Abnormal epithelial homeostasis in the cornea of mice with a destrin deletion.

PURPOSE: Dstn(corn1) mice lack normal destrin expression and develop corneal abnormality shortly after birth such as epithelial hyperplasia and total vascularization. Thus, the mice serve as a model for ocular surface disorders. To determine the nature of epithelial defects, we examined whether epithelial homeostasis is altered in these corneas. METHODS: Dstn(corn1) mice were crossed with ubiquitous GFP mice to generate a double homozygous line, GFP-Dstn(corn1), and cell movements were determined by whole-mount histology and in vivo time-lapse microscopy, tracking the change of epithelial GFP patterns. Rates of cell division and the presence of label-retaining cells (LRCs) were determined by systemic bromodeoxyuridine (BrdU). Epithelial expression of keratins 8, 12, and 15, and MUC5AC were determined by whole-mount immunofluorescence. RESULTS: Epithelial cells in an adult GFP-Dstn(corn1) cornea were generally immobile with no sign of directed movement for the entire life of the animal. These cells were not senescent because more than 70% of basal epithelial cells incorporated BrdU over a 24 h period. LRCs were widely distributed throughout a GFP-Dstn(corn1) cornea. The epithelium of a GFP-Dstn(corn1) cornea contained a mixed population of cells with a corneal and a conjunctival phenotype as judged by the expression of keratins and MUC5AC. CONCLUSIONS: Epithelial cells of an adult GFP-Dstn(corn1) cornea are generally stationary, mitotically active, and contain LRCs, indicating that the epithelium is self-sustained, which in turn suggests that epithelial stem cells are present within the cornea. Epithelial homeostasis of adult GFP-Dstn(corn1) corneas is abnormal, mimicking that of a normal conjunctiva or a pathological, conjunctivalized cornea.