Expression and distribution patterns of the stem cell marker, nestin, and the stem cell renewal factor, BMI-1, in normal human nasal mucosa and nasal polyps

Conclusions: These results suggest that nestin and BMI-1 are candidates for stem cell markers and renewal factors in human nasal mucosa, may contribute to tissue homeostasis and differentiation in the epithelium and submucosal glands of normal nasal mucosa, and may play a role in proliferation of nasal polyps. Objectives: The stem cell marker, nestin, and the stem cell renewal factor, BMI-1, have been identified in a variety of inflammatory and normal tissues, implicating these markers in tissue regeneration. Materials and methods: We investigated the expression and distribution of nestin and BMI-1 in normal nasal mucosa and nasal polyps, using RT-PCR, immunohistochemistry, and Western blotting. Results: Nestin and BMI-1 were localized to the epithelium and submucosal glands of normal nasal mucosa and nasal polyps. The expression of nestin was confined to the plasma membrane and cytoplasm, whereas BMI-1 showed a nuclear staining pattern. In normal nasal mucosa and nasal polyps, nestin and BMI-1 expression was strongest in the basal portion of the epithelial layer, and decreased toward the upper portion. In the submucosal glands, weak to strong expression was commonly detected in the glandular acini. There was no significant difference in the level of expression of nestin and BMI-1 between normal nasal mucosa and nasal polyps.