RESUMEN
This study inquired about the influences on the gene delivery efficiency of polyethylenimine. pSVbeta plasmids were transferred into COS-7 and NIH3T3 cells with polyethylenimine. Influences of plasmids factor, albumin, serum, cell density, operation methods and polyethylenimine/DNA preserve factors on transfection efficiency were investigated. Inhibitors of biological activities in plasmids could be removed by ultrafiltration with cutoff molecular weight of 3000 or 10000. Linear plasmids lowered transfection efficiency. Serum and albumin in the culture medium decreased the transfection efficiency of polyethylenimine/DNA. Cell density was associated with PEI/DNA transfection efficiency. Incubation of PEI/DNA complexes with the cells for 8 h and then aspiration for removal of the complexes could obtain an optimal transfection effect. Freezing of PEI/DNA complexes significantly decreased transfection efficiency. In conclusion, polyethylenimine could obtain optimal and reduplicate transfection results by controlling related factors.