Quantification of Single-Cell Cortical Tension Using Multiple Constriction Channels

This article presents a microfluidic system with multiple constriction channels in parallel capable of characterizing cortical tension of single cells in a continuous manner. Single cells are forced to travel through constriction channels (cross-sectional area smaller than single cells) in a quasi-static manner with front/rear membrane curves of deformed cells captured. Then the front/rear membrane curves are translated into cortical tension based on a home-developed mechanical model illustrating the relationship among cortical tension, cell deformation, aspiration pressure and geometrical parameters of constriction channels. Based on this microfluidic platform, cortical tension with sample sizes as large as thousands of single HL-60 cells were quantified for the first time where a variety of experimental conditions were used for comparison. Specifically, comparable values of cortical tension were obtained from both front and rear membrane portions of single cells while aspiration pressure rather than channel length can affect the quantified values of cortical tensions to an extent. As a demonstration, the microfluidic system was used to process HL-60 cells under a variety of cell treatments, producing higher cortical tension for the cells treated with paraformaldehyde for fixation and lower cortical tension for the cells treated with cytochalasin D for cytoskeleton compromise in comparison to wild-type counterparts. In summary, the developed microfluidic system can quantify cortical tension from single cells in a continuous fluid flow, which may function as an enabling tool in the field of single-cell analysis.