Somatic Mutations Distinguish Melanocyte Subpopulations in Human Skin

This study analyzed 297 melanocytes from 31 donors to understand melanocyte homeostasis, revealing that melanocytes with low mutation burdens, which are more stem-like and smaller, are maintained in sun-damaged skin. These LowMut melanocytes, found in both hair follicles and interfollicular epidermis, contrast with HighMut melanocytes, which reside mainly in the interfollicular epidermis. The research suggests that hair follicles offer a protective niche from UV radiation, allowing melanocytes to migrate and replenish the epidermis after photodamage. The study highlights the value of including mutational data in cell atlases to track cellular history and homeostatic processes.