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Stem-cell technique designed to save embryos
A biotech company has developed a way to generate human embryonic stem-cell colonies without intentionally destroying embryos in the process.
Lead researcher Dr. Robert Lanza of Advanced Cell Technology, based in Alameda, Calif., said Wednesday that "this removes the last rational reason for opposing" research aimed at using the cells to understand and treat diseases.
Lanza's optimism was not widely shared.
His team earned praise for trying to address ethical concerns and for technical prowess.
But opponents of embryonic stem-cell research said the new approach still poses moral dilemmas. Proponents, meanwhile, said that going to extraordinary lengths to avoid destroying embryos during research is hypocritical, considering that embryos are created and discarded every day in infertility clinics.
"The notion that it solves some kind of a scientific, social or ethical dilemma — I can't say that it does," said molecular biologist Kevin Eggan of the Harvard Stem Cell Institute, which is trying to clone human embryos to harvest stem cells.
The method, described in the current issue of the journal Nature, involves taking a normal 3-day-old embryo with eight to 10 cells and removing a single cell, which is then biochemically coaxed into producing embryonic stem cells. The original embryo, despite missing one cell, is unharmed, thus avoiding concerns about destroying a potential life, the researchers say.
Stem cells from days-old human embryos can morph into virtually every kind of tissue, including nerves to replace those destroyed by spinal injuries and cardiac muscle to fill in for cells lost in a heart attack. Scientists see stem cells as the key to a new era of regenerative medicine.
Until now, however, the only way to get these cells was to destroy embryos — which, though smaller than the period at the end of this sentence, are deemed by some people as "the youngest members of the human family."
Nature published a similar paper by Advanced Cell Technology last year demonstrating the technique's viability in mice.
The Bush administration, which has restricted federal support for human embryonic stem-cell research to prevent taxpayers from funding the destruction of potential life, said it was too soon to say whether the new approach could solve the ethical dilemma at the heart of the research.
President Bush offered little encouragement Wednesday and, if anything, raised the bar higher, suggesting he would not be comfortable unless embryos were not involved at all.
"Any use of human embryos for research purposes raises serious ethical concerns," a statement released by the White House said. "The president is hopeful that with time scientists can find ways of deriving cells like those now derived from human embryos but without the need for using embryos."
Last month, Bush vetoed a bipartisan bill to expand stem-cell funding beyond the 20 or so cell lines currently eligible to more than 100 newer ones.
Social conservatives already have begun complaining that the new technique falls short. They say the method does injure nascent embryos, and they question whether the cell that is removed from an embryo has the potential to develop on its own.
"The new study ... raises more ethical questions than answers," said Richard Doerflinger of the U.S. Conference of Catholic Bishops.
The technique relies on an old procedure known as pre-implantation genetic diagnosis, or PGD.
An embryo created through in vitro fertilization is allowed to develop into a small ball of cells known as blastomeres. Specialists use a tiny glass tube to remove one cell for genetic testing. If the tests come up clean, the embryo can be implanted in the womb.
The procedure seems to be safe, said Dr. Joe Leigh Simpson, an obstetrician-gynecologist and professor of molecular and human genetics at Baylor College of Medicine in Houston.
Lanza wanted to piggyback on the technique. If the removed blastomere were allowed to divide once, one could be used for PGD and the other would be available for research.
The key was to find a way to get the cell to multiply in a laboratory dish long enough to produce stem cells. Embryonic stem cells, which are capable of becoming any cell in the body, are typically harvested from the inner cell mass of an older embryo that contains about 150 cells.
Advanced Cell Technology was able to produce two viable stem-cell lines from 16 frozen embryos donated by fertility-clinic patients. Advanced Cell scientists have since turned some of the cells into blood vessels, eye cells and other potentially useful tissues.
The lines appeared to exhibit the full potential of embryonic stem cells to develop into any type of human tissue, the researchers reported, but additional study is needed to verify that.
"I think this will become a standard way of producing stem-cell lines," said Ronald Green, a Dartmouth College professor of ethics and human values who is an unpaid bioethics adviser to Advanced Cell Technology.
The approach avoids the ethical problem with the standard method of making stem cells: The embryo is destroyed once its inner cell mass is removed.
But it is uncertain whether the technique can meet the tough federal standard designed to protect embryos.
The legislation that funds the Department of Health and Human Services forbids the use of federal money for "research in which a human embryo or embryos are destroyed, discarded, or knowingly subjected to risk of injury or death."
Doerflinger said the safety of the single-cell biopsy procedure had not been scientifically established.
"Some embryos do not survive the process, and some survivors may have long-term effects later in life," he said.
Fertility specialists who perform the procedure acknowledge there have been no scientific efforts to study its effect on embryos or to track the children after they are born.
Dr. James Battey, who chairs the Stem Cell Task Force at the National Institutes of Health, said that would make it difficult for the funding agency to approve grant money for cells like Lanza's.
"Can I reassure people who have put this language on our appropriation that not even one time in a thousand a single-cell biopsy won't harm an embryo?" Battey said. "I can't do that."
Nicanor Austriaco, a Dominican friar and molecular biologist at Providence College in Providence, R.I., raised another potential problem. What if the single cell that has been removed can itself become an embryo?
In other mammals, researchers have found that a single blastomere can develop into an identical copy of the original embryo.
"This raises the concern that the blastomeres isolated by [Advanced Cell] in order to create a stem-cell line are in fact bona fide embryos that are destroyed in the process of creating the stem-cell lines," Austriaco said.
Stem-cell experts said that argument was speculative. While it may be possible to grow a human blastomere into a full-scale embryo, it does not occur naturally and has never been documented in a lab.
John Gearhart, a stem-cell researcher at Johns Hopkins Medical Institutions in Baltimore, said he was hopeful Lanza's approach would prove fruitful. But he was frustrated, he said, by the fact that Bush's order and the congressional appropriations rider continue to keep federal researchers from a more immediately promising resource: embryos slated for destruction at fertility clinics.
"You have to remember that all this talk of protecting embryos is being done against the background of the routine throwing away of embryos" at clinics, Gearhart said.
Advance Cell Technology, which has been struggling financially, owns about 300 patents that it hopes to develop into medical treatments. After its announcement broke Wednesday, the price of its over-the-counter stock shot up from 42 cents to close at $1.83 per share.
Material from The Washington Post, The Associated Press and Seattle Times archives is included in this report.
Copyright © 2006 The Seattle Times Company