Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Parks Road, Oxford, UK.
Biomech Model Mechanobiol. 2011 Jul;10(4):559-64. doi: 10.1007/s10237-010-0255-1. Epub 2010 Sep 18.
A widely used commercially available system for the investigation of mechanosensitivity applies a biaxial strain field to cells cultured on a compliant silicone substrate membrane stretched over a central post. As well as intended substrate strain, this device also provides a fluid flow environment for the cultured cells. In order to interpret the relevance of experiments using this device to the in vivo and clinical situation, it is essential to characterise both substrate and fluid environments. While previous work has detailed the substrate strain, the fluid shear stresses, to which bone cells are known to be sensitive, are unknown. Therefore, a fluid structure interaction computational fluid dynamics model was constructed, incorporating a finite element technique capable of capturing the contact between the post and the silicone substrate membrane, to the underside of which the pump control pressure was applied. Flow verification experiments using 10-μm-diameter fluorescent microspheres were carried out. Fluid shear stress increased approximately linearly with radius along the on-post substrate membrane, with peak values located close to the post edge. Changes in stimulation frequency and culture medium viscosity effected proportional changes in the magnitude of the fluid shear stress (peak fluid shear stresses varied in the range 0.09-3.5 Pa), with minor effects on temporal and spatial distribution. Good agreement was obtained between predicted and measured radial flow patterns. These results suggest a reinterpretation of previous data obtained using this device to include the potential for a strong role of fluid shear stress in mechanosensitivity.
一种广泛应用于机械敏感性研究的商业可用系统，将双轴应变场应用于培养在可拉伸硅橡胶基底膜上的细胞，该基底膜被拉伸在中央支柱上。除了预期的基底应变外，该设备还为培养的细胞提供了一个流体流动环境。为了将使用该设备进行的实验与体内和临床情况联系起来，对基底和流体环境进行特征描述至关重要。虽然之前的工作已经详细描述了基底应变，但对于骨细胞敏感的流体切应力尚不清楚。因此，构建了一个流体结构相互作用计算流体动力学模型，该模型采用了一种有限元技术，能够捕捉支柱和硅橡胶基底膜之间的接触，泵的控制压力施加在基底膜的下侧。使用 10-μm 直径荧光微球进行了流动验证实验。沿支柱上的基底膜，流体切应力随半径近似呈线性增加，峰值位于支柱边缘附近。刺激频率和培养基粘度的变化对流体切应力的大小产生了比例变化（峰值流体切应力在 0.09-3.5 Pa 的范围内变化），对时间和空间分布的影响较小。预测和测量的径向流动模式之间取得了良好的一致性。这些结果表明，需要重新解释以前使用该设备获得的数据，以包括流体切应力在机械敏感性中的潜在重要作用。
