Scientists find embryonic stem cells available under limited federal guidelines tainted.
Writing in the journal Nature Medicine, researchers said they found batches of available stem cells were contaminated with a non-human molecule called N-glycolylneuraminic acid (Neu5Gc) The molecule is found on the surface of animal cells but not on human cells, and is attacked by the human immune system.
The study's lead authors - Dr. Ajit Varki, of the University of California at San Diego and Dr. Fred Gage of the Salk Institute - said the only way to circumvent the finding is to grow new cell lines in ways that avoid animal contaminants. However, under the current guidelines federal funds cannot be used to create new uncontaminated stem cell batches.
"The human embryonic stem cells remained contaminated by Neu5Gc even when grown in special culture conditions with commercially available serum replacements, apparently because these are also derived from animal products," Varki said in a statement. "It would seem best to start over again with newly derived human embryonic stem cells that have never been exposed to any animal products. However, such an approach could not be pursued under existing rules for the use of federal grant dollars."
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|Article Type:||Brief Article|
|Date:||Jan 31, 2005|
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