Wille Jeremiah J, Elson Elliot L, Okamoto Ruth J
Department of Biomedical Engineering, Washington University, St. Louis, MO 63130, USA.
Ann Biomed Eng. 2006 Nov;34(11):1678-90. doi: 10.1007/s10439-006-9153-1. Epub 2006 Oct 11.
Bioartificial tissues are useful model systems for studying cell and extra-cellular matrix mechanics. These tissues provide a 3D environment for cells and allow tissue components to be easily modified and quantified. In this study, we fabricated bioartificial tissue rings from a 1 ml solution containing one million cardiac fibroblasts and 1 mg collagen. After 8 days, rings compacted to <1% of original volume and cell number increased 2.4 fold. We initiated continuous cyclic stretching of the rings after 2, 4, or 8 days of incubation, while monitoring the tissue forces. Peak tissue force during each cycle decreased rapidly after initiating stretch, followed by further slow decline. We added 2 microM Cytochalasin-D to some rings prior to initiation of stretch to determine the force contributed by the matrix. Cell force was estimated by subtracting matrix force from tissue force. After 12 h, matrix force-strain curves were highly nonlinear. Cell force-strain curves were linear during loading and showed hysteresis indicating viscoelastic behavior. Cell stiffness increased with stretching frequency from 0.001-0.25 Hz. Cell stiffness decreased with stretch amplitude (5-25%) at 0.1 Hz. The trends in cell stiffness do not fit simple viscoelastic models previously proposed, and suggest possible strain-amplitude related changes during cyclic stretch.
生物人工组织是研究细胞和细胞外基质力学的有用模型系统。这些组织为细胞提供了三维环境，并使组织成分易于修饰和量化。在本研究中，我们从含有100万个心脏成纤维细胞和1mg胶原蛋白的1ml溶液中制备了生物人工组织环。8天后，环压缩至原始体积的<1%，细胞数量增加了2.4倍。在孵育2、4或8天后，我们开始对环进行连续循环拉伸，同时监测组织力。开始拉伸后，每个周期的组织力峰值迅速下降，随后进一步缓慢下降。在开始拉伸之前，我们向一些环中添加了2μM细胞松弛素-D，以确定基质贡献的力。通过从组织力中减去基质力来估计细胞力。12小时后，基质力-应变曲线高度非线性。细胞力-应变曲线在加载过程中呈线性，并显示出滞后现象，表明具有粘弹性行为。细胞刚度随拉伸频率从0.001-0.25Hz增加。在0.1Hz时，细胞刚度随拉伸幅度（5-25%）降低。细胞刚度的趋势不符合先前提出的简单粘弹性模型，并表明在循环拉伸过程中可能存在与应变幅度相关的变化。
