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Cell Senescence and Ageing

Updated: May 25

You may or may not be familiar with the term cell senescence, but this process is a crucial element of ageing, and age-related disease - skin ageing included.

So, what is it?

To understand cell senescence, we first must note that human cells are dividing all the time, to create new, healthy cells. Most cells cannot divide forever - they have a limit, and when they reach this limit, they normally die (through apoptosis, AKA, programmed cell death).

This system means we have new healthy cells being produced all the time, and old, damaged cells that have reached their division limit, will die and be cleared away. There is however, an exception to this system - cell senescence.

Cell Senescence is when human cells that can no longer divide (despite having optimal growth conditions, and stimuli to do so), do not die. They instead resist apoptosis, and stay alive - no longer capable of dividing, but still metabolically active.

Senescent cells release pro-inflammatory molecules (inflammatory cytokines, interleukins, and growth factors).

Over our lifetime, our tissues accumulate senescent cells, which create an inflammatory environment that affects surrounding healthy cells and contributes to age-related diseases including cardiovascular disease, Alzheimer's disease, osteoarthritis, and of course - skin ageing, and general ageing.

In a skin-specific context - an accumulation of senescent keratinocytes (skin cells) and fibroblasts (collagen + elastin + hyaluronic acid producing cells) in the skin, leads to structural deterioration and decreased function of the skin.

The bottom line here is: chronic inflammation is detrimental to our health, and ultimately ages us faster.

The benefits

Cell senescence does have a purpose - it prevents cancer by stopping the replication of damaged cells, and the molecules and compounds secreted by senescent cells play important roles across our lifespan including in embryonic development, and in wound healing.

Senescence is in fact, a natural mechanism that our body needs - to a degree. The problem arises only when we accumulate senescent cells in excess, typically in our older age.

DNA damage and oxidative stress, are two "extrinsic" triggers of cell senescence that can accelerate accumulation of senescent cells. We can of course, make lifestyle alterations to avoid these triggers - again, in a skin-specific context, this would look like:

  • consistent use of sun protection

  • use of topical antioxidants (this includes vitamins A, B, and C)

  • utilising DNA repair enzymes as seen in the Aspect Platinum product range

But from both a skin health perspective, and a general health perspective - minimising DNA damage and oxidative stress looks like:

  • eating foods that are rich in antioxidants

  • exercising regularly

  • limiting intake of processed foods

  • limiting or cutting out alcohol

  • prioritising stress management where possible

  • avoiding smoking or vaping

Medical Advancements

The field of senotherapeutics, refers to research into cellular senescence and ways to counteract it.

There are two kinds of medications that can affect cellular senescence: senomorphics, and senolytics.

Senomorphics work by reducing the harm caused by senescent cells (or more accurately, reducing the harm caused by their secreted molecules).

Senolytics on the other hand, work by inducing apoptosis (cell death) in senescent cells, getting rid of them entirely.

Quercetin is an example of a senolytic, a flavonoid found in various plants and foods with a well established antioxidant anti-inflammatory and immunoprotective profile. 

Metformin, is an example of a senomorphic medication, and one that is being explored for its potential as an "anti-ageing/longevity boosting" drug. Some dermatologists and GPs are already prescribing it this way (even in New Zealand).

Our understanding of cell senescence is rapidly evolving, as is the field of senotherapeutics. There is still a lot of research to be done, but at this stage it is an exciting new frontier in anti-ageing that has a lot of potential - not only from a skin ageing perspective, but for our elderly population and for those who suffer from age-related diseases.

All of the information surrounding cell senescence, just reaffirms the importance antioxidants, topical skin care, and lifestyle factors in a positive ageing experience.

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