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Updated: Jun 23, 2025
Oxygen-Induced Retinopathy Model for Ischemic Retinal Diseases in Rodents
Published on: September 16, 2020
Molecular hydrogen promotes retinal vascular regeneration and attenuates neovascularization and neuroglial
Yatu Guo1,2,3, Jiahui Qin4,5, Ruiqiang Sun6,7
1Tianjin Key Lab of Ophthalmology and Visual Science, Tianjin Eye Hospital, Tianjin, China. yatu.guo@gmail.com.
Insights
Hydrogen gas (H2) shows promise for treating Retinopathy of Prematurity (ROP) by reducing abnormal blood vessel growth and protecting retinal cells. This neuroprotective therapy may offer a safer alternative to current ROP treatments.
Area of Science:
- Ophthalmology
- Neonatal Medicine
- Molecular Biology
Background:
- Retinopathy of Prematurity (ROP) is a leading cause of childhood blindness in premature infants.
- Current treatments like anti-VEGF and photocoagulation have significant complications.
- Hydrogen (H2) is a potential neuroprotective and antioxidant therapy with no known toxic effects.
Purpose of the Study:
- To investigate the effects of H2 on retinal angiogenesis, neovascularization, and neuroglial function in a mouse model of oxygen-induced retinopathy (OIR).
Main Methods:
- Mice exposed to oxygen-induced retinopathy were treated with varying concentrations of hydrogen gas.
- Vascular changes, neovascularization, and glial cell activation were analyzed using histology and immunohistochemistry.
- Key molecular pathways including Nrf2, VEGF, Notch, and HIF-1α were assessed via Western blot and RT-PCR.
Main Results:
- Hydrogen gas (3-4%) ameliorated vaso-obliteration and neovascularization in OIR mice without disrupting physiological angiogenesis.
- H2 treatment prevented astrocyte damage, reduced microglial activation, and promoted vascular regeneration.
- The beneficial effects were linked to Nrf2 activation, suppression of the Dll4/Notch pathway, and regulation of HIF-1α/VEGF.
Conclusions:
- Hydrogen gas demonstrates potential as a therapeutic agent for Retinopathy of Prematurity.
- Its efficacy may involve modulating the Nrf2-Notch axis and HIF-1α/VEGF pathways in the retina.
Background:
Retinopathy of Prematurity (ROP) is a proliferative retinal vascular disease occurring in the retina of premature infants and is the main cause of childhood blindness. Nowadays anti-VEGF and retinal photocoagulation are mainstream treatments for ROP, but they develop a variety of complications. Hydrogen (H2) is widely considered as a useful neuroprotective and antioxidative therapeutic method for hypoxic-ischemic disease without toxic effects. However, whether H2 provides physiological angiogenesis promotion, neovascularization suppression and glial protection in the progression of ROP is largely unknown.This study aims to investigate the effects of H2 on retinal angiogenesis, neovascularization and neuroglial dysfunction in the retinas of oxygen-induced retinopathy (OIR) mice.
Methods:
In this study, mice that were seven days old and either wild-type (WT) or Nrf2-deficient (Nrf2-/-) were exposed to 75% oxygen for 5 days and then returned to normal air conditions. Different stages of hydrogen gas (H2) inhalation were administered. Vascular obliteration, neovascularization, and blood vessel leakage were analyzed and compared. To count the number of neovascularization endothelial nuclei, routine HE staining of retinal sections was conducted. Immunohistochemistry was performed using DyLight 594 labeled GSL I-isolectin B4 (IB4), as well as primary antibodies against proliferating cell nuclear antigen (PCNA), glial fibrillary acidic protein (GFAP), and Iba-1. Western blots were used to measure the expression of NF-E2-related factor 2 (Nrf2), vascular endothelial growth factor (VEGF), Notch1, Dll4, and HIF-1α. Additionally, the expression of target genes such as NQO1, HO-1, Notch1, Hey1, Hey2, and Dll4 was measured. Human umbilical vein endothelial cells (HUVECs) treated with H2 under hypoxia were used as an in vitro model. RT-PCR was used to evaluate the mRNA expression of Nrf2, Notch/Dll4, and the target genes. The expression of reactive oxygen species (ROS) was observed using immunofluorescence staining.
Results:
Our results indicate that 3-4% H2 does not disturb retinal physiological angiogenesis, but ameliorates vaso-obliteration and neovascularization in OIR mice. Moreover, H2 prevents the decreased density and reverses the morphologic and functional changes in retinal astrocytes caused by oxygen-induced injury. In addition, H2 inhalation reduces microglial activation, especially in the area of neovascularization in OIR mice. H2 plays a protective role in vascular regeneration by promoting Nrf2 activation and suppressing the Dll4-induced Notch signaling pathway in vivo. Also, H2 promotes the proliferation of HUVECs under hypoxia by negatively regulating the Dll4/Notch pathway and reducing ROS levels through Nrf2 pathway aligning with our findings in vivo.Moreover, the retinal oxygen-sensing mechanisms (HIF-1α/VEGF) are also involved in hydrogen-mediated retinal revascularization and neovascularization suppression.
Conclusions:
Collectively, our results indicate that H2 could be a promising therapeutic agent for POR treatment and that its beneficial effect in human ROP might involve the activation of the Nrf2-Notch axis as well as HIF-1α/VEGF pathways.
