Bromfenac Sodium/Chitosan Nanoparticles For Ophthalmic Delivery: Preparation And Effect On Corneal Neovascularization In Rabbits

ObjectiveTo develop a novel nano-ophthalmic delivery―bromfenacsodium/chitosan nanoparticles. Meanwhile, to evaluate its drug releasecharacteristics in vitro, the ocular tolerance in vivo and the effect on cornealneovascularization in rabbits. Moreover, to investigate the biologicalmechanism, provide a new way for treatment of corneal neovascularizationin clinical.The experiment includes three parts:Experiment One: Preparation and in vitro drug release study of BF/CSnanoparticles.Experiment Two: Study on the tolerance of BF/CS nanoparticles inrabbit ocular surface.Experiment Three: Evaluate the effect of BF/CS nanoparticles oncorneal neovascularization of rabbits. MethodExperiment One: Bromfenac sodium/chitosan nanoparticles (BF/CSnanoparticles) were fabricated by ionotropic gelation mechanism. Thenobserved their characterization (such as particle size, zeta potential, the drugloading capacity and encapsulation efficiency, etc.) and determined the drugrelease ability in vitro.Experiment Two: The BF/CS nanoparticle suspensions were obtainedaccording to the method in experiment one. We used5female New Zealandalbino rabbits do study. Every30minutes, dropped0.1%BF/CSnanoparticle suspensions to the experimental eye (right eye), and control eye(left eye) was given the same dose of saline for6hours. The left eye wasused as the control and received an equal volume of saline. Three, six, and24hours after the first instillation, animal discomfort and clinical signs weremacroscopically evaluated, according to a modification of the scoringsystem established in the Organization for Economic Cooperation andDevelopment (OECD) guidelines(1987) for ocular irritation testing. Then,animals were euthanized by air embolism. Cornea, conjunctiva and lidtissues were removed for hematoxylin-eosin staining. Then, observemorphological difference between treated group and control group.Experiment Three: Corneal NV was induced by NaOH in rabbits.60New Zealand albino rabbits were randomly divided into three groups of20rabbits per group. In group A, animals received eyedrops of0.9%NaCl ascontrol group. In group B, the injured eyes were treated with bromfenac sodium water solution (0.1%). In group C, the injured eyes were treated withthe fabricated BF/CS nanoparticle suspensions(0.1%). At7,14,21and28days after injured, the area of corneal neovascularization was measuredeach group, and the cornea were removed for hematoxylin-eosin staining,meanwhile, COX-2and VEGF were quantified by reversetranscription-quantitative PCR (RT-qPCR) each group.ResultExperiment One: The nanoparticles were smooth and spherical. Theirsize ranged from approximately362.0±14.7~548.7±14.4nm and had apositive zeta potential ranged from22.9±4.3to43.2±4.7mV. The loadingcapacity and encapsulation efficiency of BF/CS nanoparticles were11.26–57.71%and22.48–67.11%respectively. In vitro drug release studydemonstrated an initial burst release followed by a sustained release，and hada release period of about48h.Experiment Two: According to the scoring system, the treated groupscore was1and the control group score was0. Experimental group andcontrol group were not observed differences. There was not tissue edema orabnormal inflammatory cells infiltration in any structure.Experiment Three: Alkali burn induced progressive corneal NV andinflammation in the cornea. BF/CS nanoparticles delayed the onset ofcorneal NV (P<0.05) and decreased NV areas (P<0.05) to a greater extentthan BF water solution and vehicle control. BF/CS nanoparticles decreased the inflammation in the corneas at different time points after the alkali burn.Corneal COX-2and VEGF levels were reduced by BF/CS nanoparticlestreatment.Conclusion1. Bromfenac sodium/chitosan nanoparticles were successfullyobtained by ionotropic gelation method, the method is simple、easy tooperate and strong repeatability; The fabricated bromfenac sodium/chitosannanoparticles had a stable physical and chemical property. And it had agood sustained-release capacity in vitro.2. There were no signs of inflammation or tissue alteration caused bybromfenac sodium/chitosan nanoparticles, it’s no acute toxicity for rabbitocular surface.3. Bromfenac sodium/chitosan nanoparticles can inhibit the cornealneovascularization of rabbit, and down-regulate the expression of COX-2and VEGF in corneas at different time points after the alkali burn.