• Treatment with a combination of metformin and galantamine called RJx-01 enhances physical performance and strength while reducing inflammation and denervation – detachment of the nerve from muscle cells in aged mice. 
  • RJx-01 restores autophagy – the removal of cellular waste – and replenishes stem cells in aged mice. 

Susceptibility to the progressive loss of muscle mass and strength (sarcopenia) increases with age, posing a major health threat to the elderly population. Current evidence suggests that pairing strength training with a protein-rich diet is sufficient to delay this debilitating disease; however, this particular intervention isn’t always feasible, and current pharmacological interventions are quite limited, highlighting the need for novel, safe, and effective therapeutics. 

In a new study published in JCI Insight, researchers from the University of Padova in Italy explored the muscle protective effects of a novel drug cocktail (RJx-01) containing metformin and galantamine, two pharmaceutical compounds with well-established safety profiles and inherent biological properties that strongly imply their capacity to be utilized in the treatment of sarcopenia. Tezze and colleagues show that injecting aged and sarcopenic mice with RJx-01 improves physical performance and strength while reducing inflammation and denervation. Furthermore, the investigators demonstrate that RJx-01 treatment boosts autophagy and replenishes muscle stem cells in aged mice. 

RJx-01 Preserves Muscle Strength and Function

The Italian researchers previously demonstrated that RJx-01 successfully improves muscle structure and function in worms, indicating the potential to treat sarcopenia in mammals. With this in mind, Tezze and colleagues sought to determine if their preliminary findings translated to rodents, specifically mice modeling sarcopenia. 

Compromised muscle force and fitness are primary indicators of sarcopenia, and studies suggest that inflammation and nerve deterioration (denervation) exacerbate the decline of these functions. Accordingly, the investigators examined whether RJx-01 could mitigate inflammation and denervation while preserving these two primary functions. First, sarcopenic mice were injected with RJx-01, containing 410 mg/kg metformin and 3.28 mg/kg galantamine. Then, sarcopenic mice underwent strength and conditioning testing. 

The investigators found that RJx-01 significantly improved muscle strength, with treated mice exerting over 38% more muscle force than untreated controls. They also showed that treated mice ran significantly longer (3-fold increase) during the treadmill test than their untreated counterparts, suggesting that RJx-01 preserves muscle function and endurance. Moreover, untreated mice exhibited much higher inflammation and denervation than treated mice, indicating that RJx-01 improves muscle performance and fitness by suppressing inflammation and hindering denervation.  

(Tezze et al., 2023 | JCI Insight) RJx-01 enhances physical performance and fitness. (Left) Mice treated with RJx-01 (purple) have fewer denervated fibers than untreated mice (black) and mice treated with metformin (blue) or galantamine (orange) alone. (Middle/Right) Treated mice run significantly longer and exert more muscular force than all other experimental groups.

Notably, the findings demonstrate that metformin and galantamine likely work in synergy, as treatment with either metformin or galantamine alone failed to promote similar protective effects in sarcopenic mice. Following testing in sarcopenic mice, Tezze and colleagues proceeded to conduct similar testing in naturally aged mice (22 months old ~ 64 human years) to further elucidate RJx-01’s synergistic effects. The results showed that RJx-01 enhanced grip strength by 32%, increased running endurance, and reduced denervation, corroborating the data seen in sarcopenic mice and confirming RJx-01’s synergistic effects. 

RJx-01 Boosts Autophagy and Promotes Muscle Stem Cell Growth

Autophagy is perhaps one of the most vital longevity-linked processes, contributing to our muscles’ function and structural integrity. As autophagy falters with age, so do our cellular powerhouses (mitochondria), leading to muscle fiber deterioration, weak muscles, and reduced muscle mass. Given autophagy’s role in muscle health, Tezze and colleagues wanted to see if RJx-01 could restore autophagy activity in aged mice. Accordingly, the investigators measured the activity of two essential autophagy proteins (P62 and LC3) and found that RJx-01-treated mice displayed significantly higher levels of P62 and LC3 than untreated age mice, demonstrating that RJx-01 restores autophagy. 

While autophagy is paramount to muscle health and maintenance, studies also point to satellite cells (muscle stem cells) as crucial factors for stimulating skeletal muscle growth, development, and regeneration with age. Taking this into consideration, the investigators assessed RJx-01’s ability to promote satellite cell abundance in aged muscles. Upon observation, the results revealed that aged mice treated with RJx-01 contained significantly more satellite cells than untreated controls, indicating that RJx-01 promotes satellite cell growth in aged mice. 

(Tezze et al., 2023 | JCI Insight) RJx-01 boosts autophagy and increases satellite cell abundance in aged muscles. (Left) RJx-01-treated mice (purple) have higher levels of P62 and LC3 than untreated controls (black), indicating greater autophagy activity. (Right) Treated mice have more Pax7+ cells, indicating a higher abundance of satellite cells in aged muscles. 

RJx-01’s Potential as an Anti-Aging Intervention 

Collectively, the study’s findings suggest that RJx-01 enhances muscle function and fitness by increasing autophagy and satellite cell growth, two physiological processes that are essential beyond the scope of muscle health. Moreover, several studies have found that autophagy’s link to longevity lies in its pivotal role in regulating mitochondrial homeostasis, particularly through the recycling of defective mitochondria. This not only boosts cellular energy metabolism but also lowers oxidative stress, inflammation, and mitochondrial dysfunction, all of which are known drivers of aging and disease. 

RJx-01’s ability to stimulate autophagy highlights its potential to target multiple hallmarks of aging, and the fact that the compounds (metformin and galantamine) within RJx-01 have already been tested in humans means that this drug cocktail could hit the market much sooner than novel aging therapeutics. That being said, more studies are needed to shed light on RJx-01’s potential anti-aging applications.