A novel patterned magnetic micropillar array substrate for analysis of cellular mechanical responses |
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| Affiliation: | 1. Micro-Nano Biomechanics Laboratory, Department of Intelligent Systems Engineering, Ibaraki University, Nakanarusawa-cho, Hitachi 316-8511, Japan;2. Biomechanics Laboratory, Department of Mechanical Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan;3. Biomechanics Laboratory, Department of Mechanical Science and Engineering, Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan;1. First Department of Physiology, Kawasaki Medical School, Japan;2. Department of Cardiovascular Physiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Japan;1. Biomechanics Laboratory, Department of Mechanical Systems Engineering, Graduate School of Engineering, Nagoya University, Nagoya, Japan;2. Biomechanics Laboratory, Department of Mechanical Engineering, Nagoya Institute of Technology, Nagoya, Japan;1. Biomechanics Laboratory, Department of Mechanical Systems Engineering, Graduate School of Engineering, Nagoya University, Nagoya, Japan;2. Biomechanics Laboratory, Department of Mechanical Engineering, Nagoya Institute of Technology, Nagoya, Japan;3. Ibaraki University, Hitachi, Japan;4. Nagoya University, Nagoya, Japan;1. Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA;2. Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA;1. PASTEUR, Département de Chimie, École Normale Supérieure, PSL University, Sorbonne Université, CNRS, 75005, Paris, France;2. Micro and Nano System Research Center, College of Information and Computer, Taiyuan University of Technology, Taiyuan, 030024, Shanxi, China;3. Institut Curie, CNRS UMR 144, 26 rue d’Ulm, 75248, Paris, Cedex 05, France |
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| Abstract: | Traction forces generated at cellular focal adhesions (FAs) play an essential role in regulating various cellular functions. These forces (1–100 nN) can be measured by observing the local displacement of a flexible substrate upon which cells have been plated. Approaches employing this method include using microfabricated arrays of poly(dimethylsiloxane) (PDMS) micropillars that bend by cellular traction forces. A tool capable of applying a force to FAs independently, by actively moving the micropillars, should become a powerful tool to delineate the cellular mechanotransduction mechanisms. Here, we developed a patterned magnetic micropillar array PDMS substrate that can be used for the mechanical stimulation of cellular FAs and the measurement of associated traction forces. The diameter, length, and center-to-center spacing of the micropillars were 3, 9, and 9 µm, respectively. Iron particles were embedded into the micropillars, enabling the pillars to bend in response to an external magnetic field, which also controlled their location on the substrate. Applying a magnetic field of 0.3 T bent the pillars by ∼4 µm and allowed transfer of external forces to the actin cytoskeleton through FAs formed on the pillar top. Using this approach, we investigated the traction force changes in cultured aortic smooth muscle cells (SMCs) after local compressive stimuli to release cell pretension. The mechanical responses of SMCs were roughly classified into two types: almost a half of the cells showed a little decrease of traction force at each pillar following compressive stimulation, although cell area increased significantly; and the rest showed the opposite, with increased forces and a simultaneous decrease in area. The traction forces of SMCs fluctuated markedly during the local compression. The root mean square of traction forces significantly increased during the compression, and returned to the baseline level after its release. These results suggest that the fluctuation of forces may be caused by active reorganization of the actin cytoskeleton and/or its dynamic interaction with myosin molecules. Thus, our magnetic micropillar substrate would be useful in investigating the mechanotransduction mechanisms of cells. |
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| Keywords: | Cell biomechanics Magnetic particles Microfabrication Mechanotransduction |
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