ИСТИНА

The mechanical properties of cells are responsible for maintaining the shape of the cells, their mobility and response on various biophysical and biochemical impacts. Cell stiffness often is used as a biomarker for cancer cells identification, as they are softer than healthy ones. The higher elasticity and less adhesiveness of cancer cells increases their mobility and the deformation ability, as well it helps them to migrate during metastases. Thus, there is a certain correlation between rigidity and mobility: the softer the cell, the more mobile it is. The stiffness of cells depends on the reorganization of the cytoskeleton, including intermediate filaments, such as vimentin, which maintains cellular integrity and ensures cell resistance to stress. Measurement of the stiffness (Young's modulus) of cells is carried out using an atomic force microscope. Usually, the cells are located either as monolayer or as single rounded cells on the flat substrate and are pushed by modified probes, which have microsphere shapes. In order to measure the stiffness at the leading edge of the cell, special lavsan substrates, coated with thermoplastic and with grooves at a frequency of 1.6 μm and a depth of 350 nm, were used. On these substrates the cells grow predominantly elongated along the grooves with a well­identifiable leading edge. Unlike measurement on a flat surface, it was obvious that in the case of substrates with grooves, their relief can affect the results of measuring the stiffness of cells. In this connection, additional experiments were carried out, which showed that the variations of the relief do not affect the measured Young's modulus. Thus, the developed approach makes it possible to measure the rigidity of cells precisely at the leading edge. In the course of further experiments, the stiffness of rat and mouse fibroblasts with mutant vimentin, unmutant vimentin and its absence was investigated. The work was supported by a grant from the RSF (14­14­00234).