Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, Beijing 100124, China.
Musculoskeletal Biology and Mechanics Lab, Department of Basic Medical Sciences, Purdue University, IN, USA; Weldon School of Biomedical Engineering, Purdue University, IN, USA.
Bone. 2022 May;158:116367. doi: 10.1016/j.bone.2022.116367. Epub 2022 Feb 16.
The osteocyte lacunar-canalicular system (LCS) serves as a mechanotransductive core where external loading applied to the skeleton is transduced into mechanical signals (e.g., fluid shear) that can be sensed by mechanosensors (osteocytes). The fluid velocity and shear stress within the LCS are affected by various loading parameters. However, the interactive effect of distinct loading parameters on the velocity and shear stress in the LCS remains unclear. To address this issue, we developed a multiscale modeling approach, combining a poroelastic finite element (FE) model with a single osteocytic LCS unit model to calculate the flow velocity and shear stress within the LCS. Next, a sensitivity analysis was performed to investigate individual and interactive effects of strain magnitude, strain rate, number of cycles, and intervening short rests between loading cycles on the velocity and shear stress around the osteocyte. Lastly, we developed a relatively simple regression model to predict those outcomes. Our results demonstrated that the strain magnitude or rate alone were the main factors affecting the velocity and shear stress; however, the combination of these two was not directly additive, and addition of a short rest between cycles could enhance the combination of these two related factors. These results show highly interactive effects of distinct loading parameters on fluid velocity and shear stress in the LCS. Specifically, our results suggest that an enhanced fluid dynamics environment in the LCS can be achieved with a brief number of load cycles combined with short rest insertion and high strain magnitude and rate.
骨细胞陷窝-管道系统 (LCS) 作为一种机械转导核心，骨骼所承受的外部负载被转化为机械信号（例如，流体剪切力），这些信号可以被机械感受器（骨细胞）感知。LCS 内的流体速度和剪切应力受各种加载参数的影响。然而，不同加载参数对 LCS 内速度和剪切应力的相互作用影响尚不清楚。为了解决这个问题，我们开发了一种多尺度建模方法，将多孔弹性有限元 (FE) 模型与单个骨细胞 LCS 单元模型相结合，以计算 LCS 内的流速和剪切应力。然后，进行了敏感性分析，以研究应变幅度、应变率、循环次数以及加载循环之间短暂休息对骨细胞周围速度和剪切应力的个体和交互影响。最后，我们开发了一个相对简单的回归模型来预测这些结果。我们的结果表明，应变幅度或速率单独是影响速度和剪切应力的主要因素；然而，这两个因素的组合不是直接相加的，在循环之间插入短暂休息可以增强这两个相关因素的组合。这些结果表明，不同加载参数对 LCS 内流体速度和剪切应力具有高度的相互作用影响。具体来说，我们的结果表明，通过结合少量的负荷循环、插入短暂休息以及高应变幅度和速率，可以实现 LCS 中增强的流体动力学环境。
