Cellular senescence: what it is and how it relates to skin ageing

When we think of an ageing cell, we probably imagine one that gradually works less effectively until it eventually dies.

Biology has other options.

One of them is rather more curious: the cell stops dividing, but remains alive and metabolically active.

This is what we call cellular senescence.

The concept has become one of the most widely studied areas in ageing and longevity research. And, as often happens, some of that vocabulary has now started to make its way into skincare.

But before we start talking about “reversing” ageing cells, it is worth understanding what senescence actually means and, above all, what we can demonstrate and what we cannot.

What is cellular senescence?

Cellular senescence is a state in which a cell undergoes a stable arrest of proliferation: it stops dividing, but remains alive and metabolically active.

It can arise in response to different situations, including DNA damage, oxidative stress, telomere shortening or successive cycles of cell division.

And here there is an important nuance:

senescence is not necessarily a bad thing.

It can act as a protective mechanism. In response to certain types of damage, stopping proliferation prevents a cell from continuing to divide under unsuitable conditions. Senescence is also involved in physiological processes such as wound healing and tissue remodelling.

The problem arises when certain senescent cells persist and progressively accumulate.

A senescent cell does not simply sit there doing nothing

We might imagine that a cell that has stopped dividing simply stays there, quietly retired.

Not exactly.

Senescent cells can change their morphology, metabolism and gene expression. Some also develop what is known as the SASP, or senescence-associated secretory phenotype.

This means that they release different signalling molecules into their surroundings, including cytokines, growth factors and enzymes capable of modifying the tissue around them.

A senescent cell can therefore alter the biological conversation with neighbouring cells and with the extracellular matrix.

And that is where the concept becomes particularly interesting when we try to understand the skin.

What happens when fibroblasts become senescent?

Fibroblasts are cells in the dermis involved in producing and remodelling the extracellular matrix.

Among other functions, they help maintain structural components such as collagen and elastin.

When some fibroblasts acquire characteristics associated with senescence, their proliferative capacity, morphology, response to stress and communication with their surroundings can change.

This means we need to broaden the traditional conversation about skin ageing slightly.

For a long time, the skincare explanation was:

as we age, we produce less collagen → therefore we need to stimulate collagen.

That is part of the story, but not the whole story.

Because behind collagen there are cells. And to understand how the structure of our skin changes, we also need to ask what happens to the cells responsible for maintaining it.

→ We explain this in more detail in Skin firmness: what really determines it and why we lose it with age.

Cellular senescence and ageing are not exactly the same thing

It is worth avoiding the temptation to use the two concepts interchangeably.

Cellular ageing is a broad expression that encompasses many different biological changes.

Senescence is a specific cellular state within that much more complex reality.

Therefore:

an ageing cell is not necessarily a senescent cell.

Nor does senescence alone explain skin ageing.

Oxidative stress, changes in the extracellular matrix, inflammation, alterations in barrier function, UV exposure and changes in different cellular communication systems are all involved too.

Biology has a certain reluctance to let us explain everything with a single word.

What does the sun have to do with cellular senescence?

Quite a lot.

UV radiation can generate oxidative stress and cellular damage, processes that can contribute to the development of characteristics associated with senescence.

This adds another dimension to photoageing.

Cumulative sun exposure does not only affect pigmentation, wrinkles or collagen degradation. It can also modify the behaviour of skin cells themselves.

So we can talk about peptides, exosomes and biotechnology as much as we like, but photoprotection remains one of the fundamental tools for looking after how our skin ages.

Senolytics and senomorphics: two words we are likely to hear much more often

Longevity research is exploring different strategies specifically targeting senescent cells.

Senolytics is the term used for strategies being investigated for their ability to selectively eliminate certain senescent cells.

Senomorphics or senostatics describe approaches intended to modify certain behaviours of these cells — for example, components of their secretory activity — without necessarily eliminating them.

These are particularly interesting areas of biomedical research.

But translating them directly into skincare requires caution.

Showing that an ingredient modifies a marker associated with senescence in a cellular model is not the same as demonstrating that a cream eliminates or rejuvenates senescent cells in human skin.

What did Vytrus study with Centella Reversa™?

This brings us to the research that led us to include Centella Reversa™ in Cell Reversa.

Vytrus Biotech worked with human dermal fibroblasts subjected to replicative senescence and analysed several parameters associated with this cellular state.

One of these was morphology. Under the assay conditions, senescent fibroblasts treated with Centella Reversa™ showed a morphology closer to that observed in young fibroblasts.

The study also analysed β-galactosidase, a marker commonly elevated in senescent cells. In one of the assays, Centella Reversa™ produced a 41% reduction in this marker.

In addition, the research examined parameters related to antioxidant response through peroxiredoxin-4 (PRX-4) and mechanisms related to genomic integrity through PARP-1.

Separately, in a scratch test performed on human dermal fibroblasts, Centella Reversa™ achieved 72% regenerated area after 48 hours under the experimental conditions.

Precision matters here:

These are in vitro results obtained with fibroblasts cultured in the laboratory. They do not demonstrate that a cream “reverses senescence by 41%” or “regenerates 72% of the skin”.

What these experiments allow us to investigate is whether the technology influences specific cellular characteristics associated with the senescent state and regenerative capacity.

→ If you would like to understand how the technology is obtained and what its phyto-peptide fractions contain, read Centella Reversa™: what it is and how it differs from conventional Centella asiatica.

From the laboratory to Cell Reversa: an important distinction

The results above relate to Centella Reversa™ as an ingredient and to cellular laboratory models.

But Cell Reversa is a complete cosmetic formula.

And here it is worth separating two different questions:

what mechanisms have been studied for the technology?

and

what results have been demonstrated with the finished cream?

The study carried out on Cell Reversa Firming Cream over 56 days did not measure cellular senescence. It evaluated visible and biomechanical skin parameters, as well as participants’ perceptions.

Among the results, the average roughness of the wrinkle analysed decreased by 9%, with statistical significance, and 96% of participants showed an improvement in this parameter.

In addition, 95.83% reported that their skin felt firmer, while 100% perceived an improvement in skin texture and hydration.

This means that we have two different levels of evidence that should not be confused:

• Centella Reversa™: mechanistic and in vitro research on fibroblasts, regeneration and parameters associated with senescence.
• Cell Reversa: results obtained with the finished formula on human skin, focusing on wrinkles, perceived firmness, texture and hydration.

For us, the interesting part is not turning a cellular assay into a spectacular promise.

It is about building a formula from an increasingly precise understanding of what changes in the skin over time, and then measuring what that formula actually achieves when used on the skin.

→ You can also explore what skin regeneration really means, how peptides work and what we really know about exosomes in skincare.

Discover Cell Reversa and explore the full formula.

About the author

Pharmacist and co-founder of UMOA Cosmetics, Mafalda Soto has more than 15 years of experience researching and caring for one of the world's most delicate skin types: the skin of people with albinism. Her career is closely linked to the health and inclusion of people with albinism in Africa, where she founded the NGO Beyond Suncare, recognised by the United Nations as a “Best Practice”.

At UMOA, she promotes effective, respectful and purpose-driven skincare: science, empathy and real impact.

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