EXPERIMENTAL PARAMETERS TO STUDY CELL STIFFNESS AND CELL ADHESION USING ATOMIC FORCE MICROSCOPY

Biomechanical properties of cells and tissues determine diverse cellular function. It is essential to have methodologies that precisely measure those properties in order to study the contribution of mechanical parameters in cell response. The advance of Atomic Force Microscopy (AFM), traditionally used in material sciences, is allowing to perform the measurements of biological samples. Live cells are maintained in culture medium under controlled temperature, and measurements are performed applying very precise force. Cell stiffness measurements are obtained in the pulsed force operation mode, where a force-distance (FD) curve is performed for each pixel of the scanning area. The slope of the FD curve determines the cell stiffness where the Young's Modulus is estimated considering the shape of the cantilever tip and the cell indentation. The scanning of the whole cell provides information of height and rigidity, generating a topographic map associated with stiffness map. For cell adhesion experiments, it was used a spherical AFM tip functionalized with fibronectin. The force of the interaction of the functionalized tip with the cell is calculated after 2 minutes of contact. The tip retraction of the FD curve is evaluated to determine cell adhesion. All together, we established the parameters for AFM measurement of stiffness and cell adhesion. This information is essential to understand cell biomechanics, which has been shown to be important in different physiological and pathophysiological situations.