Scientists in South Korea are reporting today that they have created the world's first mature, cloned human embryos -- an advance that could speed the development of new therapies but also brings scientists a big step closer to being able to make cloned babies.
Each embryo was grown from a cell taken from a woman, a form of reproduction -- or, more precisely, replication -- never before achieved in humans. There was no contribution from a father.
The researchers said they are pursuing medical treatments and have no interest in making cloned babies. But the clones grew vigorously in laboratory dishes up to, and even past, the stage at which fertility doctors typically put embryos into their patients' wombs. That suggests that unlike the products of previous efforts, these clones have the potential to become viable offspring.
"It would be naive to say this isn't a step closer to irresponsible people attempting reproductive cloning," said Gerald Schatten, an animal-cloning researcher at the University of Pittsburgh School of Medicine, who opposes human cloning but favors the research.
In an equally significant first, the researchers coaxed from one embryo a robust colony of human embryonic stem cells -- the highly prized cells that can morph into every kind of tissue and show great promise in their capacity to treat a wide range of diseases when transplanted into patients.
Although researchers have grown stem cells from conventional embryos created by fertilization, the new colony is the first to emerge from a cloned human embryo -- a source believed by many scientists to have far more medical potential.
"Our approach opens the door for the use of these specially developed cells in transplantation medicine," study leader Hwang Woo Suk of Seoul National University said in a statement.
Word of the South Korean successes shot through scientific, religious and political circles this week in advance of today's scheduled release of a report in the online edition of the journal Science, and it reignited a long-standing debate over human cloning and embryo research. As with other leading journals, research papers published by Science must clear a careful review by other scientists before they are accepted for publication.
Several U.S. groups renewed their calls for legislation to ban the creation of cloned babies. That goal has support across the political spectrum because of a host of ethical and medical concerns.
But it has repeatedly failed to pass congressional muster because of the insistence by some that the legislation not only ban the creation of cloned babies but also prohibit the production of cloned embryos for medical research.
"We call on Congress to follow the common-sense conclusion that most Americans have reached -- pass legislation that would prohibit reproductive cloning, but allow and encourage this kind of very exciting scientific research," said Sean Tipton, vice president of communications for the Coalition for the Advancement of Medical Research, a Washington-based advocacy group.
The new work also triggered fresh criticism of a 21/2-year-old policy of the Bush administration that bans federally funded scientists from conducting research on new human embryonic stem cell colonies.
"We're lagging in this country, and we should be at the forefront of developing all these new strategies," said Jose B. Cibelli of Michigan State University, who helped the South Korean team prove that its embryos were indeed clones.
"The U.S. has so many talented scientists," Cibelli said -- emphasizing he had no direct hand in the South Korean work, the likes of which is punishable in Michigan with a $1 million fine and 10 years in jail, even when private money is used. "All we need is the funding and we could get this done."
That is the last thing religious conservatives and some other activists want to see happen.
"This approach relies on the one thing that even President Clinton and pro-abortion members of Congress agreed a few years ago was unacceptable: creating human embryos in the laboratory solely to destroy them for research," said Richard Doerflinger of the U.S. Conference of Catholic Bishops.
The new work shows how far cloning science has come since 1996, when researchers in Scotland made Dolly the sheep, the first cloned mammal. Scientists have since begotten cloned mice, horses, pigs, cats and a handful of other animals. Until now, however, efforts to make cloned human or even monkey embryos from adult cells have failed, leading some scientists to wonder whether primates -- the class of animals that includes monkeys, apes and humans -- are not susceptible to cloning.
(Assertions by an obscure religious sect that it has made cloned babies remain unverified and are widely believed to be hoaxes.)
While stopping short of proving that a cloned human embryo can develop normally to birth, the South Korean research goes a long way toward dispelling those doubts because the embryos grew all the way to what is known as the blastocyst stage. Blastocysts contain hundreds of cells, including an inner bulge of stem cells that have the capacity to form every fetal tissue.
Hwang and his colleagues started by giving 16 female volunteers a month's course of potent hormones to make their ovaries produce abnormally high numbers of mature eggs, then used a surgical suction device to remove those eggs. The women were not paid and were told they would not benefit from the research.
Working with specially equipped microscopes, team members removed the central packet of DNA from each egg cell, leaving only the fluid that mysteriously is capable of triggering embryo growth. Then, using tiny bursts of electricity, the team fused each egg cell to one of several "cumulus cells" they had retrieved from the women's ovaries, which provided the women's DNA. In animal experiments, cumulus cells have proven especially amenable to becoming embryos when suffused with egg cell fluids.
Because the team had so many eggs to begin with -- a total of 242 -- it had the luxury of being able to see which of many techniques and chemical additives best nurtured the clones, Cibelli said. Their methods got better and better, to the point where fully 1 in 3 cloned embryos grew all the way to blastocysts -- a level of efficiency rivaling that enjoyed today by cattle and pig cloners.
All told, the South Koreans made 30 blastocysts. They collected stem cells from 20 of them, and one of those samples settled into a lab dish to become a self-reproducing colony.
"The human cost of this 'advance' is startling," Doerflinger wrote in an e-mail. "Sixteen women given risky fertility drugs and used as egg farms; as many as 213 early embryos produced and killed; and 30 human embryos 'farmed' for a week, to produce just one stem cell line."
He and others want scientists to focus on other kinds of stem cells that can be obtained from adults, but some scientists believe those stem cells would have less medical potential.
Some feminist activists, too, oppose the cloning of human embryos as a means of producing stem cells. The approach requires lots of human eggs -- and egg donors -- these critics note, and the drugs and procedures used are not risk-free.
But R. Alta Charo, an associate dean of law at the University of Wisconsin at Madison, said she sees no problem with the way the studies were done.
"We're talking about drugs that have been approved for precisely this use in other medical settings and are in no way experimental," Charo said. "And there are no apparent enticements other than a desire to assist the research, so we're not talking about a 'Godfather' situation, in which money or other inducements are used to make an offer that you can't refuse."
Even if cloning proves a useful method of obtaining stem cells, much more work is needed before those cells can be used for therapies. Researchers are just learning how to force stem cells to become specific cell types, such as nerve cells for transplantation into patients with Parkinson's disease or heart cells for transplantation into patients with heart disease.
But stem cells from embryos that are clones of those patients would be superior to stem cells from other embryos, scientists say, because they would be genetically identical to the patient and so would probably not be rejected by the immune system.
Sen. Arlen Specter (R-Pa.), who supports stem cell research, said the cloning issue is "still percolating" in Congress even though, for now, the Senate appears "deadlocked" on whether to ban all human embryo cloning or only cloning that would lead to the birth of a baby.
