title: Resonant microchannel volume and mass measurements show that suspended cells swell during mitosis.
abstract: Osmotic regulation of intracellular water during mitosis is poorly understood because methods for monitoring relevant cellular physical properties with sufficient precision have been limited. Here we use a suspended microchannel resonator to monitor the volume and density of single cells in suspension with a precision of 1% and 0.03%, respectively. We find that for transformed murine lymphocytic leukemia and mouse pro-B cell lymphoid cell lines, mitotic cells reversibly increase their volume by more than 10% and decrease their density by 0.4% over a 20-min period. This response is correlated with the mitotic cell cycle but is not coupled to nuclear osmolytes released by nuclear envelope breakdown, chromatin condensation, or cytokinesis and does not result from endocytosis of the surrounding fluid. Inhibiting Na-H exchange eliminates the response. Although mitotic rounding of adherent cells is necessary for proper cell division, our observations that suspended cells undergo reversible swelling during mitosis suggest that regulation of intracellular water may be a more general component of mitosis than previously appreciated.
authors.affiliation: Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02142 Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139.
authors.forename: Sungmin
authors.initials: S
authors.lastname: Son
authors.affiliation: Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02142 Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139.
authors.forename: Joon Ho
authors.initials: JH
authors.lastname: Kang
authors.affiliation: Department of Systems Biology, Harvard Medical School, Boston, MA 02115.
authors.forename: Seungeun
authors.initials: S
authors.lastname: Oh
authors.affiliation: Department of Systems Biology, Harvard Medical School, Boston, MA 02115.
authors.forename: Marc W
authors.initials: MW
authors.lastname: Kirschner
authors.affiliation: Department of Systems Biology, Harvard Medical School, Boston, MA 02115.
authors.forename: T J
authors.initials: TJ
authors.lastname: Mitchison
authors.affiliation: Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02142 Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 srm@mit.edu.
authors.forename: Scott
authors.initials: S
authors.lastname: Manalis
mesh_terms: D000818:Animals; D018929:Cell Culture Techniques; D045744:Cell Line, Tumor; D048429:Cell Size; D004705:Endocytosis; D051379:Mice; D008938:Mitosis; D009685:Nuclear Envelope / Q000378:metabolism