Friday, September 26, 2008
By Rob Stein
The Washington Post

WASHINGTON -- Scientists are reporting they've overcome a major obstacle to using a promising alternative to embryonic stem cells, bolstering prospects for bypassing the political and ethical tempest that has embroiled hopes for a new generation of medical treatments.

The researchers said they found a safe way to coax adult cells to regress into an embryonic state, alleviating what had been the most worrisome uncertainty about developing the cells into potential cures.

"We have removed a major roadblock for translating this into a clinical setting," said Konrad Hochedlinger, a Harvard University stem cell researcher whose research was published online yesterday by the journal Science. "I think it's an important advance."

"This is a huge step forward -- it could be the breakthrough we've been looking for," said Dr. Robert Lanza, a stem cell researcher at Advanced Cell Technology in Worcester, Mass.

Embryonic stem cells are believed to be capable of becoming any type of cell in the body. Researchers hope eventually to use them to create replacement tissue and body parts tailored to individual patients.

But the work has been mired in controversy because the cells were obtained by destroying very early embryos. As a result, President Bush has restricted federal funding for such work.

Scientists last year shook up the scientific and political landscape by discovering how to manipulate genes in adult cells to revert them into the equivalent of embryonic cells -- entities dubbed "induced pluripotent stem," or "iPS," cells -- which could then be transformed into any type of cell in the body. Work since has found that the cells can alleviate symptoms of Parkinson's disease and sickle-cell anemia in mice.

But the first iPS cells were created by ferrying four genes into the DNA of adult cells using retroviruses, which can cause cancer in animals. There was also concern because the viruses integrated their genes into the cells' DNA in the course of transforming them.

In the new work, Dr. Hochedlinger and his colleagues used a different type of virus, known as an adenovirus, which does not integrate its genes into a cell's DNA and thus is believed to be harmless, to ferry the same four transformative genes into the DNA of mouse skin and liver cells.

"The adenovirus will infect the cells, but then will clear themselves from the cells. After a few cell divisions, there are no traces of the virus in the cell," he said.

Tests showed that the cells were indistinguishable from embryonic stem cells and could be transformed into any type of tissue -- including lung, brain, heart and muscle.

First published on September 26, 2008 at 9:15 am

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