Abstract
Purpose: :
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.
Methods: :
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.
Results: :
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.
Conclusions: :
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.
Keywords: antioxidants • neuroprotection