UCLA Scientists Rejuvenate Aging Mouse Muscle but Warn of Hidden Stem Cell Survival Trade-Offs

UCLA researchers uncover a "survival trade-off" in aging muscle stem cells, where the protein NDRG1 slows healing to prevent total cellular depletion.

By: AXL Media

Published: Feb 24, 2026, 8:18 AM EST

Source: The information in this article was sourced from University of California - Los Angeles Health Sciences

The Hidden Mechanism Behind Slowed Tissue Repair

As biological systems age, the ability of skeletal muscle to regenerate after trauma significantly diminishes, a process long attributed to simple cellular exhaustion. However, new research from UCLA suggests that muscle stem cells do not necessarily lose their functional capacity, but instead undergo a fundamental shift in priorities. According to the study published in Science, older stem cells accumulate high concentrations of a specific protein that inhibits their activation. This shift effectively places the cells in a state of suspended animation, making them less responsive to injury signals while paradoxically ensuring their continued presence within the aging body.

Identifying the Protein Brake in Aging Muscle

The research team, led by Dr. Thomas Rando, pinpointed a protein known as NDRG1 as the driver of this cellular sluggishness. In comparisons between young and old mice, the researchers found that NDRG1 levels were 3.5 times higher in aged cells. This protein functions by dampening the mTOR signaling pathway, which is the primary molecular engine responsible for cell growth and tissue repair. According to the findings, this internal "brake" prevents stem cells from immediately transitioning into the repair phase after an injury, explaining the characteristic delay in healing observed in older subjects.

Reversing Age Related Decline Through Genetic Inhibition

To test if they could restore youthful function, scientists blocked NDRG1 activity in mice equivalent in age to 75-year-old humans. The results were immediate and dramatic, as the older muscle stem cells began to activate and repair tissue with the speed and efficiency of younger cells. According to Jengmin Kang and Daniel Benjamin, the study’s lead authors, removing this protein barrier effectively "reprograms" the cells to ignore the stresses of the aging environment. This suggests that the machinery for rapid repair remains intact within the cells but is held back by the high NDRG1 concentrations.