Quantitative rheological measurements of confluent cell using atomic force microscopy

Rheological properties of cells are associated with various cell functions and thus are considered to be an indicator for diagnosing cell disease. Atomic force microscopy (AFM) is a powerful tool for quantifying the mechanical properties of isolated single cells. For example, our AFM technique reported previously revealed that the complex shear modulus of single cells exhibited a large cell-to-cell variation which depended on frequency. By contrast, rheological properties of cell population such as cells in confluent condition have been less understood. Thus, it is valuable to investigate how quantitatively the AFM technique can be applied to cell population such as cells in confluent condition. As a result, rheological properties of cells in confluent conditions can be relatively rapidly measured by our AFM setup modifying a force modulation AFM mode. This suggests that the AFM technique is useful for diagnosing not only single cells but also cell population and cell assembly.