, and further are affected by load magnitude. In physiological conditions, the mechanical environment of cells are even more complex due to the anisotropy, depth-dependent inhomogencity, and tension-compression non-linearity of the cartilage matrix. Therefore, it is feasible to speculate that biosynthetic responses of chondrocytes to cyclic loading depend on cell location and load magnitude. Published by Elsevier Ltd.