FLUID DYNAMICS OF MECHANICALLY STIMULATED CELL CULTURES

机械刺激细胞培养物的流体动力学

基本信息

批准号：
2413985
负责人：
THOMAS DUDLEY BROWN
金额：
$ 21.15万
依托单位：
UNIVERSITY OF IOWA
依托单位国家：
美国
项目类别：
财政年份：
1995
资助国家：
美国
起止时间：
1995-05-09 至 1999-04-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/2413985
关键词：
biomechanics computer simulation fluid flow growth media mechanical pressure surface property tissue /cell culture

项目摘要

DESCRIPTION: (Adapted from the Investigator's Abstract) Recent interest in the adaptive response of strain-sensitive musculoskeletal tissues has led to the development of various devices aimed at delivering well controlled mechanical stimuli to laboratory cell culture preparations. In many of these devices, the targeted cells are adhered to the surface of a compliant substrate membrane, which, in turn, undergoes cyclic transverse displacements, induced either by imposed pressure differentials or by direct platen contact. In such "cell stretching" systems, it is assumed that the induced substrate deformation is the dominant mechanical stimulus delivered to the target cells. However, almost no attention has been directed to the potentially severely confounding effects of reactive shear and/or normal stresses imparted to the adhered cells due to the coupled motion of the overlying fluid medium. The applicants have developed a preliminary finite element model of one representative, widely-used cell stimulus system. By means of a specially instrumented testing chamber, they have shown that the finite element formulation reasonably models the culture substrate's motions and deformation, both statically and under complex dynamic loading conditions. Detailed stress distribution data from that finite element model strongly suggest that there are many situations in contemporary cell culture practice wherein the cell strains induced by coupled motions of the nutrient medium may be of at least the same order of magnitude as the cell deformations induced by the input membrane strains. The preliminary finite element model appears to accurately simulate the major inertial effects present in the nutrient medium. However, as presently formulated, that model has no provision to estimate fluid shear stress, likely also an important stimulus for cellular mechano- transduction. For that reason, the investigator proposed (Aim 1) to amend their constitutive treatment of the nutrient medium - for simplicity, initially modeled as a very compliant hyperplastic continuum - to address the considerably more complex behavior of a Newtonian fluid. A set of physical validation experiments is planned, including both substrate and fluid kinematics (Aim 2). They then will use this physically validated finite element model plus a spatially refined near- surface model to identify specific experimental conditions under which the stress state of cells adhered to the membrane culture surface becomes appreciably influenced by the kinetics of the nutrient medium of the present system (Aim 3), as well as for several other mechano- stimulus system designs (Aim 4). Finally, for the present system at selected operation settings above and below the computed fluid-influence threshold(s), they will conduct cell culture experiments to detect differentials of biological response, monitoring cyclin D1 and DNA synthesis (Aim 5). If coupled nutrient medium motions can indeed induce biologically consequential reactive strains to cells in culture, then it is very important to identify the operational conditions under which such an effect occurs.

描述：（改编自调查员的摘要）最近的兴趣在应变敏感的肌肉骨骼组织的自适应反应中导致了旨在提供良好设备的各种设备的开发控制机械刺激到实验室细胞培养的制剂。在许多这些设备中，靶向细胞被粘附到表面兼容的底物膜，该膜反过来经历循环横向位移，由施加的压力引起差速器或通过直接板条接触。在这样的“细胞拉伸”中系统，假定诱导的底物变形是传递到靶细胞的主要机械刺激。然而，几乎没有关注可能严重的关注反应性剪切和/或赋予的正常应力的混杂作用由于上覆的流体的耦合运动而引起的粘附细胞中等的。申请人已经开发了一个初步的有限元模型代表性，广泛使用的细胞刺激系统。通过特殊的仪器测试室，他们表明有限元素配方合理地对培养基底物的动作进行了合理的建模变形，无论是静态还是在复杂的动态加载下状况。来自该有限元素的详细压力分布数据模型强烈表明当代有很多情况细胞培养实践，其中耦合诱导的细胞菌株营养培养基的运动可能至少具有相同的顺序大小作为输入膜诱导的细胞变形菌株。初步有限元模型似乎可以准确模拟营养培养基中存在的主要惯性作用。但是，如该模型目前尚未估算流体剪切应力，也可能是细胞机械的重要刺激转导。因此，调查员提出（目标1）修改其构成对养分培养基的处理 - 简单性，最初被建模为非常合规的增生连续性 - 解决牛顿的更复杂的行为体液。计划了一组物理验证实验，包括底物和流体运动学（AIM 2）。然后他们会使用这个经过物理验证的有限元模型加上空间完善的接近表面模型以确定特定的实验条件粘附在膜培养表面的细胞的应力状态受到营养培养基动力学的影响目前的系统（AIM 3）以及其他几种机械刺激系统设计（AIM 4）。最后，对于当前系统所选的操作设置在计算的流体影响上方和下方阈值，他们将进行细胞培养实验以检测生物反应的差异，监测细胞周期蛋白D1和DNA 合成（目标5）。如果偶联营养中等运动确实可以诱导在生物学上对培养细胞的反应性反应性菌株，然后确定操作条件非常重要发生这种效果。