Glycerol enhancement of ligand-polylysine/DNA transfection

Primary human fibroblasts and a series of cell lines (A549, BNL, CL.2, H225, NIH 3T3 and Rat-1) are efficiently transfected by using positively charged complexes of plasmid DNA and transferrin-polylysine or polylysine in the presence of glycerol (1 molar to 1.8 molar, depending on the cell type). An increase in gene expression of up to several-hundredfold (compared to complexes without glycerol) is obtained if the transfection mixture is incubated with the cells for 3-4 h at 37 degrees C. This simple method has been used for transient expression of luciferase, beta-galactosidase and interleukin-2, and also for the generation of stably transfected cells.