Defining the Hair Follicle Stem Cell (Part I)

The document discussed the role of hair follicle (HF) stem cells, particularly those located in the bulge region, in maintaining the regenerative capacity of hair follicles through their ability to cycle predictably through phases of degeneration, rest, and regeneration. It highlighted the use of various experimental models and markers, such as keratin-15 and CD34, to study these stem cells. The research demonstrated that bulge cells serve as a repository of long-lived multipotent stem cells capable of differentiating into various cell types necessary for hair follicle regeneration and wound repair. Despite advancements in understanding the molecular mechanisms governing HF stem cells, the initial generation of these cells and their niche composition remained incompletely understood. The review also noted the potential for adult HF neogenesis following skin wounding, suggesting that typically unipotent epidermal keratinocytes might undergo HF specification. The document served as a preface to further exploration of the heterogeneity within the HF stem cell niche.