title: Ranibizumab efficiently blocks migration but not proliferation induced by growth factor combinations including VEGF in retinal endothelial cells.
abstract: BACKGROUND
  Proliferation and migration of retinal endothelial cells (REC) are associated with the development of proliferative diabetic retinopathy. REC proliferation is stimulated by isoforms of vascular endothelial growth factor-A (i.e., VEGF₁₂₁ and VEGF₁₆₅), basic fibroblast growth factor (bFGF), and insulin-like growth factor (IGF-1) of which VEGF₁₆₅ also enhances migration of REC. Effects induced by VEGF-A can be blocked with ranibizumab, a VEGF-binding Fab fragment used in therapy of diabetic macular edema. In this study, we investigated potential angiogenic effects of placental growth factors (PlGF-1, PlGF-2) as other members of the VEGF family and whether the primary action of VEGF₁₆₅ is modulated in the presence of bFGF, IGF-1 and PlGF-1/-2. We also studied how effects of growth factor combinations can be attenuated with ranibizumab.
  
  
  METHODS
  Effects of single growth factors or their combinations on proliferation and migration of immortalized bovine retinal endothelial cells (iBREC) were studied with or without ranibizumab or the inhibitor of VEGF receptors KRN951.
  
  
  RESULTS
  Proliferation of iBREC was significantly stimulated by 1-100 ng/ml PlGF-1 or PlGF-2, but additive effects were not observed with various combinations of the tested growth factors. Ranibizumab neutralized VEGF's effect on proliferation but was not effective when the other growth factors were used in combination with VEGF. bFGF and IGF-1 but not PlGF-1 or PlGF-2 stimulated iBREC migration as single agents, and they further enhanced VEGF-induced migration. The effects of such growth factor combinations including VEGF on migration were efficiently blocked by targeting only VEGF with ranibizumab. Migration induced by VEGF plus bFGF and IGF-1 was also almost completely inhibited by KRN951 interfering with VEGF receptor signalling.
  
  
  CONCLUSIONS
  Migration but not proliferation of iBREC induced by combinations of bFGF, IGF-1, PlGF-1 or PlGF-2 together with VEGF is efficiently suppressed by ranibizumab. VEGF-mediated signalling through VEGFR2 seems to control REC migration dominantly in the presence of other growth factors.
authors.affiliation: Department of Ophthalmology, University of Ulm, Prittwitzstrasse 43, 89075, Ulm, Germany, heidrun.deissler@uniklinik-ulm.de.
authors.forename: Heidrun L
authors.initials: HL
authors.lastname: Deissler
authors.forename: Helmut
authors.initials: H
authors.lastname: Deissler
authors.forename: Gerhard K
authors.initials: GK
authors.lastname: Lang
authors.forename: Gabriele E
authors.initials: GE
authors.lastname: Lang
mesh_terms: D020533:Angiogenesis Inhibitors / Q000494:pharmacology*; D000818:Animals; D061067:Antibodies, Monoclonal, Humanized / Q000494:pharmacology*; D002417:Cattle; D002460:Cell Line; D002465:Cell Movement / Q000187:drug effects*; D049109:Cell Proliferation / Q000187:drug effects*; D004338:Drug Combinations; D042783:Endothelial Cells / Q000473:pathology*; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D036341:Intercellular Signaling Peptides and Proteins / Q000494:pharmacology*; D010671:Phenylurea Compounds / Q000494:pharmacology; D000072483:Placenta Growth Factor; D011257:Pregnancy Proteins / Q000494:pharmacology; D011804:Quinolines / Q000494:pharmacology; D000069579:Ranibizumab; D040262:Receptors, Vascular Endothelial Growth Factor / Q000037:antagonists & inhibitors; D012171:Retinal Vessels / Q000473:pathology; D042461:Vascular Endothelial Growth Factor A / Q000494:pharmacology*
chemical_list: D020533:Angiogenesis Inhibitors; D061067:Antibodies, Monoclonal, Humanized; D004338:Drug Combinations; D036341:Intercellular Signaling Peptides and Proteins; D010671:Phenylurea Compounds; D011257:Pregnancy Proteins; D011804:Quinolines; D042461:Vascular Endothelial Growth Factor A; D016222:Fibroblast Growth Factor 2; D000072483:Placenta Growth Factor; C553176:tivozanib; D007334:Insulin-Like Growth Factor I; D040262:Receptors, Vascular Endothelial Growth Factor; D000069579:Ranibizumab