van Loon J J W A, van Laar M C, Korterik J P, Segerink F B, Wubbels R J, de Jong H A A, van Hulst N F
DESC@OCB-ACTA, UVA-VU, van der Boechorststraat 7, Amsterdam, The Netherlands.
J Microsc. 2009 Feb;233(2):234-43. doi: 10.1111/j.1365-2818.2009.03113.x.
We present a novel atomic force microscope (AFM) system, operational in liquid at variable gravity, dedicated to image cell shape changes of cells in vitro under hypergravity conditions. The hypergravity AFM is realized by mounting a stand-alone AFM into a large-diameter centrifuge. The balance between mechanical forces, both intra- and extracellular, determines both cell shape and integrity. Gravity seems to be an insignificant force at the level of a single cell, in contrast to the effect of gravity on a complete (multicellular) organism, where for instance bones and muscles are highly unloaded under near weightless (microgravity) conditions. However, past space flights and ground based cell biological studies, under both hypogravity and hypergravity conditions have shown changes in cell behaviour (signal transduction), cell architecture (cytoskeleton) and proliferation. Thus the role of direct or indirect gravity effects at the level of cells has remained unclear. Here we aim to address the role of gravity on cell shape. We concentrate on the validation of the novel AFM for use under hypergravity conditions. We find indications that a single cell exposed to 2 to 3 x g reduces some 30-50% in average height, as monitored with AFM. Indeed, in situ measurements of the effects of changing gravitational load on cell shape are well feasible by means of AFM in liquid. The combination provides a promising technique to measure, online, the temporal characteristics of the cellular mechano-response during exposure to inertial forces.
我们展示了一种新型原子力显微镜（AFM）系统，它可在可变重力的液体环境中运行，专门用于对体外细胞在超重力条件下的形状变化进行成像。超重力原子力显微镜是通过将一台独立的原子力显微镜安装在大直径离心机中实现的。细胞内外的机械力之间的平衡决定了细胞的形状和完整性。与重力对完整（多细胞）生物体的影响相比，重力在单个细胞层面似乎是一种微不足道的力，例如在近失重（微重力）条件下，骨骼和肌肉会承受极低的负荷。然而，过去在太空飞行以及基于地面的细胞生物学研究中，无论是在低重力还是超重力条件下，都已显示出细胞行为（信号转导）、细胞结构（细胞骨架）和增殖的变化。因此，重力在细胞层面的直接或间接影响作用仍不明确。在这里，我们旨在探讨重力对细胞形状的作用。我们专注于验证新型原子力显微镜在超重力条件下的使用。我们发现有迹象表明，通过原子力显微镜监测，暴露在2至3倍重力下的单个细胞平均高度降低了约30 - 50%。实际上，借助液体环境中的原子力显微镜对细胞形状因重力负荷变化所产生的影响进行原位测量是完全可行的。这种组合提供了一种很有前景的技术，可在线测量细胞在受到惯性力作用期间机械响应的时间特性。
