Analysis and comparison of electrical pulse parameters for gene electrotransfer of two different cell lines.

Knowledge of the parameters which influence the efficiency of gene electrotransfer has importance for practical implementation of electrotransfection for gene therapy as well as for better understanding of the underlying mechanism. The focus of this study was to analyze the differences in gene electrotransfer and membrane electropermeabilization between plated cells and cells in a suspension in two different cell lines (CHO and B16F1). Furthermore, we determined the viability and critical induced transmembrane voltage (ITV(c)) for both cell lines. In plated cells we obtained relatively little difference in electropermeabilization and gene electrotransfection between CHO and B16F1 cells. However, significant differences between the two cell lines were observed in a suspension. CHO cells exhibited a much higher gene electrotransfection rate compared to B16F1 cells, whereas B16F1 cells reached maximum electropermeabilization at lower electric fields than CHO cells. Both in a suspension and on plated cells, CHO cells had a slightly better survival rate at higher electric fields than B16F1 cells. Calculation of ITV(c) in a suspension showed that, for both electropermeabilization and gene electrotransfection, CHO cells have lower ITV(c) than B16F1 cells. In all cases, ITV(c) for electropermeabilization was lower than ITV(c) for gene electrotransfer, which is in agreement with other studies. Our results show that there is a marked difference in the efficiency of gene electrotransfer between suspended and plated cells.