Recruitment of marrow-derived endothelial cells to experimental choroidal neovascularization by local expression of vascular endothelial growth factor.
OBJECTIVE
The question of whether adult animals maintain a reservoir of endothelial progenitor cells (EPCs) in the bone marrow that is involved in neovascularization is under investigation. The following study was undertaken to examine the potential contribution of EPCs to the development of choroidal neovascularization (CNV) in adult mice and to examine the role of local expression of vascular endothelial growth factor (VEGF) in this process.


METHODS
Lethally irradiated, adult female nude mice were engrafted with whole bone marrow isolated from male transgenic mice expressing LacZ driven by the endothelial specific Tie-2 promoter. Two months, following bone marrow reconstitution, confirmed by quantitative Taqman PCR, an E1-deleted adenoviral vector expressing vascular endothelial growth factor (165) (Ad.VEGF(165)) was injected subretinally to induce CNV, confirmed by collagen IV immunohistochemistry. Bone marrow-derived endothelial cells were detected using either X-gal staining or Y chromosome in situ hybridization. Y chromosome positive cells within the CNV were confirmed to be endothelial cells by lectin staining.


RESULTS
Subretinal Ad.VEGF(165) was capable of inducing CNV. Four-week old lesions were found to contain LacZ expressing cells within the CNV in bone marrow transplanted animals but not in negative control animals. Eighteen percent of all Y chromosome positive cells within the CNV were found to be lectin positive while 27% of all endothelial cells within the CNV were Y chromosome positive.


CONCLUSIONS
Engrafted bone marrow-derived EPCs were shown to differentiate into endothelial cells at the site of subretinal VEGF-induced CNV in mice. These results suggest that EPCs contribute to the formation of neovascularization and that subretinal expression of VEGF might play an important role in recruitment of these cells to the site of CNV.
Csaky
Karl G
KG
National Institutes of Health, National Eye Institute, Building 10-10B11, 9000 Rockville Pike, Bethesda, MD 20892-1857, USA. kcasky@helix.nih.gov
Baffi
Judit Z
JZ
Byrnes
Gordon A
GA
Wolfe
Jeremy D
JD
Hilmer
Sara C
SC
Flippin
Jessica
J
Cousins
Scott W
SW
D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D016026:Bone Marrow Transplantation; D020256:Choroidal Neovascularization / Q000378:metabolism / Q000473:pathology*; D042783:Endothelial Cells / Q000473:pathology*; D005260:Female; D005822:Genetic Vectors; D006085:Graft Survival; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000473:pathology*; D007763:Lac Operon; D008297:Male; D051379:Mice; D008819:Mice, Nude; D016133:Polymerase Chain Reaction / Q000379:methods; D042787:Receptor, TIE-2 / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D014998:Y Chromosome
D042461:Vascular Endothelial Growth Factor A; D042787:Receptor, TIE-2