Interfacing 3D magnetic twisting cytometry with confocal fluorescence microscopy to image force responses in living cells

Nat Protoc. 2017 Jul;12(7):1437-1450. doi: 10.1038/nprot.2017.042. Epub 2017 Jun 22.

Abstract

Cells and tissues can undergo a variety of biological and structural changes in response to mechanical forces. Only a few existing techniques are available for quantification of structural changes at high resolution in response to forces applied along different directions. 3D-magnetic twisting cytometry (3D-MTC) is a technique for applying local mechanical stresses to living cells. Here we describe a protocol for interfacing 3D-MTC with confocal fluorescence microscopy. In 3D-MTC, ferromagnetic beads are bound to the cell surface via surface receptors, followed by their magnetization in any desired direction. A magnetic twisting field in a different direction is then applied to generate rotational shear stresses in any desired direction. This protocol describes how to combine magnetic-field-induced mechanical stimulation with confocal fluorescence microscopy and provides an optional extension for super-resolution imaging using stimulated emission depletion (STED) nanoscopy. This technology allows for rapid real-time acquisition of a living cell's mechanical responses to forces via specific receptors and for quantifying structural and biochemical changes in the same cell using confocal fluorescence microscopy or STED. The integrated 3D-MTC-microscopy platform takes ∼20 d to construct, and the experimental procedures require ∼4 d when carried out by a life sciences graduate student.

MeSH terms

  • Animals
  • Cell Physiological Phenomena*
  • Cytological Techniques / methods*
  • Humans
  • Image Processing, Computer-Assisted / methods*
  • Magnetics
  • Microscopy, Confocal / methods*
  • Microscopy, Fluorescence / methods*
  • Microspheres
  • Stress, Mechanical*