Luteinizing hormone-releasing hormone agonist and transferrinfunctionalizations enhance nanoparticle delivery in a novel bovine exvivo eye model

[摘要] Purpose: To determine whether topical ocular delivery of <100 nmnanoparticles can be enhanced by coating their exterior with peptide orprotein ligands for cell surface receptors.Methods: A novel ex vivo bovine eye model was validated for itsintegrity up to 60 min. Using this model, the uptake of 20 nmpolystyrene nanoparticles (administered as a single 50 μl drop)before and after surface conjugation with deslorelin, a luteinizinghormone-releasing hormone (LHRH) agonist, or transferrin was determinedat 5 and 60 min in individual layers of cornea and aqueous humor.Selected studies were done in the absence of corneal epithelium in theex vivo model or using excised cornea and conjunctiva. LHRH andtransferrin receptor mRNA and protein expression in corneal epitheliumand conjunctiva were determined by real-time PCR and western blot,respectively.Results: Corneal histology, ZO-1 immunostain pattern, and mannitolpermeability were similar in controls and at the end of the ex vivostudy. Corneal epithelial nanoparticle uptake in the absence of surfacemodification was 1.1-1.6% at 5 min and remained at about this level evenat 60 min. Removal of the corneal epithelium resulted in about 22%particle uptake in the corneal stroma at 5 and 60 min compared to about0.5% in the presence of epithelium, indicating the barrier nature ofcorneal epithelium. Deslorelin and transferrin conjugation enhancedcorneal epithelial uptake of nanoparticles by 3- and 4.5 fold at 5 minand by 4.5- and 3.8 fold at 60 min, respectively. The total cornealuptake in 5 min is approximately 2.4, 9, and 16% with plain,deslorelin-functionalized, and transferrin-functionalized nanoparticles.In all groups, the nanoparticle uptake per unit tissue weight was in theorder: corneal epithelium>stroma>endothelium with levels in theaqueous humor being undetectable. In excised cornea and conjunctivastudies, nanoparticle transport and uptake was elevated for bothdeslorelin and transferrin conjugated nanoparticles. Expression of LHRHand transferrin receptors was observed in corneal epithelium as well asconjunctiva.Conclusions: The ex vivo bovine eye model is a useful tool inunderstanding disposition of nanoparticles after topical delivery. Thecorneal epithelium is a significant barrier for topical nanoparticledelivery to the anterior segment. Surface modification of nanoparticlesby conjugating an LHRH agonist or transferrin is a useful approach toprovide rapid, efficient delivery of intact nanoparticles into and/oracross cornea and conjunctiva.

[学科分类] 生物化学/生物物理