Novel ophthalmic hyaluronic acid-hydrogel with curcumin nanoparticles for enhanced healing of ulcerative keratitis in rabbit model

Abstract

Corneal ulcers, whether melting or indolent, are common in humans and companion animals. Treatment involves local administration of antibiotic eye drops and corneal healing drugs. Compared to traditional treatments for ulcerative keratitis, herbal medicines offer unique advantages, such as potent anti-inflammatory effects and inhibition of proinflammatory cytokines. Curcumin, extracted from the Curcuma Longa plant, possesses extensive pharmacological properties, such as anti-inflammatory, anti-cancer, and antioxidant properties, and is used in various medicines. In this study, we developed a novel ophthalmic drop hydrogel using a formulation of Curcumin NPs encapsulated with β-cyclodextrin and hyaluronic acid, to accelerate corneal healing and improve the quality of healed structures. The formation of Curcumin NPs into Hyaluronic acid-based hydrogels was characterized by zeta, FTIR, and scanning electron microscope (SEM) analyses. A total of 25 healthy male New Zealand Albino rabbits were experimentally induced with ulcerative keratitis and treated individually with topical medication. Rabbits were divided into five groups. Fluorescein dye staining, corneal clarity score, Schirmer tear test, proinflammatory cytokine measurement, and pathologic factors assessments were used to evaluate the optimised Curcumin NPs with β-cyclodextrin in Hyaluronic acid hydrogel. Our results demonstrated that the optimized Curcumin NPs with β-cyclodextrin in hyaluronic acid hydrogel significantly reduced the frequency of medication administration compared to conventional therapies, enhancing the quality of healed structures and effectively treating ulcerative keratitis. All findings in this study provide new insight into designing and fabricating novel ophthalmic medicine for ulcerative keratitis for topical usage.

Keywords: Curcumin nanoparticles; Hyaluronic acid; Hydrogel; Ulcerative keratitis; Β- cyclodextrin.

Fig. 1

Experimental alkali burn induction in rabbits’ eyes. (a) Pre-surgery eye preparation (b) filter paper soaking in NaOH 1M (c) Ulcer induction proceeding (d) Ulcer appearance post-surgery (e) Ulcerative keratitis (f) Ulcerative keratitis confirmation (g) Post-surgery Schirmer tear test.

Fig. 2

(a) Administrating ophthalmic drops to a rabbit’s eye (b) Administrating tramadol subcutaneously.

Fig. 3

SEM images of Curcumin NPs into Hyaluronic acid-based hydrogel at the scale of (A) 10 μm, (B) 1 μm and (C) 200 nm. (D) FTIR analysis hyaluronic acid-curcumin sample at spectrum of 400 to 4000 cm^–1.

Fig. 4

(a) Reduction of the corneal damage in the rabbits’ eyes in fluorescein dye staining (b) Comparison the corneal ulcer sizes between groups.

Fig. 5

(a) Applying a Schirmer tear test strip into the rabbit’s eye (b) Comparison of the tear production between groups.

Fig. 6

(a) Corneal cloudiness and clarity (b) Comparison of the corneal clarity scores between groups.

Fig. 7

(a) H&E staining of the eyes (b) Comparison of the pathological factors between groups.

Fig. 8

(a) IL-6 measurement in aqueous humour (pg/ml) (b) TNF-α measurement in aqueous humour (pg/ml).