Identification and Optimization of Influencing Factors on Polyethylenimine Transfection Efficiency

Polyethylenimine(PEI) polycation can condense DNA into granules of around nanometer size. which can be used for delivering gene into mammalian cells. This paper studied the influencing factors on polyethylenimine ( M r 25?000, branched) gene delivery efficiency in order to develop a more complicated nonviral gene delivery vector. \%In vitro\% cytotoxic effects of polyethylenimine were quantified by MTT assay.When polyethylenimine incubated with the cells for 24 hours, the survival rate of COS\|7 cells was 80% with 6 μg/ml of polyethylenimine,64% with 7 μg/ml.40% with 8 μg/ml. Gel electrophoresis retardation assays showed that PEI completely retarded DNA migration at 3 0 polyethylenimine nitrogen per DNA phosphate. Chloroquine enhanced the transfection efficiency of polyethylenimine. Bovine serum albumin and bovine serum in the culture medium decreased the transfection efficiency. The transfection efficiency of PEI/DNA diluted with 0 9% NaCl was higher than that with 5% glucose. After adding PEI/DNA complex, level shake (≤30 min) of culture plates improved the transfection efficiency. Polyethylenimine was an efficient gene transfection agent of eukaryotes in vitro, and could be used for synthesizing more complicated gene delivery carriers for in vivo gene therapy.