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HUMAN CLONING

Not now, maybe never

by Rowan Hooper

As far as self-publicity goes, the U.S.-based Raelian cult has done better than most. Based on the alleged experiences of a one-time motor-racing journalist, Claude Vorilhon, who claimed to have been inspired by an extraterrestrial power lunch with Mohammed, Christ and Buddha, the cult drew attention by the outlandish nature of its claims.

According to the Raelians, humans were created by aliens who cloned us and placed us on Earth. Oh, and then came back later to take Vorilhon for lunch with the dead but cloned founders of the world’s major religions.

In any case, after 9-11, the Raelians announced their plan to prevent future terrorist action: to clone each victim of any attack, so making the attacks redundant in the first place. Only one group had a plan less likely to prevent terrorism, and that was the Bush administration.

But the Raelians’ real coup was earlier this year. Brigitte Boisselier, the director of a Raelian company, Clonaid, announced that a woman in their care had given birth to a human clone. Without any evidence to back up such a massive claim, the cult gained instant front-page coverage on almost every national newspaper in the world, including The Japan Times.

Predictably, little more has been heard of them and the tests that they promised would prove their claims have not materialized.

Scientists, at the time, were incredulous. Lord May of Oxford, president of the U.K. National Academy of Science, said: “The Royal Society remains extremely skeptical about claims that human reproductive cloning has been carried out.”

And last week in Science a paper was published that suggests why human cloning may, in fact, be impossible, at least with current techniques.

In reproductive cloning, which aims to initiate a successful pregnancy, DNA from a normal somatic (“body”) cell is transferred to an egg cell that has been emptied of its own DNA. The egg then divides and grows as normal, using the transferred DNA. (In therapeutic cloning, limited cell division is induced in an unfertilized egg cell to produce embryonic stem cells, potentially useful in a wide range of medical treatments.)

Normally, when a cell is about to divide, its chromosomes duplicate themselves and line up on a network of tracks inside the cell called the spindle. The chromosomes then travel to opposite ends of the spindle, and the cell divides down the middle. However, according to a team of researchers from the Pittsburgh Development Center in Pennsylvania, when reproductive cloning is attempted in primates, the usual process of cell division fails.

“The chromosomes do not split properly,” said Gerald Schatten, senior author of the study and professor of the departments of obstetrics, gynecology and reproductive sciences, and of cell biology, at the University of Pittsburgh School of Medicine. “From the very first cell division, development is inappropriate in vital ways.”

Schatten and colleagues used nuclear transfer techniques, such as those used to clone Dolly the sheep, on 724 eggs retrieved from female rhesus macaques. Of these 724, 33 resulted in embryos that were transferred into surrogate macaque mothers after initial cell division. But no pregnancies were established.

To find out why, the scientists used fluorescent markers to look at the DNA and the basic structure of the embryos. They found that while cell division continued in a superficially normal manner, there were major problems within each individual cell.

“We used antibodies to tag the cell proteins and DNA so that we could track progress,” said Calvin Simerly, associate professor of obstetrics, gynecology and reproductive sciences at Pittsburgh School of Medicine and the paper’s first author. “When cells divide, there are very basic things that are supposed to happen, and they just didn’t happen.”

Even the most basic proteins involved in spindle formation were absent or inadequate, said Simerly. As a result, the cells were disorganized, the chromosome counts unequal: Some cells had too many, some too few. Embryo development soon failed.

“Current techniques such as those used to create Dolly the sheep, mice and other domestic animals do not work in nonhuman primates,” said Schatten. “I don’t want to say that this will never happen. Given enough time and materials, we may discover how to make it work. It just doesn’t work now.”

Why are primates different in this aspect of their cell division from cows and pigs, rabbits, cats and mice? No one knows.

The new study emphasizes what scientists such as Ian Wilmut, of the Roslin Institute in Scotland, the leader of the team that cloned Dolly, have long said about human reproductive cloning: that it is premature to attempt it, and potentially dangerous. Not to mention fraught with ethical problems.

It is the ethical issues that opponents of cloning have seized on, arguably exploiting the public’s confusion about the terms “reproductive” and “therapeutic cloning.” In the United States, this has led to a bill calling for a ban on all forms of cloning, including therapeutic cloning.

In response to the announcement by the Raelian cult earlier this year, Peter Raven, chairman of the American Association for the Advancement of Science, cautioned that “human reproductive cloning also should not be confused with methods for developing cells to treat debilitating diseases and injuries.”

Now it seems that a human clone is still a long way off. “This reinforces the fact that the charlatans who claim to have cloned humans have never understood enough cell or developmental biology,” Schatten said.

All that the charlatans did understand, it seems, was the art of public relations and self-promotion.