title: Changes in HL-60 cell deformability during differentiation induced by DMSO.
abstract: We have investigated changes in cellular deformability during promyelocytic leukemic HL-60 cell maturation. HL-60 cells were induced to mature with 1.25% dimethyl sulfoxide. Cellular deformability was evaluated by single-cell micropipette aspiration at one day, four days and seven days after induction. HL-60 cells were found to decrease in size and increase in deformability with maturation. When tested under the same aspiration pressures (0.5-1.3 kPa), cytoplasmic viscosity was found to vary from 210 to 85 Pa.s for cells prior to induction; it varied from 85 to 40 Pa.s for cells seven days after induction. Further, cytoplasmic viscosity exhibits power-law dependence on shear rate, mu = mu c (gamma m/gamma c)-b, where mu is cytoplasmic viscosity, gamma m is mean shear rate during cell entry, mu c is the characteristic viscosity at the characteristic shear rate, gamma c, and b is a material coefficient. Cells of all maturities showed similar dependence on shear rate (b approximately 0.5), but the characteristic viscosity decreased with maturation except for Day 1. When gamma c was set to 1 s-1, mu c = 236 +/- 5 Pa.s for cells prior to induction, mu c = 239 +/- 7, 209 +/- 7 and 175 +/- 14 Pa.s for cells on Days 1, 4 and 7 of induction, respectively.
authors.affiliation: Department of Biophysics, University of Rochester School of Medicine and Dentistry, NY 14642, USA. mts1@medinfo.rochester.edu
authors.forename: M A
authors.initials: MA
authors.lastname: Tsai
authors.forename: R E
authors.initials: RE
authors.lastname: Waugh
authors.forename: P C
authors.initials: PC
authors.lastname: Keng
mesh_terms: D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D003593:Cytoplasm / Q000187:drug effects / Q000502:physiology; D004121:Dimethyl Sulfoxide; D016193:G1 Phase; D018922:HL-60 Cells / Q000187:drug effects* / Q000502:physiology; D018056:Hemorheology; D006801:Humans; D016192:Resting Phase, Cell Cycle; D014783:Viscosity
chemical_list: D004121:Dimethyl Sulfoxide