The BBC provides an overview of recent research into why stem cells fail with age and what can be done about it: "The study found special stem cells come to the rescue of damaged young muscles, but are not triggered in older ones. ... tests on mice suggest something in young blood spurs the stem cells into action to repair the muscle damage. ... We need to consider the possibility that the niche in which stem cells sit is as important in terms of stem cell aging as the cells themselves. ... This is an exciting leap in the research. It proves the fact that you can reverse this problem. But it's no small task to identify the factor in the blood that's involved." It's good to see this work gaining wider notice.