From MSNBC:
One of the medical marvels of stem cells is that they continue to divide and renew themselves when other cells would quit. But what is it that gives stem cells this kind of immortality? Researchers report in the journal Nature that microRNAs — tiny snippets of genetic material that have now been linked to growth regulation in normal cells as well as cancer growth in abnormal cells — appear to shut off the “stop signals” or brakes that would normally tell cells to stop dividing. “What we think we see is that there is a special mechanism to get rid of the brakes,” said University of Washington biochemist Hannele Ruohola-Baker, a leading member of the research team.
Stem cells have been the focus of intense research interest because of their role in regenerating all the body’s tissue types, from blood cells to brain cells. MicroRNAs could conceivably be harnessed to give a boost to aging stem cells, or even add some of the qualities of stem cells to more ordinary types of cells.
More here.