Prawn cells bombarded with particles containing DNA from the green fluorescent jellyfish protein gene.
Dr Bin Wang and Professor Steve Reid.
Professor David Garrod.
University of Manchester.
Professor Robert Newbold.
Professor Tet Fatt Chia.
Nanyang Technological University, Singapore.
Small DNA-coated particles of gold, or another inert metal, can easily penetrate cell membranes. Once in the cell the DNA disassociates from the micrometre-sized metal particle (a micrometre is one ten thousandth of a centimetre) and can express its genes. This approach to gene transfer technology is well known and is capable of delivering genes to cells to replace absent or defective genes. It could be an effective therapy against cancer. But how can one deliver the particles in a targeted manner without disrupting surrounding tissue?
The answer is a gun - but no ordinary gun. Original experiments with 'gene guns' in plants used gunpowder acceleration for the particles, but this 'shotgun' approach was not appropriate for animal or human use due to contamination issues. Gas acceleration using helium as the propellant was another approach. However, the gas blast causes a shock wave that can produce extensive damage to delicate cells on the surface of the target organ, restricting the technique to external use in humans.
Now a third generation of gene gun has been developed, which uses electromagnetic forces to propel the particles. 'The new design is the result of an interdisciplinary approach to the problem', says Bin Wang, a mechanical engineer who has worked with colleagues in the biological sciences to develop the device. 'The ""coil gun""can generate a controlled high delivery speed for the gene therapy particles but without the shock wave associated with other technologies.'
The compact nature of the gene gun means that it has the potential to be developed into an endoscope type of unit for gene and other drug delivery, as part of the suite of 'key-hole' technologies in clinical practice. It also allows an extension of the gene gun technique to blood research and other applications beyond solid tissue targets that could not be considered previously.
The advantages of the gene gun approach to cancer therapy include an alternative delivery system for genes in place of complex biological systems (such as viruses), no use of toxic chemotherapy, cell-receptor-independent delivery, the ability to deliver different sizes of DNA fragments (including very lar