ULTRASOUND ENHANCES GENE-EXPRESSION OF LIPOSOMAL TRANSFECTION

RATIONALE AND OBJECTIVES. Cationic liposomes are under development as delivery agents for gene therapy. The authors studied the effect of ul trasound on gene expression in cell cultures during liposomal transfec tion experiments. METHODS. Cationic liposomes of dipalmitoylethylphosp hocholine and dioleoylphosphatidylethanolamine were used to transfect cultured HeLa, NIH/3T3, and C127I cells with the chloramphenicol acety l transferase (CAT) gene, A cell viability assay was performed on cult ured HeLa cells that were exposed to varying durations (5 seconds or 3 0 seconds) and intensities of 1 MHz continuous-wave therapeutic ultras ound after transfection, and gene expression was measured 48 hours lat er. RESULTS. Cells survived 30 seconds or less at a power level of 0.5 watts/cm(2) but died when exposed for 60 seconds or longer. Exposures of 5 seconds and 30 seconds of ultrasound resulted in significant inc reases in gene expression in all three cell types tested in this exper iment, CONCLUSIONS. Relatively low levels of ultrasound energy can be used to enhance gene expression from liposomal transfection, Additiona l experiments are needed to optimize this process and clarify the mech anisms involved.