Gene transfer into mammalian cells by rapid freezing.

In this paper, we describe a simple technique to introduce DNA into cells through cracks and/or pores in cell membranes caused by intracellular ice crystal formation induced by liquid nitrogen. We mixed mouse BALB 3T3 cells and pSV2-neo DNA and froze the cell suspension under various conditions to determine those optimum for the introduction of DNA into mammalian cells. We found that brief treatment with liquid nitrogen, which showed only moderate cell killing, resulted in the induction of G-418 resistant colonies. These results suggest that this new technique is useful for transfection of genes into mammalian cells.