Laboratory of Biomechanical Orthopedics, Ecole Polytechnique Fédérale Lausanne, EPFL/STI/IBI/LBO, Station 15, Switzerland.
J Biomech. 2010 Mar 22;43(5):933-7. doi: 10.1016/j.jbiomech.2009.11.004. Epub 2009 Dec 9.
An analytical model of the fluid/cell mechanical interaction was developed. The interfacial shear stress, due to the coupling between the fluid and the cell deformation, was characterized by a new dimensionless number N(fs). For N(fs) above a critical value, the fluid/cell interaction had a damping effect on the interfacial shear stress. Conversely, for N(fs) below this critical value, interfacial shear stress was amplified. As illustration, the role of the dynamic fluid/cell mechanical coupling was studied in a specific biological situation involving cells seeded in a bone scaffold. For the particular bone scaffold chosen, the dimensionless number N(fs) was higher than the critical value. In this case, the dynamic shear stress at the fluid/cell interface is damped for increasing excitation frequency. Interestingly, this damping effect is correlated to the pore diameter of the scaffold, furnishing thus target values in the design of the scaffold. Correspondingly, an efficient cell stimulation might be achieved with a scaffold of pore size larger than 300 microm as no dynamic damping effect is likely to take place. The analytical model proposed in this study, while being a simplification of a fluid/cell mechanical interaction, brings complementary insights to numerical studies by analyzing the effect of different physical parameters.
建立了一种流体/细胞力学相互作用的分析模型。界面剪切应力由于流体和细胞变形的耦合而具有一个新的无量纲数 N(fs)。当 N(fs)超过临界值时，流体/细胞相互作用对界面剪切应力具有阻尼效应。相反，当 N(fs)低于这个临界值时，界面剪切应力被放大。作为说明，在涉及细胞接种在骨支架中的特定生物学情况下研究了动态流体/细胞力学耦合的作用。对于所选择的特定骨支架，无量纲数 N(fs)高于临界值。在这种情况下，随着激励频率的增加，流体/细胞界面处的动态剪切应力被阻尼。有趣的是，这种阻尼效应与支架的孔径相关，从而为支架的设计提供了目标值。相应地，具有大于 300 微米孔径的支架可能实现有效的细胞刺激，因为不太可能发生动态阻尼效应。本研究提出的分析模型虽然是流体/细胞力学相互作用的简化，但通过分析不同物理参数的影响，为数值研究提供了补充见解。
