[Nestin-Labelled Stem Cells in the Hair Follicle]

by

Acknowledgement

I would take this opportunity to thank my research supervisor, family and friends for their support and guidance without which this research would not have been possible.

DECLARATION

I, [type your full first names and surname here], declare that the contents of this dissertation/thesis represent my own unaided work, and that the dissertation/thesis has not previously been submitted for academic examination towards any qualification. Furthermore, it represents my own opinions and not necessarily those of the University.

Signed __________________ Date _________________

Nestin-Labelled Stem Cells in the Hair Follicle

Abstract

We have recently shown that the expression of nestin, the neural stem cell marker protein, is expressed in bulge-area stem cells of the hair follicle. We used transgenic mice with GFP expression driven by the nestin regulatory element [nestin-driven GFP (ND-GFP)]. The ND-GFP stem cells give rise to the outer-root sheath of the hair follicle as well as an ND-GFP interfollicular vascular network. In this study, we demonstrate that ND-GFP stem cells isolated from the hair-follicle bulge area that are negative for the keratinocyte marker keratin 15 can differentiate into neurons, glia, keratinocytes, smooth muscle cells, and melanocytes in vitro. These pluripotent ND-GFP stem cells are positive for the stem cell marker CD34, as well as keratin 15-negative, suggesting their relatively undifferentiated state. The apparent primitive state of the ND-GFP stem cells is compatible with their pluripotency. Furthermore, we show that cells derived from ND-GFP stem cells can differentiate into neurons after transplantation to the subcutis of nude mice. These results suggest that hair-follicle bulge-area ND-GFP stem cells may provide an accessible, autologous source of undifferentiated multipotent stem cells for therapeutic application.

Discussion

The hair follicle is dynamic, cycling between growth (anagen), regression (catagen), and resting (telogen) phases throughout life. Stem cells located in the hair-follicle bulge area give rise to the follicle structures during each anagen phase. Taylor et al. reported that hair-follicle bulge stem cells are potentially bipotent because they can give rise not only to cells of the hair follicle but also to epidermal cells. Other experiments also have provided evidence that the bulge-area stem cells differentiate into hair-follicle matrix cells, sebaceous-gland basal cells, and epidermis. A similar result was obtained by Fuchs and coworkers, who engineered transgenic mice to express histone H2B-GFP controlled by a tetracycline-responsive regulatory element as well as a keratinocyte-specific promoter. Bulge cells retained the GFP label, consistent with their role as stem cells. During anagen, newly formed GFP-positive populations derived from the bulge stem cells, form the outer-root sheath hair matrix cells and inner-root sheath. Also, in response to wounding, some GFP-labeled stem cells exited the bulge, migrated, and proliferated to repopulate the infundibulum and epidermis. (Dayer 2003 563-572) Morris et al. used a keratinocyte promoter to drive GFP expression in the hair-follicle bulge cells. They showed that bulge cells in adult mice generate all epithelial cell types within the intact follicle and hair during normal hair-follicle cycling. Toma et al. reported that multipotent adult stem cells isolated from mammalian skin dermis, termed skin-derived precursors (SKPs), ...