Cellular senescence is a durable state in which a cell stops dividing in response to stress or damage while remaining metabolically active and often changing the signals it releases to nearby tissue.
Why cells become senescent
Cells can enter senescence after DNA damage, excessive replication, oncogene activation and other forms of stress. Stopping division can be protective because it prevents a damaged cell from continuing to proliferate.
Senescence is therefore not simply a failure state. It participates in normal processes such as development, wound repair and tumor suppression.
The senescence-associated secretory phenotype
Many senescent cells change the proteins and signaling molecules they release, a pattern often called the senescence-associated secretory phenotype, or SASP. Depending on cell type and context, these signals can recruit immune cells, alter tissue remodeling or promote inflammation.
There is no single universal marker that identifies every senescent cell. Researchers usually combine multiple molecular and functional measurements.
What changes with age
Senescent cells tend to accumulate in some tissues with age, while immune clearance and tissue repair also change. Animal studies have linked certain senescent-cell populations to age-related dysfunction, but human biology is more complex and effects differ among tissues.
NIH’s SenNet program is mapping senescent cells across human tissues and the lifespan to develop a more precise framework for where and when senescence matters.
Senolytics and what is still unknown
Senolytics are experimental approaches intended to remove selected senescent cells, while “senomorphics” aim to alter their harmful signaling. These strategies are active research areas, not established general anti-aging treatments.
Because senescence can be beneficial in some contexts, safely targeting it requires knowing which cells, at what time, in which tissue should be changed. Medical decisions should be based on evidence from appropriate clinical trials, not anti-aging marketing claims.
