By Science Writer
updated 2/16/2004 11:39:46 PM ET 2004-02-17T04:39:46

Gene injections in rats can double muscle strength and speed, researchers have found, raising concerns that the virtually undetectable technology could be used illegally to build super athletes.

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A University of Pennsylvania researcher seeking ways to treat illness said that studies in rats show that muscle mass, strength and endurance can be increased by injections of a gene-manipulated virus that goes to muscle tissue and causes a rapid growth of cells.

“The things we are developing with diseases in mind could one day be used for genetic enhancement of athletic performance,” Lee Sweeney of the University of Pennsylvania said Monday at the national meeting of the American Association for the Advancement of Science.

Betrayal of ideals
Sports officials said the gene therapy has the potential of betraying the very essence of sport — athletes using their natural talents and training to compete.

It would, said Tom Murray of the Hastings Center, a research organization, be like allowing an athlete to compete in the Boston Marathon wearing roller blades.

“Performance-enhancing drugs have been a concern in sports and gene therapy has the potential to kick it up a notch,” said Murray, who has studied the issue of doping in athletics. “It makes the challenges greater (of controlling performance-enhancing measures).”

Murray said he “has no doubt athletes will be in touch with Sweeney” when they learn of his research.

Sweeney said that already half the e-mails he receives are from athletes or sports trainers.

Playing catch-up
Richard Pound of McGill University and the World Anti-Doping Agency, which controls doping in athletics, said the sports community lost control of drugs for performance-enhancement in the 1960s to 1990s and “we’ve been playing catch-up ever since.”

Now gene therapy looms as an even more serious threat, he said.

“Sport is and should be an effort to see how far you can go with your natural talents honed by exercise and skill perfection,” he said, and not by manipulating genes to build muscle.

He said the international sports community already has regulations forbidding gene therapy for performance improvement, and his agency hopes to be active in efforts to control use of the technique as the science develops.

Muscle strength doubled
Sweeney said that his laboratory studies show that injecting into muscles a manipulated virus that carries a gene for insulinlike growth factor 1, also known as IGF1, causes target muscles in rats to grow in size and strength by 15 to 30 percent. The inserted gene causes formation of extra IGF1 which, in turn, prompts the growth of muscle cells.

When the technique was used on rats that were also put through an exercise program, the animals doubled their muscle strength, he said.

“If a normal person would inject this, their muscles would get stronger without them doing anything,” said Sweeney. “If they are athletes in training, the rat study indicates that their training would be much more effective, injury would be overcome more easily and the effect of the training would last a much longer time.”

The effect appeared to last throughout the life of the rats.

He said the technique was designed so that the IGF1 gene stays in the target muscle and does not move into the bloodstream where it could cause damage to other organs.

The research was published in the March issue of the Journal of Applied Physiology.

Treatment for muscular maladies
Sweeney said the gene therapy was being developed to treat muscular dystrophy and the natural decline in muscle strength associated with aging.

Unlike performance-enhancing drugs, Sweeney said the gene therapy could not be detected by blood or urine tests. He said it would require a biopsy of specific muscles followed by a sophisticated DNA laboratory study to detect the use of gene therapy in an athlete.

Sweeney said because of the potential of cancer and other side effects, it may be years before the muscle-strengthening gene therapy is ready for human trials.

“There are issues of safety,” he said. “It is not going to be as trivial as taking a drug.”

Before it is tested in humans, said Sweeney, his lab hopes to develop a way to turn the inserted genes on and off. That way, if problems develop then the gene could be shut down.

Gene therapy regulated
Gene therapy has been conducted experimentally for some diseases, but it is tightly controlled by federal regulation in the United States. At least one patient, being treated for a liver disorder, died in a gene therapy trial. Two children in Europe treated with inserted genes for immune deficiency later developed leukemia.

Sweeney said the gene therapy technique is highly complex and requires expert laboratory preparation.

“This is not something an athlete could do in his garage,” he said. “The athlete couldn’t do this without a lot of help.”

He said that some countries, in a drive for athlete glory, could allow the gene therapy, just as earlier in history Olympic programs in some countries tolerated the use of performance-enhancing drugs.

“That is the short-term fear,” said Sweeney.

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