Researchers here show that a greater number of senescent cells in skin correlates with a greater loss of skin elasticity. As we age, skin becomes less elastic. Damage to the structures of the extracellular matrix that determines this and other physical properties of tissue occurs due to a number of processes, such as cross-linking and the activities of senescent cells. Developing methods to remove cross-links and clear senescent cells would allow the production of therapies to reverse these and numerous other issues associated with aging:
Senescent cells are more prevalent in aged human skin compared to young, but evidence that senescent cells are linked to other biomarkers of aging is scarce. We counted cells positive for the tumor suppressor and senescence associated protein p16INK4a in sun-protected upper-inner arm skin biopsies from 178 participants (aged 45-81 years) of the Leiden Longevity Study. Local elastic fiber morphology, facial wrinkles, and perceived facial age were compared to tertiles of p16INK4a counts, while adjusting for chronological age and other potential confounders.
The numbers of epidermal and dermal p16INK4a positive cells were significantly associated with age-associated elastic fiber morphologic characteristics, such as longer and a greater number of elastic fibers. The p16INK4a positive epidermal cells (identified as primarily melanocytes) were also significantly associated with more facial wrinkles and a higher perceived age. Participants in the lowest tertile of epidermal p16INK4a counts looked 3 years younger than those in the highest tertile, independently of chronological age and elastic fiber morphology.
In conclusion, p16INK4a positive cell numbers in sun-protected human arm skin are indicative of both local elastic fiber morphology and the extent of aging visible in the face.