An electroporation system is used for nonviral delivery of genetic materials into the target tissues or cells via electric pulses.Scince 1982 electroporation has been routinely used in many laboratories for transfecting the genes of interest into cells to study the gene function because the gene transfer experiments by means of electroporation are simple and convenient.However the conventional electroporation methods are not necessarily satisfactory in terms of cell viability or transfection efficiency particularly for difficult-to-transfect cells in vitro such as primary neurons.Therefore the recent trend is that special electroporation buffer reagents are combined with electric pulses to improve transfection efficiency and viability.But the trouble is that those reagents are expensive and high running costs are requested for continuing transfection experiments.In addition, those additive can have unwanted effects on the cell and at least create another parameter which must be considered.Based on these backgrounds, Nepa Gene recently developed NEPA21, a novel electroporation system that can achieve high transfection efficiency and viability without a combination of special reagents for not only standard cell lines but also difficult-to-transfect cells including primary neurons.NEPA21 s 3-step multiple electric pulse wave pattern that is quite different from the other electroporators simple patterns is the key to this successful achievement.This transfection system can be used for not only cell suspensions but also cells (e.g.neurons) in adherent state in regular culture plates.Forthermore, it can be a highly effective tool for in-vivo gene transfection as well with the use of special electrodes designed for brain, retina, spinal cords, etc.Trasnfecting mouse/rat embryonic brains in utero via electroporation is one of the representative applications of the NEPA21.If it is better to study tissues (e.g.brain slices) outside of the organism, the tissues can be transferred ex vivo using this state-of-the-art system.