I noticed this posted on another site
Lots of great speakers. For example
Hair Follicle Stem Cells – Epithelial
Speaker: George Cotsarelis, MD
University of Pennsylvania, Philadelphia, PA, USA
Over 15 years ago, we proposed that quiescent keratinocytes in the hair follicle bulge were epithelial stem cells important for hair follicle cycling, epidermal renewal, wound healing and carcinogenesis. Since that time, we identifi ed cytokeratin 15 (K15) expression as a marker for these cells and developed several transgenic mouse models using the K15 promoter to further study the bulge cells. Using K15-EGFP mice, we isolated bulge cells and demonstrated that they possessed an epithelial stem cell phenotype of quiescence, high proliferative potential and multipotency. We also characterized the cells at the molecular level using microarrays and identifi ed approximately 150 differentially expressed genes in these cells. Through genetic lineage analysis using an inducible K15-CrePR;R26R bigenic mouse, we showed that bulge cells generate all of the epithelial lineages within the lower anagen hair follicle. However, ablation of bulge cells using K15-thymidine kinase mice resulted in permanent hair loss but survival of the epidermis. Over a prolonged period, bulge cells did not contribute to epidermal homeostasis, but in response to wounding bulge cell progeny rapidly moved into the wound area to assist in reepithelialization. Bulge derived cells did not persist in the epidermis indicating that epidermal stem cells and hair follicle stem cells are distinct populations each with self renewing capabilities.
Wnt-Dependent De Novo Hair Follicle
Regeneration in Adult Mouse Skin
Ito, Mayumi; Yang, Zaixin; Andl, Thomas; Cui, Chunhua;
Kim, Noori; Millar, Sarah; Cotsarelis, George; Department of
Dermatology, University of Pennsylvania School of Medicine,
Philadelphia, PA, USA
The mammalian hair follicle is a complex “miniorgan” thought to form only during development; loss of an adult follicle is considered permanent. Here we show that, after wounding, hair follicles form de novo in genetically normal adult animals. The regenerated hair follicles establish a stem cell population, express known molecular markers of follicle differentiation, produce a hair shaft, and progress through all stages of the hair follicle cycle. Lineage analysis demonstrated that the nascent follicles arise from epithelial cells outside of the hair follicle stem cell niche, suggesting that epidermal cells surrounding the wound assume a hair follicle stem cell phenotype. Inhibition of Wnt signaling after reepithelialization completely abrogates this wounding induced folliculogenesis, while overexpression of Wnt ligand in the epidermis increases the number of regenerated hair follicles. These remarkable regenerative capabilitie of the adult support the notion that wounding induces an embryonic phenotype in skin, and that this provide a window for manipulation of hair follicle neogenesis by Wnts. These findings suggest novel treatments for wounds, hair loss and other degenerative skin disorders.