Endocrine Controls of Primary Adult Human Stem Cell Biology: Thyroid Hormones Stimulate Keratin 15 Expression, Apoptosis, and Differentiation in Human Hair Follicle Epithelial Stem Cells In Situ and In Vitro

The study demonstrated that thyroid hormones T3 and T4 significantly influenced human hair follicle epithelial stem cells (eHFSCs) by enhancing the expression of KERATIN 15 and CD200, both in situ and in vitro. These hormones induced apoptosis and differentiation while inhibiting clonal growth of these progenitor cells. The findings suggested that eHFSCs were subject to profound hormonal regulation by thyroid hormones, which could be exploited to understand endocrine controls of human epithelial stem cells. The research provided insights into the potential therapeutic manipulation of eHFSCs for conditions like scarring alopecia and other hormone-dependent hair disorders.