Yunchao Chen, Abstract Co-Author: Nothing to Disclose

Hai-Dong Liang PhD, Presenter: Nothing to Disclose

Qing-ping Zhang, Abstract Co-Author: Nothing to Disclose

Martin John Blomley MD, Abstract Co-Author: Nothing to Disclose

Qi-long Lu PHD, Abstract Co-Author: Nothing to Disclose

Ultrasound shows promise as a physical delivery system in gene therapy. We have investigated the low-frequency therapeutic ultrasound system to observe its functions in gene delivery in vitro

Therapeutic ultrasound（US）parameters: 1MHz, 0.5-3W cm-2, 20% duty cycle). Plasmid encoding green fluorescent protein (pEGFP) was used as a reporter. Transfection rates and cell viability were assessed by fluorescent microscopy, FACS and trypan blue exclusion. We exposed ultrasound with varying intensity and duration to evaluate their effect on cell viability and transfection efficiency in three cell lines (C2C12,3T3-MDEI and CHO）. We also added ultrasound contrast agent, Optison（10%）, to observe its function in ultrasound induced gene transfection. Experiments were performed in triplicate.

1. As the ultrasound intensity and the exposure time increasing, the cell transfection rate increased and the cell viability decreased, but at high power (high intensity and long exposure time), the cell viability decreased dramatically which induced the cell transfection rate decrease as well. The most efficiency ultrasound power to induce gene transfer was 1 W cm-2 with duration of 20 s, which produced about 12% cell transfection rate and 60% cell viability; 2. In the same power intensity, different intensity induced different cell gene transfer rate and viability. Higher ultrasound intensity met its maximum gene transfer rate first and had higher cell toxicity as well. 3. Microbubbles (10%Optison) could increase ultrasound induced cell gene transfer rate about 2 times mainly in lower power intensities. Moreover, MB could raise the maximum gene transfer rate mediated by US, but decreased cell viability as well.

Therapeutic ultrasound can induce cell gene transfer. The cellular gene transfer rate and viability relate with not only the ultrasound power intensity but also the power combinations that the higher ultrasound intensity achieve its maximum transfer rate first and the most efficiency ultrasound power to induce gene transfer is 1 W cm-2 20 s, whilst the microbubbles can significantly increase its maximum gene transfer rate in vitro.

Chen, Y, Liang, H, Zhang, Q, Blomley, M, Lu, Q, Ultrasound with Microbubbles: Their Functions in Gene Transfer in Vitro.  Radiological Society of North America 2005 Scientific Assembly and Annual Meeting, November 27 - December 2, 2005 ,Chicago IL. http://archive.rsna.org/2005/4414099.html