Remodeling 3D Morphology of Neonatal Hair Follicle by In Vitro Culturing of Hair Follicle Outer Root Sheath

Hair follicle is one of the important appendage organs and plays a role in skin repair. This study evaluated the mechanism of stem cells initiation, differentiation and regeneration to repair the wound surface when the hair follicle is injured. KM neonatal mice were dissected, and the vibrissa hair follicle outer root sheath was separated and cultured in vitro. Immunofluorescence histochemistry was used to observe EdU, AP-1, Sox2 and macrophage distribution to explore regeneration rules of hair follicle. On Day 5, the basic morphology of hair follicle was rebuilt, and neonatal hair follicle dermal papilla morphology was observed. Furthermore, regeneration, differentiation and direction of migration of stem cells were illustrated by using EdU labeled neonatal cells, and the glassy membrane, the boundary of hair follicle, of wound surface was also updated. AP-1 protein in neonatal hair follicle site was uniformly distributed in the glassy membrane, which involves the JNK signaling pathway, and was responsible for regulating programmed cell death, differentiation and pro-regeneration of hair follicle stem cells. This indicated that apoptosis after injury during hair follicle rebuilding could trigger hair follicle stem cells regeneration. The study findings established and demonstrated the in vitro culture method of vibrissa hair follicle outer root sheath to rebuild neonatal hair follicle. Also the hair follicle regeneration and other related mechanisms were elucidated with a new in vitro 3D morphological model at the time of hair follicle cell injury.