Advances in gene therapy research

Researchers gathered at the American Society of Gene Therapy meeting in Minneapolis, Minnesota last week, to hear about new approaches and techniques in this promising area of medicine. A new type of gene therapy, involving injections of 'naked DNA' generated much excitement, when University of Wisconsin scientists presented their experiments in mice. Other researchers reported successfully treating animals affected by spinocereballa ataxia type 1 (SCA1), an inherited brain disorder. Meanwhile, in the UK, biotech company Oxford Biomedica is launching the world's first gene therapy trial to treat pancreatic cancer.

The Wisconsin team has developed a new way to get therapeutic genes into the tissues where they are needed, without the use of viruses. Instead, they inject naked DNA - DNA that is not coated in proteins or any other substance - directly into the muscle or blood vessels. It is thought to be safer than using a virus to deliver DNA, which can potentially trigger an immune system response in the body. The researchers tested the approach by injecting many copies of a 'reporter' gene directly into the limb veins of laboratory animals. They found that the genes spread throughout the muscle cells, where they were switched on, enabling them to make the test protein.

The scientists say their method is a clinically viable, safe and effective way of delivering genes to muscle cells, and hope that the next step will be a clinical trial in humans. 'I think this is going to change everything relating to gene therapy for muscle problems and other disorders', said team member Jon Wolff.

Other researchers, based at the University of Iowa, used a technique called RNAi (RNA interference), to see if they could 'silence' the defective gene that causes SCA1. They found that animals bred to have the neurodegenerative disease improved when treated with RNA molecules designed to block the gene's activity. They say that their findings provide hope for other brain disorders caused by genes that make a toxic protein, for example Huntington's disease.

In the UK, Oxford Biomedica is to start a gene therapy trial for pancreatic cancer, using a 'Trojan Horse' treatment called MetXia. It consists of a virus, which contains a gene that triggers the conversion of an inactive cancer drug into an active one. It should mean that the drug will only target tumour cells, where the gene treatment is delivered, and not harm healthy tissues. The company will initially recruit nine patients, for a 'proof of principle' trial, New Scientist magazine reports.