Experiments done on mice indicate it may be possible to reverse certain aspects of the again process. Researchers at Harvard Medical School used a chemical called NAD to rejuvenate muscle in mice. They say the results were similar to transforming muscle in a 60 year old person into that of a 20 year old. Levels of NAD diminish in cells as people grow older. The researchers want to start clinical trials in 2015. Their study findings are published in the journal "Cell".