1. ¹Department of Gene Therapy, National Heart and Lung Institute, Faculty of Medicine, Imperial College, London, UK
2. ²UK Cystic Fibrosis Gene Therapy Consortium, London, UK
3. ³Ultrasound Group, Imaging Sciences Department, MRC Clinical Sciences Centre, Faculty of Medicine, Imperial College, London, UK
4. ⁴School of Engineering, University of Cardiff, Cardiff, UK
5. ⁵Genzyme Corporation, Framingham, MA, USA

Correspondence: Dr U Griesenbach, Department of Gene Therapy, National Heart and Lung Institute, Imperial College, 1B Manresa Road, London SW3 6LR, UK. E-mail: u.griesenbach@imperial.ac.uk

Received 5 September 2006; Revised 21 December 2006; Accepted 21 December 2006; Published online 15 February 2007.

Abstract

We have assessed if high-frequency ultrasound (US) can enhance nonviral gene transfer to the mouse lung. Cationic lipid GL67/pDNA, polyethylenimine (PEI)/pDNA and naked plasmid DNA (pDNA) were delivered via intranasal instillation, mixed with Optison microbubbles, and the animals were then exposed to 1 MHz US. Addition of Optison alone significantly reduced the transfection efficiency of all three gene transfer agents. US exposure did not increase GL67/pDNA or PEI/pDNA gene transfer compared to Optison-treated animals. However, it increased naked pDNA transfection efficiency by approximately 15-fold compared to Optison-treated animals, suggesting that despite ultrasound being attenuated by air in the lung, sufficient energy penetrates the tissue to increase gene transfer. US-induced lung haemorrhage, assessed histologically, increased with prolonged US exposure. The left lung was more affected than the right and this was mirrored by a lesser increase in naked pDNA gene transfer, in the left lung. The positive effect of US was dependent on Optison, as in its absence US did not increase naked pDNA transfection efficiency. We have thus established proof of principle that US can increase nonviral gene transfer, in the air-filled murine lung.