Department of Mechanical Engineering and the Mechanics and Control of Living Systems Lab, Cleveland State University, Cleveland, OH, USA.
Human Performance Lab, Department of Biomedical Engineering, University of Calgary, Calgary, AB, Canada.
Biomech Model Mechanobiol. 2018 Feb;17(1):159-168. doi: 10.1007/s10237-017-0951-1. Epub 2017 Aug 24.
Computational studies of chondrocyte mechanics, and cell mechanics in general, have typically been performed using single cell models embedded in an extracellular matrix construct. The assumption of a single cell microstructural model may not capture intercellular interactions or accurately reflect the macroscale mechanics of cartilage when higher cell concentrations are considered, as may be the case in many instances. Hence, the goal of this study was to compare cell-level response of single and eleven cell biphasic finite element models, where the latter provided an anatomically based cellular distribution representative of the actual number of cells for a commonly used [Formula: see text] edge cubic representative volume in the middle zone of cartilage. Single cell representations incorporated a centered single cell model and eleven location-corrected single cell models, the latter to delineate the role of cell placement in the representative volume element. A stress relaxation test at 10% compressive strain was adopted for all simulations. During transient response, volume- averaged chondrocyte mechanics demonstrated marked differences (up to 60% and typically greater than 10%) for the centered single versus the eleven cell models, yet steady-state loading was similar. Cell location played a marked role, due to inhomogeneity of the displacement and fluid pressure fields at the macroscopic scale. When the single cell representation was corrected for cell location, the transient response was consistent, while steady-state differences on the order of 1-4% were realized, which may be attributed to intercellular mechanical interactions. Anatomical representations of the superficial and deep zones, where cells reside in close proximity, may exhibit greater intercellular interactions, but these have yet to be explored.
软骨细胞力学和细胞力学的计算研究通常使用嵌入细胞外基质构建体的单细胞模型进行。单细胞微结构模型的假设可能无法捕捉细胞间相互作用，或者在考虑更高细胞浓度时无法准确反映软骨的宏观力学，因为在许多情况下可能就是这种情况。因此，本研究的目的是比较单细胞和十一细胞双相有限元模型的细胞水平响应，后者提供了一种基于解剖学的细胞分布，代表了软骨中间区域中常用的[Formula: see text]边缘立方代表性体积元素中的实际细胞数量。单细胞表示形式包括一个中心单细胞模型和十一个位置校正的单细胞模型，后者用于描绘代表体积元素中细胞位置的作用。所有模拟均采用 10%压缩应变的应力松弛测试。在瞬态响应期间，体积平均软骨细胞力学对于中心单细胞与十一细胞模型之间表现出明显差异（高达 60%，通常大于 10%），而稳态加载则相似。由于宏观尺度上位移和流体压力场的不均匀性，细胞位置起着明显的作用。当单细胞表示形式针对细胞位置进行校正时，瞬态响应是一致的，而稳态差异约为 1-4%，这可能归因于细胞间力学相互作用。浅层和深层区域的解剖表示，其中细胞紧密相邻，可能表现出更大的细胞间相互作用，但这些尚未得到探索。
