Impedance spectroscopy applied to the fast wounding dynamics of an electrical wound-healing assay in mammalian cells

Electrical wound-healing assays are often used as a means to study in vitro cell migration and proliferation. In such analysis, a cell monolayer that sits on a small electrode is electrically wounded and its spectral impedance is then continuously measured in order to monitor the healing process. The relatively slow dynamics of the cell healing have been extensively studied, while those of the much faster wounding phase have not yet been investigated. An analysis of the electrical properties of a particular cell type during this phase could give extra information about the changes in the cell membrane due to the application of the wounding current, and could also be useful to optimize the wounding regime for different cell types. The main issue when trying to register information about these dynamics is that the traditional measurement scheme employed in typical wound-healing assays doesn't allow the simultaneous application of the wounding signal and measurement of the system's impedance. In this paper, we overcome this limitation by implementing a measurement strategy consisting of cycles of fast alternating low- and high-voltage signals applied on electrodes covered with mammalian cells. This approach is capable of registering the fast impedance changes during the transient regime corresponding to the cell wounding process. Furthermore, these quasi-simultaneous high- and low-voltage measurements can be compared in order to obtain an empirical correlation between both quantities.