The Bush-approved embryonic stem cell line has been found to be contaminated by an animal sugar already known to find its way into cultures of ordinary human cells. This means they cannot be used for any human therapies and it calls into question all scientific work carried out on the cells. Most experts are calling for new lines to be established.
The article is available here: http://www.newscientist.com/article.ns?id=mg18524844.500
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