UV Damage Increases Cellular Senescence. Here's How to Stop It.

There’s a reason every dermatologist’s first skincare recommendation is SPF: unprotected sun exposure causes skin cancer and is responsible for up to 90% of visible signs of aging, which means that SPF might be the best preventative aging solution that we have.

But for many of us, a lot of the damage has already been done. Blame it on your tanning bed years or just the ignorance of youth: photodamage that you experience in your early years can have very real impacts on your skin health for the rest of your life, including increased rates of cellular senescence and chronic inflammation. So what can we do about the damage that’s already been done? Let’s take a closer look at how photogaging works and the promising new therapies available to help reverse its effects.

UV Damage is the #1 Extrinsic Aging Factor

Let’s quickly review the two major types of aging: intrinsic aging is largely determined by your genetic profile while extrinsic aging occurs as a result of environmental exposures and daily lifestyle habits. While there are many extrinsic aging factors– air pollution and cigarette smoke just to name a couple–UV radiation is by far the most common and potent aging factor that we face in our daily lives.

Like intrinsic aging, photoaging is cumulative and adds up over a lifetime. However, while intrinsic aging naturally requires the passage of time, photoaging can occur very quickly depending on the degree of sun exposure and the amount of UV-blocking pigment naturally present in your skin. This means that if you’re very fair-skinned and rarely wear sunscreen, your skin will actually age much faster than it ordinarily would without UV damage. This increases the biological age of your skin and reduces your skinspan–the amount of time your skin is healthy.

UV Damage Induces Cellular Senescence & Accelerates Aging

On the cellular level, UV exposure causes cells to prematurely enter senescence, a state in which a cell has reached the end of its lifecycle and should be cleared away, but instead lingers. A central hallmark of skin aging, cellular senescence is the accumulation of aged, zombie cells that induce aging in neighboring cells. The faster that our cells fall into senescence, the more difficult it is for the body to efficiently clear them away – precipitating a cascade of aging that can result in impaired skin regeneration, chronic inflammation, and even skin cancer. As skin is exposed to more UV radiation, this damage accelerates even further, leading to premature aging.

What does UV-induced Senescence Look Like?

Photoaging is associated with a number of visible symptoms, including dryness, deep wrinkles, skin laxity, slow wound healing, a higher risk of skin cancer, and leathery skin caused by thickening of the epidermis.¹

Many of these symptoms occur because UV-induced senescent cells alter proteins, like collagen and elastin, which keep the skin plump and firm. Without proper function of these proteins, the skin begins to show common signs of aging like skin sagging, wrinkles, and laxity. This effect on collagen and elastin may occur because UV-induced senescent cells show high expression of MMPs, a family of enzymes that break down structural proteins in the skin.¹ Research also shows that UV-induced senescence leads to an increase in melanogenesis, the production of melanin pigment within the skin. This can cause age-related hyperpigmentation or sun spots.²

Senotherapeutics Could Be the Next Frontier in Addressing Photoaging

Regularly applying SPF is widely considered the most effective way to protect against UV radiation. While scientists don’t know for certain whether sunscreens protect against UV-induced senescence, there is overwhelming evidence that SPF shields against DNA damage and reduces the levels of MMPs within the skin.

But what about the UV-induced senescence already present in your skin from your sunbathing days? That’s where senotherapeutics can help. Specifically designed to target senescent cells within the skin, senotherapeutics like the OS-01 peptide are a promising strategy for reducing UV-induced senescence and extending skinspan.¹

The OS-01 Peptide Protects Skin Cells from UVB-Induced Cellular Senescence

In lab studies on ex vivo human skin cells, the OS-01 peptide has been shown to reduce the total number of senescent skin cells while maintaining the overall number of skin cells, demonstrating its potential to help reverse a key driver of aging.³ But can OS-01 actually protect skin cells from UV damage, too?

In vitro human dermal fibroblasts (HDFs) isolated from 30 yo donors were exposed to UVB radiation (0.1J/cm^2) then immediately treated with the OS-01 peptide (12.5uM) and stained with senescence-associated beta galactosidase (SA-Bgal). Senescence levels were analyzed by counting the number of UVB-induced senescent cells. Data normalized to control. (Zonari, et al., npj Aging, 2023)

To answer this question, our scientists exposed in vitro human skin cells to UVB radiation, then immediately treated them with the OS-01 peptide. By selectively staining the samples with an enzyme that turns senescent cells blue, our researchers were able to count the total number of UVB-induced senescent cells.

The samples that were immediately treated with the OS-01 peptide experienced 42.5% less UV-induced senescent cells than the skin that was not treated with OS-01. This data indicates that the OS-01 peptide is capable of protecting skin cells from UVB damage, one of the main extrinsic aging factors. ³

How to Support Your Skin with OS-01

Despite OS-01’s powerful protective capacity, daily SPF is still an essential step in any healthy skin regimen. To get the most from both your daily SPF and the OS-01 peptide, apply OS-01 FACE before SPF in the morning and again in the evening after you wash your face.

Key Takeaways:

UV damage is the number one cause of extrinsic skin aging.
By increasing cellular senescence, UV radiation accelerates skin aging and leads to the degradation of collagen and elastin.
While scientists believe SPF prevents UV-induced senescence, more evidence is necessary.
Senotherapeutics like the OS-01 peptide are a promising emerging option for reducing UVB-induced senescence.
In addition to reducing the overall number of senescent cells, the OS-01 peptide has been shown to decrease UV-induced senescence by 42.5% in human skin samples exposed to UVB radiation.

References

Last Updated June 16, 2025

Reviewed by

Alessandra Zonari

PhD, Chief Scientific Officer (CSO) and Co-Founder of OneSkin

Alessandra earned her Master’s degree in stem cell biology, and her PhD in skin regeneration and tissue engineering at the Federal University of Minas Gerais in Brazil in collaboration with the 3B’s Research Group in Portugal. Alessandra did a second post-doctoral at the University of Coimbra in Portugal. She is a co-inventor of three patents and has published 20 peer-reviewed papers in scientific journals.

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