Three independent teams of scientists on Wednesday said that they have developed experimental approaches using the skin cells of mice to create embryonic stem cells without creating or destroying embryos -- a technique that could "quench" the "ho[t] bioethical controvers[y]" surrounding human embryonic stem cell research, the Washington Post reports. Shinya Yamanaka of Kyoto University and colleagues published their findings on Thursday in the journal Nature, and two U.S. teams -- one led by Rudolf Jaenisch of the Whitehead Institute for Biomedical Research and the other by Konrad Hochedlinger of Massachusetts General Hospital -- published their findings on Thursday in the journal Cell Stem Cell, the Post reports.

For the studies, the three teams infected mouse skin cells with viruses genetically engineered to activate four key genes that have the ability to turn other genes on and off in the proper configuration to make skin cells revert to an embryonic state, the Post reports. According to the studies, about one in 10,000 of those infected cells became an "induced pluripotent stem" cell, which has all the characteristics of an embryonic stem cell (Weiss, Washington Post, 6/7). The new studies are extensions of a study conducted last year by Yamanaka and colleague Kazutoshi Takahasi that identified the four essential genes, the New York Times reports (Wade, New York Times, 6/7).

Kathrin Plath of the University of California-Los Angeles, who co-led one of the studies with Hochedlinger, and other researchers said the new approach would have to be altered for use with human cells. The researchers said that the viruses used to stimulate the four genes in mice can cause cancer, so researchers are now searching for alternatives, such as feeding the cells small molecules that can activate the key genes. They also said that there might be a different, unidentified set of genes essential for reprogramming in human cells, the Post reports (Washington Post, 6/7).

Plath said it could take as little as two months to reprogram cells from humans, but other scientists have said it could take years or decades (Kaplan, Los Angeles Times, 6/7). According to the Wall Street Journal, 20% of the baby mice born in Yamanaka's latest experiments developed tumors. "I would predict that making (embryonic-like) cells from human cells is more demanding," Yamanaka said (Naik, Wall Street Journal, 6/7).

Reaction
In effect, the researchers' work "turn[s] back the clock from adult to embryonic stem cells," Hochedlinger said (Nickerson, Boston Globe, 6/7). "From the point of view of moving biomedicine and regenerative medicine faster, this is about as big a deal as you could imagine," Irving Weissman -- a leading stem cell biologist at Stanford University, who was not involved in the new research -- said. David Scadden, a stem cell biologist at Harvard Medical School, said the finding that cells could be reprogrammed with simple biochemical techniques "is truly extraordinary and frankly something most assumed would take a decade to work out" (New York Times, 6/7).

The findings have generated "tumult" on Capitol Hill, where lawmakers are scheduled to vote Thursday on a bill that would loosen restrictions on federal funding for human embryonic stem cell research, the Post reports. The researchers said that their success with mouse cells does not guarantee quick success with human cells, and they called on Congress to pass the bill, according to the Post. "A human is not a mouse, so a lot more work has to be done," Marius Wernig, who co-led the other U.S. study with Jaenisch, said.

Opponents of human embryonic stem cell research said the findings strengthen their arguments that stem cell research can progress without harming human embryos. "Morally and practically, this new approach appears to be far superior," Richard Doerflinger of the United States Conference of Catholic Bishops said (Washington Post, 6/7). Doerflinger added that the approach "raises no serious moral problem because it creates embryonic-like stem cells without creating, harming or destroying human lives at any stage." Ronald Green, an ethicist at Dartmouth College, said it would be "very hard for people to say that what is created here is a nascent form of human life that should be protected." The new technique, if adaptable to human cells, "will be one way this debate could end," he added. James Battey, vice chair of the NIH Stem Cell Task Force, said he sees "no impediment at all" to federal support of researchers using the new technique on human cells (New York Times, 6/7).

Separate Study
In a separate study, published in the June 7 issue of the journal Nature, Kevin Eggan of Harvard Stem Cell Institute and colleagues removed the DNA from a fertilized mouse egg that had no potential to become a healthy embryo because it had chromosomal abnormalities and substituted that DNA with the DNA from a mouse skin cell, the Post reports. Stem cell production by this method until this point has required healthy, unfertilized eggs, according to the Post. Eggan's study suggests that human versions of stem cells with genetic abnormalities could be made using chromosomally abnormal fertilized eggs that are often discarded by fertility clinics, the Post reports. Eggs with such severe defects "can never make a child," so there should be no ethical debate about using them in research, Eggan said (Washington Post, 6/7). He said that the study could reinvigorate interest in all forms of embryonic stem cell research, adding, "States will pour more money into this research" (Wall Street Journal, 6/7).

Abstracts of Yamanaka's study, Eggan's study, Jaenisch's study and Hochedlinger's study are available online.

NBC's "Nightly News" on Wednesday reported on the studies. The segment includes comments from Hochedlinger and Wernig (Bazell, "Nightly News," NBC, 6/6). Video of the segment is available online.

NPR's "All Things Considered" on Wednesday also reported on the studies. The segment includes comments from Jaenisch; Eggan; and William Hurlbut, an associate professor of social and medical ethics at Stanford University (Palca, "All Things Considered," NPR, 6/6). Audio and a partial transcript of the segment are available online.