Thursday, July 17, 2003, 1:05:12 PM CT
Adult human cells have been reset to a stem-like state by molecules in the nucleus of immature frog eggs.
John Gurdon from Cambridge University in the UK hopes that reprogramming ordinary adult cells from the skin or blood could yield a limitless supply of donor-matched stem cells.
These stem cells could be used to repair tissue damage in patients who suffer from such diseases as Parkinson's and multiple sclerosis.
Converting specialized adult cells into a more immature state could get around ethical and practical limitations of using stem cells from excess early-stage human embryos left over from fertility treatments.
Adult stem cells are more readily available but their potential is uncertain.
Stem cell marker
Reporting in the journal Current Biology (read abstract), Gurdon and colleagues describe injecting immature xenopus frog eggs with nuclei from adult mouse or human blood cells.
After two days, the researchers noticed that a molecule called Oct4 RNA -- a definitive stem cell marker -- appeared in the hybrid.
"This is the first step in reprogramming cells," developmental geneticist Wolf Reik of Cambridge told Nature News Service.
He cautions, however, that there might still be problems with the procedure as some genes remaining in their adult form could cause cells to become cancerous.
Molecules in the frog nucleus could be the reason for the egg's revitalizing abilities, and finding them could be a major step towards resetting adult cells.
"Frog eggs are large and easy to manipulate," cell biologist Rudolf Jaenisch of the Whitehead Institute in Cambridge, Massachusetts told Nature News Service.
"They give you a useful tool for finding the genes that are involved
in reprogramming," he says.
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