Slice of human dermal tissue is positioned between electrodes connected to a generator

Injecting the surface of a small slice of human dermal tissue with a GFP-expressing plasmid (Green Fluorescent Protein, a protein that emits fluorescent green light). This tissue is a dermal substitute engineered from cells taken during a skin biopsy. The tissue was positioned between electrodes connected to a generator which transmitted electrical impulses with known parameters. These pulses induced a transitory permeabilisation of the membranes of the tissue cells and enabled the GFP-expressing plasmid to penetrate the cells. After 24 or 48 hours, the tissue was examined by multiphoton microscope in order to locate and quantify the amount of GFP-expressing cells. This experiment enabled us to obtain in vitro rates of transfection comparable to those obtained in vivo. It thus proved possible to create a substitute for human skin in vitro, i.e. a dermal model that can be used in the laboratory. This will allow us to limit the number of in vivo tests on animal models.