Molecular Genetic Applications of Electroporation

Abstract

Both academic and industrial applications of molecular biology depend on being able to efficiently express cloned genes in various eukaryotic cells. The traditional method of gene transfer, by uptake of calcium phosphate/DNA coprecipitates (Graham and Van der Eb, 1973), works well with fibroblasts but has proved difficult to apply to other differentiated mammalian cell types such as lymphocytes or neuronal cells, and is completely unsuited to plant cells or parasites. The solution to this problem has been provided by a completely new approach—electroporation. In studying the effect of high-voltage electric discharges on biological membranes, it was discovered that such shocks could induce cells to fuse via their plasma membranes, apparently by creating holes or pores in the cell membrane (Zimmermann et al., 1976; Senda et al., 1979; Scheurich et al., 1980; Neumann et al., 1980; for review, see Zimmermann and Vienken, 1982). Neumann and his colleagues (Neumann et al., 1982; Wong and Neumann, 1982) then found that mouse fibroblasts (L cells) take up and express exogenous DNA when subjected to electric shock. However, because L cells are easily made to take up DNA by traditional methods, it was not clear that the procedure could be applied to any other type of cell. We extended and modified electroporation (Potter et al., 1984) to allow the introduction of exogenous DNA into a broad spectrum of cell types, including neuronal cells, endocrine cells, primary animal cells, hepatoma cells, hematopoietic stem cells, and plant protoplasts (Fromm et al., 1985; Igarashi et al., 1986; Potter and Montminy, 1986; Montminy et al., 1986; Ou-Lee et al., 1986; Sureau et al., 1986; Toneguzzo et al., 1986; Potter, 1987). Electroporation yields a high frequency of permanent transfectants, has a high efficiency of transient gene expression, and is substantially easier to carry out than alternative techniques. Thus, for various reasons electroporation is becoming increasingly popular. Indeed, in the last few years, electroporation has moved out of a few developmental laboratories to become the method of choice for gene transfer in many situations (Fig. 1).