Ex vivo cornea chemical injury model with chloropicrin and wound healing efficacy of supersaturated oxygen emulsion

Abstract

Purpose : Ocular exposure to toxic chemical agents like chloropicrin (CP) can lead to immediate lacrimation and pain, edema, inflammation, corneal necrosis and blindness. CP is a broad-spectrum pesticide that has been used in chemical warfare due to its harmful effects on humans since it causes severe ocular toxicity in addition to lung damage. Studies were conducted to identify cornea injury biomarkers to assess CP ocular exposure and test the efficacy of supersaturated oxygen emulsion (SSOE). It is evident that oxygen plays a vital role in ocular tissue preservation as well as tissue preservation and wound repair, especially in case of chemical injuries.

Methods : For developing an ex vivo rabbit cornea injury model, corneas from New Zealand white rabbits were exposed to CP (500 or 700 nmol) for 2 h, and then washed and cultured in media with or without supersaturated oxygen emulsion (SSOE; 55%) for 24 h or 96 h. Cornea sections were collected and hematoxylin and eosin stained as well as subjected to molecular analyses for apoptotic cell death, DNA damage and inflammation.

Results : We have previously shown that application of the SSOE (55%) to human corneal epithelial cells increased cell viability, wound (scratch) healing and reversed CP induced DNA damage, apoptotic cell death, and oxidative stress markers. In the present study, CP ex vivo cornea exposure caused an increase in epithelial degradation, epithelial and keratocyte cell death, p-H2A.X (DNA damage) and an increase in several inflammatory cytokines including IL1α, IL17A, IL21, Leptin, MIP-1β, MMP9 and TNF-α. SSOE treatment abrogated the CP (500 nmol)-induced cell death and epithelial degradation at 24 h post exposure. At 96 h, SSOE treatment enhanced healing of the epithelial layer as well as reversed CP-induced keratocyte cell death. SSOE treatment also decreased the CP (700nmol) -induced increase in the levels of p-γH2AX at both the time points.

Conclusions : Our studies have identified biomarkers of CP corneal injury in ex vivo rabbit cornea. SSOE exposure decreased CP-induced DNA damage and cell death, and ameliorated injury; however, inflammatory markers were not significantly reversed. Further studies to examine the treatment efficacy of SSOE alone and in combination with an anti-inflammatory agent in more effectively reversing chemical injury or enhancing wound healing are warranted.

This is a 2020 ARVO Annual Meeting abstract.