The optimization of parameters on DNA transfection in MCF-7 cancer cells combining ultrasound with polyethyleneimine / 中华超声影像学杂志

ABSTRACT

Objective To study the optimized condition of transfection efficiency for MCF-7 cells enhanced by ultrasound(US) irradiation and contrast agent combined with polyethyleneimine(PEI) and observe whether the combination can have a synergistic effect to increase DNA transfection. Methods MCF-7 cells were transfected with the compounds prepared by the vector of plasmid DNA encoding luciferase (pCMV-luciferase-GL3) and PEI.SonoVue microbubble was added to the cell suspension to serve as nucleation sites for aeoustic cavitation before US irradiation. The DNA expression of luciferase plasmid and viability of cells were evaluated. The strategy of US irradiation was optimized. Furthermore, the influencing factor, such as the concentration of plasmid, incubation time, serum, the type of solvent and the volume of culture media, were examined. Results The viability of cells and US-induced enhancement of luciferase activity were influenced by the US intensity,exposure time and duty cycle.US irradiation under an appropriate condition enables ceils to accelerate the permeation of the PEI/DNA complex through the cell membrane, resulted in enhanced transfection efficiency of plasmid DNA. Optimal US condition for the enhancement was determined to be 1 W/cm2,10% DC for 3 min. In contrast to the PEI/DNA complex alone without US irradiation or US irradiation alone, the combination of US irradiation with contrast agent and PEI had a significantly enhanced luciferase activity (P<0.01). The 2 h pre-irradiation incubation with PEI/DNA complex for MCF-7 ceils exhibited a significantly enhanced lueiferase activity (P<0.01). Besides,serum,type of solvent and the volume of culture media did affect the transfection efficiency. Conclusions The optimized parameters of US and transfection provide efficient gene delivery in MCF-7 cancer cells. The combination of US irradiation with contrast agent and PEI has a synergistic effect to increase DNA transfection. This is a simple and promising method to enhance the gene expression of plasmid DNA.