Effect of Notch1 on Vocal Fold Re‐Epithelization After Acute Injury

Objective To investigate the role of Notch1 signaling in Lrig1‐expressing vocal fold (VF) epithelial stem cells during epithelial repair following acute injury. Methods Lrig1Cre ERT2/+ , Lrig1Cre ERT2/+ Notch1 F/+ , and Lrig1Cre ERT2/+ Notch1 F/F mice were generated. Cre‐mediated recombination was induced by tamoxifen (100 mg/kg, intraperitoneally) on two consecutive days. Acute epithelial injury was induced by naphthalene (NAPH; 250 mg/kg, intraperitoneally), while corn oil was used as a control. Whole larynges were collected at 1, 3, and 7 days post‐injury for histological and immunofluorescence analyses. Results Following injury, conditional deletion of Notch1 in Lrig1‐expressing epithelial stem cells disrupted epithelial repair, with the most pronounced phenotype in homozygous Lrig1Cre ERT2/+ Notch1 F/F mice. Expansion of P63 positive basal cells and increased Ki‐67 positive proliferating cells peaked at 3 days and persisted through 1 week post injury. Moreover, epithelial stratification was altered, as indicated by expansion of KRT14 positive epithelial layers and increased expression of the differentiation markers KRT13 and KRT17. Notably, accumulation of IBA1 positive immune cells increased in VF mucosa at 3 days and remained elevated at 1 week, indicating prolonged inflammation. Conclusion Collectively, these results suggest that Notch1 plays an important role in regulating epithelial cell fate and coordinating the timing of repair processes in the VF epithelium following acute injury. Level of Evidence N/A.