Estrogen modulates epithelial progenitor cells in rat vagina

PURPOSE: The expression of epithelial progenitor cells (EPCs) in rat vagina was recently reported. The aims were to investigate the effects of estrogen on vaginal EPCs in the oophorectomized female rat model. MATERIALS AND METHODS: Female Sprague-Dawley rats (230–240 g, n=30) were divided into 3 groups: control (n=10), bilateral oophorectomy (OVX, n=10), and bilateral OVX followed by subcutaneous injections of 17β-estradiol (50 µg/kg/day, n=10). After 4 weeks, the expression of EPC-specific markers (CD44, estrogen receptor alpha [ERα], and progesterone receptor) were evaluated by immunohistochemistry and Western blot. RESULTS: The CD44/ERα double-labeled cells were mainly expressed in basal cell layers and suprabasal layers as shown by confocal immunofluorescence. Confocal microscopy revealed that the number of CD44+/ERα+ cells decreased in the OVX group compared with the controls but was similar to control levels in rats receiving estrogen replacements. The protein expression of CD44 and ERα decreased after OVX and was restored to control levels after estrogen supplementation. CONCLUSIONS: Markers of EPCs were expressed in the vagina, and the expression of resident EPCs was regulated by estrogen. These findings imply that resident EPCs may have an important role in the regeneration of vaginal mucosa by estrogen replacement.