Abstract
Purpose :
Corneal abrasions are the most commonly diagnosed acute eye injury in children and young adults. No treatments are currently available that specifically target the wound healing process, such that severe abrasions may result in inefficient wound closure. Nitric oxide (NO) has gained attention for its role in facilitating fundamental wound healing processes while being cytoprotective. NO, administered using novel copper-chitosan composites (Cu-Ch), may be effective in accelerating corneal epithelial wound healing in vitro.
Methods :
Human corneal epithelial (HCE) and human limbal epithelial (HLE) cells were mechanically injured and monitored under five treatments: no-scratch (CON), untreated scratch (CS), scratch + plain chitosan composite (0%), scratch + 1% copper solution Cu-Ch (1%), scratch + 2% copper solution Cu-Ch (2%). Cell migration, cytotoxicity using a lactate dehydrogenase (LDH) assay, apoptosis using a cell death ELISA kit and total [NOx] using Griess reagents were measured at 24, 48 and 72hrs post-injury. Inducible NO synthase (iNOS) protein expression in HLE cells was determined at 72hrs using immunoblotting techniques. All data are presented as a one-way or two-way ANOVA, with Tukey’s or Bonferroni post-hoc, respectively.
Results :
Cell migration increased significantly in HCE cells (N=3) treated with 1% and 2% Cu-Ch compared to CS after 72hrs [F(3, 8) = 6.317, p = 0.0167]. HLE cells (N=3) showed a significant decrease in wound closure with both Cu-Ch doses when compared to CS [F(3, 8) = 13.35, p = 0.0018]. Cytotoxic fragments were significantly decreased in both Cu-Ch treatments in HCE cells only at 72hrs [F(4, 10) = 12.46, p = 0.0007]. Apoptosis in both HCE and HLE cells remained unchanged. NO levels in HCE cells were not significantly different with Cu-Ch treatment. NO levels in HLE cells showed a significant increase with 2% Cu-Ch treatment compared to CS at 72hrs [F(4, 40) = 3.591, p = 0.0136]. This increase is complemented with an up-regulation of iNOS.
Conclusions :
Overall, NO is effective in treating mechanically injured HCE cells in vitro, but not with HLE cells. In light of these responses to NO within these two cell types, novel differences in NO signaling and metabolism during injury have been uncovered. Further research targeting these differences can help further our understanding of the mechanistic properties of the ocular surface during injury.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.