Why stem cells lose capacity to repair damaged muscle with aging revealed

A new study has revealed the reason behind why when people get older; the stem cells in their bodies start to lose the ability to repair even the normal muscle damage.

Researchers from the Ottawa Hospital Research Institute and University of Ottawa have discovered as muscle stem cells age, their reduced function was a result of a progressive increase in the activation of a specific signalling pathway. Such pathways transmit information to a cell from the surrounding tissue. The particular culprit identified was called the JAK/STAT signalling pathway.

What's happening was that the skeletal muscle stem cells are not being instructed to maintain their population. As peopleget older, the activity of the JAK/STAT pathway shoots up and this changes how muscle stem cells divide. To maintain a population of these stem cells, which are called satellite cells, some have to stay as stem cells when they divide.

With increased activity of the JAK/STAT pathway, fewer divide to produce two satellite cells (symmetric division) and more commit to cells that eventually become muscle fibre. This reduces the population of these regenerating satellite cells, which results in a reduced capacity to repair and rebuild muscle tissue.

Dr. Michael Rudnicki, senior scientist at the Ottawa Hospital Research Institute and his team was now exploring the therapeutic possibilities of drugs to treat muscle-wasting diseases such as muscular dystrophy.

The study is published in the influential journal Nature Medicine.