title: Erythropoietin receptor positive circulating progenitor cells and endothelial progenitor cells in patients with different stages of diabetic retinopathy.
abstract: OBJECTIVE
  To investigate the possible involvement of erythr opoietin (EPO)/erythropoietin receptor (EPOR) system in neovascularization and vascular regeneration in diabetic retinopathy (DR).
  
  
  METHODS
  EPOR positive circulating progenitor cells (CPCs: CD34(+)) and endothelial progenitor cells (EPCs: CD34(+)KDR(+)) were assessed by flow cytometry in type 2 diabetic patients with different stages of DR. The cohort consisted of age- and sex-matched control patients with out diabetes ( n=7),non-proliferative DR (NPDR, n=7),non-proliferative DR (PDR, n=8), and PDR complicated with diabetic nephr opathy (PDR-DN, n=7).
  
  
  RESULTS
  The numbers of EPOR(+) CPCs and EPOR(+) EPCs were reduced remarkably in NPDR compared with the control group (both Pü0.01), whereas rebounded in PDR and PDR-DN groups in varyingdegrees. Similar changes were observed in respect of the proportion of EPOR(+)CPCs in CPCs (NPDR vs. control, Pü0.01) and that of EPOR(+) EPCs in EPCs (NPDR vs. control, Pü0.05).
  
  
  CONCLUSIONS
  Exogenous EPO, mediated via the EPO/EPOR system of EPCs, may alleviate the impaired vascular regeneration in NPDR, whereas it might aggravate retinal neovascularization in PDR due to a rebound of EPOR(+)EPCs associated with ischemia.
authors.affiliation: Department of Ophthalmology,Peking Union Medical College Hospital, Chinese Academy of Medical Sciences& Peking Union Medical College, Beijing 100730, China.
authors.forename: Liu-mei
authors.initials: LM
authors.lastname: Hu
authors.forename: Xia
authors.initials: X
authors.lastname: Lei
authors.forename: Bo
authors.initials: B
authors.lastname: Ma
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhang
authors.forename: Yan
authors.initials: Y
authors.lastname: Yan
authors.forename: Ya-lan
authors.initials: YL
authors.lastname: Wu
authors.forename: Ge-zhi
authors.initials: GZ
authors.lastname: Xu
authors.forename: Wen
authors.initials: W
authors.lastname: Ye
authors.forename: Ling
authors.initials: L
authors.lastname: Wang
authors.forename: Guo-xu
authors.initials: GX
authors.lastname: Xu
authors.forename: Guo-tong
authors.initials: GT
authors.lastname: Xu
authors.forename: Li
authors.initials: L
authors.lastname: Wei-Ye
mesh_terms: D000368:Aged; D002452:Cell Count; D003924:Diabetes Mellitus, Type 2 / Q000150:complications*; D003930:Diabetic Retinopathy / Q000473:pathology*; D004730:Endothelium, Vascular / Q000166:cytology*; D004921:Erythropoietin / Q000097:blood; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017467:Receptors, Erythropoietin / Q000032:analysis*; D013234:Stem Cells / Q000502:physiology*
chemical_list: D017467:Receptors, Erythropoietin; D004921:Erythropoietin