WASHINGTON — Scientists at a California company reported Thursday that they had created the first mature cloned human embryos from single skin cells taken from adults, a significant advance toward growing personalized stem cells for patients suffering from disease.
The embryos — grown from cells taken from the company’s chief executive and one of its investors — also offered evidence that few, if any, technical barriers might remain to the creation of cloned babies. That reality could prompt renewed controversy on Capitol Hill, where the debate over human cloning has died down of late.
Five of the embryos grew in laboratory dishes to the stage that fertility doctors consider ready for transfer to the womb — a degree of development that clones of adult humans have never achieved before.
No one knows whether those embryos were healthy enough to grow into babies. The study leader, who is also the medical director of a fertility clinic, said they looked robust. However, he emphasized that he has no interest in cloning people.
“It’s unethical, and it’s illegal, and we hope no one else does it either,” said Samuel Wood, chief executive of Stemagen in La Jolla, whose skin cells were cloned and who led the study with Andrew French, the firm’s scientific officer.
The closely held company hopes to make embryos that are clones, or genetic twins, of patients, then harvest stem cells from those embryos and grow them into replacement tissues. When transplanted into patients, the tissues would not be rejected, because the immune system would see them as “self.”
“All our efforts are being directed toward personalized medicine and diseases,” Wood said. He added that the scientists did not try to extract stem cells from the first embryos they made because they were focused on proving they could make the clones.
Other stem-cell scientists expressed optimism but said they wanted to see the work repeated and more details presented.
“I’d really like to believe it, but I’m not sold yet,” said Robert Lanza of Advanced Cell Technology in Worcester, Mass. He said the report did not show the results of molecular tests that scientists typically do to prove that the cloning process was complete.
The work is the latest evidence that the field is recovering from the scientific and public relations debacle of 2005, when similar claims by Korean scientists proved to have been fabricated. But opponents of research on human embryos lashed out at the approach.
“This study seems to confirm that human cloning . . . is technically possible,” said Richard Doerflinger of the U.S. Conference of Catholic Bishops. “It does not show that a viable or normal embryonic stem-cell line can be derived this way or that any such cell has ‘therapeutic’ value. It does not answer the ethical or social questions about the mass production of developing human lives in order to destroy them. . . . It only tells us that these questions are more urgent than ever.”
In the new work, the team took skin cells — some from Wood’s arm and some from an anonymous Stemagen investor — and fused them to eggs donated by women undergoing fertility treatments.
Wood’s team obtained the eggs within an hour or so of when they were retrieved from the women’s ovaries.
Although researchers are typically given the poorest quality “leftover” eggs from fertility patients, donors in this experiment gave away several of their best eggs because, in each case, they had produced far more than they needed.
All three donors got pregnant with the eggs they kept.
“They are the heroes in this,” Wood said. “Think about it. You’re spending $25,000 (trying to get pregnant) and you’re giving some of those eggs away.”
R. Alta Charo, a professor of law and bioethics at the University of Wisconsin, said the approach was attractive because the egg donors were not subjected to the medical risks of ovarian stimulation and egg retrieval just for research.
Asked what it was like to look at embryos that were replicas of himself, Wood said, “I have to admit, it’s a very strange feeling. It is very difficult to look at an embryo and realize it is what you were a few decades ago. It is you, in a way.”
What is cloning?
Cloning involves fusing an ordinary body cell with a woman’s egg cell whose DNA has been removed. Chemical factors inside the egg reprogram the body cell’s DNA so that the newly created cell develops into an embryo that is a genetic twin of the person or animal that donated the body cell.
No law bans cloned baby- making, but the Food and Drug Administration has said such experiments would require its approval.
