A new model for endothelial injury in TAZ deficient mice using phototherapeutic keratectomy

Abstract

Purpose : Mice deficient in Wwtr1, the gene that encodes transcriptional co-activator with PDZ-binding motif (TAZ) are associated with decreased corneal endothelial cell (CEnC) density and alteration in Descemet’s membrane reminiscent of late-onset Fuchs’ endothelial dystrophy. The purpose of this study was to evaluate the regenerative capacity of CEnCs following excimer laser-induced injury in TAZ deficient (Wwtr1^+/-) and wildtype (WT) mice.

Methods : A phototherapeutic keratectomy (PTK) was performed with an excimer laser (2 mm diameter, 40 Hz, 20 μm depth) in both eyes of 6-month-old Wwtr1^+/- and WT mice (N=6 for each genotype). Prior to PTK and on postoperative days 1, 3, 5, 7, 10 and 14, slit lamp biomicroscopy, Fourier-domain optical coherence tomography and in vivo confocal microscopy (IVCM) were performed to monitor clinical progression, central corneal thickness (CCT) and CEnC density, respectively. Following euthanasia on day 14, corneas were excised and stained with Alizarin red and zonula occludens-1 (ZO-1) to evaluate CEnC density and morphology.

Results : Prior to PTK, there were no statistical difference in CCT and CEnC density between WT and Wwtr1^+/- mice at 89 ± 10.2 μm and 2668 ± 208 cells/mm² versus 99 ± 6.7 μm and 2485 ± 133 cells/mm², respectively. Following PTK, corneal edema and an associated increase in CCT were observed which peaked on day 7 in WT (125 ± 14.4 μm) and day 10 in Wwtr1^+/- (141 ± 32.5 μm) but returned to baseline on day 14 in both genotypes. There was no statistical difference in CCT between each genotype at all timepoints. On day 14, CEnC density was decreased from baseline values in both genotypes with IVCM and was significantly lower in Wwtr1^+/- (1017 ± 302 cells/mm², P < 0.05) versus WT mice (1592 ± 333 cells/mm²) with Alizarin red staining. The ZO-1 expression was more reduced in Wwtr1^+/- versus WT mice.

Conclusions : Regeneration of CEnCs was significantly delayed in Wwtr1^+/- mice following PTK-induced injury, suggesting that Wwtr1 may be crucial to CEnC regeneration. Further, we speculate that this model may be useful to evaluate novel medical therapies for CEnC regeneration.

This is a 2020 ARVO Annual Meeting abstract.