Experimental study of enhanced gene delivery to cultured tumor cells in vitro by ultrasound and contrast agent
RAN Hai-tao~1, REN Hong~2, WANG Zhi-gang~(1*), ZHENG Yuan-yi~1, ZHANG Qun-xia~1, XU Chuan-shan~1 (1.Institute of Ultrasonic Image, Chongqing University of Medical Sciences, Chongqing 400010, China; 2.Institute of Viral Hepatitis of Chongqing Medical University, Chongqing 400010, China)
Objective To investigate whether ultrasound mediated microbubbles destruction could enhance the gene transfection in cultured tumor cells in vitro. Methods Cultured HepG2 cells were devided into three groups. Group 1 was taken as simple microbubble transfection group: a mixture of microbubbles and P~(EGFP) plasmid (5 μg) was added to the cells; Group 2 was taken as liposome transfection group: 5 μg plasmid was used for liposome transfection as normal. Group 3 was taken as ultrasound irradiation plus microbubble group: after added a mixture of microbubbles and plasmid to the cells, ultrasound with the intensity of 0.25 W/cm~2, 0.5 W/cm~2, 1.0 W/cm~2 was applied under the bottom of the plate for 10 s. Twenty-four hours later, the expression of GFP in the cells was observed by fluorescence microscope, the numbers of positive expression cells in every high power field (×400) were counted. Results There was no positive expression cell in Group 1; there were different quantity of positive expression cells in Group 3. The highest GFP expression was seen in the group in which ultrasound with intensity of 0.5 W/cm~2 was applied. The mean number of positive expression cells under each high power field were (20.7±3.2)/HP, higher than that in other subgroup (0.25 W/cm~2 or 1.0 W/cm~2) of Group 3, and there was no significant difference compared to Group 2 (P0.05). Conclusion Ultrasound and microbubbles could highly enhance the gene transfection to tumor cells in vitro. The condition of ultrasound irradiation was a important factor for gene transfection. There was no significant difference between the suitable ultrasound energy and liposome transfection method.