Wnt-Responsive Stem Cell Fates in the Oral Mucosa

Epithelia of the oral cavity exhibit variations in morphologies and turnover rates. Are these differences related to environment or to region-specific stem cell populations? A lineage-tracing strategy allowed visualization of Wnt-responsive cells, and their progeny, in the hard and soft palates. In both anatomic locations, Wnt-responsive basal cells self-renewed and gave rise to supra-basal cells. Palatal injuries triggered an enlargement of this population, and their descendants were responsible for wound re-epithelialization. Compared with the hard palate, soft palate stem cells exhibited an earlier, more robust burst in proliferation, culminating in significantly faster repair. Thereafter, excess Wnt-responsive basal cells were removed, and stem cell numbers were restored back to homeostatic level. Thus, we uncovered a stem cell population in oral mucosa, and its relative abundance is correlate with the rate of oral wound healing. Besides the activation during injury, an endogenous mechanism exists to constrain the stem cell pool after repair.