WEDNESDAY, Dec. 24, 2008 (HealthDay News) -- Researchers say they've found a formula to capture indefinitely the basic embryonic stem cells of a mammal, including long-sought rat stem cells.
If the findings hold up, scientists will then be able to mimic human disease in readily produced, genetically altered strains of rats. As humans and rats are physiologically very similar, medical study of rats is more directly applicable to people than mice. For example, people and rats tend to respond to drugs in a similar manner, while the rodents' larger size also makes them easier to work than, say, mice.
The new studies, conducted by teams at the University of Edinburgh in England and the University of Southern California (USC), Los Angeles, were published in the Dec. 26 issue of Cell.
Since 1981, researchers have been able to genetically alter mice embryonic stem cells to create and study disease models. They have been unable to capture and isolate the cells from rats or other animals.
Earlier in 2008, the simple two- to three-ingredient formula was shown to keep mice embryonic cells in their undifferentiated or "pluripotent" state, retaining their ability to later differentiate into any cell or tissue type. This allows them to multiply into generic stem cells.
Human embryonic stem cell lines do exist, but ethical concerns and other issues do not always make them the best or easiest cells to work with, study author Qi-Long Ying of USC, who worked on both studies, said in a news release issued by the journal's publisher.
"In the past two decades, embryonic stem cells have been routinely used to create loss of function (knockout) or gene replacement (knock-in) mutations by homologous recombination in the mouse, providing an invaluable tool for the functional characterization of genes," Ying's group wrote. "Now, the availability of true rat embryonic stem cells provides an opportunity to adapt the technology developed in the mouse to the rat."
The U.S. National Institutes of Health has more about stem cells.