Scientists turn ordinary skin cells into stem cells
San Francisco Chronicle | November 20, 2007
By Sabin Russell
Separate teams of scientists on two continents on Tuesday revealed they have created stem cells from human skin cells - a development that could eventually allow researchers to sidestep the contentious moral issues that have hobbled early studies in the promising field.
The startling breakthrough was hailed by parties on all sides of the stem cell debate, because it raised the prospect that the controversial destruction of human embryos and the need to harvest eggs from women donors might one day no longer be needed.
"This has the potential to reshape the politics and science of stem cell research," said Jesse Reynolds, a policy analyst for the Center for Genetics and Society, an Oakland-based organization that favors stem cell studies.
The Rev. Thomas Berg, executive director of the Westchester Institute, a Catholic ethics think tank in Thornwood, N.Y., said the new technique described in the two papers is a major advance that passes ethical muster. "This is almost a magical moment," he said. "We wanted to see science go forward, but in a way that will respect human life."
Published in online versions of two competing scientific journals, the reports detail how ordinary skin cells were transformed into stem cells by treating them with four genes - a technique pioneered last year in laboratory mice by Dr. Shinya Yamanaka and his colleagues at Kyoto University in Japan.
Yamanaka, who is setting up a lab at the UCSF-affiliated Gladstone Institute of Cardiovascular Disease in San Francisco, reported in an online edition of the Journal Cell how his team used the same type of human genes to make stem cells from skin.
The newly made human stem cells subsequently proved their versatility. They morphed into nerve cells and microscopic clumps of human heart tissue that beat rhythmically in a laboratory dish.
A nearly identical study, using a different group of four genes, was carried out successfully by scientists at the University of Wisconsin-Madison. It was reported Tuesday in an online edition of the journal Science.
"The two results are significant, maybe even astounding," said Christopher Scott, a director of the Stanford Center for Biomedical Ethics. He predicted that the success in producing stem cells from skin cells will bring on calls for ending research using human embryos.
"You can bet on it," he said. "But at this stage of the game, you can't call it one way or another. There is no reason to think we should drop one type of research in favor of another."
University of Wisconsin researcher Dr. James Thompson, who developed the original technique of harvesting human embryonic stem cells in 1995 and coauthored his team's paper on the new approach, said that the success of the new method will eventually make the controversial older process obsolete. "The world has changed because of this new result," he said.
The ultimate promise of stem cell technology is that these master cells might be coaxed into producing organs and tissues to replace those lost by trauma or degenerative diseases - a potential bounty that led California voters in 2004 to approve a $3 billion bond issue for stem cell research.
That effort won favor in part because state voters disagreed with the decision by President Bush in August 2001 to forbid the use of federal funds for stem cell research that involved the destruction of human embryos. However, the new technique described Tuesday will pass muster with the administration.
"It's wonderful news," said Dr. Jim Battey, vice chair of Stem Cell Task Force at the National Institutes of Health in Bethesda, Md. "We would be quite enthusiastic to fund this research in the future."
Much of the current research in California is aimed at developing stem cells from cloned human embryos. The goal is to hollow out a human egg, and then infuse it with the nucleus of an ordinary cell - like one from the skin. The egg produces chemical signals that cause the implanted genes to begin developing a human embryo, from which can be harvested the multi-tasking stem cells.
In addition to opposition from the Roman Catholic Church and the anti-abortion movement, women's rights advocates have raised concerns that the technology poses a danger to the young female donors whose eggs are needed for research and would be needed in vast quantities for therapies.
"I don't think they realize what an invasive procedure egg harvesting is for women," said Diane Beeson, professor of sociology at California State University, East Bay. The potential for exploitation of low-income women also troubles her. "Women's eggs are very valuable now," she said.
Richard Murphy, interim president of the California Institute for Regenerative Medicine, which was created by the 1994 initiative to distribute that money, said the new findings were exciting, but do not take away the need for more research using human embryos.
"It was human embryonic stem cell work that gave rise to these new findings," he said. State grants will be provided to pay for both kinds of stem cell research. "You fund the very best science," he said.
A major disadvantage of the new technique is that the stem cells produced are likely to cause cancer. In subsequent experiments by Yamanaka, the method did produce cancer in mice.
Yamanaka's team reported this summer that, when it fused the newly created stem cells with a mouse embryo, the researchers were able to produce living mice carrying the genes originally derived from skin cells. But these cloned mice subsequently developed neck tumors.
This creation of cloned mice raises the prospect that a similar set of laboratory techniques might be used to clone a human being - an act that would be universally condemned by scientists as unethical.
Dr. Bernard Lo, an ethicist at UCSF Medical Center, said that because substantial extra laboratory manipulation of these stem cells would be required to make human cloning possible, the risk remains purely theoretical.
Until last week, some researchers believed that the process was too complex for primates - the order of mammals that includes monkeys and humans. But Oregon researchers disclosed they had successfully cloned monkey embryos, and produced stem cells from them.
"If it is possible to clone primates, then maybe it is possible to clone human beings. But as human beings, we are able to draw the line," Lo said.
Highlights of latest stem cell development
What happened: Scientists transformed an ordinary skin cell into a stem cell, which has to potential to grow into any organ or tissue in the human body.
How they did it: They used a virus to carry four specialized genes into the skin cell. Those genes sent the same sort of signal a human embryo uses to start making stem cells.
Why this is important: The current method of making stem cells requires the harvesting of eggs from women and the destruction of living human embryos, a technique that has raised moral objections.
The catch: Right now, these stem cells made from skin cells probably can cause cancer. Researchers must find ways to scrub out the cancer-causing traits.
