Vanderploeg Eric J, Imler Stacy M, Brodkin Kathryn R, García Andrés J, Levenston Marc E
George W. Woodruff School of Mechanical Engineering, Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, USA.
J Biomech. 2004 Dec;37(12):1941-52. doi: 10.1016/j.jbiomech.2004.02.048.
Several modes of mechanical stimulation, including compression, shear, and hydrostatic pressure, have been shown to modulate chondrocyte matrix synthesis, but the effects of mechanical tension have not been widely explored. Since articular cartilage is primarily loaded in compression, tension is not generally viewed as a major contributor to the stress state of healthy tissue. However, injury or attempted repair may cause tension to become more significant. Additionally, fibrocartilaginous tissues experience significant tensile stresses in their normal mechanical environment. In this study we investigated mechanical tension as a means to modulate matrix synthesis and cytoskeletal organization in bovine articular chondrocytes and meniscal fibrochondrocytes (MFCs) in a three-dimensional fibrin construct culture system. Oscillatory tension was applied to constructs at 1.0 Hz and 0-10% displacement variation using a custom device. For nearly all conditions and both cell types, oscillatory tension inhibited matrix synthesis as indicated by 3H-proline and 35S-sulfate incorporation. Additionally, oscillatory tension significantly increased proliferation by chondrocytes but not MFCs. Confocal imaging revealed that all cells initially displayed a rounded morphology, but over time MFCs spontaneously developed a three-dimensional, stellate morphology with numerous projections containing organized cytoskeletal filaments. Interestingly, while unloaded chondrocytes remained rounded, chondrocytes subjected to oscillatory tension developed a similar stellate morphology. Both the biochemical and morphological results of this study have important implications for successfully developing cartilage and fibrocartilage tissue replacements and repair strategies.
包括压缩、剪切和流体静压在内的几种机械刺激模式已被证明可调节软骨细胞基质合成，但机械张力的影响尚未得到广泛研究。由于关节软骨主要承受压缩载荷，张力通常不被视为健康组织应力状态的主要因素。然而，损伤或修复尝试可能会使张力变得更加显著。此外，纤维软骨组织在其正常力学环境中会承受显著的拉应力。在本研究中，我们在三维纤维蛋白构建体培养系统中研究了机械张力作为调节牛关节软骨细胞和半月板纤维软骨细胞（MFCs）基质合成和细胞骨架组织的一种手段。使用定制设备以1.0Hz的频率和0 - 10%的位移变化对构建体施加振荡张力。对于几乎所有条件和两种细胞类型，如通过3H - 脯氨酸和35S - 硫酸盐掺入所示，振荡张力抑制了基质合成。此外，振荡张力显著增加了软骨细胞的增殖，但对MFCs没有影响。共聚焦成像显示，所有细胞最初呈现圆形形态，但随着时间推移，MFCs自发形成了具有许多包含有组织细胞骨架细丝的突起的三维星状形态。有趣的是，未加载的软骨细胞保持圆形，而受到振荡张力的软骨细胞则形成了类似的星状形态。本研究的生化和形态学结果对于成功开发软骨和纤维软骨组织替代物及修复策略具有重要意义。
