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