The Effect of Neovascularization on Human Retinal Pigment Epithelium after Hyperbaric Oxygen Therapy

Abstract

Objective: To investigate the neovascularization effect of hyperbaric oxygen (HBO) therapy on human retinal pigment epithelium (REP) cells. Methods:Human REP cells were cultured in vitro, and divided into normoxic control group and hypoxic control group randomly. The experimental groups were then divided into three subgroups via the different HBO pressure, 0.15 MPa exposed group, 0.2 MPa exposed group, and 0.25 MPa exposed group. The experimental groups were exposed to 100% pure oxygen for 60 and 90 minutes twice, with a 24 hours interval. After HBO exposure the expression of pigment epithelium-derived factor (PEDF) and tumor necrosis factor alpha (TNF-α) by RPE cells were measured by western blot. Results:The western blot result showed that the level of PEDF expression in both experimental groups had an increased trend as the pressure increases with statistical significance (P<0.01). The expression of PEDF in the normoxic group was higher than the hypoxic group. The results showed that the level of TNF-α expression by RPE cells in both experimental groups have a decrease trend as the pressure increases with statistical significance (P<0.01). The results showed that the expression of TNF-α in the hypoxic group was higher when compared to the normoxic group. The duration of HBO exposure has no statistical significance on the level of PEDF and TNF-α expression. Conclusion:This study supports the idea that HBO increases the release of PEDF by RPE cells whither in normoxic and hypoxic conditions, and decreases the release of TNF-α by RPE cells in both conditions, especially in hypoxic state. We also found that HBO can raise the level of PEDF and decrease the level of TNF-α in RPE cells, and has an anti-angiogenic effect which can suppress the formation of neovascularization.

Hyperbaric Oxygen Effects on Contrast and Macular Light Sensitivity in Dry Type Age-Related Macular Degeneration Patients

“…Keane found that the strongest correlatian detected between decreased contrast sensitivity and increased total volume of subretinal tissue (Keane, et al, 2010). Previous study by Chao stated that HBOT can decrease the release of TNF-α by RPE cells therefore decreased inflammation (Chao & Chao, 2017). We believed the improvement on contrast sensitivity in our patients were becaused of the decreased inflammation on subretinal tissue by HBOT.…”

“…Although macular light sensitivity improved in HBOT group during one-day of follow up, the trend was not statistically significant. this can be explained from previous study that stated photoreceptor consumed a large amount of oxygen to convert light energy into readable neuronal signals for the brain to translate (Chao & Chao, 2017). The pivotal role of oxygen for photoreceptor survival was reported.…”

“…Category 3 participants had no advanced AMD but had at least 1 large drusen (125 µm), extensive area of intermediate drusen or geographic atrophy (GA) not involving the center of macula. Category 4 participants had advanced AMD, central geographic atrophy (CGA) or neovascular AMD in one eye (Chew et al 2013).…”