6 8 10 12 14 16 18 20 0
50 100 150 200 250 300 350
400 Hyalocytes
time (days after birth)
cells / mm²
6 8 10 12 14 16 18 20
0 100 200 300 400 500 600
Microglial cells in peripheral zone
time (days after birth)
cells / mm²
6 8 10 12 14 16 18 20
0 100 200 300 400 500 600
Microglial cells in central zone
time (days after birth)
cells / mm²
Retinal microglia in the mouse model of oxygen-induced retinopathy
Fischer F; Martin G; Agostini HT
University Eye Hospital Freiburg, Germany
Contact: G. Martin, gottfried.martin@uniklinik-freiburg.de
Retinal neovascularization has been
intensively investigated in the mouse model of oxygen-induced retinopathy (OIR). Here, we studied the contribution of microglial cells to cell loss and reactive angiogenesis in
mice expressing green fluorescent protein (GFP) under the microglial cell-specific
promotor Cx3cr1.
Background
● Microglial cell density is always higher in the superficial than in the deep retinal layer.
● Hyalocytes density decreases with retinal vascularisation.
● The density of microglial cells in the deep layer decreases significantly after return to normal room air.
● It is unclear if microglial cells move from the deep to the superficial layer.
● Activated microglial cells are observed in the superficial retinal layer from P8 to P10 and from P16 to P18.
● Thus, microglial cells may be involved in the formation of the central avascular zone as well as in retinal revascularisation.
Conclusion
Methods
Results
● Animals: heterozygous Cx3cr1-GFP mice (background: C57Bl/6)
● Retinal flat-mounts were stained with lectin and investigated by fluorescence microscopy
● Numbers of microglial cells and hyalocytes in 12 fields were determined from postnatal day 7 to day 20
● Cells were counted:
A) in two zones of the retina (central and peripheral zone) B) in two layers of the retina (superficial and deep layer) C) hyalocytes in vitreous
A) Retinal flat mount, Lectin staining, OIR P17
superficial layer
deep layer
activated
microglia cells
OIR-model
control group without oxygen treatment
central zone
peripheral zone
superficial layer
deep layer
Mouse model of oxygen-induced retinopathy (OIR)
superficial layer
deep layer
B) Cryosection of a OIR-treated mouse, OIR P17, GFP+ microglial cells (green)
room air
P0 P7 P12 P17
retinal vascularisation vessel loss neovascularisation regression of the NV
75 % O
2room air
central avascular zone
peripheral zone
OIRcontrol group
Hyalocytes in the central avascular zone of the retina,
vessels stained with lectin
Hyalocytes are positive for GFP and lectin. In contrast to the microglial
cells, they have a larger round cellular body and no processes.
Activated microglial cells
OIR P17
These cells are found in the superficial layer of the retinal avascular zone.
Activated microglial cells express GFP and are additionally positive for lectin. They undergo a
morphological change from
ramified cells to cells with short and broad processes.
bar = 50μm Error bars indicate standard error
central zone P12 central zone P14
Microglial cells expressing GFP (green) in the deep retinal layer, vessels are stained with lectin (red)
bar = 50μm