A mechanical biomarker of cell state in medicine.

The mechanical properties of cells have been shown to be useful markers of cell state by the biophysics community. Here, I highlight clinical and research problems that this label-free, potentially inexpensive cellular biomarker can address and discuss technical challenges to realize automated instruments to achieve robust and high-throughput mechanical measurements. Important features found in traditional fluorescence-based flow cytometry that can enable cytometry based on mechanical properties (i.e., deformability cytometry) are emphasized, especially the need for throughput, simple operation, multidimensional data visualization, and internal controls. Next-generation approaches to automate deformability measurements of cells are surveyed, and future directions are outlined that promise to bring low-cost mechanical measurements to medicine and biological research.