Scientists Discover Why ‘Zombie Cells’ Build Up as We Age

Scientists have uncovered a possible reason why so-called “zombie cells” become harder for the body to remove as people grow older.

The cells, formally known as senescent cells, have stopped dividing normally but can remain alive inside tissues. While some senescent cells play useful roles during processes such as wound healing, their long-term accumulation has been linked to inflammation and several age-related diseases.

A new study led by researchers at Albert Einstein College of Medicine and published in Nature Aging on October 5, 2026, points to a decline in a cellular recycling system called chaperone-mediated autophagy, or CMA.

CMA helps cells identify and break down damaged or unnecessary proteins. The researchers found that this recycling process becomes less active with age, affecting both senescent cells and macrophages — immune cells responsible for clearing unwanted cells and debris.

In experiments, older cells failed to increase their CMA activity when they became senescent. This allowed certain unwanted proteins to accumulate and contributed to the release of substances that could affect nearby healthy cells.

At the same time, older macrophages showed reduced CMA activity and became less effective at engulfing and removing senescent cells.

The researchers also tested a small molecule called CA77.1 that activates CMA. In aged mice, several months of treatment reduced the buildup of senescent cells and signs of inflammation and fibrosis.

The findings may eventually help scientists develop new approaches to age-related diseases. However, the research is still at an experimental stage. Most of the work was conducted in mice, while analyses of human lung tissue were used to investigate whether the biological mechanism could also be relevant to people.

The researchers say the next challenge is determining whether restoring this cellular recycling system can be developed into a safe and effective treatment for humans.

The discovery offers a different way of thinking about aging. Instead of simply trying to destroy “zombie cells,” scientists may eventually be able to help the body’s own immune system recognize and remove them more effectively.

Source: Albert Einstein College of Medicine; Nature Aging