β-catenin Mutations Are Not Involved in Early-stage Hepatocarcinogenesis Induced by Protoporphyrinogen Oxidase Inhibitors in Mice

Ectopically Localized Epithelial Cell Clumps in Ulcers Are Derived from Reserved Crypt Stem Cells in a Mouse Model of Ulcerative Colitis

BACKGROUND

We previously reported that clumps of a few epithelial cells were scattered in ulcer regions in a dextran sulfate sodium (DSS)-induced mouse model of ulcerative colitis (UC).

AIMS

To determine the ectopically localized epithelial clumps might be derived from stem cells or their daughter progenitor cells.

METHODS

Female BALB/c mice were administered DSS in drinking water for 6 days, followed by withdrawal of DSS for 6 days. Histological and immunohistochemical examinations were conducted in the distal region and proximal region of the colorectum to determine expression of stem cell markers in the epithelial clumps.

RESULTS

Similar to the characteristics of UC, the ulcers were more severe in the distal region close to the anus than in the proximal region of the colorectum. Quantitative analyses revealed that the epithelial clumps appeared in relation to the severity of the ulcer, and they expressed the cell adhesion molecules E-cadherin and β-catenin. Among stem cell markers, the epithelial clumps primarily expressed +5 cell marker Dll1 as reserved intestinal stem cells, followed by +4 cell marker Bmi1 and crypt stem cell marker Lgr5 in that order. Nuclear expression of Sox9, but not nuclear β-catenin, was identified in the clumps.

CONCLUSION

The present results suggest that most epithelial clumps comprised crypt-derived, reserved stem cells, which might have potential for mucosal healing.