Manipulating muscle stem cells in older people could promote regeneration and prevent muscle breakdown.

Bradley Olwin at the University of Colorado Boulder and his colleagues demonstrated that a protein called p38 prevents stem cells in old muscles from renewing. When the authors took muscle stem cells from old mice and treated the cells with drugs to suppress p38, this allowed the stem cells to respond to growth signals and to replicate themselves.

In a separate study, Helen Blau and her colleagues at Stanford University in California grew old muscle stem cells on a gel while treating them with p38 inhibitors. The researchers then transplanted the stem cells into the muscles of living old mice, in which they began repairing the degenerating muscle tissue. When the group tested these muscles, they were stronger in response to a stimulus than muscles that had received non-treated stem cells.

Nature Med. http://doi.org/rhg; http://doi.org/rhh (2014)