21.11.2016; Kolloquium
Seminar “Measurement Systems”
Feeling for Function: Real-Time Deformability Cytometry for Label-Free Cell Functional Assays
The mechanical properties of cells have long been considered as a label-free, inherent marker of biological function in health and disease. Wide-spread utilization has so far been impeded by the lack of a convenient measurement technique with sufficient throughput, sensitive to cytoskeletal changes. Our new method, real-time deformability cytometry (RT-DC), probes cell stiffness at rates of several 100 cells per second by exposing them to a shear flow in a microfluidic channel al-lowing for mechanical phenotyping based on single cell deformability. However, in RT-DC, cell deformation is not only de-termined by cell stiffness, but also depends on flow speed and cell size relative to channel size. We disentangle mutual con-tributions of cell size, flow speed and cell stiffness to cell deformation by a theoretical analysis in terms of hydrodynamics and linear elasticity theory. Performing RT-DC experiments on both, model spheres of known elasticity and biological cells, we demonstrate that our analytical model does not only predict cell deformation inside the channel but also allows for quantification of cell mechanical parameters. Finally, we perform RT-DC on whole blood and highlight its potential to iden-tify subsets in heterogeneous cell populations without any labelling or extensive sample preparation.