The University of California-Berkeley bioengineers say their achievement sets the path for research on new treatments for age-related degenerative conditions such as muscle atrophy or Alzheimer's and Parkinson's diseases.

The scientists identified two key regulatory pathways that control how well adult stem cells repair and replace damaged tissue. They then tweaked how those stem cells reacted to biochemical signals to revive the ability of muscle tissue in old mice to repair itself nearly as well as the muscle in much younger mice.

Assistant Professor Irina Conboy who led the research said because the findings relate to adult stem cells that reside in existing tissue, the approach to rejuvenating degenerating muscle eliminates the ethical and medical complications associated with transplanting tissues grown from embryonic stem cells.

"We are one step closer to having a point of intervention where we can rejuvenate the body's own stem cells so we don't have to suffer from some of the debilitating diseases associated with aging," said Morgan Carlson, the study's lead author.

The findings are reported in the online edition of the journal Nature.