Unbiased High-Precision Cell Mechanical Measurements with Microconstrictions

Janina R. Lange, Claus Metzner, Sebastian Richter, Werner Schneider, Monika Spermann, Thorsten Kolb, Graeme Whyte, Ben Fabry

Research output: Contribution to journalArticle

Abstract

We describe a quantitative, high-precision, high-throughput method for measuring the mechanical properties of cells in suspension with a microfluidic device, and for relating cell mechanical responses to protein expression levels. Using a high-speed (750 fps) charge-coupled device camera, we measure the driving pressure Δp, maximum cell deformation εmax, and entry time tentry of cells in an array of microconstrictions. From these measurements, we estimate population averages of elastic modulus E and fluidity β (the power-law exponent of the cell deformation in response to a step change in pressure). We find that cell elasticity increases with increasing strain εmax according to E ∼ εmax, and with increasing pressure according to E ∼ Δp. Variable cell stress due to driving pressure fluctuations and variable cell strain due to cell size fluctuations therefore cause significant variability between measurements. To reduce measurement variability, we use a histogram matching method that selects and analyzes only those cells from different measurements that have experienced the same pressure and strain. With this method, we investigate the influence of measurement parameters on the resulting cell elastic modulus and fluidity. We find a small but significant softening of cells with increasing time after cell harvesting. Cells harvested from confluent cultures are softer compared to cells harvested from subconfluent cultures. Moreover, cell elastic modulus increases with decreasing concentration of the adhesion-reducing surfactant pluronic. Lastly, we simultaneously measure cell mechanics and fluorescence signals of cells that overexpress the GFP-tagged nuclear envelope protein lamin A. We find a dose-dependent increase in cell elastic modulus and decrease in cell fluidity with increasing lamin A levels. Together, our findings demonstrate that histogram matching of pressure, strain, and protein expression levels greatly reduces the variability between measurements and enables us to reproducibly detect small differences in cell mechanics.
Original languageEnglish
Pages (from-to)1472-1480
Number of pages9
JournalBiophysical Journal
Volume112
Issue number7
DOIs
Publication statusPublished - 11 Apr 2017

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mechanical measurement
cells
modulus of elasticity
proteins
histograms

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Lange, J. R., Metzner, C., Richter, S., Schneider, W., Spermann, M., Kolb, T., ... Fabry, B. (2017). Unbiased High-Precision Cell Mechanical Measurements with Microconstrictions. Biophysical Journal, 112(7), 1472-1480. https://doi.org/10.1016/j.bpj.2017.02.018
Lange, Janina R. ; Metzner, Claus ; Richter, Sebastian ; Schneider, Werner ; Spermann, Monika ; Kolb, Thorsten ; Whyte, Graeme ; Fabry, Ben. / Unbiased High-Precision Cell Mechanical Measurements with Microconstrictions. In: Biophysical Journal. 2017 ; Vol. 112, No. 7. pp. 1472-1480.
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Lange, JR, Metzner, C, Richter, S, Schneider, W, Spermann, M, Kolb, T, Whyte, G & Fabry, B 2017, 'Unbiased High-Precision Cell Mechanical Measurements with Microconstrictions', Biophysical Journal, vol. 112, no. 7, pp. 1472-1480. https://doi.org/10.1016/j.bpj.2017.02.018

Unbiased High-Precision Cell Mechanical Measurements with Microconstrictions. / Lange, Janina R.; Metzner, Claus; Richter, Sebastian; Schneider, Werner; Spermann, Monika; Kolb, Thorsten; Whyte, Graeme; Fabry, Ben.

In: Biophysical Journal, Vol. 112, No. 7, 11.04.2017, p. 1472-1480.

Research output: Contribution to journalArticle

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AU - Lange, Janina R.

AU - Metzner, Claus

AU - Richter, Sebastian

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AU - Fabry, Ben

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Lange JR, Metzner C, Richter S, Schneider W, Spermann M, Kolb T et al. Unbiased High-Precision Cell Mechanical Measurements with Microconstrictions. Biophysical Journal. 2017 Apr 11;112(7):1472-1480. https://doi.org/10.1016/j.bpj.2017.02.018