Regulation of trachebronchial tissue-specific stem cell pool size.

Tissue-specific stem cell (TSC) number is tightly regulated in normal individuals but can change following severe injury. We previously showed that tracheobronchial epithelial TSC number increased after severe naphthalene (NA) injury and then returned to normal. This study focused on the fate of the supernumerary TSC and the signals that regulate TSC pool size.

Context-dependent differentiation of multipotential keratin 14-expressing tracheal basal cells.

Multipotential (MP) differentiation is one characteristic of a tissue-specific stem cell (TSC). Lineage tracing of tracheobronchial basal cells after naphthalene (NA) injury or in the postnatal period demonstrated that basal cells were MP progenitors for Clara-like and ciliated cells. These studies, as well as reports of spatially restricted, label-retaining basal cells, and MP differentiation by human bronchial cells support the hypothesis that a TSC maintained and repaired the tracheobronchial epithelium.