Sub-lethal hypoxic damage promotes primary retinal ganglion cell survival and VEGF may play an essential role

Abstract

Purpose : The purpose of this study was to investigate the effect of sub-lethal hypoxic damage on primary retinal ganglion cell (RGC) survival. Moreover, to investigate their mechanism including the functional role of vascular endothelial growth factor (VEGF) in RGC survival.

Methods : The retinas were separated from enucleated eyeballs of SD-Rat on postnatal day 1 to 4. RGCs were purified using immunopanning-magnetic separation (IMS) system. Harvested cells were maintained for 24 h in a defined medium and then hypoxic damage was given to the cells using the CO2 chamber. RGCs were then treated with 800 μM hydrogen peroxide (H2O2) for 24 hours to induce oxidative stress. After the treatment, survival rate of each RGCs were confirmed by lactate dehydrogenase assay and flow cytometry. Also, Anti-VEGF (Bevacizumab, 0.001, 0.01, 0.1, 1 and 10 mg/ml) was treated after hypoxic damage of RGCs and the survival rate of each RGCs were compared.

Results : According to our study, hypoxic damage of between 4 and 8 hours significantly increased RGC survival compared to the control group. (P<0.05) We also demonstrate that VEGF may act importantly on hypoxic RGCs to promote survival. We observed that sub-lethal hypoxic damage increased VEGF concentration. On the other hand, RGC death was exacerbated by high dose anti-VEGF (>1 mg/ml), and more cells died in proportion to the anti-VEGF dose.

Conclusions : Sub-lethal hypoxic damage showed neuroprotective effects to the primary RGC survival in our study. Not all but only a certain constant section of hypoxic damage showed neuroprotective effect. With the in vitro condition, strong inhibition of VEGF developed with the increase of RGC death. These data may indicate that certain amount of VEGF may play an essential role to promote the cell survival during the hypoxic period.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.