Related Experiment Video
Updated: Aug 8, 2026
Live Imaging and Characterization of Microglia Dynamics and Interactions with Synapses in Diseased Murine Retina
Published on: January 16, 2026
Microglia and macrophages are increased in response to ischemia-induced retinopathy in the mouse retina
Michael H Davies1, Joshua P Eubanks, Michael R Powers
1Department of Pediatrics, Casey Eye Institute, Oregon Health and Science University, Portland, OR 97239, USA.
Purpose:
The ability of microglial cells (MG) and macrophages (MAC) to release cytokines, induce apoptosis, as well as perform phagocytic functions suggests a possible role in wound healing following oxygen-induced injury. This study was performed to determine the temporal and spatial expression of F4/80 (F4/80+) positive microglia/macrophages (MG/MAC) in areas of retinal damage in the mouse model of oxygen-induced retinopathy.
Methods:
C57BL/6 postnatal day 7 (P7) mice were exposed to 75% O2 for 5 days (P12) then allowed to recover in room air. Hyperoxia-exposed (O2) mice (O2 refers to hyperoxia exposure from P7 to P12 only) were sacrificed on P12, P14, P17, and P21 and their eyes were examined. Localization of F4/80+ cells in FITC-dextran-perfused retinas allowed coordinate visualization of retinal vessels and MG/MAC via fluorescence microscopy. BrdU, a cellular proliferation marker, was injected intraperitoneally 1 h prior to sacrifice. Immunostaining was performed for a microglia and macrophage-specific antigen (F4/80) and BrdU. CCL2 (monocyte chemoattractant protein-1; MCP-1) expression was examined by quantitative real time reverse transcriptase polymerase chain reaction (RT-PCR).
Results:
There was a marked increase (>500%) in MG/MAC in hyperoxia-exposed retinas on P17O2 and P21O2 compared to control retinas. At P17O2, MG/MAC were localized in areas of neovascularization (NV), revealing an intimate relationship between MG/MAC and neovascular tufts. However, P21O2 retinas demonstrated MG/MAC associated with avascular regions in the outer layers of the retina. Immunostaining for F4/80 and BrdU revealed rare co-localization in hyperoxia-exposed retinas. Real time RT-PCR results demonstrated increased expression of CCL2 in P14O2- and P17O2- exposed retinas.
Conclusions:
Our results suggest that resident retinal microglia proliferation occurs at a low frequency in response to injury in this model. The substantial increase in total F4/80+ cells in hyperoxia-exposed retinas in conjunction with the upregulation of CCL2 is consistent with recruitment of hematogenous macrophages into the retina. The temporal and spatial localization of MG/MAC adjacent to neovascular tufts suggests these cells are modulating the retinal response to ischemia-induced retinopathy.
Insights
Microglia/macrophages (MG/MAC) increase significantly in oxygen-induced retinopathy, suggesting hematogenous macrophage recruitment. These cells are associated with neovascularization, potentially modulating the retinal injury response.
Area of Science:
- Ophthalmology
- Immunology
- Cell Biology
Background:
- Microglial cells (MG) and macrophages (MAC) possess functions relevant to wound healing, including cytokine release, apoptosis induction, and phagocytosis.
- Oxygen-induced retinopathy (OIR) is a significant cause of vision impairment, characterized by retinal damage and abnormal blood vessel growth.
Purpose of the Study:
- To investigate the temporal and spatial expression of F4/80 positive microglia/macrophages (MG/MAC) in the context of oxygen-induced retinopathy in a mouse model.
- To understand the role of MG/MAC in retinal injury and neovascularization following hyperoxia exposure.
Main Methods:
- C57BL/6 mice were exposed to hyperoxia (75% O2) from postnatal day 7 to 12, followed by recovery in room air.
- Eyes were examined at postnatal days 12, 14, 17, and 21 to assess F4/80+ cell localization using fluorescence microscopy.
- Cell proliferation was assessed using Bromodeoxyuridine (BrdU) incorporation, and CCL2 (monocyte chemoattractant protein-1) expression was quantified by RT-PCR.
Main Results:
- A significant increase (>500%) in MG/MAC was observed in hyperoxia-exposed retinas on days 17 and 21 compared to controls.
- MG/MAC were found in close proximity to neovascular tufts at day 17, and in avascular outer retinal layers by day 21.
- Rare co-localization of F4/80 and BrdU indicated low frequency of resident microglia proliferation, while CCL2 expression was upregulated in early stages of OIR.
Conclusions:
- The substantial increase in F4/80+ cells suggests recruitment of circulating macrophages into the retina in OIR.
- Upregulation of CCL2 supports the role of chemoattraction in MG/MAC infiltration.
- The localization of MG/MAC near neovascularization indicates their involvement in modulating the retinal response to ischemic injury.
