Substrate-dependent cell elasticity measured by optical tweezers indentation |
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| Institution: | 1. Institute of Materials (IOM-CNR), Area Science Park, Basovizza, S.S. 14, Km 163.5, 34149 Trieste, Italy;2. Nanotechnology, University of Trieste, 34149 Trieste, Italy;3. International Centre for Theoretical Physics (ICTP), 34149 Trieste, Italy;4. Department of Physics, Cheikh Anta Diop University, Dakar 5005, Senegal;5. Department of Medical Sciences (DSM), University of Trieste, 34149, Italy;6. Department of Biological and Medical Science, University of Udine, Santa Maria della Misericordia Hospital, 33100 Udine, Italy;1. Key Lab of In-fiber Integrated Optics, Ministry Education of China, Harbin Engineering University, Harbin, China;2. Centre for Micro-Photonics Swinburne University of Technology, P.O. Box 218 Hawthorn, Vic 3122, Australia;1. Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands;2. Department of Physics, Nanosystems Initiative Munich and Center for Nanoscience, Ludwig-Maximilians-University Munich, Munich, Germany;1. Biophysics Group, Department of Physics, Friedrich-Alexander University of Erlangen-Nuremberg, Erlangen, Germany;2. Division of Molecular Genetics, German Cancer Research Center (DKFZ), Heidelberg, Germany;3. IB3: Institute of Biological Chemistry, Biophysics and Bioengineering, Department of Physics, Heriot-Watt University, Edinburgh, United Kingdom |
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| Abstract: | In the last decade, cell elasticity has been widely investigated as a potential label free indicator for cellular alteration in different diseases, cancer included. Cell elasticity can be locally measured by pulling membrane tethers, stretching or indenting the cell using optical tweezers. In this paper, we propose a simple approach to perform cell indentation at pN forces by axially moving the cell against a trapped microbead. The elastic modulus is calculated using the Hertz-model. Besides the axial component, the setup also allows us to examine the lateral cell–bead interaction. This technique has been applied to measure the local elasticity of HBL-100 cells, an immortalized human cell line, originally derived from the milk of a woman with no evidence of breast cancer lesions. In addition, we have studied the influence of substrate stiffness on cell elasticity by performing experiments on cells cultured on two substrates, bare and collagen-coated, having different stiffness. The mean value of the cell elastic modulus measured during indentation was 26±9 Pa for the bare substrate, while for the collagen-coated substrate it diminished to 19±7 Pa. The same trend was obtained for the elastic modulus measured during the retraction of the cell: 23±10 Pa and 13±7 Pa, respectively. These results show the cells adapt their stiffness to that of the substrate and demonstrate the potential of this setup for low-force probing of modifications to cell mechanics induced by the surrounding environment (e.g. extracellular matrix or other cells). |
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| Keywords: | Cell elasticity Biomechanics Optical tweezers Elastic modulus Substrate stiffness |
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