Gene therapy strengthens rat muscles

Rats injected with a gene that promotes tissue growth develop stronger muscles after regular exercise, according to research presented at the annual meeting of the American Association for the Advancement of Science (AAAS) in Seattle. Scientists based at the University of Pennsylvania in Philadelphia, US, are hoping to develop new treatments for muscle-wasting diseases, but the study has also prompted speculation that such techniques could be used by athletes to enhance their performance. Team leader Lee Sweeney said that the prospects 'are especially high' that athletes would use muscle-directed gene therapy, 'in the same way that many drugs are used and abused today'.

The researchers used a virus to deliver a therapeutic gene to one of the hind legs of the rats, where it triggered production of a growth-promoting protein called IGF-1. The scientists then subjected the rats to an intensive regime of ladder-climbing, and found that the treated leg muscles became 15-30 per cent stronger than the untreated muscles. The treated legs also kept more of their muscle strength after the rats had stopped exercising, say the team, who will publish the study in the Journal of Applied Physiology next month. The results are promising for research into treatments for inherited muscle-wasting conditions such as muscular dystrophy, or for muscle loss due to ageing or disuse. But Sweeney said that since the beneficial effects were seen in young animals, as well as old animals and those with muscle disease, it could also be used to enhance normal muscle performance.

Dick Pound, chairman of the World Anti-Doping Agency (WADA) said that the prospect of 'gene-doping' in sport could be realistic by the 2012 Olympic Games. The world anti-doping code already bans the practice of gene transfer technology, and WADA is apparently working with researchers to develop ways of detecting athletes who use gene therapy to cheat. Sweeney told delegates at the AAAS meeting that he had already been approached by athletes and trainers, even though the gene therapy technique is still in its infancy. Before testing the technique in humans, Sweeney's team hope to develop a way of turning the injected gene on and off, so that it could be shut down if it caused problems. However, he cautioned, it could be 'years' before the therapy is ready for human trials.