Michael Delaine-Smith Robin, Javaheri Behzad, Helen Edwards Jennifer, Vazquez Marisol, Rumney Robin Mark Howard
Institute of Bioengineering, School of Engineering and Material Sciences, Queen Mary University of London , London, UK.
The Royal Veterinary College , London, UK.
Bonekey Rep. 2015 Aug 19;4:728. doi: 10.1038/bonekey.2015.97. eCollection 2015.
It is well established that bone responds to mechanical stimuli whereby physical forces are translated into chemical signals between cells, via mechanotransduction. It is difficult however to study the precise cellular and molecular responses using in vivo systems. In vitro loading models, which aim to replicate forces found within the bone microenvironment, make the underlying processes of mechanotransduction accessible to the researcher. Direct measurements in vivo and predictive modeling have been used to define these forces in normal physiological and pathological states. The types of mechanical stimuli present in the bone include vibration, fluid shear, substrate deformation and compressive loading, which can all be applied in vitro to monolayer and three-dimensional (3D) cultures. In monolayer, vibration can be readily applied to cultures via a low-magnitude, high-frequency loading rig. Fluid shear can be applied to cultures in multiwell plates via a simple rocking platform to engender gravitational fluid movement or via a pump to cells attached to a slide within a parallel-plate flow chamber, which may be micropatterned for use with osteocytes. Substrate strain can be applied via the vacuum-driven FlexCell system or via a four-point loading jig. 3D cultures better replicate the bone microenvironment and can also be subjected to the same forms of mechanical stimuli as monolayer, including vibration, fluid shear via perfusion flow, strain or compression. 3D cocultures that more closely replicate the bone microenvironment can be used to study the collective response of several cell types to loading. This technical review summarizes the methods for applying mechanical stimuli to bone cells in vitro.
众所周知，骨骼会对机械刺激产生反应，通过机械转导，物理力在细胞之间转化为化学信号。然而，使用体内系统来研究精确的细胞和分子反应是困难的。体外加载模型旨在复制骨骼微环境中发现的力，使研究人员能够了解机械转导的潜在过程。体内直接测量和预测模型已被用于定义正常生理和病理状态下的这些力。骨骼中存在的机械刺激类型包括振动、流体剪切力、基质变形和压缩载荷，所有这些都可以在体外应用于单层和三维（3D）培养物。在单层培养中，振动可以通过低幅度、高频加载装置轻松施加到培养物上。流体剪切力可以通过简单的摇摆平台应用于多孔板中的培养物，以产生重力流体运动，或者通过泵应用于附着在平行板流动室内载玻片上的细胞，该流动室可以进行微图案化以用于骨细胞。基质应变可以通过真空驱动的FlexCell系统或通过四点加载夹具施加。3D培养物能更好地复制骨骼微环境，也可以受到与单层相同形式的机械刺激，包括振动、通过灌注流产生的流体剪切力、应变或压缩。更紧密复制骨骼微环境的3D共培养物可用于研究几种细胞类型对加载的集体反应。本技术综述总结了体外对骨细胞施加机械刺激的方法。
