Tsai M A, Waugh R E, Keng P C
Department of Biophysics, University of Rochester School of Medicine and Dentistry, NY 14642, USA.
Biorheology. 1996 Jan-Feb;33(1):1-15. doi: 10.1016/0006-355x(96)00002-9.
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.
我们研究了早幼粒细胞白血病HL-60细胞成熟过程中细胞变形性的变化。用1.25%的二甲基亚砜诱导HL-60细胞成熟。在诱导后的第1天、第4天和第7天，通过单细胞微量吸管抽吸法评估细胞变形性。发现HL-60细胞随着成熟，尺寸减小，变形性增加。在相同的抽吸压力（0.5 - 1.3 kPa）下进行测试时，发现诱导前细胞的细胞质粘度在210至85 Pa·s之间变化；诱导后第7天的细胞，其细胞质粘度在85至40 Pa·s之间变化。此外，细胞质粘度对剪切速率呈现幂律依赖性，即μ = μc(γm/γc)-b，其中μ为细胞质粘度，γm为细胞进入时的平均剪切速率，μc为特征剪切速率γc下的特征粘度，b为材料系数。所有成熟阶段的细胞对剪切速率都表现出相似的依赖性（b约为0.5），但除第1天外，特征粘度随成熟而降低。当γc设定为1 s-1时，诱导前细胞的μc = 236 ± 5 Pa·s，诱导第1天、第4天和第7天细胞的μc分别为239 ± 7、209 ± 7和175 ± 14 Pa·s。
