Changes in the expression of stem cell markers in oral lichen planus

Despite the pivotal role of stem cells in homeostasis of oral epithelia the location of this cell population within the tissue is uncertain. How disease influences these cells in vivo also remains to be elucidated. In this study we have used six molecular markers to identify stem cells in normal and diseased buccal mucosa. Samples of normal oral mucosa (NOM), hyperkeratosis (OHK) and oral lichen planus (OLP) were immunostained for α6 and β1 integrins, keratin 15 (K15), melanoma-associated chondroitin sulphate proteoglycan (MCSP), NG2 the rat homologue of human MCSP and notch 1. K15, NG2 and β1 staining was continuous in the basal layer of NOM whilst α6 and MCSP were limited to basal cells at the tips of connective tissue papillae. K15 was downregulated in OLP whereas α6, β1 and MCSP were upregulated in both OLP and OHK. NG2 remained unchanged and notch 1 was absent in all samples. Therefore, the stem cell phenotype in OLP and OHK maybe altered in response to pathological signaling. Classification of these changes is essential to understand the role of adult stem cells in the pathogenesis of oral diseases characterised by abnormal keratinocyte proliferation and differentiation. (J. Oral Sci. 49, 133-139, 2007)