Different Effects of Pro-Inflammatory Factors and Hyperosmotic Stress on Corneal Epithelial Stem/Progenitor Cells and Wound Healing in Mice.

Chronic inflammation and severe dry eye are two important adverse factors for the successful transplant of cultured limbal stem cells. The aim of this study was to investigate the effects of inflammation and hyperosmotic stress (a key pathological factor in dry eye) on corneal epithelial stem cells (CESCs) and corneal epithelial wound healing. We observed that the CESCs exhibited significant morphological changes when treated with interleukin-1 beta (IL-1β), tumor necrosis factor alpha (TNF-α), or hyperosmotic stress. Colony-forming efficiency or colony-forming size was decreased with the increasing concentrations of IL-1β, TNF-α, or hyperosmotic stress, which was exacerbated when treated simultaneously with pro-inflammatory factors and hyperosmotic stress. However, the colony-forming capacity of CESCs recovered more easily from pro-inflammatory factor treatment than from hyperosmotic stress treatment. Moreover, when compared with pro-inflammatory factors treatment, hyperosmotic stress treatment caused a more significant increase of apoptotic and necrotic cell numbers and cell cycle arrest in the G2/M phase. Furthermore, the normal ability of corneal epithelial wound healing in the mice model was suppressed by both pro-inflammatory factors and hyperosmotic stress treatment, and especially severely by hyperosmotic stress treatment. In addition, inflammation combined with hyperosmotic stress treatment induced more serious epithelial repair delays and apoptosis in corneal epithelium. Elevated levels of inflammatory factors were found in hyperosmotic stress-treated cells and mice corneas, which persisted even during the recovery period. The results suggested that pro-inflammatory factors cause transient inhibition, while hyperosmotic stress causes severe apoptosis and necrosis, persistent cell cycle arrest of CESCs, and severe corneal wound healing delay. Stem Cells Translational Medicine 2019;8:46-57.