Effect of cell sample size in atomic force microscopy nanoindentation

Stefania Marcotti; Gwendolen C Reilly; Damien Lacroix

doi:10.1016/j.jmbbm.2019.03.018

Effect of cell sample size in atomic force microscopy nanoindentation

J Mech Behav Biomed Mater. 2019 Jun:94:259-266. doi: 10.1016/j.jmbbm.2019.03.018. Epub 2019 Mar 18.

Authors

Stefania Marcotti¹, Gwendolen C Reilly², Damien Lacroix³

Affiliations

¹ Insigneo Institute for in silico Medicine, University of Sheffield, Mappin Street, Sheffield S1 3JD, UK; Department of Mechanical Engineering, University of Sheffield, Western Bank, Sheffield S10 2TN, UK; Randall Centre for Cell and Molecular Biophysics, King's College London, Guy's Campus, London SE1 1UL, UK. Electronic address: stefania.marcotti@kcl.ac.uk.
² Insigneo Institute for in silico Medicine, University of Sheffield, Mappin Street, Sheffield S1 3JD, UK; Department of Materials Science and Engineering, University of Sheffield, Western Bank, Sheffield S10 2TN, UK. Electronic address: g.reilly@sheffield.ac.uk.
³ Insigneo Institute for in silico Medicine, University of Sheffield, Mappin Street, Sheffield S1 3JD, UK; Department of Mechanical Engineering, University of Sheffield, Western Bank, Sheffield S10 2TN, UK. Electronic address: d.lacroix@sheffield.ac.uk.

PMID: 30928670
DOI: 10.1016/j.jmbbm.2019.03.018

Abstract

Single-cell technologies are powerful tools to evaluate cell characteristics. In particular, Atomic Force Microscopy (AFM) nanoindentation experiments have been widely used to study single cell mechanical properties. One important aspect related to single cell techniques is the need for sufficient statistical power to obtain reliable results. This aspect is often overlooked in AFM experiments were sample sizes are arbitrarily set. The aim of the present work was to propose a tool for sample size estimation in the context of AFM nanoindentation experiments of single cell. To this aim, a retrospective approach was used by acquiring a large dataset of experimental measurements on four bone cell types and by building saturation curves for increasing sample sizes with a bootstrap resampling method. It was observed that the coefficient of variation (CV_%) decayed with a function of the form y = ax^b with similar parameters for all samples tested and that sample sizes of 21 and 83 cells were needed for the specific cells and protocol employed if setting a maximum threshold on CV_% of 10% or 5%, respectively. The developed tool is made available as an open-source repository and guidelines are provided for its use for AFM nanoindentation experimental design.

Keywords: Atomic force microscopy; Bone cells; Nanoindentation; Sample size.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

3T3 Cells
Animals
Biomechanical Phenomena
Mechanical Phenomena*
Mice
Microscopy, Atomic Force*
Nanotechnology*
Single-Cell Analysis