VEGF induces neuroglial differentiation in bone marrow-derived stem cells and promotes microglia conversion following mobilization with GM-CSF.
OBJECTIVE
Evaluation of potential tropic effects of vascular endothelial growth factor (VEGF) on the incorporation and differentiation of bone-marrow-derived stem cells (BMSCs) in a murine model of anterior ischemic optic neuropathy (AION).


METHODS
In the first approach, small-sized subset of BMCs were isolated from GFP donors mice by counterflow centrifugal elutriation and depleted of hematopoietic lineages (Fr25lin(-)). These cells were injected into a peripheral vein (1 × 10(6) in 0.2 ml) or inoculated intravitreally (2 × 10(5)) to syngeneic mice, with or without intravitreal injection of 5 μg/2μL VEGF, simultaneously with AION induction. In a second approach, hematopoietic cells were substituted by myelablative transplant of syngeseic GFP + bone marrow cells. After 3 months, progenitors were mobilized with granulocyte-macrophage colony-stimulating factor (GM-CSF) followed by VEGF inoculation into the vitreous body and AION induction . Engraftment and phenotype were examined by immunohistochemistry and FISH at 4 and 24 weeks post-transplantation, and VEGF receptors were determined by real time PCR.


RESULTS
VEGF had no quantitative effect on incorporation of elutriated cells in the injured retina, yet it induced early expression of neuroal markers in cells incorporated in the RGC layer and promoted durable gliosis, most prominent perivascular astrocytes. These effects were mediated by VEGF-R1/Flt-1, which is constitutively expresses in the elutriated fraction of stem cells. Mobilization with GM-CSF limited the differentiation of bone marrow progenitors to microglia, which was also fostered by VEGF.


CONCLUSIONS
VEGF signaling mediated by Flt-1 induces early neural and sustained astrocytic differentiation of stem cells elutriated from adult bone-marrow, with significant contribution to stabilization retinal architecture following ischemic injury.
The Krieger Eye Research Laboratory, Felsenstein Medical Research Center, Tel Aviv University, Petach Tikva, Israel.
Bat-Chen R
BC
Avraham-Lubin
Nitza
N
Goldenberg-Cohen
Tamilla
T
Sadikov
Nadir
N
Askenasy
D053687:Adult Stem Cells / Q000378:metabolism* / Q000473:pathology; D000818:Animals; D001253:Astrocytes / Q000378:metabolism / Q000473:pathology; D001854:Bone Marrow Cells / Q000378:metabolism* / Q000473:pathology; D002454:Cell Differentiation / Q000187:drug effects*; D004195:Disease Models, Animal; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology*; D019650:Hematopoietic Stem Cell Mobilization; D051379:Mice; D008822:Mice, Transgenic; D017628:Microglia / Q000378:metabolism* / Q000473:pathology; D018917:Optic Neuropathy, Ischemic / Q000378:metabolism / Q000473:pathology / Q000628:therapy; D012160:Retina / Q000378:metabolism / Q000473:pathology; D033581:Stem Cell Transplantation; D013234:Stem Cells / Q000378:metabolism* / Q000473:pathology; D014184:Transplantation, Homologous; D042461:Vascular Endothelial Growth Factor A / Q000494:pharmacology*; D040281:Vascular Endothelial Growth Factor Receptor-1 / Q000096:biosynthesis; D014822:Vitreous Body / Q000378:metabolism / Q000473:pathology
D042461:Vascular Endothelial Growth Factor A; C467480:vascular endothelial growth factor A, mouse; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; C501163:Flt1 protein, mouse; D040281:Vascular Endothelial Growth Factor Receptor-1