Single cell transcriptomics of human epidermis shows decreased expression of several structural genes associated with skin barrier development in aged skin

Epidermal keratinocytes are continuously dividing cells which, upon differentiation establish the outer skin barrier, the stratum corneum. In older age the epidermis becomes thinner, papillary protrusions flatten and the capacity for skin barrier repair decreases. Here we performed single-cell RNA sequencing of epidermal keratinocytes obtained by suction blisters from the volar forearm of younger (20-30) and older (65-70) healthy female individuals. Overall design: Eight healthy women participated in this study – 4 in the younger age group (24, 24, 29,29 yrs) and 4 in the older age group (71,67, 66, 71 yrs). All women in the older age group were menopaused for at least 10 years and were not taking hormonal substitution therapies. None of the women in the younger age group was taking oral contraceptives. All women in both groups were non-smokers, none had a history of skin disease, none were visiting tanning parlors.