Characterization of cytoplasmic viscosity of hundreds of single tumor cells based on micropipette aspiration

Background: Cytoplasmic viscosity (μc) is a key biomechanical parameter for evaluating the status of cellular cytoskeletons. Previous studies focused on white blood cells, but the data of cytoplasmic viscosity for tumor cells were missing.
Methodology: Tumor cells (H1299, A549 and drug-treated H1299 with compromised cytoskeletons) were aspirated continuously through a micropipette at a pressure of -10 kPa or -5 kPa where aspiration lengths as a function of time were obtained and translated to cytoplasmic viscosity based on a theoretical Newtonian fluid model. Quartile coefficients of dispersion were quantified to evaluate the distributions of cytoplasmic viscosity within the same cell type while neural network based pattern recognitions were used to classify different cell types based on cytoplasmic viscosity.
Results: The single-cell cytoplasmic viscosity with three quartiles and the quartile coefficient of dispersion were quantified as 16.7 Pa•S, 42.1 Pa•S, 110.3 Pa•S and 74% for H1...