Compound SA-10 Mitigates Retinal I/R Injury in Mice by Increasing Hmox1 Expression and Promotes RGC Survival in Human Retinal Explants

Abstract

Purpose : In this study, we investigated the potential of SA-10, a hybrid nitric oxide donating and sulfone ROS scavenging molecule, to promote the survival of retinal ganglion cells (RGCs) against glaucomatous damage. We investigated its neuroprotective effects following retinal ischemia/reperfusion (I/R) injury in mice and ex vivo following neurotrophic factor (NF) deprivation in human retinal explants (HREs).

Methods : Acute I/R injury was induced in C57BL/6J mice (n=2-3 mice/group/sex) through intracameral pressure elevation to 120 mmHg for 1 hour. The mice were pre-treated topically with a PLGA nanosuspension of SA-10 (1% SA-10-NPs) and treated for 14 days (7 doses) after I/R injury. The obtained retinal sections were stained with anti-heme oxygenase-1 antibody (Hmox1, a marker of protective response to oxidative stress) to quantify its expression levels. H&E sections were used to measure retinal thickness.

In another set of experiments, biopsy punches from HREs (n=3 donors) were isolated and treated with either SA-10 [10 μM] or vehicle and maintained without NF for 7 days ex vivo (DEV). Four control punches were collected on day 0 (0 DEV). After 7 days, HREs were immunostained with RBPMS (RGC-specific marker), and cell survival was analyzed. Analysis of Variance (ANOVA) was performed for all experiments.

Results : In the nerve fiber and ganglion cell layers (ganglion cell complex, GCC), I/R injury caused a significant reduction in Hmox1 expression in female (79.8%, p<0.05) and male (54.5%, p<0.05) mice, compared to the sham control. Additionally, I/R injury led to a decline in GCC thickness by 27.5% (p=0.23) in females and 32.7% (n=2) in males. However, treatment with SA-10-NPs increased Hmox1 expression by 4.2-fold (p<0.05) in females and by 0.5-fold (p=0.43) in males. SA-10-NPs also preserved GCC thickness by 17.6% (p=0.68) in females and 27.1% in males. In human retinal explants, the 7 DEV vehicle-treated group had a significant loss in RGCs by 45.2% (p<0.01) compared to 0 DEV. In contrast, SA-10 treatment enhanced RGC survival at 7 days with an 83.1% (p<0.01) higher RGC counts than the vehicle group.

Conclusions : SA-10 and its nanosuspension exhibited significant neuroprotective effects by enhancing Hmox1 expression, preserving retinal thickness, and promoting RGC survival, highlighting its potential as a therapeutic candidate for glaucoma and ischemic stroke.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.