EAGER: Development of Methods to Study Dynamical Mechanical Properties of the Pericellular Layer of Cells

细胞周层是细胞的重要组成部分，但尚未得到充分研究。它覆盖了所有哺乳动物细胞和大多数细菌的细胞体。这一层的变化与许多进行性疾病有关，包括心血管疾病、炎症和癌症。有证据表明，它在衰老过程中也很重要。正如最近发现的，这一层在细胞力学中扮演着重要的角色。虽然这一层的静态力学性能最近已经成为一个研究的主题，但它的动态力学性能仍然是完全未知的。与此同时，这些特性应该定义许多正常生理和病理生理过程中的细胞-细胞相互作用--包括干细胞治疗期间的血流、癌细胞侵袭和细胞运动。我们知识上这种差距的主要原因是缺乏实验工具来测量细胞周层的动态机械性能。由这一早期概念探索性研究奖助金支持的研究将专注于开发这样一种变革性工具，它允许直接研究细胞周层的动态机械特性。这项研究既包括硬件方面的进步，也包括在纳米和亚微米水平进行测量所必需的计算分析方面的进步。获得的实验数据将被分析，以勾勒出细胞周层的力学性质。最重要的长期目标是使用这一新工具来研究细胞周层在癌症和衰老中的作用。研究成果将被纳入材料和生物工程课程的教学单元。这项研究将开发一种基于原子力显微镜平台的动态力学分析仪，在该分析仪中，所有频率都可以同时测量。这种模式被称为傅里叶变换纳米DMA，或FT-NanoDMA。一种新颖的反馈系统将允许精确控制探针与样品的相互作用，以测量作为频率函数的细胞周层的存储和损失模数。利用Sneddon公式建立了一个从纳米压痕测量中提取存储和损失的新的力学模型。该装置和模型将使用商业超软聚合物进行验证。第一批细胞周膜动态力学性能的实验数据将在固定的哺乳动物细胞上获得，这使得能够精确地分离糖萼分子和细胞周膜波纹对细胞周刷层的动态响应的影响。这些数据将与现有的细胞生物力学力学模型进行比较。这些知识将有助于理解现有模型是否能够描述观察到的数据，或者是否必须开发新的模型。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The pericellular layer is an important but not fully studied part of cells. It covers the cell body of all mammalian cells and the majority of bacteria. Changes in this layer have been connected with many progressive diseases, including cardiovascular disorders, inflammation, and cancer. There is evidence that it is also important in aging. As has recently been discovered, this layer plays an important role in cell mechanics. Although static mechanical properties of this layer have recently become a subject of investigation, dynamical mechanical properties of this layer remain totally unknown. At the same time, these properties should define cell-cell interactions in many normal physiological and pathophysiological processes - including blood flow, invasion of cancer cells, and cell motion during stem cell therapy. The main reason for this gap in our knowledge is the lack of experimental tools to measure dynamical mechanical properties of the pericellular layer of cells. The research supported by this EArly-concept Grant for Exploratory Research (EAGER) award will focus on the development of such a transformative tool, which allows direct studying the dynamical mechanical properties of the pericellular layer of cells. This research involves both advances in hardware and advances in computational analysis necessary to make measurements at the nano and submicron level. The obtained experimental data will be analyzed to outline the mechanical nature of the pericellular layer. The overarching long-term goal is to use this new tool to study the role of the pericellular layer in cancer and aging. The research results will be incorporated into modules for teaching Materials and Bioengineering courses. This research will develop a dynamical mechanical analyzer, based on the atomic force microscopy platform, in which all frequencies are measured at the same time. The mode is called Fourier transform nanoDMA, or FT-NanoDMA. A novel feedback system will allow for precise controlling of the probe?sample interaction to measure storage and loss moduli of the pericellular layer as a function of frequency. A new mechanical model extracting the storage and loss from the nanoindentation measurements will be developed using Sneddon formalism . The device and the model will be verified using commercial ultrasoft polymers. The first experimental data of the dynamic mechanical properties of the pericellular coat will be obtained on fixed mammalian cells, which allow precise separation of the impact of the glyocalyx molecules and the corrugations of the pericellular membrane to the dynamic response of the pericellular brush layer. The data will be compared against existing mechanical models of cellular biomechanics. This knowledge will help to understand if the existing models can describe the observed data or if new models have to be developed.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.