Physical parameters affecting ultrasound/microbubble-mediated gene delivery efficiency in vitro

Gene therapy progress and prospects: Ultrasound for gene transfer

“…The development of ultrasound enhanced gene transfer (UEGT) began when a number of research groups speculated that the physical perturbations induced by an ultrasound beam would encourage plasmid DNA uptake and transgene expression. Although the early results were at best modest, achieving 10-to 30-fold increases in transfection efficiency in vitro, technical refinements have meant that enhancements of up to several thousand fold in vitro are now being observed, [1][2][3][4][5][6][7][8][9] sufficient to encourage studies of UEGT in vivo.…”

Microvascular free tissue transfer for gene delivery: in vivo evaluation of different routes of plasmid and adenoviral delivery

“…[29][30][31] Briefly, signal from a waveform generator (model 33220A, Agilent Technologies Inc., Loveland, CO, USA) was fed into an RF power amplifier (58 dB gain, model BT00500 BETA, Tomco Technologies, Norwood, Australia) and thence to a custom-made 1 MHz ultrasound transducer (Imasonics, Besancon, France). The transducer was spherically focused, of 20 mm diameter and 68% bandwidth, with the focal point of the ultrasound beam 67 mm from the transducer face.…”

“…Dosimetry of the 1 MHz transducer in its focal plane has been previously described. 29,30 To expose the tissue flap at the focal distance, a cylindrical perspex 'stand-off' was made to fit around the transducer: a layer of cling-film was used to retain a column of water in this tube through which the ultrasound was transmitted. The internal diameter of 38 mm was such that there was negligible disturbance of the acoustic field at the focal distance (that is, at the end of the tube).…”

“…The latter was used to prevent reflections and standing wave generation leading to unquantifiable exposure conditions; the effectiveness of this material in eradicating reflections has been demonstrated. 29,30 Before exposure of the tissue flap to ultrasound, a total volume of 0.4 ml of 0.9% (w/v) sodium chloride containing 50 mg p.Luc and 4% (v/v) SonoVue microbubbles (Bracco, High Wycombe, UK) was injected into the tissue flap through the cannulated artery. A further 0.6 ml 0.9% (w/v) sodium chloride was injected and the artery was clamped.…”

Ultrasound assisted particle and cell manipulation on-chip

“…Microbubbles can be used to generate transient porosity in cells and vasculature at diagnostic ultrasound intensities to facilitate drug and gene delivery both in vitro and in vivo [115,116]. It is generally considered that both stable and inertial cavitation lead to the generation of bio-effects which either mechanically rupture the phospholipid structure of the cell membrane or disrupt/invoke cell-regulated pathways.…”