Cellular Senescence and Aging: Here’s What You Need to Know

Hate it or embrace it, we all recognize the telltale signs of aging – the ever-increasing wrinkles, the gradually stiffening joints, the graying hair. But did you know that there’s a process behind all of this that works on a cellular level? Keep reading to learn more about senescence and aging.



Reference LAB

July 15, 2020

01What is cellular senescence?

Cellular senescence is one of the nine major hallmarks of aging. Derived from the Latin root senex, meaning “old age,” senescent cells accumulate when environmental and internal stressors drive the loss of cell division[ 1 ].

Cellular senescence is a natural process that occurs throughout our entire lifespan. From the very start, our cells are constantly dividing and replicating in order to replace old and damaged cells. As we age, numerous forms of damaging stimuli, like DNA damage or oncogenic stress, contribute to the cessation of cell division and cause cells to enter into cellular senescence. Senescent cells emit chemical signals to encourage nearby healthy cells to enter into a senescent state and contribute to age-related diseases.

Mapping senescent cell accumulation with age using beta-galactosidase staining. Senescent cells are shown here in blue.

02So, what’s the impact of cellular senescence on my health?

When we’re young, our bodies are able to clear senescent cells (the dying, old cells) from our body in order to make room for young and healthy cells. However, as we age, not only do we have an increase in cellular senescence but our bodies also become less efficient at clearing these cells. This results in the accumulation of senescent cells in our body tissues, including our skin (Figure 1).

Aged skin is characterized by an accumulation
of flattened, senescent cells, leading 
to a decrease in epidermal thickness, 
abnormal pigmentation (shown in brown) and 
inflammation (shown in blue and red dots).

03Cellular senescence and aging

And there’s more. Just like a rotten apple begins to brown and sends rotting signals to neighboring apples, senescent cells behave in a similarly aggravating way to neighboring cells. Additionally, the signals senescent cells exude are pro-inflammatory and create an environment that’s well suited for the development of chronic diseases[ 2 ]. As a result, research demonstrates that senescent cells are regarded as one of the main drivers of aging and age-related diseases, such as cancer and heart disease.

The sad truth is that the senescent cells in our skin can contribute to an increased presence of wrinkles, susceptibility to skin cancer, and a damaged skin barrier (which normally helps protect the body against external pathogens) (Figure 2). When left to linger in tissues, these senescent cells cause inflammation and lead to an increased rate of aging[ 3 ]. Suffice it to say, it’s hard to think positively about growing old when faced with that.

04Slowing down cellular senescence and aging

So, is it possible to slow down cellular senescence and aging? The good news is that studies are now discovering[ 4 ] that this process is potentially more reversible than we’ve been led to believe. As scientists continue to focus on longevity and healthspan, research has shown that there are ways to actually slow down the accumulation of these senescent cells and, in turn, slow down the aging process.

And on that tantalizing cliffhanger … let’s just say we’ve got you covered in a future post!

References
  • [1] van Deursen, Nature, 2014.
  • [2] Schosserer et. al. Front. Oncol., 2017.
  • [3] Zimmer, The Scientist, 2020.
  • [4] Zumerle et al. Nature Cell Biology, 2020.