title: Effect of intravitreal bevacizumab on vascular endothelial growth factor expression in patients with proliferative diabetic retinopathy.
abstract: OBJECTIVE
  To investigate the effect of bevacizumab (Avastin; Genentech, San Francisco, CA, USA) on vascular endothelial growth factor (VEGF) expression and inflammation in fibrovascular membranes in patients with proliferative diabetic retinopathy (PDR).
  
  
  METHODS
  Fibrovascular membranes from 19 eyes of 18 patients with PDR were studied using immunohistochemistry and analyzed in the following 3 groups; group 1: 4 inactive PDR eyes, group 2: 10 active PDR eyes treated preoperatively with adjunctive intravitreal bevacizumab, group 3: five active PDR eyes not treated preoperatively with bevacizumab. Immunohistochemical staining for VEGF, CD31 and CD68 were done.
  
  
  RESULTS
  The immunoreactivity to VEGF and CD 31-positive blood vessels was significantly higher in membranes from group 3 than group 1 (p = 0.007 for VEGF, 0.013 for CD 31-positive vessels). Intravitreal bevacizumab caused a reduction in VEGF expression and vascular densities in 4 out of 10 (40%) excised membranes from eyes with PDR. However, six membranes (60%) in group 2 still demonstrated relatively strong VEGF expression and high vascular density. Infiltration of macrophages was observed in 16 out of the 19 membranes, and the density of macrophages was increased in group 2 compared with group 1 (p = 0.043).
  
  
  CONCLUSIONS
  Intravitreal bevacizumab injections caused some reduction in VEGF expression and vascular densities in a limited number of active PDR patients. A single intravitreal bevacizumab injection may not be enough to induce complete blockage of VEGF and pathologic neovascularization in active PDR patients. Repeated injections, panretinal photocoagulation and/or PPV may be necessary following intravitreal bevacizumab to reinforce the anti-VEGF effect of the drug.
authors.affiliation: Department of Ophthalmology, NHIC Ilsan Hospital, Goyang, Korea.
authors.forename: Eun Jee
authors.initials: EJ
authors.lastname: Chung
authors.forename: Shin Jeong
authors.initials: SJ
authors.lastname: Kang
authors.forename: Ja Seung
authors.initials: JS
authors.lastname: Koo
authors.forename: Yoon Jung
authors.initials: YJ
authors.lastname: Choi
authors.forename: Hans E
authors.initials: HE
authors.lastname: Grossniklaus
authors.forename: Hyoung Jun
authors.initials: HJ
authors.lastname: Koh
mesh_terms: D000328:Adult; D020533:Angiogenesis Inhibitors / Q000627:therapeutic use*; D000911:Antibodies, Monoclonal / Q000627:therapeutic use*; D061067:Antibodies, Monoclonal, Humanized; D000068258:Bevacizumab; D003930:Diabetic Retinopathy / Q000188:drug therapy* / Q000378:metabolism*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D008297:Male; D008875:Middle Aged; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*
chemical_list: D020533:Angiogenesis Inhibitors; D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D042461:Vascular Endothelial Growth Factor A; D000068258:Bevacizumab