Stem Cells of Epidermis: A Critical Introduction

Stem cells are the cells having some distinguishing characteristics like longevity, high capacity of self-renewal and differentiation, quiescence and highly error-free proliferation. Almost all stem cells have the potential of lineage reprogramming, i.e. inter-conversion of cell lineages. They also have the potential to differentiate into almost all kinds of cells. These cells have been found in almost every organs of human body. Pool of stem cells found in epidermis is termed as Epidermal Stem Cells (Blanpain and Fuchs, 2006). Many researchers around the world have reported different kinds of stem cells in skin, based on their cell surface makers, while they have not categorized these cells chronically (De Rosa and De Luca, 2012). It is worth mentioning here that all kinds of stem cells reported in skin, i.e. keratinocyte stem cells, limbal stem cells, hair follicle and bulge stem cells, SG (sebaceous gland) stem cells, and spinous keratinocytes express specific types of cytokeratin protein (e.g. K1, K3, K5, K10, K12, K14, K15, K19 etc.) on their surfaces (Bose et al., 2013; Forni et al., 2012; Ghadially, 2012).