High Throughput Screening Methodology to Probe Cell Deformability

Abstract

Cell and nucleus mechanical properties are implicated in a wide range of biological contexts: for example, the multi-lobed nucleus of neutrophil cells correlates with increased cell deformability; cancer cells show decreased stiffness compared to benign cells. The mechanical properties of cells and nuclei could thus be valuable label-free markers for a cell's physiological state. Most conventional techniques used to study cell mechanics are labor-intensive and limited in throughput - typically < 10-20 cell types can be probed within a reasonable timeframe. Here we introduce a novel high throughput method to probe cell deformability. The device uses filtration to simultaneously probe several hundreds of different cell types; the entire assay is complete within ∼30 min. The key component of the technique is a porous membrane interfacing with a 96- or 384-well plate; cells are placed on top of this membrane; an applied pressure generates physical forces on them, causing the cells to pass through the membrane pores and into the collection well; the number of passaged cells is counted and provides a measure of cell mechanical properties. We characterize the number of passaged cells as a function of initial loading density, pressure amplitude and duration, membrane pore size, and cell deformability; in parallel we develop a theoretical description of cell passage building on theories describing bulk filtration. In proof of concept experiments, we apply the method to probe differentiated versus non-differentiated human promyelocytic leukemia (HL60) cells: a larger number of differentiated, neutrophil-type cells passaged compared to the non-differentiated cells; these results are consistent with previous literature. We also show differences in cell deformability due to cytoskeletal perturbing drugs. These results validate the feasibility of this technique for high throughput screening of cells based on their deformability, for example, against a library of drugs.