The role of VEGF and VEGFR2/Flk1 in proliferation of retinal progenitor cells in murine retinal degeneration.
OBJECTIVE
To analyze the role of VEGF and its receptors, VEGFR2/Flk1 and VEGFR1/Flt1, on retinal progenitor cells (RPCs) in a murine model of inherited retinal degeneration (rd1 mice).


METHODS
After proliferating RPCs in the retina of rd1 mice were labeled with bromodeoxyuridine (BrdU), expressions of VEGFR2/Flk1 and VEGFR1/Flt1 were immunohistochemically analyzed. To examine its effect on the proliferation of BrdU-positive RPCs in rd1 mice, VEGF was administered into retinal culture medium with or without blocking agents against VEGFR2/Flk1 or VEGFR1/Flt1 in vitro or injected into vitreous cavity in vivo.


RESULTS
BrdU-labeled RPCs in rd1 mice expressed VEGFR2/Flk1 but not VEGFR1/Flt1. These cells later expressed retinal neuronal markers such as Pax6 and rhodopsin. Exposure of the retinas from postnatal day (P) 9 rd1 mice to VEGF increased the number of proliferating RPCs by 61% in vitro. This effect was blocked by concomitant administration of VEGFR2/Flk1 kinase inhibitor. In vivo, a single intravitreal injection of VEGF in rd1 mice at P9 increased by 138% the number of RPCs and cells that developed from RPCs in the peripheral retina at P18.


CONCLUSIONS
VEGF stimulates the proliferation of RPCs through VEGFR2/Flk1 in rd1 mice. The observed proliferation of RPCs that have the potential to differentiate into retinal neurons may enhance the regeneration of the degenerating retina.
Nishiguchi
Koji M
KM
Department of Ophthalmology, Nagoya University Graduate School of Medicine, Nagoya, Japan. kojinish@med.nagoya-u.ac.jp
Nakamura
Makoto
M
Kaneko
Hiroki
H
Kachi
Shu
S
Terasaki
Hiroko
H
D000818:Animals; D000831:Animals, Newborn; D001973:Bromodeoxyuridine / Q000378:metabolism; D002452:Cell Count; D002454:Cell Differentiation; D049109:Cell Proliferation / Q000187:drug effects*; D004195:Disease Models, Animal; D005136:Eye Proteins / Q000378:metabolism; D019084:Fluorescent Antibody Technique, Indirect; D018398:Homeodomain Proteins / Q000378:metabolism; D020287:In Situ Nick-End Labeling; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D009924:Organ Culture Techniques; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism; D012160:Retina / Q000378:metabolism / Q000473:pathology*; D012162:Retinal Degeneration / Q000378:metabolism / Q000473:pathology*; D012243:Rhodopsin / Q000378:metabolism; D013234:Stem Cells / Q000378:metabolism / Q000473:pathology*; D042461:Vascular Endothelial Growth Factor A / Q000494:pharmacology / Q000502:physiology*; D040281:Vascular Endothelial Growth Factor Receptor-1 / Q000378:metabolism; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism*
D005136:Eye Proteins; D018398:Homeodomain Proteins; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors; C000605732:Pax6 protein, mouse; D012097:Repressor Proteins; D042461:Vascular Endothelial Growth Factor A; C467480:vascular endothelial growth factor A, mouse; D012243:Rhodopsin; D040281:Vascular Endothelial Growth Factor Receptor-1; D040301:Vascular Endothelial Growth Factor Receptor-2; D001973:Bromodeoxyuridine