DNA May Soon Be in Play

Dr. James Wilson never intended to create super-monkeys.

A pioneer in genetic engineering, he was experimenting with a way to insert single genes into muscle cells, a technique that could eventually be used to treat a variety of genetic illnesses.

He chose a gene that boosts levels of erythropoietin, or EPO, a key hormone in the production of oxygen-toting red blood cells and a convenient marker to measure his experiment’s success.

But EPO has another claim to fame. Its synthetic version, created in the 1980s to treat anemia, is one of the most notorious performance-enhancing drugs in competitive sports, able to increase endurance by raising the oxygen supply to muscles.

In less than two weeks, many of Wilson’s rhesus monkeys had red cell counts greater than those of world-class runners who train at high altitude.

By three weeks, they had a higher concentration of red cells than even the worst EPO abusers in sports.

And no drug was ever injected.

As the sports world vainly struggles against the epidemic of illegal drugs, science has already opened the door to the next frontier in fraud: “gene doping.”

By introducing specific genes, the experimental technology has created bigger muscles, faster metabolism and greater endurance in laboratory animals. Hidden in cells, gene enhancements in humans would be much harder to detect than drugs.

“We know that gene therapy at some point will be abused,” said Olivier Rabin, the director of science for the World Anti-Doping Agency in Montreal. “It will happen.”

There is no evidence that any athlete has tried genetic alteration, but the agency added it last year to the international list of “banned methods” and had begun funding research to detect gene abuse.

The temptations for athletes are high. But they are not without risks.

For example, all eight monkeys in Wilson’s experiment are dead.

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Wilson, a boyish-looking professor of medicine at the University of Pennsylvania, knows the highs and lows of gene therapy, a field barely three decades old.

He led one of the earliest trials in humans -- to introduce genes to cure cystic fibrosis. In 1992, at 37, he became the first director of the university’s Institute for Human Gene Therapy.

But seven years later, he found himself at the center of gene therapy’s biggest disaster. Jesse Gelsinger, an 18-year-old from Tucson with a rare liver disorder, enrolled in one of Wilson’s clinical trials. He received a genetic injection, which his body rejected. Four days later he was dead.

The university shut down the institute. The Food and Drug Administration, which ruled that Wilson should have stopped the experiment sooner, has moved to bar him from leading human trials.

Despite the setback, Wilson and other scientists are pushing ahead. There have been nearly 1,000 gene therapy clinical trials worldwide.

The field remains one of medicine’s best hopes in the fight against disorders caused by defects in genes, such as diabetes and Parkinson’s disease.

The concept of gene therapy first appeared in the late 1960s. As scientists learned how to manipulate DNA, they came to believe that genetic defects could be fixed by installing new genes.

To accomplish that, they had to figure out how to deliver the therapeutic genes to cells. The leading method today uses viruses, which naturally invade cells. Researchers snip out the harmful parts of the virus and splice in the new gene.

These “viral vectors” are typically injected into the body. In some cases, they are designed to permanently merge the new gene into the subject’s DNA so that it is replicated and passed on when cells divide. In other cases, the virus deposits the new gene as a self-contained ring of DNA in the cell nucleus, where it remains for the life of the cell.

The problem is that the interactions among genes are still poorly understood and the therapeutic genes do not always land where scientists intend.

In humans, success has been limited and sobering. The most-cited example is the treatment of a fatal immune disorder known as X-linked SCID -- or “bubble boy disease” -- in 10 children in France. Eight recovered. Two developed leukemia after the new gene landed in a dangerous spot.

The stakes in gene therapy are unusually high. “You can’t turn it off,” Wilson said. “That’s the problem.”

It could be years or decades before viable therapies are on the market. Most clinical trials are conducted on terminally ill patients seeking a last resort.

Despite the risks, it didn’t take long for sports officials to recognize the potential for athletes to abuse genetic technology.

“We know that some athletes are willing to take very high risks to enhance their performance,” said Rabin, the antidoping official.

How much is an extra tenth of a second worth?

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The week that H. Lee Sweeney, a physiologist at the University of Pennsylvania, announced that he had genetically engineering a group of freakishly muscular mice, he received a call from a high school football coach.

Could Sweeney inject the entire team with the gene he had used to bulk up the mice?

Later came a similar request from a wrestling coach.

Sweeney’s mice, which had been given a muscle-building gene, developed hind limbs that rippled like mini-Mr. Universe thighs. They were up to 30% bigger than those in their unmodified cousins. No exercise was required.

Sweeney explained to both coaches that the gene had never been tried in humans and that using their athletes as guinea pigs could land them in prison.

He had little interest in helping athletes. His research seeks to slow the muscle breakdown that occurs with aging and degenerative diseases such as muscular dystrophy.

The building and repair of muscle is partly controlled by a protein known as insulin-like growth factor 1, or IGF-1. Sweeney introduced a gene in mice that would manufacture IGF-1 in muscle cells.

