Hallows K R, Frank R S
Department of Biophysics, University of Rochester Medical Center, NY 14642.
Biorheology. 1992 Mar-Jun;29(2-3):295-309. doi: 10.3233/bir-1992-292-309.
We measured changes in the deformability of human promyelocytic leukemic (HL-60) cells induced to differentiate for 5-6 days along the granulocyte pathway by 1.25% dimethylsulfoxide (DMSO). Differentiation resulted in an approximately 90% reduction in the transit times of the cells through capillary-sized pores over a range of aspiration pressures. Cell volume, as measured by two methods, decreased by an average of 35%. To account for the contribution of the volume decrease to the decrease in transit time, the liquid drop model, developed to describe neutrophil deformability, was used to calculate an apparent viscosity of the cells during this deformation. The apparent viscosity of both uninduced and induced HL-60 cells was a function of aspiration pressure, and an approximately 80% reduction in viscosity occurred with induction, as determined by regression analysis. The deformation rate-dependent viscosities of the induced cells were between 65 and 240 Pa-sec, values similar to those measured for circulating neutrophils. To assess the role of polymerized actin in these viscosity changes, intracellular F-actin content was measured, and the effect of dihydrocytochalasin B (DHB), an agent that disrupts actin polymerization, was determined. Despite the significant decrease in cellular viscosity, F-actin content per cell volume did not change significantly after induced differentiation. Treatment with 3 and 30 microM DHB lowered cellular F-actin content in a dose-dependent manner in both uninduced and induced cells. Cellular viscosity of both uninduced and induced cells decreased sharply with 3 microM DHB treatment (85% and 76% respectively). 30 microM DHB treatment caused a further significant reduction in the viscosity of uninduced cells, but for induced cells the additional decrease in viscosity was not significant. These data indicate that reductions in both cell volume and intrinsic viscosity contribute to the increased deformability of HL-60 cells with DMSO-induced differentiation. However, changes in the concentration of F-actin cannot account for the decrease in cellular viscosity that occurs.
我们测量了经1.25%二甲基亚砜（DMSO）诱导沿粒细胞途径分化5 - 6天的人早幼粒细胞白血病（HL - 60）细胞变形能力的变化。分化导致细胞在一系列抽吸压力下通过毛细血管大小孔隙的转运时间减少了约90%。通过两种方法测量的细胞体积平均减少了35%。为了说明体积减小对转运时间减少的贡献，我们使用为描述中性粒细胞变形能力而建立的液滴模型来计算细胞在这种变形过程中的表观粘度。未诱导和诱导的HL - 60细胞的表观粘度均是抽吸压力的函数，通过回归分析确定，诱导后粘度降低了约80%。诱导细胞的变形速率依赖性粘度在65至240帕秒之间，与循环中性粒细胞的测量值相似。为了评估聚合肌动蛋白在这些粘度变化中的作用，我们测量了细胞内F - 肌动蛋白含量，并确定了破坏肌动蛋白聚合的药物二氢细胞松弛素B（DHB）的作用。尽管细胞粘度显著降低，但诱导分化后每细胞体积的F - 肌动蛋白含量没有显著变化。用3和30微摩尔/升的DHB处理未诱导和诱导细胞，细胞内F - 肌动蛋白含量均呈剂量依赖性降低。用3微摩尔/升的DHB处理未诱导和诱导细胞，细胞粘度均急剧下降（分别为85%和76%）。用30微摩尔/升的DHB处理导致未诱导细胞的粘度进一步显著降低，但对于诱导细胞，粘度的额外降低并不显著。这些数据表明，细胞体积和固有粘度的降低都有助于DMSO诱导分化的HL - 60细胞变形能力的增加。然而，F - 肌动蛋白浓度的变化不能解释所发生的细胞粘度降低。
