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A. J. Ondricek, A. Mukerjee, J. K. Vishwanatha; Formulation and Characterization of N-Acetyl Cysteine Loaded PLGA Nanoparticles for Neuroprotection to Retinal Ganglion Cells in an in vitro Model of Glaucomatous Cell Death. Invest. Ophthalmol. Vis. Sci. 2009;50(13):2410.
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The eye is a preferential environment to study sustained delivery methods due to its isolation from peripheral circulation via the blood retina barrier. Likewise, poly-L-lactic-co glycolic acid (PLGA) is a preferential polymer to encapsulate drugs for sustained delivery because it is biodegradable, biocompatible and FDA approved. The purpose of this study is to formulate and characterize N-acetyl cysteine (NAC) loaded PLGA nanoparticles and study the effect of them delivering neuroprotective antioxidants to retinal ganglion cells. We hypothesize that NAC loaded PLGA nanoparticles (NAC-PLGA nps) will afford sustained neuroprotection to retinal ganglion cells (RGCs) via activation of cell survival pathways when compared to NAC alone.
PLGA nanoparticles were synthesized utilizing double emulsion solvent evaporation technique. Nanoparticles were then characterized for size using a particle size analyzer, Nanotrac. Intracellular localization in RGC-5 and to the RGC cell layer in pig eyes was determined using Nile Red. Encapsulation efficiency was determined by direct method utilizing the thiol-reactive probe, monobromibimane. Cell survival assay was carried out using Calcien AM assay. Western blotting analysis was used for determination of cell signaling events.
NAC-PLGA nps were optimized based on preferred size (100-250 nm) and encapsulation efficiency. It was found that NAC-PLGA nps localize intracellularly in vitro in RGC-5s and ex vivo to RGCs in pig eyes. NAC-PLGA nps affords neuroprotection to RGC-5s against Iodoacetic Acid induced cytotoxicity. NAC-PLGA nps induce sustained phosphorylation of ERK1 and 2, and S6 over 24 hours compared with control.
NAC-PLGA nanoparticles have potential to become an effective treatment, in vitro, against the generation of oxidative stress and cytotoxicity. They are a plausible for application in glaucoma because of the ability to localize intracellularly in RGCs. The application of such a sustained delivery method could improve patient outcomes and compliance when combined with IOP-lowering treatments or in normal tension glaucomas alone.
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