Dresden 2014 – scientific programme
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BP: Fachverband Biologische Physik
BP 33: Active cell and tissue mechanics (focus session) I
BP 33.2: Talk
Thursday, April 3, 2014, 10:00–10:15, HÜL 386
Surface tension governs the shape of confined mitotic HeLa cells — •Elisabeth Fischer-Friedrich1,2, Anthony A. Hyman2, Frank Jülicher1, Daniel J. Müller3, and Jonne Helenius3 — 1MPI PKS, Dresden, Germany — 2MPI CBG, Dresden, Germany — 3D-BSSE, ETHZ, Basel, Switzerland
During mitosis, adherent cells round up, by increasing the tension of the contractile actomyosin cortex while increasing the internal hydrostatic pressure. In the simple scenario of a liquid cell interior, the surface tension is related to the local curvature and the hydrostatic pressure by Laplace’s law. However, verification of this scenario for cells requires accurate measurements of cell shape. Here, we use wedged micro-cantilevers to uniaxially confine single cells and determine confinement forces while concurrently determining cell shape using confocal microscopy. We fit experimentally measured confined cell shapes to shapes obeying Laplace’s law with uniform surface tension and find quantitative agreement. Geometrical parameters derived from fitting the cell shape, and the measured force were used to calculate hydrostatic pressure and surface tension of cells. We find that HeLa cells increase their internal hydrostatic pressure and surface tension from ≈40 Pa and 0.2 mNm−1 during interphase to ≈400 Pa and 1.6 mNm−1 during metaphase. The method introduced provides a means to determine pressure and surface tension of rounded cells accurately and with minimal cellular perturbation, and should be applicable to characterize the mechanical properties of various cellular systems.