Implications of heterogeneous bead behavior on cell mechanical properties measured with magnetic twisting cytometry

Magnetic twisting cytometry (MTC) measures cellular mechanical properties, such as cell stiffness and viscosity, by applying mechanical stress to spec ific cell surface receptors via ligand-coated ferromagnetic beads. MTC meas ures simultaneously the rotation of approximately 50,000 beads attached to 20,000-40,000 cells. Here we show direct evidence of heterogeneous bead beh avior and examine its consequences in the interpretation of cell mechanical properties. (C) 1999 Elsevier Science B.V. All rights reserved.