Polymeric nanocapsules: a potential new therapy for corneal wound healing

Corneal injuries are one of the most frequently observed ocular diseases, leading to permanent damage and impaired vision if they are not treated properly. In this sense, adequate wound healing after injury is critical for keeping the integrity and structure of the cornea. The goal of this work was to assess the potential of polymeric nanocapsules, either unloaded or loaded with cyclosporine A or vitamin A, alone or in combination with mitomycin C, for the treatment of corneal injuries induced by photorefractive keratectomy surgery. The biopolymers selected for the formation of the nanocapsules were polyarginine and protamine, which are known for their penetration enhancement effect. The results showed that, following topical instillation to a mouse model of corneal injury, all the nanocapsule formulations, either unloaded or loaded with cyclosporine A or vitamin A, were able to stimulate corneal wound healing. In addition, the healing rate observed for the combination of unloaded protamine nanocapsules with mitomycin C was comparable to the one observed for the positive control Cacicol®, a biopolymer known as a corneal wound healing enhancer. Regarding the corneal opacity, the initial grade of corneal haze (>3) induced by the photorefractive keratectomy was more rapidly reduced in the case of the positive control, Cacicol®, than in corneas treated with the nanocapsules. In conclusion, this work shows that drug-free arginine-rich (polyarginine, protamine) nanocapsules exhibit a positive behavior with regard to their potential use for corneal wound healing.