Arnoczky Steven P, Lavagnino Michael, Whallon Joanne H, Hoonjan Amardeep
Laboratory for Comparative Orthopaedic Research, College of Veterinary Medicine, Michigan State University, East Lansing 48824, USA.
J Orthop Res. 2002 Jan;20(1):29-35. doi: 10.1016/S0736-0266(01)00080-8.
Cell and cell nucleus deformations have been implicated in the mechanotransduction of mechanical loads acting on tissues. While in situ cell nucleus deformation in response to increasing tissue strains has been examined in articular cartilage this phenomenon has not been investigated in tendons. To examine in situ cell nuclei deformation in tendons undergoing tensile strain rat tail tendons were harvested from adult Sprague-Dawley rats and stained with acridine orange to highlight the cell nuclei. The tendons were mounted on a custom-designed, low-load, tensile testing device affixed to the mechanical stage of a confocal laser microscope. Cells within the tendons were isolated for analysis. Images of individual cells were captured at 0% strain as well as sequentially at 2%, 4% and 6% grip-to-grip tendon strain. Digital images of the cell nuclei were then measured in the x (length) and y (height) axis and deformation expressed as a percentage of cell nuclei strain. In addition, centroid-to-centroid distances of adjacent cell nuclei within each image were measured and used to calculate local tissue strain. There was a weak (r2 = 0.34) but significant (p < 0.01) correlation between local tissue strain and cell nucleus strain in the x axis. The results of this study support the hypothesis that in situ cell nucleus deformation does occur during tensile loading of tendons. This deformation may play a significant role in the mechanical signal transduction pathway of this tissue.
细胞和细胞核变形与作用于组织的机械负荷的机械转导有关。虽然已经在关节软骨中研究了原位细胞核在组织应变增加时的变形情况，但在肌腱中尚未对这一现象进行研究。为了研究承受拉伸应变的肌腱中的原位细胞核变形，从成年Sprague-Dawley大鼠身上采集大鼠尾腱，并用吖啶橙染色以突出细胞核。将肌腱安装在定制设计的低负荷拉伸测试装置上，该装置固定在共聚焦激光显微镜的机械载物台上。分离肌腱中的细胞进行分析。在0%应变时以及在2%、4%和6%的肌腱夹距应变下依次采集单个细胞的图像。然后在x（长度）和y（高度）轴上测量细胞核的数字图像，并将变形表示为细胞核应变的百分比。此外，测量每个图像中相邻细胞核的质心到质心距离，并用于计算局部组织应变。局部组织应变与x轴上的细胞核应变之间存在弱（r2 = 0.34）但显著（p < 0.01）的相关性。本研究结果支持这样的假设，即在肌腱拉伸加载过程中确实会发生原位细胞核变形。这种变形可能在该组织的机械信号转导途径中起重要作用。
