Effects of In-vivo Application of Cold Atmospheric Plasma on Corneal Wound Healing in New Zealand White Rabbits

Abstract

Cold Atmospheric Plasma (CAP) has been shown to influence tissue wound healing but little is known about the impact of CAP on healthy corneal tissues and their ability to respond to injuries. The objective of this study is to examine the effect of CAP on wound healing after corneal epithelial and basement membrane ablation in New Zealand white rabbits. The rabbits were assigned into three groups. Ten Rabbits from two groups underwent a 6 mm corneal ablation to the right eyes. After ablation, five rabbits in group (A) received 2 minutes of CAP whereas the other five rabbits (B) were not treated with CAP. A third group (C) included two rabbits and received CAP without ablation. Eyes monitored for corneal haze, epithelial healing, lens clarity and any signs of inflammation. At 24 hours, two rabbits from group A and two from group B were sacrificed to harvest the corneas. Twenty days, all remaining rabbits in groups A, B, and C were sacrificed and corneas were harvested. Corneas were fixed in formalin and stained with H&E or used for immunofluorescence microscopy to assess scar formation using antibodies against fibronectin and a-smooth muscle actin. At 24 hours, corneas from group A had average epithelial defect of 9.25 mm 2 on day 1 whereas those from group B had average defect of 12.05 mm 2 , a difference of 2.8 mm 2 (P=0.57). H & E stained corneal sections didn't show abnormal responses to injury at 24 hours and 20 days. Epithelial thickness and stromal cell counts 20 days after injury showed no significant differences. Analysis of immunofluorescence microscopy images showed no differences between all groups. In conclusion, CAP application to cornea doesn't appear to have obvious adverse effects. CAP does not interfere with rate of wound closure or induce increased inflammation. CAP did not have an effect on corneal wound healing or lead to scar formation.

Safety evaluation of the atmospheric low-temperature plasma (ALTP) on the conjunctiva: an animal study and histopathological findings; 6-month follow-up

“…According to their findings, the short-term application of CAP (for 0.5–5 min) could act as an effective and rapid ocular disinfectant for bacteria and fungi without significant damage to the ocular cells and tissues [ 15 ]. In another study, Alhabshan et al (2013) examined the effect of CAP on wound healing in animal models after the corneal epithelial and basement membrane ablation [ 16 ]. They showed that CAP application to the cornea led neither to any evident adverse effects such as scar formation nor to any corneal wound healing.…”

Foundations of plasmas for medical applications

“…Even though a gentle disinfection of eye surfaces by CAP was demonstrated several years ago [323], plasma application in ophthalmology is a subject of little research so far. It has been repeatedly demonstrated in some studies in vitro and in first animal experiments, that CAP is effective to inactivate microorganisms without harmful effects on the cornea [324][325][326][327][328]. In a case series including four patients with therapy-resistant corneal ulcers, the clinical potential of CAP to treat infections as well as ulcerations of the cornea was demonstrated [329].…”

Argon cold atmospheric plasma eradicates pathogens in vitro that are commonly associated with canine bacterial keratitis

“…Furthermore, in chronic wounds important processes relying on radicals are impaired and can be re-stimulated by increasing intracellular concentrations of reactive species (1). Corneas treated for up to 5 min did not show histopathological changes in studies using different devices (15,23,45,69,70). The rate of corneal epithelization in rabbits was not affected by the application of CAP for 2 min (69).…”