Atomic force microscopy of 3T3 and SW-13 cell lines: an investigation of cell elasticity changes due to fixation.

Mechanical properties of single cells are of increasing interest both from a fundamental cell biological perspective and in the context of disease diagnostics. In this respect, atomic force microscopy (AFM) has become a powerful tool for imaging and assessing mechanical properties of biological samples. However, while these tests are typically carried out on chemically fixed cells, the most important data is that on living cells. The present study applies AFM technique to assess the Young's modulus of two cell lines: mouse embryonic fibroblasts (NIH/3T3) and human epithelial cancer cells (SW-13). Both living cells and those fixed with paraformaldehyde were investigated. This analysis quantifies the difference between Young's modulus for these two conditions and provides a coefficient to relate them. Knowing the relation between Young's modulus of living and fixed cells, allows carrying out and comparing data obtained during steady-state measurements on fixed cells that are more frequently available in the clinical and research settings and simpler to maintain and probe.