Hair Follicle Stem Cells: the Signaling Hub of the Skin

Abstract

Hair follicle stem cells (HFSCs) are recognized as multipotential stem cells with exceptional proliferative capacity. Their regulatory effect on skin homeostasis is orchestrated through intricate signaling pathways, including Wnt/β-catenin, transforming growth factor-β/bone morphogenetic protein (TGFβ/BMP), Notch, and Hedgehog. Concurrently, HFSCs inhabit the bulge region of the outer root sheath of the hair follicle (HF), serving as the epicenter for skin-organizing signaling during homeostasis, engaging in dynamic interactions with other functionally specialized niche cells. This comprehensive review delineates the nuanced interplay of both cell-intrinsic and cell-extrinsic mechanisms governing HFSCs within the skin. The aspiration is that this synthesis of knowledge will contribute meaningfully to the theoretical foundations underpinning further investigations into skin disorders.