What is Cellular Senescence?

Written and Reviewed by: Elysium Health

What is Cellular Senescence?

Key Takeaways:

  • Cellular senescence is a phenomenon in which cells cease to divide but remain metabolically active. It’s triggered by common cellular stressors.

  • As we age, our immune system’s ability to clear senescent cells declines. As senescent cells accumulate, they can secrete problematic molecules which impact neighboring healthy tissues.

  • Senolytics are compounds that selectively target senescent cells and aid in their removal. 

Related Product:

  • Senolytic Complex: Based on leading institutional research in the field of cellular senescence, the Senolytic Complex contains senolytic compounds proven to clear human senescent cells in laboratory studies. 
  • Format: An advanced immune support system consisting of a daily immune supplement and a twice-monthly, intermittent senolytic complex for clearing senescent cells and targeting immune aging.


The Hayflick limit suggests that a normal human cell can replicate and divide roughly fifty times before it cannot divide anymore (this is known as ‘replicative senescence’). Certain stressors mean that a cell can become senescent before it reaches the Hayflick limit.

Cellular senescence is a phenomenon in which cells cease to divide but remain metabolically active. This means they are still ‘alive’ and growing, creating energy, and generating and eliminating waste. A senescent cell is notably enlarged, which is due to their growth in the absence of division. 

Common cellular stressors—such as oxidative stress, DNA damage, and mitochondrial dysfunction—can also trigger cellular senescence in cells before they lose their ability to proliferate. Though no longer able to divide, because senescent cells remain metabolically active, they secrete numerous pro-inflammatory and proteolytic (enzymes that break down protein) factors as part of the senescence-associated secretory phenotype (‘SASP’), a profile marked by the secretion of proinflammatory cytokines, among other damaging mechanisms. These SASP factors are thought to stimulate the removal of senescent cells by the immune system.

Senescent cells have been shown to accumulate with age; a phenomenon that impedes innate and adaptive immune responses.

As the burden of senescent cells increases, the SASP can alter the local microenvironment, altering tissue structure and function. Whether the increasing burden of senescent cells impairs immune function, or the failure of the aging immune system to remove senescent cells enables their accumulation, remains to be understood.

What is immunosenescence?

Immunosenescence broadly describes age-related decline in the immune system. Cells of the immune system, such as B, T, and NK (Natural Killer) cells, are crucial to a robust immune system. B cells are responsible for producing antibodies, while T cells provide cell immunity. NK cells are part of the innate immune system which is the first line of your body's defense.

These cells have been shown to become senescent in healthy elderly individuals, which is believed to contribute to age-related immune decline. For instance, senescent B cells have an impaired ability to proliferate, differentiate, and generate an optimal antibody response.  Senescent immune cells are also believed to contribute to age-related inflammation – or inflammaging – observed in older adults, owing to the unique SASP that they acquire.

Senolytics and the immune system

Techniques to remove senescent cells from the body, using a class of compounds called senolytics, like those found in our advanced immune product Format and standalone Senolytic Complex are emerging as a viable approach to alleviate conditions associated with increased senescent cell burden and to support healthy cellular aging. Senolytics selectively target senescent cells’ pro-survival mechanisms, without compromising the viability of neighboring healthy cells. In this sense they are like special ops—sent in to take care of very specific issues without negatively impacting their surroundings. 

By targeting senescent cells, senolytics actually support a healthy aging process on a cellular level within the body, thus promoting the proper function of tissues and organs within the body and supporting the immune system.


Get Elysium news, subscriber-only product offers, and a monthly digest of new research in the field of aging. Sign up for our newsletter.

Related Articles:

Did You Know You Have Two Types of Immune Systems?

Did You Know You Have Two Types of Immune Systems?

The immune system consists of two main components—the innate and adaptive immune systems. Think of the innate immune system as the first line of defense—it is nonspecific and responds in the same way to all pathogens. In contrast to the fast-acting innate immune system, the adaptive immune system takes longer (days to weeks) and is highly targeted.
Can You Really Boost Your Immune System?

Can You Really Boost Your Immune System?

The idea of “boosting” your immune system is an understandably appealing concept—who wouldn’t want a supercharged immune system that goes above and beyond to keep you healthy? The reality, however, is a bit more complex.
What is Autophagy?

What is Autophagy?

Autophagy is a process where our cells remove components that are no longer functional or necessary and recycle them to build healthy new ones. This “cellular housekeeping” is crucial for immune health and the body’s ability to respond to immune aging.