Chown Matthew G, Kumar Sanjay
Department of Bioengineering, University of California, Berkeley, CA 94720-1762, USA.
Int J Nanomedicine. 2007;2(3):333-44.
The structure, physiology, and fate of living cells are all highly sensitive to mechanical forces in the cellular microenvironment, including stresses and strains that originate from encounters with the extracellular matrix (ECM), blood and other flowing materials, and neighbouring cells. This relationship between context and physiology bears tremendous implications for the design of cellular micro-or nanotechnologies, since any attempt to control cell behavior in a device must provide the appropriate physical microenvironment for the desired cell behavior. Cells sense, process, and respond to biophysical cues in their environment through a set of integrated, multi-scale structural complexes that span length scales from single molecules to tens of microns, including small clusters of force-sensing molecules at the cell surface, micron-sized cell-ECM focal adhesion complexes, and the cytoskeleton that permeates and defines the entire cell. This review focuses on several key technologies that have recently been developed or adapted for the study of the dynamics of structural micro-and nanosystems in living cells and how these systems contribute to spatially-and temporally-controlled changes in cellular structure and mechanics. We begin by discussing subcellular laser ablation, which permits the precise incision of nanoscale structural elements in living cells in order to discern their mechanical properties and contributions to cell structure. We then discuss fluorescence recovery after photobleaching and fluorescent speckle microscopy, two live-cell fluorescence imaging methods that enable quantitative measurement of the binding and transport properties of specific proteins in the cell. Finally, we discuss methods to manipulate cellular structural networks by engineering the extracellular environment, including microfabrication of ECM distributions of defined geometry and microdevices designed to measure cellular traction forces at micron-scale resolution. Together, these methods form a powerful arsenal that is already adding significantly to our understanding of the nanoscale architecture and mechanics of living cells and may contribute to the rational design of new cellular micro-and nanotechnologies.
活细胞的结构、生理学和命运对细胞微环境中的机械力高度敏感，这些机械力包括与细胞外基质（ECM）、血液及其他流动物质以及相邻细胞相互作用产生的应力和应变。这种环境与生理学之间的关系对细胞微技术或纳米技术的设计具有重大意义，因为在设备中控制细胞行为的任何尝试都必须为期望的细胞行为提供合适的物理微环境。细胞通过一组整合的、多尺度的结构复合体来感知、处理和响应其环境中的生物物理线索，这些复合体跨越从单个分子到几十微米的长度尺度，包括细胞表面的小簇力敏分子、微米大小的细胞 - ECM 黏着斑复合体以及贯穿并界定整个细胞的细胞骨架。本综述重点关注最近开发或改进的几种关键技术，这些技术用于研究活细胞中结构微系统和纳米系统的动力学，以及这些系统如何促成细胞结构和力学在空间和时间上的可控变化。我们首先讨论亚细胞激光消融技术，该技术允许精确切割活细胞中的纳米级结构元件，以识别其力学特性及其对细胞结构的贡献。然后我们讨论光漂白后荧光恢复和荧光斑点显微镜技术，这两种活细胞荧光成像方法能够定量测量细胞中特定蛋白质的结合和转运特性。最后，我们讨论通过构建细胞外环境来操纵细胞结构网络的方法，包括微制造具有特定几何形状的 ECM 分布以及设计用于以微米级分辨率测量细胞牵引力的微型装置。这些方法共同构成了一个强大的技术库，已经极大地增进了我们对活细胞纳米级结构和力学的理解，并可能有助于合理设计新的细胞微技术和纳米技术。
