Mechanical properties of HeLa cells at different stages of cell cycle by time-resolved acoustic microscope

Abstract

Scanning acoustic microscopy (SAM), particularly time-resolved acoustic microscopy, is one of the few techniques for study of the mechanical properties of only the cell’s interior, cytosol and nucleus. Unfortunately, time-resolved acoustic microscopes typically do not provide sufficient resolution to study the elasticity of single cells. We demonstrate that the high-frequency, time-resolved acoustic microscope developed at the Fraunhofer Institute for Biomedical Technology (IBMT), Germany, is capable of imaging and characterizing elastic properties of micron size structures in cell’s cytoskeleton with a theoretical resolution limit of 10 m/s for sound speed measurements. Measurements were performed on cells of the HeLa cell line derived from human cervics carcinoma. SAM measurements of the sound speed of adherent HeLa cells at different states of the cell cycle were conducted. They yielded an average value of 1540 m/s. B-Scan images of HeLa cells at different states of the cell cycle show distinct patterns inside the cell. A method for estimating sound attenuation inside HeLa cells is outlined as such a method is critical for the determination of a cell’s viscoelasticity. [Work supported by Alexander von Humboldt Foundation and the European Framework Program 6, Project ‘‘CellProm.’’]