(CNN) -- In a pair of landmark studies, two groups of scientists announced Tuesday that they have reprogrammed human skin cells to act like embryonic stem cells, whose potential to mature into any other kind of cell in the body may ultimately prove key to curing a number of diseases.
One of the breakthrough teams works in the lab of James Thomson, here with lab manager Jessica Antosiewicz.
Researchers have long considered research into embryonic stem cells as a promising avenue to replacing certain disease-damaged cells.
For example, diabetes results when the pancreas cells that produce insulin are damaged or die. If those cells could be replaced by healthy cells, the disease might be cured.
The work is also promising in the areas of Parkinson's disease and spinal cord injury.
But the destruction of embryos inherent in such work has raised a raft of ethical, legal and political questions. Tuesday's announcement may allow scientists to sidestep those concerns.
"This is the beginning of the end of the controversy," researcher James Thomson, of the University of Wisconsin-Madison, told reporters in a conference call. Thomson, who wrote one of Tuesday's papers, developed the first human embryonic stem-cell line almost a decade ago.
Both papers reported a new, simple method that reprograms human skin cells to act like embryonic stem cells. CNN's Elizabeth Cohen explains the stem cell advance »
In the other paper, published in the online journal Cell, a group led by Shinya Yamanaka of Kyoto University reported that inserting four genes into human skin cells reprogrammed them into what scientists call "induced pluripotent cells" (iPS) -- which look and act like stem cells.
The cells were taken from a 36-year-old woman's face and a 69-year-old man's connective tissue.
Studying the differences in the techniques used by the two groups may help researchers figure out how to turn back the developmental clock, Yamanaka said.
But he said it is unclear how closely the new cells mimic stem cells. "Further studies are required to determine whether iPS cells can replace human embryonic stem cells," he said.
Last year -- using mouse cells -- Yamanaka proved that this process of reprogramming "adult" stem cells to an embryonic state was possible.
The paper from the study led by Thomson, published in the online journal Science, says the group reported that it reprogrammed human skin cells from a baby's foreskin.
Two of the genes Thomson used to convert the cells are different from those used by Yamanaka.
Despite the scientists' excitement, much work remains to be done before the advances can be used to treat disease in people, they said.
In both studies, the induced cells that were formed contained several copies of viruses that were used to insert the genes into the skin cells. "Those could easily lead to mutations that might cause tumors in tissues grown from the cells," an editorial accompanying the Science report said.
But researchers said further advances may overcome that drawback.
"This is an exciting advance" said Dr. John Gearhart, a stem-cell researcher at the Johns Hopkins School of Medicine, who was not involved in either study. "This opens up a huge field for researchers."
However, Gearhart said, scientists "shouldn't abandon embryonic stem cell research" because the safety of the new cells has to be established.
In a written statement, the White House said President Bush was "very pleased" with the reports.
"By avoiding techniques that destroy life, while vigorously supporting alternative approaches, President Bush is encouraging scientific advancement within ethical boundaries."
Bush has twice vetoed bills that would have eased restrictions on the use of federal funds for research involving embryonic stem cells.
Stem cell research is not banned. Private research using embryonic stem cells is allowed, but federal money -- the largest single source of funding for such work -- is limited to research involving embryonic stem cells that were created before August 2001, when Bush announced that federal funds could be used only for work on lines already in existence.
Some researchers say the cells left available are not useful for current work. E-mail to a friend
CNN's Miriam Falco contributed to this report.
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