Cell poration and cell fusion using an oscillating electric field.

It has been shown in previous studies that cell poration (i.e., reversible permeabilization of cell membrane) and cell fusion can be induced by applying a pulse (or pulses) of high-intensity DC (direct current) electric field. Recently we suggested that such electro-poration or electro-fusion can also be accomplished by using an oscillating electric field. The DC field relies solely on the dielectric breakdown of the cell membrane to induce cell fusion. The oscillating field, on the other hand, can produce not only a dielectric breakdown, but also a sonicating motion in the membrane that could result in a structural fatigue. Thus, a combination of a DC field and an oscillating field is expected to enhance the efficiency of cell poration and cell fusion. This study is an experimental test of such an idea. Here, pulses of high-intensity, DC-shifted RF (radio frequency) electric field were used to induce cell poration and cell fusion. The fusion experiments were done on human red blood cells. The poration experiments were done on a fibroblast cell line using a molecular probe (which is a DNA plasmid containing the marker gene chloramphenicol acetyltransferase, CAT) and assayed by a gene transfection technique. It was found that the pulsed RF field is highly efficient in both cell fusion and cell poration. Also, in comparison with electro-poration using a DC field, the RF field results in a higher percentage of cells surviving the exposure to the electric field.