Senescent cell subtypes do not respond equally to treatment, study shows

A new research paper was published in Volume 17, Issue 8 of Aging-US on August 7, 2025, titled “Senescent cell heterogeneity and responses to senolytic treatment are related to cell cycle status during senescence induction.”

This study, led by first authors Francesco Neri and Shuyuan Zheng, together with corresponding authors Denis Wirtz, Pei-Hsun Wu, and Birgit Schilling from the Buck Institute for Research on Aging, the USC Leonard Davis School of Gerontology, and Johns Hopkins University, reveals that not all aging cells behave the same. The researchers identified key differences between senescent cell subtypes that may influence how well they respond to senolytic drugs. These findings could help guide the development of more effective therapies for age-related diseases.

Senescent cells are aged or damaged cells that stop dividing and accumulate in tissues over time. While they play a role in wound healing and protecting against cancer early in life, they can drive chronic inflammation and tissue decline with age. Researchers are exploring ways to selectively remove these cells using senolytic drugs. However, the large variety of senescent cell types has made it difficult to design treatments that work for all of them. This study aimed to better understand the functional differences among senescent cell subpopulations.

Using high-resolution imaging, the team analyzed thousands of human endothelial and fibroblast cells growing in the lab. They observed that cells that exited the cell cycle (stopped dividing) in a later phase showed stronger signs of senescence and were more sensitive to senolytic treatment. These cells also produced more IL-6, a molecule associated with inflammation. The findings suggest that DNA content, which varies depending on the cell cycle phase, plays an important role in how aging cells function and how they respond to drugs.

“We found that G2-arrested senescent cells feature higher senescence marker expression than G1-arrested senescent cells.”

This is the first clear evidence that senescent cells do not all respond equally to treatment. The results suggest that future senolytic therapies could be more successful if they are designed to target specific subtypes of senescent cells, especially those with greater inflammatory potential.

While this research was conducted in laboratory cell cultures, it provides a foundation for studying how these findings apply to living tissues. Future work will examine whether similar patterns occur in the body and how this knowledge could lead to more precise and effective treatments for age-related conditions. Understanding the diversity of aging cells is key to developing therapies that are both safer and more targeted.