Age spots are full of senescent skin cells

Age spots, known medically as senile lentigo, develop from years of UV exposure. They appear darker because they contain more pigment cells. But the study, published in the Journal of Investigative Dermatology, reveals that these spots also harbour an elevated number of senescent cells, keratinocytes and melanocytes that have stopped dividing but have not died.

Senescent cells are cells that have halted division while remaining metabolically active. They secrete a mix of inflammatory signals, collectively called the SASP (senescence-associated secretory phenotype). In skin, both fibroblasts and keratinocytes have previously been linked to skin ageing, but this is among the first studies to map senescent cells specifically within age spots.

UV damage as the trigger

The researchers collected skin biopsies from nine participants of Korean ethnicity, from both spotted and adjacent normal skin. Using established markers for senescent cells, including p16INK4A and lamin B1, they confirmed that age spots contained substantially more senescent cells. This aligns with earlier findings in actinic keratosis, a precancerous skin condition with similar accumulation patterns.

What this means for skin treatment

If senescent cells actively drive the altered structure and pigmentation of age spots, treatments designed to clear these cells, senolytics, may offer a meaningful approach to skin ageing. Research to date suggests such treatments can affect skin function, but published human data remain surprisingly scarce. The researchers also note that it remains unclear which specific cell types are responsible for the pigmentation pattern itself.

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