title: Antiapoptotic properties of erythropoietin: novel strategies for protection of retinal pigment epithelial cells.
abstract: BACKGROUND
  Oxidative damage of the retinal pigment epithelium (RPE) may play a role in the development and progression of age-related macula degeneration (ARMD). Therapeutic reduction of oxidative stress failed or had only slight effects in ARMD patients. This study evaluates antiapoptotic properties of erythropoietin (epo) at the RPE as a novel approach to protect RPE cells against oxidative damage.
  
  
  METHODS
  Cultured ARPE-19 cells were exposed to hydroxyl (OH) radicals generated from H(2)O(2) under catalysis of Fe(3+) (Fenton reaction) for 5 min. Apoptosis rate was determined by Annexin V labelling and terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling assay. Epo was added in concentrations from 0 to 100 U/ml to the media 24 and 1 h before radical exposure as well as shortly after radical exposure. Expression of epo receptor was determined by western blotting.
  
  
  RESULTS
  Hydroxyl radical exposure induced an increase of apoptosis rate from virtually 0 to 11.8+/-1.7%. Apoptosis was detectable up to 24 h after radical exposure and reached its maximum after 6 h. Epo reduced apoptosis rate by up to 88% even if applied after the radical exposure. Best protection was achieved at 5 U/ml epo. Western blot confirmed presence of epo receptor independent of a pre-incubation of the cells with epo.
  
  
  CONCLUSIONS
  Epo exerts antiapoptotic effects on cultured RPE cells even if applied after the radical exposure. This might qualify epo as future candidate for therapy and prevention of dry ARMD.
authors.affiliation: Universitätsklinikum Hamburg-Eppendorf, Klinik und Poliklinik für Augenheilkunde, Hamburg, Germany.
authors.forename: A E
authors.initials: AE
authors.lastname: Gawad
authors.forename: L
authors.initials: L
authors.lastname: Schlichting
authors.forename: O
authors.initials: O
authors.lastname: Strauss
authors.forename: O
authors.initials: O
authors.lastname: Zeitz
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D002478:Cells, Cultured; D004921:Erythropoietin / Q000494:pharmacology*; D006801:Humans; D017665:Hydroxyl Radical / Q000494:pharmacology; D008268:Macular Degeneration / Q000503:physiopathology; D018384:Oxidative Stress / Q000187:drug effects* / Q000502:physiology; D017467:Receptors, Erythropoietin / Q000032:analysis; D055213:Retinal Pigment Epithelium / Q000166:cytology / Q000187:drug effects*
chemical_list: D017467:Receptors, Erythropoietin; D004921:Erythropoietin; D017665:Hydroxyl Radical