gene therapy and viral vector delivery

An interesting heads up article on gene therapy and importantly the improvement in the viral vectors used to deliver it. It is viral vectors that are ddRNAi's all important delivery issue, just as synthetic siRNA's have started overcoming theirs (but with much more publicity).

"The doctors said 'you need to prepare yourself for the fact that Nina probably isn't going to survive'," says Graeme.

A year-and-a-half later, Nina is a happy little girl with a functioning immune system. She has gene therapy – and its latest improvements – to thank for it.

SCID was the first condition to be treated with gene therapy more than 20 years ago. A virus was used to replace a faulty gene with a healthy one. But in subsequent trials, four young patients were diagnosed with leukaemia two years after receiving a similar treatment. An 18-year-old also died following a reaction to a virus used in gene therapy for a liver condition. It was the start of a rocky road (see "Trials and tribulations of gene therapy").

Gene therapy has come a long way since, and Nina's case, along with others, mark a turning point: researchers seem to have found a safer way of manipulating our genes.


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Viruses are the obvious choice as they survive and spread by inserting their genes into the host's genome. Retroviruses work like this, so were the first choice for the initial gene therapy trials. The problem is that they insert genes at random locations in the genome, as well as inserting regulatory sequences that can sometimes activate nearby genes and trigger cancer.

To overcome this, researchers have turned to lentiviruses. These still insert genes randomly, but can be modified to disable some regulatory sequences. "The new generation of lentiviral vectors is much safer, although the risk is not zero," says Patrick Aubourg at the French National Institute of Health and Medical Research in Paris.

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In Madrid last week, Amit Nathwani of the Royal Free NHS Trust in London announced that six people treated for haemophilia using AAV in early 2011 are still producing the blood clotting factor they previously lacked.
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http://www.newscientist.com/article/mg22029413.200-bubble-kid-success-puts-gene-therapy-back-on-track.html?page=2