Ultrasound-mediated microbubble destruction enhances gene transfection in pancreatic cancer cells

Introduction: The purpose of this study was to determine whether ultrasound exposure combined with microbubble destruction could be used to enhance non-viral gene delivery in human pancreatic carcinoma cells (PANC-1). Methods: The study was performed with four experimental groups: Group P, plasmid alone; Group P+M, plasmid and microbubbles; Group P+U, plasmid and ultrasound; Group P+U+M, plasmid with ultrasound and microbubbles. Plasmid DNA encoding enhanced green fluorescent protein (pEGFP) was gently mixed with commercially available ultrasound microbubble contrast agents (SonoVue (R); Bracco Diagnostics Inc, Milan, Italy) in Group P+M and Group P+U+M. The different combinations of DNA and DNA plus microbubbles were added to cultured PANC-1 cells under different conditions. Transfection efficiency and cell viability were assessed by FACS analysis (Becton Dickinson, San Jose, CA, USA), confocal laser scanning microscopy, and trypan blue staining. Results: The results demonstrated that microbubbles with ultrasound exposure could significantly enhance the reporter gene expression as compared with other groups (Group P+U+M, 21.4%+/- 3.16%; Group P, 2.9%+/- 0.45%; Group P+M, 3.1%+/- 0.51%; Group P+U, 6.1%+/- 1.27%; P < 0.01). No statistically significant difference was observed in the PANC-1 cell viability between Group P+U+M and other groups (P > 0.05). Conclusions: Our in-vitro findings suggest that ultrasound-mediated microbubble destruction has the potential to promote efficient gene transfer into PANC-1 cells without significant cell death. This non-invasive gene transfer method may be a useful tool for safe clinical gene therapy of pancreatic cancer in the future.