A groundbreaking study shows that by reactivating stem cells from aging mice’s muscles, researchers can significantly enhance muscle growth and recovery from injury. This innovative approach may pave the way for rejuvenating aging muscles in humans.

“Theoretically, if muscle stem cells from older individuals were extracted, rejuvenated, and reintroduced, we could see enhanced functionality,” states James White from Duke University, North Carolina.

Muscle stem cells typically remain dormant in muscle tissue but spring into action when damage occurs, facilitating the repair process. “Muscle tissue is particularly vulnerable to mechanical strain and relies on regeneration,” explains White. “The soreness you feel after a workout is a sign of muscle damage. Your immune system interacts with stem cells, enabling the repair of muscle tissue through the creation of new cells.”

As we age, however, the quantity of muscle stem cells diminishes, complicating the regeneration process. In experiments with mice, White and his team found that aging muscle stem cells exhibit a reduction in the enzyme glutaminase, which hampers the production of essential lipid molecules, such as palmitate and oleate. “Stem cells must significantly enlarge to become muscle cells, requiring lipids for building cell membranes and energy,” emphasizes White.

To address this deficiency, researchers harvested muscle stem cells from older mice and enriched them with additional palmitic and oleic acids. These enhanced stem cells were injected into the injured leg muscles of other aged mice, resulting in a 45 percent increase in muscle fiber growth compared to untreated stem cells. The mice also demonstrated improved mobility during treadmill tests and other physical assessments.

Similar reductions in glutaminase levels in human muscle stem cells with age may explain the observed decline in muscle mass, strength, and recovery capacity, which often leads to decreased mobility and an increased risk of falls.

Researchers propose that increasing glutaminase or lipid levels in muscle stem cells could mitigate or even reverse muscle degeneration, according to David Lee, also from Duke University. “We are currently exploring avenues to translate these findings into clinical applications,” he adds.

However, consuming glutaminase, palmitate, or oleate as oral supplements may not be effective, as inadequate amounts can reach the stem cells within the muscles. Furthermore, there is a potential cancer risk associated with these substances, as they are also utilized by cancer cells. White suggests a safer approach may involve extracting stem cells from older individuals, activating them with enzymes and nutrients in a lab setting, and reintegrating them into the body.

It is important to note that young athletes and bodybuilders may not achieve greater muscle growth or recovery through this method, as they typically do not experience a deficiency in stem cells. “Their muscles are already abundant with functional stem cells,” White remarks.

In related research, the Florida-based company Longveron is investigating the potential of injecting young individuals’ stem cells to rejuvenate muscle function and combat frailty in older adults. This involves harvesting mesenchymal stem cells capable of transforming into various cell types, including muscle cells, from healthy bone marrow donors aged 18 to 45. Clinical trials have shown promising results, with frail volunteers aged 75 to 80 able to walk more effectively after intravenous injections of young stem cells.