Objective: To investigate the feasibility of ultrasound (US) mediated enhanced green fluorescent protein (EGFP) gene delivery in subcutaneous transplanted tumors of human cervical carcinoma (Hela) and the contribution of lipid shell microbubble (LSMB) on gene transfection. Methods: LSMB and plasmid were injected into nude mice by tail vein followed local US irradiation (P + LSMB + US group). US exposure parameter was set at 2.0 W/cm2, 2 min, duty cycle 20%. EGFP expression was evaluated by imaging for 7 days. Nude mice undergoing plasmid injection alone (P group), plasmid injection and US exposure (P + US group), plasmid and LSMB injection (P + LSMB group) were used as controls. Frozen section and histological examinations were conducted. Expression of EGFP was scored. Kinetics of protein expression post transfection and localization in vivo were evaluated. Results: Plasmid injection with LSMB plus US exposure strongly increased gene transfer efficiency. Strong EGFP expression was mainly seen in LSMB + P + US group. It was significantly higher than any of the following groups, P group, US + P group, or LSMB + P group (P < 0.01). In vivo expression level of post-US 3 days was significantly higher than any other time points (P < 0.01). There was not significant expression level of EGFP in other organs or tissues regardless of US exposure. No tissue damage was seen histologically. Conclusion: The combination of LSMB and US exposure could effectively transfer plasmid DNA to transplanted tumors without causing any apparently adverse effect. LSMB could be effective as a non-viral vector system in in vivo gene delivery. It would be a safe gene delivery method and provide an alternative to current clinical gene therapy.
Zhiyi Chen, Mingxing Xie, Xinfang Wang, Qing Lv, Shangwei Ding Department of Ultrasonography, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology
