Oral mucosal epithelia are subject to a wide range of environmental insults that result in abrasions, wounds, burns, bacterial invasion and even malignant change. Functional epithelial structure is normally maintained through rapid tissue renewal associated with patterns of cellular proliferation based on stem and amplifying cell hierarchies. There is now much information available about stem cell properties and the number, pattern of distribution, and mechanisms controlling the proliferation of stem and amplifying cells are becoming better understood. However, uncertainty persists concerning several aspects of stem cell behaviour and two new areas of special basic and clinical interest have recently developed. First, it appears that somatic stem cells have much greater plasticity that previously believed and that this can be manipulated and combined with tissue engineering procedures to generate new tissues for clinical use. Second, it is now apparent that stem cells are the likely target of carcinogens and that epithelial tumours in vivo, and also cell lines derived from them, retain proliferative stem cell patterns similar to those of normal epithelia. Asymmetric division is a characteristic property of somatic stem cells and changes occuring during malignancy appear essential for tumour growth and metastasis.
Keywords: stem cells, oral mucosa, oral epithelia, cancer