Rats received the same injection, but in only one leg. After an eight-week training regimen that included scaling ladders with weights on their backs, they emerged imbalanced. The genetically altered legs had twice the strength of the normal legs.

Some athletes are already familiar with IGF-1. The body makes it in response to human growth hormone, a banned drug in competitive sports.

The gene-made version of IGF-1 would offer athletes two advantages. The hormone would stay in the muscle and out of the blood, where it is known to increase the risk of cancer and heart problems. And since blood and urine would be useless in detecting the gene implant, an invasive muscle biopsy would be the only way to find it.

“The regulatory agencies are freaked out,” Sweeney said.

On the surface, tampering with genes is merely a sophisticated form of sports cheating.

“I want to be sure when I cheer that I’m cheering for the [athlete] and not his or her chemist,” said Leon Kass, a fellow at the American Enterprise Institute and head of the President’s Council on Bioethics.

But the situation is not as simple as it seems.

What if gene therapy becomes a standard method of treating injuries? Should an athlete given a muscle-building gene to repair an injury be banned from competing?

Technologies on the distant horizon further blur the debate.

It might someday be possible, for example, for parents to engineer children at birth to be athletic.

Molecular physiologist Ronald Evans, of the Salk Institute for Biological Studies in La Jolla, reported this week that by injecting a single gene into the nucleus of a fertilized egg, he created mice born with more efficient muscles, faster metabolisms and stronger hearts.

“When we put these mice on a treadmill, their very first run, they were able to run an hour longer than the unmodified mice,” said Evans, who is also an investigator at the Howard Hughes Medical Institute at the University of Maryland.

Thomas Murray, president of the Hastings Center, an independent bioethics institute in Garrison, N.Y., said there was no easy answer to whether athletes genetically altered as embryos should be allowed to compete.

“This child didn’t choose to have this gene put in, just as none of us choose our genes,” he said. “I think that’s going to be a very tough case for sport to handle. Thankfully, we don’t have to deal with it just yet.”

In the meantime, the phone keeps ringing in Sweeney’s office. He receives a few calls every week, mostly from power lifters and wrestlers.

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If the athletes had seen Jim Wilson’s monkeys, perhaps they would think twice.

Soon after Wilson injected the gene into the legs of the eight monkeys, their EPO levels began to rise.

The body naturally produces EPO in the kidneys. But it turns out that almost any cell in the body retrofitted with the EPO gene will produce the compound.

In the monkeys, tiny rings of DNA deposited in muscle cell nuclei were making the hormone and releasing it into the blood, signaling bone marrow to manufacture more red blood cells.

But the monkeys were not well.

In less than a month, the red cell counts in four of them began to reach dangerous levels. Too many red cells thicken the blood, increasing the risk of stroke.

The damage was irreversible, enmeshed in their DNA like the code for their dark eyes and long tails.

The animal handlers had to insert needles in the monkeys’ forearms -- twice a month, on average -- to thin their blood. It was the only way to keep the monkeys alive.

That result was not unexpected, but Wilson was perplexed at what happened to the other four monkeys.

Within two weeks, their EPO levels began to fall -- sharply. Red cell counts soon followed.

Their bodies had identified the EPO produced in the muscle cells as a foreign invader and mounted an immune response. But the attack was not limited to the new EPO. The natural EPO made in the kidneys was also being destroyed.

The monkeys had severe anemia. Wilson had no choice but to euthanize them.

The other four monkeys were kept alive for more than a year to monitor their EPO production. Then, they too were euthanized.

“It’s hard for me to believe that [any athlete] would try to do this,” Wilson said.

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But there is a grim resignation among sports officials that eventually somebody will try some form of gene doping.

“The world may be about to watch one of its last Olympic Games without genetically enhanced athletes,” Sweeney, the creator of the muscular mice, wrote in the July issue of Scientific American.

The arms race has begun.

The World Anti-Doping Agency will spend up to $1 million this year -- more than a fifth of its research budget -- to fund studies aimed at detecting gene doping.

“I cannot go into too much detail,” Rabin said, emphasizing the need for secrecy.

A piece of good news came early this month. Francoise Lasne, at the French National Anti-Doping Laboratory, reported that EPO produced in muscle tissue in monkeys varied slightly from the natural variety produced in the kidneys. The difference was detectable in blood.

But Philippe Moullier, a gene transfer expert at the French national health laboratories and an author of the study, said he had identified a different organ in the body that produced indistinguishable EPO. He plans to publish the results soon.

Even if the antidoping authorities catch up, researchers are already experimenting with a technique that could further complicate detection.

Wilson and Moullier have begun working on EPO-producing genes that can be turned on and off with common drugs, such as antibiotics.

The technique could be an enormous benefit for medicine, providing doctors with the ability to control the therapeutic output of the genes they install. They could keep hormones at desired levels. And when the gene has done its work, it can be switched off, hidden away until needed again.

For sports cheaters, of course, it’s a dream come true.