Anderson Eric J, Knothe Tate Melissa L
Department of Mechanical & Aerospace Engineering, Case Western Reserve University, Cleveland, OH, USA.
Biomed Eng Online. 2007 Dec 4;6:46. doi: 10.1186/1475-925X-6-46.
A major stumbling block for researchers developing experimental models of mechanotransduction is the control of experimental variables, in particular the transmission of the mechanical forces at the cellular level. A previous evaluation of state of the art commercial perfusion chambers showed that flow regimes, applied to impart a defined mechanical stimulus to cells, are poorly controlled and that data from studies in which different chambers are utilized can not be compared, even if the target stress regimes are comparable.
This study provides a novel chamber design to provide both physiologically-based flow regimes, improvements in control of experimental variables, as well as ease of use compared to commercial chambers. This novel design achieves controlled stresses through five gasket designs and both single- and dual-flow regimes.
The imparted shear stress within the gasket geometry is well controlled. Fifty percent of the entire area of the 10 x 21 mm universal gasket (Gasket I, designed to impart constant magnitude shear stresses in the center of the chamber where outcome measures are taken), is exposed to target stresses. In the 8 mm diameter circular area at the center of the chamber (where outcome measures are made), over 92% of the area is exposed to the target stress (+/- 2.5%). In addition, other gasket geometries provide specific gradients of stress that vary with distance from the chamber inlet. Bench-top testing of the novel chamber prototype shows improvements, in the ease of use as well as in performance, compared to the other commercial chambers. The design of the chamber eliminates flow deviations due to leakage and bubbles and allows actual flow profiles to better conform with those predicted in computational models.
The novel flow chamber design provides predictable and well defined mechanical forces at the surface of a cell monolayer, showing improvement over previously tested commercial chambers. The predictability of the imparted stress improves both experiment repeatability as well as the accuracy of inter-study comparisons. Carefully controlling the stresses on cells is critical in effectively mimicking in vivo situations. Overall, the improved perfusion flow chamber provides the needed resolution, standardization and in vitro model analogous to in vivo conditions to make the step towards greater use in research and the opportunity to enter the diagnostic and therapeutic market.
开发机械转导实验模型的研究人员面临的一个主要障碍是实验变量的控制，尤其是细胞水平上机械力的传递。先前对现有商用灌注室的评估表明，用于向细胞施加特定机械刺激的流动状态控制不佳，并且即使目标应力状态相当，使用不同室进行的研究数据也无法进行比较。
本研究提供了一种新颖的室设计，以提供基于生理学的流动状态，改善实验变量的控制，并与商用室相比更易于使用。这种新颖的设计通过五种垫圈设计以及单流和双流状态实现了可控应力。
垫圈几何形状内施加的剪切应力得到了很好的控制。10×21毫米通用垫圈（垫圈I，设计用于在进行结果测量的室中心施加恒定大小的剪切应力）整个面积的50%暴露于目标应力。在室中心8毫米直径的圆形区域（进行结果测量的地方），超过92%的面积暴露于目标应力（±2.5%）。此外，其他垫圈几何形状提供了随距室入口距离变化的特定应力梯度。与其他商用室相比，新型室原型的台式测试在易用性和性能方面都有改进。室的设计消除了由于泄漏和气泡导致的流动偏差，并使实际流动剖面更好地符合计算模型中预测的剖面。
新颖的流动室设计在细胞单层表面提供了可预测且定义明确的机械力，比先前测试的商用室有改进。施加应力的可预测性提高了实验的可重复性以及研究间比较的准确性。仔细控制细胞上的应力对于有效模拟体内情况至关重要。总体而言，改进后的灌注流动室提供了所需的分辨率、标准化以及类似于体内条件的体外模型，从而朝着在研究中更多使用迈进，并为进入诊断和治疗市场提供了机会。
