Abstract
Purpose :
The presence of corneal scarring or fibrosis in children can have a significant adverse effect on visual and global development, making it important to understand the mechanisms of fibrosis in children. To date, relatively little is known regarding corneal fibrosis in the pediatric population, and so the purpose of this study was to characterize fibrosis in young versus adult mice using an established model of mechanical corneal injury.
Methods :
Corneal injury was induced by the mechanical removal of the epithelium and anterior stroma in young (3-4 week old) and adult (9-10 week old) C57BL/6 mice using an Algerbrush II burr. Mice were then followed for two weeks. Mice were evaluated by slit-lamp examination to quantify corneal opacity using the Fantes scale and by anterior segment OCT to determine central corneal thickness (CCT). In Vivo Confocal Microscopy (IVCM) was used to evaluate corneal stromal keratocyte density. At day seven, corneas were collected to evaluate mRNA expression of alpha smooth muscle actin (α-SMA) and type 1 collagen (COL1A1) by RT-PCR. At day 14, corneas were collected and evaluated for the density of α-SMA+ stromal cells (myofibroblasts) by immunostaining.
Results :
At 14 days post-injury, young mice compared to adult mice showed: (i) an increased corneal opacity score (2.3±1.3 vs. 1.0±0.5, p=0.04); (ii) CCT (152.7±30. vs. 79.6±5.0μm, p=0.03); (iii) increased stromal keratocyte density (407±28 mm-2 vs. 271±23 mm-2, p=0.02); and (iv) an increase in α-SMA+ stromal cell density (353±32mm-2 vs. 147±33mm-2, p=0.01). At 7 days post-injury, young mice compared to adult mice showed higher corneal mRNA expression of both α-SMA (21.9 ± 2.77 vs. 9.0 ± 1.1 fold change relative to naive, p<0.01) and COL1A1 (8.5±0.6 vs. 0.8±0.2 fold change relative to naive, p<0.01). Of note, there was complete epithelial wound closure in both groups at the end of follow-up.
Conclusions :
Our results demonstrate that following mechanical corneal injury, young mice show a more robust pro-fibrotic response than adult mice, as evidenced by increased clinical corneal opacity, increased α-SMA+ stromal cell density and relatively higher expression of α-SMA and COL1A1.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.