Recipe for capturing authentic embryonic stem cells may apply to any mammal, stud...( Researchers have what they think may...)

Researchers have what they think may be a basic recipe for capturing and maintaining indefinitely the most fundamental of embryonic stem cells from essentially any mammal, including cows, pigs and even humans. Two new studies reported in the December 26th issue of the journal Cell, a Cell Press publication, show that a cocktail first demonstrated to work in mice earlier this year, which includes inhibitory chemicals, also can be used to successfully isolate embryonic stem cells from rats.

Authentic rat embryonic stem cells had never before been established.

The new discovery made in labs at both the University of Edinburgh and the University of Southern California (USC), Los Angeles, is a major breakthrough for biomedical research, said Qi-Long Ying, an author on both studies who was at the University of Edinburgh and is now at USC. That's because it will allow researchers to readily produce genetically altered strains of rats, with conditions that mimic human disease, in a very targeted way. Austin Smith led the team at the University of Edinburgh and Ying led the USC team.

Humans and rats are physiologically more similar than humans and mice, making the study of rats more directly applicable to people, and rats' larger size also makes them easier to work with in many cases, according to the researchers. Humans and rats also tend to have similar responses to drugs.

The findings lend support to the notion that embryonic stem cells will remain in their undifferentiated, pluripotent state when they are shielded from particular outside signals. (Pluripotent refers to the ability to differentiate into any cell or tissue type). Scientists had previously thought that the maintenance of stem cells depended on activating signals from outside, including growth factors and other chemicals.

Embryonic stem cells are derived from the inner cell mass of blastocysts. Blastocysts are hollow balls of cells that form in early
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