Abstract
Purpose :
Elevated intraocular pressure (IOP) is a significant risk factor for developing Primary Open Angle Glaucoma (POAG). Previously, we published that a single eye drop of a novel dual-acting antioxidant-nitric oxide compound SA-2 nanoparticles (NPs) reduced IOP, was neuroprotective and increased superoxide dismutase in rodent models of glaucoma. The current goal was to evaluate SA-2’s antioxidant activity in human glaucomatous TM (hGTM) cells and assess the frequency of eye drop dosing of a modified SA-2-NP formulation. for sustained IOP reduction beyond 72h using microbead occlusion model (MOM) of glaucoma.
Methods :
Primary human TM cells were isolated from post-mortem normal and glaucomatous donor eyes (n =3 each), cultured, and treated with SA-2 (100µM) in the presence or absence of tertbutyl hydroperoxide (TBHP) (150-300µM) for 24h. Using ELISA, cell lysates were analyzed for total antioxidant enzymes, catalase (CAT), and glutathione peroxidase (GPx) activities. SA-2 loaded PLGA NPs were prepared and characterized for size, zeta potential, and drug loading efficacy using a single emulsion technique. C57BL6 male mice (12-weeks old, n=6-8) were anesthetized, underwent MOM surgery, and were monitored for 2-3 weeks for baseline IOP elevation. At days 0, 6, and 13, the IOP-elevated eye was treated with a single eye drop of either 1% SA-2NP (2µl) or 1% blank NP. IOP was measured daily for 23 days using a tonometer.
Results :
TBHP treatment significantly decreased hGTM antioxidant enzyme activity (p <0.5-0.001). SA-2 treatment significantly increased total antioxidant, CAT (3-fold, p<0.001), and GPx activities (2.0-2.5-fold) when compared to untreated hNTM cells. TBHP+SA-2 treatment demonstrated (2.0-2.5-fold) increase in GPx and CAT activities in glaucomatous TM cells compared to the TBHP group. Sustained and significant IOP reduction (30-40%) was observed over the 23 days after SA-2NP treatment, with the effect lasting >10 days post-last dosing as compared to the vehicle control.
Conclusions :
SA-2 demonstrated broad-spectrum antioxidant activity in both normal and glaucomatous human TM cells The modified SA-2NP provided sustained IOP reduction and a longer duration of action in mouse eyes compared to previous formulations. Further in vivo efficacy and pharmacokinetic studies are in progress.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.