REGIONAL BIOMECHANICAL PROPERTIES OF CELLS

细胞的区域生物力学特性

• 批准号: 6149710
• 负责人: Frank C Yin
• 金额: $ 21.21万
• 依托单位: BARNES-JEWISH HOSPITAL
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-02-08 至 2003-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6149710
• 关键词: atomic force microscopy; bioengineering /biomedical engineering; bioimaging /biomedical imaging; biomechanics; cytoskeleton; elasticity; method development; nanotechnology; physical property

To function properly, the cell cytoskeleton undergoes tightly orchestrated changes in organization at the submicron level, particularly at the periphery. Despite many studies, there are major gaps in our understanding of the mechanisms that affect and control cytoskeletal organization and function, due primarily to inability to examine the detailed mechanical properties of the cell. The most commonly used technique for studying cells, indirect immunofluorescence and electron microscopy, are insufficient because (1) they have inadequate temporal and spatial resolution and (2) they provide only structural information. Both dynamical structural and functional data at the submicron level are required to fully understand how cells work. Previous measurements of cell stiffness also did not have the required spatial resolution. One promising new method is nano-identification using atomic force microscopy (AFM). Since its invention 10 years ago, AFM has become recognized as a potentially useful tool for studying regional properties in living cells. However, all existing studies of biological materials have analyzed AFM data based on equations derived assuming infinitesimally small deformations, linear elasticity, and homogeneity. None of these assumptions are likely to pertain to biological structures. Hence, the estimates of cell stiffness in the literature are almost certainly wrong. Our goal is to develop a systematic approach to address some critical methodological issues related to AFM, such as how to better calibrate the cantilevers and how to better understand the mechanics of indentation with pyramidal-shaped tips. We propose to use finite-element methods of structural analyses to tackle these problems. We will specifically focus on the conditions under which linear elasticity theory can and can not be applied to the finite-deformation mechanics of indentation. We will also investigate how and if heterogeneity of mechanical properties can be assessed by indentation. These studies will serve both as guidelines for indentation studies as well as a foundation for reliable analyses for future indentation results. Once these goals are achieved, we will have the tools to begin answering some crucial questions about cell function using AFM.

为了正常运作，细胞细胞骨架在亚微米级别，特别是在外围的组织中经历了紧密策划的组织变化。尽管进行了许多研究，但我们对影响和控制细胞骨架组织和功能的机制的理解仍有主要差距，这主要是由于无法检查细胞的详细机械性能。研究细胞的最常用技术，间接的免疫荧光和电子显微镜不足，因为（1）它们的时间和空间分辨率不足，并且（2）它们仅提供结构信息。需要在亚微米水平上的动态结构和功能数据，以充分了解细胞的工作方式。先前对细胞刚度的测量也没有所需的空间分辨率。一种有希望的新方法是使用原子力显微镜（AFM）进行纳米识别。自10年前其发明以来，AFM已被公认为是研究活细胞中区域特性的潜在有用工具。但是，所有现有的生物材料研究都基于衍生的方程进行了分析，假设无限的变形，线性弹性和均匀性。这些假设都不可能与生物结构有关。因此，文献中细胞刚度的估计几乎肯定是错误的。我们的目标是开发一种系统的方法来解决与AFM相关的一些关键方法论问题，例如如何更好地校准悬臂以及如何通过金字塔形状的尖端更好地理解凹痕机制。我们建议使用有限元的结构分析方法来解决这些问题。我们将专门关注线性弹性理论可以并且不能应用于有限的凹痕机制的条件。我们还将调查如何以及如何通过凹痕评估机械性能的异质性。这些研究既将作为压痕研究的指南，也将作为对未来压痕结果的可靠分析的基础。一旦实现了这些目标，我们将有工具开始回答有关使用AFM的细胞功能的一些关键问题。