A cell-stretching system as a model system for the study of biomechanics

1.为了阐明体外系统中机械应力对细胞的影响，我们制造了一种培养系统，其允许细胞培养基质在长时间内重复单向拉伸。2.由于肌细胞是在机械活动的环境中形成和维持的，因此以肌细胞为模型研究了机械应力对培养细胞的影响，观察到拉伸引起的两个显著现象：1）牵张依赖性细胞排列和2）肌细胞肥大如下：1）当大鼠主动脉平滑肌细胞（A10）和小鼠C2成肌细胞在标准条件下培养，然后以1Hz的频率和20%的振幅重复拉伸基底时，细胞变得与拉伸方向成约70 °的角度取向。肌动蛋白丝 ...更多信息 因此在相同的方向上取向，但是丝取向先于细胞取向。我们发现，这种拉伸依赖性细胞取向完全被100 mM钆，拉伸激活离子通道的抑制剂，和放线菌酮阻断，但丝重定向不受这些代理商在所有。从这些结果中，可以得出结论，细丝的方向和细胞的方向是密切相关的，但调节不同。2）在肌肉细胞（肌管）的情况下，在纵向细胞轴的拉伸是重要的，从生理学的观点。由于细胞取向的重排没有发生在拉伸肌管对齐沿着的凹槽，它是可能的拉伸肌管在纵向细胞轴的方向超过一个星期。我们观察到，肌管直径增加显着相比，没有拉伸培养的对照肌管。我们进一步发现，约67 kDa的蛋白质积累在拉伸的肌管。我们根据抗原性、大小和pI鉴定了该蛋白与白蛋白。白蛋白与培养基中的白蛋白相同，此外，在拉伸的肌管中也检测到添加到培养基中的生物素化白蛋白。因此，我们得出结论，白蛋白在培养基中纳入肌管在拉伸依赖性的方式。牵张依赖性白蛋白摄取的生理学意义有待进一步研究。少

1.With an aim to clarify the effects of mechanical stress on cells in an in vitro system, we manufactured a culture system which permits unidirectional stretch of a cell culture substrate repeatedly over long periods. Thin elastic silicon membrane with fine parallel grooves as a substrate for cell culture and an appropriate culture medium were also devised.2.Since muscle cells are formed and maintained under a mechanically active environment, the effects of mechanical stress on cultured cells were examined with muscle cells as a model and observed two remarkable phenomena caused by stretching : 1) stretch-dependent cell arrangement and 2) hypertrophy of the muscle cells as follows :1) When rat aortic smooth muscle cells (A10) and mouse C2 myoblasts were cultured under a standard condition and then the substrate was stretched repetitively at a frequency of 1 Hz with an amplitude of 20%, the cells became oriented at an angle of about 70o to the direction of stretching. Actin filaments al … More so oriented in the same direction, but filament orientation preceded cell orientation. We found that this stretch-dependent cell orientation was completely blocked by 100 mM gadolinium, an inhibitor of a stretch-activated ion channel, and cycloheximide, but filament reorientation was not affected by these agents at all. From these results, it is concluded that orientation of filaments and the orientation of the cells are closely related but regulated differently.2) In the case of muscle cells (myotubes), stretching in a longitudinal cell axis is important from a physiological view point. Since rearrangement of cell orientation did not occur during stretching of myotubes aligned along the grooves, it was possible to stretch myotubes for more than a week in the direction of the longitudinal cell axis. We observed that myotube diameters increased significantly as compared with the control myotubes cultured without stretch. We further found that a protein of about 67 kDa accumulated in the stretched myotubes. We identified this protein with albumin based on antigenicity, size and pI.The albumin was the same as that in the culture medium and in addition, biotinized albumin added to the medium was also detected in the stretched myotubes. Therefor, we conclude that albumin in the medium was incorporated into myotubes in a stretching-dependent manner. Physiological implication of stretch-dependent albumin uptake remains for future investigation. Less