Electropermeabilization of cells in tissues assessed by the qualitative and quantitative electroloading of bleomycin

Using cells in suspension, electropermeabilization is a technique extensively used to transfect living cells or to introduce a variety of compounds inside the cells. Here we demonstrate the reality of the tissue electropermeabilization using qualitative and quantitative determinations of the electroloading of bleomycin considered as an nonpermeant molecule that serves as an indicator of the permeabilization. In tissues, cell electropermeabilization is achieved for electric field intensities lower than those necessary to permeabilize the same cells in suspension. We also emphasize the importance of the geometry of the electric field lines defined by the electrodes for permeabilizing a whole tissue, for example a tumor.