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Researchers `Turn Back Clock,' Reverting Adult Cell to Embryonic Stem Cell
By HELEN BRANSWELL
The Canadian Press
22 August 2005
TORONTO (CP) - Researchers at Harvard University have managed to reprogram adult skin and bone cells, teaching them how to revert to embryonic stem cells with all the potential for therapeutic regeneration those progenitor cells hold.
Though the process is far from ready for prime time, experts suggested Monday it points to a day when cells from an individual could be used to grow new tissues that would be an identical genetic match to the donor, avoiding the rejection problems associated with transplantation.
It would also provide researchers with an easy and accessible source of embryonic stem cells, a source untainted by the controversy that currently surrounds stem cell generation.
Embryonic stem cell lines _ considered the most malleable form of these important cells _ are currently generated from discarded fetuses, a practice opposed by many religious conservatives including U.S. President George Bush who has imposed funding restrictions on such work in the United States.
A leading Canadian expert said the Harvard team's work opens new vistas for stem cell research.
"What this paper really defines is really most likely step 1 of many 10, maybe 100 steps before achieving that Holy Grail, which is: How do you take a normal cell in the adult and make it behave like an embryonic stem cell and reprogram it?" said Mick Bhatia of the University of Western Ontario.
"We need to figure that out. But this is the first step in saying: Hey, you know what? That is something that is achievable."
In a scientific paper to be published in Friday's issue of Science and released early by the journal, the authors describe how they turned back time for adult skin and bone cells by fusing them to embryonic stem cells.
Adult skin and bone cells were induced to behave exactly like embryonic stem cells after going through the process, the authors noted.
"It set back the clock on an adult cell to the embryonic state," senior author Kevin Eggan said in a conference call with media.
"By every battery of assays we have for testing embryonic stem cells, we saw that these hybrid cells looked like ES (embyronic stem) cells."
Embryonic stem cells can "differentiate" or mature into any type of tissue, and the reprogrammed cells appeared to have that skill. The researchers enticed them to mature into nerve cells, hair follicles, muscle cells and cells from the gut.
However, the fused cells carried a full set of genes from both the adult and the embryonic stem cells. Researchers need to figure out a way to strip out the embryonic stem cell genes while still maintaining the adult cells in their reverted state before this process of stem cell generation could be used for perfectly matched tissue transplantation, for instance.
The researchers hope that in the process of finding out how to do that they will learn how to reprogram adult cells without the need for embryonic stem cell material.
"If we or some other group are able to figure out how to remove the embryonic stem cell chromosomes, either before or after fusion and still have the cells maintain that activity, it could be a complete solution and one would no longer need oocytes (human eggs)," Eggan said.
Bhatia, who in January will take directorship of a newly created stem cell research institute at McMaster University in Hamilton, said he and his team have been kicking around the notion of attempting similar work, using adult bone marrow cells.
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