WASHINGTON Researchers have transformed ordinary human skin cells into batches of cells that look and act like embryonic stem cells -- but without using cloning technology and without making embryos.
Their breakthroughs, reported on Tuesday, could make possible the long-sought goal of tailor-made medicine, but without the political, scientific and ethical roadblock of using human eggs or embryos.
The White House immediately welcomed the development, given President George W. Bush's long opposition to embryo research, even as scientists said the finding should not be the end of such research.
"We weren't avoiding the ethical controversy -- we just thought this was an alternative approach that would work quicker," said James Thomson of the University of Wisconsin in Madison, who led one of the teams.
"This work represents a tremendous scientific milestone -- the biological equivalent of the Wright Brothers' first airplane," said Dr. Robert Lanza of Advanced Cell Technology, a Massachusetts company working in the same field.
"It's not practical to use right now, but it might be in a few years. This is truly the Holy Grail -- to be able to take a few cells from a patient -- say a cheek swab or few skin cells -- and turn them into stem cells in the laboratory."
The researchers agree it will be years before the technique could be used to treat people. More immediately, they say it can be used to study diseases and to screen drugs.
"We have to be sure the cells are safe," Shinya Yamanaka of Kyoto University in Japan and the University of California San Francisco said in an e-mailed statement.
Yamanaka and colleagues reported their finding in the journal Cell. Thomson and colleagues reported theirs in the journal Science.
The new cells are called induced pluripotent stem cells and look and act much like embryonic stem cells -- the master cells that give rise to every cell and tissue in the body.
Both teams used just four genes to transform ordinary skin cells called fibroblasts into induced pluripotent stem cells -- iPS cells for short.
Yamanaka's team got the cells to develop into heart cells, which then beat in unison.
Each method is likely to be patented separately.
Both teams said the new cells are not ready to use in people yet because they used a type of virus called a retrovirus to carry the new genes into the skin cells. It is not clear whether this virus might cause genetic mutations that could cause cancer or other side effects.
"Even though we have this nice new source of cells it doesn't solve the downstream problem of getting them into the body and functioning," Thomson added.
The discoveries also were unlikely to resolve the long-running political and ethical debate about stem cells.
The controversy has split the U.S. Congress along unusual lines, pitting staunch abortion opponents such as Utah Republican Sen. Orrin Hatch, who supports human embryonic stem cell research, against equally conservative Kansas Republican Sen. Sam Brownback, who opposes it.
"This exciting breakthrough means that we can conduct embryonic-type stem cell research without destroying human life, and I call on supporters of embryonic stem cell research to recognize that we have no realistic need to destroy embryos," Brownback said in a statement.
But Democratic Sen. Tom Harkin of Iowa agreed with Thomson, who said it is too early to abandon embryonic stem cell research.
"Scientists may yet find that embryonic stem cells are more powerful," Harkin said in a statement. "We need to continue to pursue all alternatives as we search for treatments for diabetes, Parkinson's, and spinal cord injuries."
(Editing by Bill Trott)