There is growing evidence that the cells in the maculae flavae are tissue stem cells and that the maculae flavae are a stem cell niche of the human vocal fold mucosa. The stem cell system of the tissue stem cells of the human vocal fold mucosa, including their stemness, asymmetric cell division, cellular hierarchy and lineage determination, was reviewed and summarized.
Regarding the stemness, the cells in the human maculae flavae have stemness and multipotency. Subcultured cells form a colony-forming unit. The cell features in the maculae flavae meet the minimal criteria defining mesenchymal stem cells. In addition, subcultured cells differentiate into ectoderm, mesoderm and endoderm. Cell divisions in the maculae flavae reflect asymmetric self-renewal in vitro. Regarding the heterogeneity and hierarchy of cells in the maculae flavae of the human adult vocal fold mucosa, three phenotypes of cells (cobblestone-like polygonal cells, vocal fold stellate cell-like cells possessing lipid droplets in the cytoplasm and fibroblast-like spindle cells) are present in the human adult maculae flavae. The cobblestone-like polygonal cells are at the top of the cellular hierarchy in the stem cell system. The lineage determination of the tissue stem cells has not yet been elucidated. The cells in the maculae flavae of the human adult vocal fold mucosa have heterogeneity and hierarchy in the stem cell system.
