title: Expression of erythropoietin receptor in human epiretinal membrane of proliferative diabetic retinopathy.
abstract: OBJECTIVE
  It is widely accepted that intravitreous levels of erythropoietin (Epo) are elevated in patients with ischaemic retinal diseases such as proliferative diabetic retinopathy (PDR). The aim of this study was to examine the expression of Epo and the Epo receptor (EpoR) in epiretinal membranes with and without diabetes.
  
  
  METHODS
  Eighteen epiretinal membranes (PDR (n = 10), idiopathic epiretinal membranes (IERMs) without diabetes (n = 4) and inner limiting membranes (ILMs) (n = 4)) were obtained during pars plana vitrectomy. Formalin-fixed and paraffin-embedded tissues were examined by immunohistochemistry with anti-Epo and EpoR antibodies.
  
  
  RESULTS
  The histopathological findings demonstrated that PDR membranes consisted of a variety of endothelial cells forming a microvascular cavity with red blood cells and non-vascular stromal mononuclear cells. Membranous and cytoplasmic immunoreactivity for EpoR was strongly detected in endothelial cells and stromal cells in all PDR patients. Although microvessels were not observed in IERMs and ILMs, immunoreactivity for EpoR was noted in the cellular component of IERMs, and was weakly detected in ILMs. Epo was not expressed in any membrane.
  
  
  CONCLUSIONS
  EpoR was strongly expressed in microvessels of all PDR membranes. The in vivo evidence in this study suggests that Epo in the vitreous binds to EpoR in PDR membranes, which subsequently leads to the proliferation of new retinal vessels. EpoR immunoreactivity in non-vascular stromal cells in PDR membranes, and IERMs and ILMs might be indirectly correlated with ischaemia.
authors.affiliation: Department of Ophthalmology and Visual Sciences, Hokkaido University Graduate School of Medicine, N15 W7, Kita-ku, Sapporo 060-8638 Japan. kaseron@med.hokudai.ac.jp
authors.forename: Satoru
authors.initials: S
authors.lastname: Kase
authors.forename: Wataru
authors.initials: W
authors.lastname: Saito
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Ohgami
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Yoshida
authors.forename: Naoki
authors.initials: N
authors.lastname: Furudate
authors.forename: Akari
authors.initials: A
authors.lastname: Saito
authors.forename: Masahiko
authors.initials: M
authors.lastname: Yokoi
authors.forename: Manabu
authors.initials: M
authors.lastname: Kase
authors.forename: Shigeaki
authors.initials: S
authors.lastname: Ohno
mesh_terms: D000368:Aged; D003930:Diabetic Retinopathy / Q000378:metabolism* / Q000473:pathology; D042783:Endothelial Cells / Q000473:pathology; D019773:Epiretinal Membrane / Q000378:metabolism* / Q000473:pathology; D004921:Erythropoietin / Q000032:analysis; D005260:Female; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D008297:Male; D008833:Microcirculation; D008875:Middle Aged; D017467:Receptors, Erythropoietin / Q000032:analysis*
chemical_list: D017467:Receptors, Erythropoietin; D004921:Erythropoietin