Stem Cells, Exercise, and Muscle Repair: Dr. Marni Boppart Study

Exercise triggers stem cells needed for muscle repair. It helps reduce the risk of death from heart disease and stroke. It helps prevent diabetes, strengthens bones and enhances immunity against illness. It lifts depression, lifts your spirits and releases chemicals in your brain that give you an overall sense of wellbeing. It clears the mind, helps you concentrate and enhances mental processing. It may lengthen your lifespan.

It’s regular exercise — and for the past 20 to 30 years, we’ve known its benefits. Surely, you know that exercise is good for your health—but did you know just how good it is?

Working with lab mice, scientists from the University of Illinois have found that a single bout of exercise leads to an increase in the type of stem cell that helps skeletal muscles heal from injury or disease.

What this discovery means is that scientists can develop new therapeutic techniques to treat injured muscles and prevent or restore the muscles in people whose muscles have atrophied.

People lose muscles naturally, as they age. But their muscles can also atrophy from disuse and disability—when an illness forces them to take a prolonged bed rest, for instance, or when they have to wear a cast after an accident.

People’s muscles also atrophy when they are sick with atrophying nerve diseases like poliomyelitis, Lou Gehrig’s disease or amyotrophic lateral sclerosis, Charcot Marie Tooth syndrome (CMT) and Guillain-Barré syndrome, or atrophying muscle diseases like muscular dystrophy, myotonia congenital and myotonic dystrophy.

What’s worse is that atrophying muscles don’t only lessen a person’s physical strength, but also increase the risk for metabolic diseases like obesity, diabetes and cardiovascular disease.

Building on previous research that showed that mesenchymal stem cells (MSCs) developed in skeletal muscles in response to muscle tissue damage and inflammation induced deliberately by scientists with injections of chemicals, the University of Illinois researchers set out to investigate if MSCs also responded to strain during exercise—and if so, how.

What the researchers found, for the first time, was that MSCs in muscle or muscle-derived mesenchymal stem cells (or mMSCs) are very responsive to mechanical strain, accumulating in muscles of mice after just one exercise session.

Found throughout the body, MSCs—like other stem cells—can differentiate into a variety of cell types needed to regenerate damaged tissue. The study found that mMSCs also indirectly facilitate tissue healing.

“Since exercise can induce some injury as part of the remodeling process following mechanical strain, we wondered if MSC accumulation was a natural response to exercise and whether these cells contributed to the beneficial regeneration and growth process that occurs post-exercise,” says lead researcher, Dr. Marni Boppart, kinesiology and community health professor at the University of Illinois.

Cellular basis for muscle health
The researchers then determined that while mMSCs don’t directly contribute to building new muscle fibers, they provide the cellular basis for enhanced muscle health following exercise by releasing growth factors that spur other cells in muscle to fuse and generate new muscle.

“What we’ve been able to show in this paper and our current work is that mMSCs are not directly contributing to muscle growth, but do in fact secrete a variety of different factors that positively impact muscle growth” says Dr. Boppart.

According to the University of Illinois researchers, it’s important to understand the body’s responses to factors like exercise and injury because identifying “the critical mechanisms that underlie beneficial adaptations to physical activity can be informative in the development of effective molecular- or cell-based therapies.”

“We are very excited because this work is an important step towards developing effective interventions that can prevent the loss of muscle that occurs with aging and disease,” concludes Dr. Boppart, who is also affiliated with the University of Illinois Beckman Institute for Advanced Science and Technology.

“The fact that MSCs in muscle have the potential to release high concentrations of growth factor into the circulatory system during exercise also makes us wonder if they provide a critical link between enhanced whole-body health and participation in routine physical activity,” he adds.

The team published its findings in the journal PLoS One.

Preliminary data suggests that MSCs becomes deficient in muscle with age, and Dr. Boppart’s team wants to find out next if mMSCs contribute to the decline in muscle mass over a person’s lifetime.

Over the long haul, the team also says it hopes to develop a therapy that combines molecular and stem-cell-based strategies to prevent age-related muscle loss.

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