Human vellus hair units undergo cellular and metabolic remodeling during skin aging

In a study of healthy young and aged human males, researchers constructed a single-nucleus transcriptomic atlas of vellus hair pilosebaceous units from back skin. They mapped widespread cellular and transcriptional remodeling across this niche during aging. Aged units showed a reduced relative representation of bulge hair follicle stem cells, alongside altered regeneration-associated transcriptional programs. In contrast, sebocytes exhibited heightened androgen responsiveness and increased lipid biosynthetic activity. The researchers also detected an expanded ion channel-enriched follicular cell population marked by stress and inflammatory signatures. Additionally, an innate immune-like melanocyte subset declined, coinciding with shifted melanocyte-immune communication patterns. Immune subsets in aged follicles showed coordinated alterations in metabolic pathway signatures, highlighting the unit as a convergence site for epithelial, immune, and metabolic aging.