Distribution of label‐retaining cells and their properties in the vocal fold mucosa

OBJECTIVE: The latest research suggests cells in the maculae flavae (MFe) are putative stem cells of the vocal fold mucosa and the MFe are a candidate for a stem cell niche. Distribution and properties of label‐retaining cells (LRCs) in the vocal fold mucosa were investigated. STUDY DESIGN: Histologic analysis of the rat vocal folds. METHODS: Oral administration of bromodeoxyuridine (BrdU) was given to rats and the LRCs in the vocal fold mucosa were observed by immunohistochemistry. Immunoreactivity to antibodies directed to BrdU, Ki67, cytokeratin, vimentin, glial fibrillary acidic protein, desmin, Sox17, CD34, CD45, Type I collagen, and CD44 was studied. Extracellular matrices around LRCs were observed by Alcian blue staining and hyaluronidase digestion study. RESULTS: LRCs were present in the MFe and were resting cells (G0‐phase). They expressed epithelium, muscle, neural, and mesenchymal cell–associated intermediate filament proteins, and an endodermal marker, indicating cells in the MFe are undifferentiated and express proteins of all three germ layers. They expressed hematopoietic markers (CD34, CD45) and Type I collagen, which are the major markers of bone marrow derived circulating fibrocytes. The hyaluronan concentration in the MFe was high and the cells in the MFe expressed the surface hyaluronan receptor CD44, indicating that the MFe were a hyaluronan‐rich matrix. CONCLUSION: LRCs reside in the MFe and MFe had a hyaluronan‐rich matrix. The results of this study are consistent with the hypothesis that the cells in the MFe are putative stem cells and the MFe are a candidate for a stem cell niche. LEVEL OF EVIDENCE: N/A