In a new study, researchers found that regular exercise restores youthfulness to tissue repair.
In older animals, muscle stem cells start to look and behave like those of much younger animals.
The researchers also identified a molecular pathway involved in turning back the clock on the cells. Drugs that manipulate the pathway might be an effective substitute for exercise, they suggest.
The research was conducted by a team at Stanford School of Medicine.
Unlike embryonic or induced pluripotent stem cells, which can give rise to any tissue in the body, tissue-specific stem cells are restricted in their potential.
Muscle stem cells wait in the wings along the muscle fibers in a resting state known as quiescence until called upon to repair the damage.
Previous research has shown that tissue regeneration decreases with age and that this is due to a declining function in adult stem cells.
Many researchers are looking for a way to restore youthfulness.
While no researchers have discovered a reliable fountain of youth, it’s well known that certain lifestyle adjustments can be beneficial.
Exercise is known to reduce the risk of a wide variety of age-related problems, including cardiovascular disease, cancer, and perhaps even Alzheimer’s disease.
There’s a lot of interest in understanding how exercise confers these health benefits.
In particular, the researchers wanted to know whether and how voluntary exercise affects the function of muscle stem cells in mice.
The animals were exercising at the intensity levels at which they were comfortable, much like what people do for their own health.
This is a less stressful situation than resistance training or intense endurance exercise, which may themselves affect muscle stem cell function.
The team showed that the muscle stem cells of the exercising animals remained quiescent and that the animals did not develop big numbers of new muscle fibers in response to the exercise.
After three weeks of nightly aerobics for the active groups, the researchers compared the ability of the animals to repair muscle damage.
They found that the aged, sedentary mice were much less able to repair muscle damage than younger sedentary mice.
However, the older animals that had exercised regularly were much better at repairing muscle damage than were their counterparts that did not exercise.
This exercise benefit was not observed in younger animals.
Similar results were obtained when muscle stem cells from older mice that had exercised were transplanted into younger mice.
The stem cells from the exercising animals contributed more to the repair process than did those from their sedentary peers.
The researchers say that exercise stimulates the production of some factors that then circulate in the blood and enhance the function of older stem cells.
If there is a drug that mimics this effect, people may be able to experience the benefit without having to do months of exercise.
One author of the study is Thomas Rando, MD, Ph.D., professor of neurology, and neurological sciences.
The study is published in Nature Metabolism.
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