Electrochemical synchronization of cell spreading on solid surfaces

Cell synchronization is important for the analysis of molecular events involved in cell spreading and motility. Electrostatic interactions between cells and surfaces were investigated in order to synchronize the first step in cell adhesion. LimE- GFP marked Dictyostelium discoideum cells were used for fluorescent tracking of actin polymerization events. Oscillating LimE fluorescent peaks were observed for individual cells in standard phosphate buffer during spreading. At low ionic concentration (phosphate sucrose buffer 0.17 mM), cells levitate over the conductive surfaces (Indium Tin Oxide, ITO) due to electrostatic repulsion. An electrochemical device was designed in order to apply an overpotential pulse (+2.5 V/Ag,AgCl) during 0.1 s to the ITO surface. In these conditions, protons are produced by water oxidation, which reduce the ITO negative surface charge and thus, attracting the levitating cells simultaneously. Consequently, these irreversible contacts with the surface triggered the onset of cell spreading. Therefore, we obtained synchronization of the spreading of a cell population for the first time thanks to an electrochemical method.