| dc.description.abstract | During embryonic development, cell division supplies the organism with new cell types and contributes to the growing cell number. In the adult, cell proliferation is mainly responsible for maintaining a more or less stable number of cells in each tissue, for example, after cell death or injury. However, in adult tissues most cells are short-lived and terminally differentiated thus lacking the ability to proliferate. A specific population of adult stem cells is therefore essential to ensure cellular turnover throughout the postnatal life. Such population is constituted by multipotent, undifferentiated cells that self-renew, and that are usually found in specific niches. These cells retain their stem cell characteristics throughout life while giving rise to progenitor cells that then undergo terminal differentiation.
The clinical success achieved with stem cell therapy highlights the crucial importance of this field. Due to its accessibility and well-studied developmental stages, the skin and, specifically, the epidermal stem cells are an excellent model for the study of adult stem cells. The study of epidermal stem cells will potentially yield new clinical approaches to skin injury, skin diseases, hair loss and skin cancer.
The present work aims to highlight the importance of epidermal stem cells as a scientific model. We start of by describing the main developmental stages of the epidermis and the hair follicle as well as some of the important signalling pathways so far linked to skin development and homeostasis. These include Wnt/!- catenin, BMP, p63 and Shh signalling. We describe the epidermal stem cell niches identified to date and some of their defining characteristics. Finally, we explore some of the consequences of epidermal stem cell malfunction and molecular cues that have been studied in association with ageing and skin cancer. | |
