BACKGROUND AND OBJECTIVES A considerable portion of the hair follicle remains attached to plucked hair and can be used for follicle cell culture. In this study we have phenotyped these cells in an attempt to identify the stem cell fraction. Reports in the literature have indicated that this cell population may be positive for cytokeratin (CK) 19. Because stem cells in general need to be protect...

The intermediate filament protein, nestin, marks progenitor cells of the CNS. Such CNS stem cells are selectively labeled by placing GFP under the control of the nestin regulatory sequences. During early anagen or growth phase of the hair follicle, nestin-expressing cells, marked by GFP fluorescence in nestin-GFP transgenic mice, appear in the permanent upper hair follicle immediately below the...

Gab1 is a scaffold protein that acts downstream of receptor tyrosine kinases. Here, we produced conditional Gab1 mutant mice (by K14- and Krox20-cre) and show that Gab1 mediates crucial signals in the control of both the hair cycle and the self-renewal of hair follicle stem cells. Remarkably, mutant hair follicles do not enter catagen, the destructive phase of the hair cycle. Instead, hair foll...

Aml1/Runx1 controls developmental aspects of several tissues, is a master regulator of blood stem cells, and plays a role in leukemia. However, it is unclear whether it functions in tissue stem cells other than blood. Here, we have investigated the role of Runx1 in mouse hair follicle stem cells by conditional ablation in epithelial cells. Runx1 disruption affects hair follicle stem cell activa...

The hair follicle is a skin appendage with a complex structure containing many cell types that produce highly specialised proteins. The hair follicle is in a continuous cycle: anagen is the hair growth phase, catagen the involution phase and telogen is the resting phase. The follicle offers many potential therapeutic targets. Hoffman and colleagues have pioneered hair-follicle-specific targetin...

Adult stem cells are essential for tissue renewal, regeneration, and repair, and their expansion in culture is of paramount importance for regenerative medicine. Using the whisker follicle of the rat as a model system, we demonstrate that (i) clonogenicity is an intrinsic property of the adult stem cells of the hair follicle; (ii) after cultivation for >140 doublings, these stem cells, transpla...

Hair follicle stem cells (HfSCs) play crucial roles in hair follicle morphogenesis and hair cycling. These stem cells are self-renewable and have the multi-lineage potential to generate epidermis, sebaceous glands, and hair follicle. The separation and identification of hair follicle stem cells are important for further research in stem cell biology. In this study, we report on the successful e...

Stem cells are vital for the homeostasis of self-renewing tissues such as the hair follicle. Epithelial stem cells have been implicated in tumorigenesis and wound healing, and their manipulation may have wide ranging applications including gene therapy and tissue transplantation. Rodent hair follicle stem cells have been localized to an area of the follicle called the bulge, however, the identi...

The epithelial-mesenchymal interactions between keratinocyte stem cells and dermal papilla (DP) cells are crucial for normal development of the hair follicle as well as during hair cycling. During the cyclical regrowth of a new lower follicle, the multipotent hair follicle stem cells are stimulated to proliferate and differentiate through interactions with the underlying mesenchymal DP cells. T...