Quantitative Deformability Cytometry: Rapid, Calibrated Measurements of Cell Mechanical Properties

Abstract

Advances in methods that determine cell mechanical phenotype, or mechanotype, have demonstrated the utility of biophysical markers in clinical and research applications ranging from cancer diagnosis to stem cell enrichment. Here, we introduce quantitative deformability cytometry (q-DC), a method for rapid, calibrated, single-cell mechanotyping. We track changes in cell shape as cells deform into microfluidic constrictions, and we calibrate the mechanical stresses using gel beads. We observe that time-dependent strain follows power-law rheology, enabling single-cell measurements of apparent elastic modulus, E, and power-law exponent, β. To validate our method, we mechanotype human promyelocytic leukemia (HL-60) cells and thereby confirm q-DC measurements of E = 0.53 ± 0.04 kPa. We also demonstrate that q-DC is sensitive to pharmacological perturbations of the cytoskeleton as well as differences in the mechanotype of human breast cancer cell lines (E = 2.1 ± 0.1 and 0.80 ± 0.19 kPa for MCF-7 and MDA-MB-231 cells). To establish an operational framework for q-DC, we investigate the effects of applied stress and cell/pore-size ratio on mechanotype measurements. We show that E increases with applied stress, which is consistent with stress stiffening behavior of cells. We also find that E increases for larger cell/pore-size ratios, even when the same applied stress is maintained; these results indicate strain stiffening and/or dependence of mechanotype on deformation depth. Taken together, the calibrated measurements enabled by q-DC should advance applications of cell mechanotype in basic research and clinical settings.

Stress hormone signaling through β‐adrenergic receptors regulates macrophage mechanotype and function

“…Higher retention indicates a population of cells that has a higher probability to occlude pores compared with a suspension of cells that more readily transit through pores. Cells with higher elastic modulus as measured by atomic force microscopy tend to have a higher probability of occluding micron-scale pores (31,32).…”

“…To measure the deformability of single cells, we used quantitative deformability cytometry as described in our previous studies (31,33). Briefly, cell suspensions were flowed through polydimethylsiloxane (PDMS) microfluidic devices with channels that were 5 mm 3 10 mm (width 3 height); the timescale of cell transit, or transit time, provides a measure of cell deformability (34).…”

“…To validate the b-AR-induced changes in deformability using an independent method, we used quantitative deformability cytometry to measure the timescale for individual macrophages to transit through 5 mm constrictions in a microfluidic device (31,33); cells that are stiffer have longer transit times (33). Activation of b-AR signaling increased the transit time (TT) of macrophages (median TT Veh vs. TT Iso : 6.9 vs. 9.4 ms, P , 0.0001) (Fig.…”

Integrin Antibody Decreases Deformability of Patient‐Derived Pre‐B Acute Lymphocytic Leukemia Cells as Measured by High‐Frequency Acoustic Tweezers

“…Rosenbluth et al prepared SU‐8 photoresist microwells (Microchem, Newton, MA) on a glass wafer, which were used to immobilize nonadherent cells; however, additional fabrication tasks were required to characterize nonadherent cells. Quantitative deformability cytometry is a high‐throughput assessment based on microfluidic concepts that can be used to obtain the Young modulus of cells . However, the programming required to run quantitative deformability cytometry is extremely time‐consuming.…”

“…Quantitative deformability cytometry is a highthroughput assessment based on microfluidic concepts that can be used to obtain the Young modulus of cells. 5 However, the programming required to run quantitative deformability cytometry is extremely time-consuming. Each image captures a single cell transiting through a micrometer-scale constriction; the elastic modulus is obtained by measuring the transition time.…”