Analysis of the changes in internalshvctures and mechanical propertiesofvasctilazsmooth naivete cells after tensile strain application

本文设计了一套用于分析培养细胞在拉伸应变作用下内部结构和力学性能变化的系统。利用该系统对血管平滑肌细胞施加静态拉伸应变前后的刚度进行了测定和比较.该系统包括一个倒置显微镜配备了共聚焦激光扫描仪单元，原子力显微镜（AFM）的单位，和一个专门设计的细胞拉伸装置。将细胞培养在安装在细胞拉伸装置上并同时从其两侧拉伸的薄硅酮膜上。装置的底部由盖玻片制成，以便从底部观察细胞。在拉伸膜之后，粘附到膜的中心部分的细胞不移动。细胞的机械性能可以通过使用AFM的微压痕测试来测量。如果对细胞内结构进行荧光染色，则可以在AFM测量后通过共聚焦激光扫描显微镜观察结构.在单个平滑肌细胞中的应变分布由在施加10%静态拉伸应变之前和之后记录的细胞和附着在细胞表面上的小聚苯乙烯颗粒的图像确定。即使在胞质区，应变分布也不均匀，胞质区的应变远大于核区.血管平滑肌细胞的刚度测量与系统之前和之后拉伸其基板10%。观察到通过施加应变而使单元的刚度增加的趋势。细胞通过拉伸其基质而增加的刚度可能归因于肌动蛋白丝张力的增加。

A system for the analysis of the changes in internal structures and mechanical properties of cultured cells after the application of tensile strain has been designed. Using this system, the stiffness of vascular smooth muscle cells before and after application of static tensile strain have been determined and compared.1. The system consists of an inverted microscope equipped with a confocal laser scanner unit, an atomic force microscope (AFM) unit, and a specially designed cell stretching apparatus. Cells are cultured on a thin silicone membrane that is mounted to the cell stretching apparatus and stretched from its both side at the same time. The bottom of the apparatus is made of cover glass so as to observe the cells from the bottom. The cells adhered to the central portion of the membrane do not move after stretching the membrane. Mechanical properties of the cells can be measured by micro indentation test using the AFM. If intracellular structures were fluorescently stained, the structure can be observed by means of confocal laser scanning microscopy after AFM measurement.2. The strain distribution in single smooth muscle cells was determined from the images of cells and small polystyrene particles attached on the surface of cells recorded before and after the application of 10% static tensile strain. The strain distribution was not uniform even in the cytoplasmic regions; the strain was much larger in the cytoplasmic regions than in the nuclear regions.3. The stiffness of vascular smooth muscle cells was measured with the system before and after stretching their substrate by 10%. A tendency that the stiffness of the cells was increased by the application of strain was observed. The increased stiffness of cells by stretching their substrate might be attributable to the increase in the tension in actin filaments.