Keratin 79 Identifies a Novel Population of Migratory Epithelial Cells That Initiates Hair Canal Morphogenesis and Regeneration

The study identified a novel population of migratory epithelial cells expressing keratin 79 (K79) that played a crucial role in hair canal morphogenesis and regeneration. These K79+ keratinocytes moved outward from the hair germ into the epidermis before lumen formation in embryos and were similarly involved in hair regeneration in adult mice. During homeostasis, K79+ cells lined the hair follicle infundibulum, maintained by Lrig1+ stem cell-derived progeny. The study suggested that the upward movement of these cells sustained the infundibulum, and their loss was associated with acne progression. This research revealed significant long-distance cell movements in the hair follicle's life cycle, proposing a new mechanism for generating its hollow core through outward cell migration.