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March 19, 2008

More precise and safe gene therapy is highly promising

A way to carry out genetic surgery [more precise gene therapy] has been devised by a British Nobel prizewinner that is already under test on diabetic patients and being readied for use to treat Aids, blocked blood vessels and chronic pain. Safety and precision problems and concerns have been holding back wider use of gene therapy. If gene therapy were completely safe and precise, then many like gene therapy pioneer H. Lee Sweeney would switch to recommending treatments like myostatin inhibitors for increasing muscle mass by up to 4 times because they would make people healthier.

Sir Aaron Klug, a Nobel laureate working at the Medical Research Council's Laboratory of Molecular Biology in Cambridge, has developed a more efficient way to target genes, so gene therapy can be done with surgical precision. They have modified a piece of natural cellular machinery called "zinc fingers".

They have devised synthetic versions, called zinc-fingered nucleases, which have the capacity to recognise specific sequences of DNA which makes them extremely good at latching on to a specific spot, targeting particular genes without affecting others, so they can carry out genetic surgery to knock out genes or introduce new ones.

The new method is already being tested on more than 100 young diabetic patients who have lost sensation, a common complication, by the Californian company Sangamo BioSciences, after encouraging results in preliminary tests of the method to introduce a gene encoding a growth factor that can help restore sensation.



Sir Aaron explains: "The beauty of zinc-finger nucleases lies in their simplicity. Where other methods are long, arduous and often messy, it is relatively easy to switch off genes using this method.

"The zinc-finger design allows us to target a single gene, while the nuclease disrupts the gene. The single step process is extremely quick and reliable and opens up exciting possibilities for research and gene therapy."


FURTHER READING
BBC news also has coverage

Animal trials are already under way to use the technique to knock out the receptor of HIV in immune system T-cells of patients with Aids.

If successful this will render the T-cells immune from HIV infection, and enable them to fight disease.

Clinical trials to aid patients with blocked blood vessels are also under way.



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