title: Different properties of VEGF-antagonists: Bevacizumab but not Ranibizumab accumulates in RPE cells.
abstract: BACKGROUND
  Vascular endothelial growth factor (VEGF) antagonists are currently the therapy of choice for age-related macular degeneration. Here we compared the effects of FDA-approved Ranibizumab and off-label used Bevacizumab on RPE cells, investigating their respective uptake by RPE cells over time.
  
  
  METHODS
  Primary porcine RPE cells were treated with Bevacizumab or Ranibizumab, respectively. Uptake of the respective VEGF-antagonists was assessed with confocal laser scanning microscopy and flow cytometry. Cell death was assessed with MTT assay and VEGF secretion was measured with ELISA.
  
  
  RESULTS
  When clinical doses were applied for 1 h, Bevacizumab was taken up by RPE cells as assessed by confocal laser scanning microscopy and flow cytometry. After 24 h of incubation, and further assessed after 1d, 5d, and 7d, Bevacizumab was detected in RPE cells where it accumulated over time. The presence of Bevacizumab within RPE cells after 7d was confirmed by flow cytometry. While some Ranibizumab was found in RPE cells after 1 h of incubation when assessed with confocal laser microscopy but not by flow cytometry, no signal above control was detected after 1d, 5d, or 7d. Neither substance induced significant cell death after 7 days and no inhibitory effect on VEGF secretion was observed after day 3 of culture.
  
  
  CONCLUSIONS
  Bevacizumab, but not Ranibizumab, accumulates in RPE cells over time, implying substantial differences between these two drugs.
authors: Department of Ophthalmology, University of Kiel, Campus Kiel, Hegewischstr. 2, 24105 Kiel, Germany. aklettner@ophthalmol.uni-kiel.de
authors: Alexa Karina
authors: AK
authors: Klettner
authors: Marie-Luise
authors: ML
authors: Kruse
authors: Tim
authors: T
authors: Meyer
authors: Daniela
authors: D
authors: Wesch
authors: Dieter
authors: D
authors: Kabelitz
authors: Johann
authors: J
authors: Roider
mesh_terms: D020533:Angiogenesis Inhibitors / Q000494:pharmacology*; D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D061067:Antibodies, Monoclonal, Humanized; D000068258:Bevacizumab; D002470:Cell Survival; D002478:Cells, Cultured; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D018613:Microscopy, Confocal; D009924:Organ Culture Techniques; D000069579:Ranibizumab; D055213:Retinal Pigment Epithelium / Q000187:drug effects* / Q000378:metabolism; D013552:Swine; D042461:Vascular Endothelial Growth Factor A / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D020533:Angiogenesis Inhibitors; D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D042461:Vascular Endothelial Growth Factor A; D000068258:Bevacizumab; D000069579:Ranibizumab