Anagen Hair Follicle Repair: Timely Regenerative Attempts from Plastic Extra-Bulge Epithelial Cells

The document from 2019 discusses the regenerative process of anagen hair follicle repair (AHFR), which is crucial for restoring hair growth after follicles are damaged, for instance, by chemotherapy or radiotherapy. It explains that extra-bulge epithelial cells, which are located in the outer root sheath and lower proximal cup of the hair follicle, are rapidly mobilized to regenerate all cell types in the lower segment of anagen hair follicles due to their stem cell-like properties and high plasticity. In contrast, bulge stem cells are activated in more severe injuries but regenerate only part of the outer root sheath with slower dynamics and limited plasticity. The study suggests that enhancing the mobilization of extra-bulge epithelial cells could help reduce hair loss from cancer treatments. It also discusses the role of mTOR and Wnt signaling pathways in the repair process and the potential of these pathways as therapeutic targets. The document does not report on empirical data from a study with participants but rather reviews the mechanisms of hair follicle repair and the implications for therapy.