Age spots are packed with senescent skin cells

Age spots (also called senile lentigines) develop after prolonged UV exposure and are characterised by darker areas of skin. Researchers took skin biopsies from nine participants and compared tissue from inside the spots with tissue from immediately beside them. Using specific protein markers, they looked for cells that had entered a state of permanent growth arrest, known as cellular senescence. The study was published in the Journal of Investigative Dermatology.

More senescent cells inside the spot

In the outer skin layer (the epidermis) within the spots, the researchers found more senescent cells than in surrounding tissue. They specifically examined keratinocytes (the most common cells in the outer skin layer), melanocytes (cells that produce pigment) and fibroblasts (structural support cells). The presence of these aged cells was associated with altered skin structure and changed cell behaviour.

Senescent cells stop dividing but are not dead. They secrete a mixture of signalling molecules that can affect neighbouring cells. This process is called the senescence-associated secretory phenotype (SASP). The authors note that this phenomenon is poorly understood in skin cells compared to other cell types.

Links to skin ageing and prior research

The finding connects to earlier work linking senescent cells to other forms of sun-induced skin damage, such as actinic keratosis (a precancerous skin lesion). The researchers also point to individuals with progeria (a rare condition causing accelerated ageing), who display widespread skin pigmentation abnormalities.

Whether removing these senescent cells could reduce age spots or slow skin ageing cannot be concluded from this study alone. Targeted clinical trials would be needed. The finding does provide a molecular starting point for further research into UV-driven skin ageing.

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