Researchers discover a molecular signature to flag dysfunctional aging cells

UCLA researchers have identified a rogue population of immune cells that quietly accumulates in aging tissues and in the livers of people with fatty liver disease. Clearing these cells, they found, dramatically reduced inflammation and reversed liver damage in mice - even while the animals remained on an unhealthy diet.

The study, published in Nature Aging, centers on a process called cellular senescence, a stress response in which cells stop dividing but refuse to die. Instead of quietly fading away, these so-called "zombie cells" linger in tissues and pump out a toxic cocktail of inflammatory signals.

"Senescent cells are fairly rare, but think of them like a broken-down car on the 405," said Anthony Covarrubias, senior author of the study and a member of the Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research at UCLA.

Just one stalled car can back up traffic for miles. Now imagine five or ten of them slowly accumulating. That's what these cells do to a tissue: even a small number causes enormous disruption."