Intravitreal injection of erythropoietin protects against retinal vascular regression at the early stage of diabetic retinopathy in streptozotocin-induced diabetic rats

Exp Eye Res. 2013 Jan;106:64-73. doi: 10.1016/j.exer.2012.11.001. Epub 2012 Nov 21.


A single intravitreal injection of erythropoietin (EPO) (50 ng/eye) or phosphate-buffered saline was administered to 5-week-old Sprague-Dawley rats at the onset of diabetes mellitus (DM) to determine and evaluate the protective effect of EPO on retinal microvessels. DM was induced by an intraperitoneal injection of streptozotocin (STZ; 60 mg/kg body weight). Morphological changes in microvessels in flat retinal preparations were evaluated during the subsequent 4 weeks by three-dimensional imaging of all blood vessels stained with fluorescein isothiocyanate-conjugated tomato lectin, following immunofluorescence techniques. No marked differences were observed in the shape or density of retinal vessels and the number of retinal capillary branches of the four groups [control, EPO, DM, and DM/EPO] up to 4 weeks after STZ administration. We also observed unique type IV collagen-positive filamentous structures that lacked both cellular elements and blood circulation (lectin-/type IV+ acellular strands), suggesting regressed vessel remnants. The lectin-/type IV+ acellular strands were detected soon after the onset of DM in the diabetic rats, and the number of these structures increased in the DM group (P < 0.01). A single intravitreal injection of EPO caused a significant reduction in the number of lectin-/type IV+ acellular strands to levels observed in the control group. However, the lectin-/type IV+ acellular strands were observed in the central area of the retina near the optic disc in all four groups. Intravitreal injection of EPO resulted in downregulation of the EPO receptor, vascular endothelial growth factor (VEGF), and VEGF receptor at 4 weeks. We conclude that EPO may play a primary role against the progression of diabetic retinopathy by reducing blood vessel degeneration at a very early disease stage.

MeSH terms

  • Animals
  • Blood Glucose / metabolism
  • Cell Proliferation / drug effects
  • Collagen Type IV / metabolism
  • Diabetes Mellitus, Experimental / metabolism
  • Diabetes Mellitus, Experimental / prevention & control*
  • Diabetic Retinopathy / metabolism
  • Diabetic Retinopathy / prevention & control*
  • Endothelium, Vascular / metabolism
  • Erythropoietin / administration & dosage
  • Erythropoietin / pharmacology*
  • Fluorescent Antibody Technique, Indirect
  • Fluorescent Dyes
  • Imaging, Three-Dimensional
  • Intravitreal Injections
  • Male
  • Plant Lectins
  • RNA, Messenger / metabolism
  • Rats
  • Rats, Sprague-Dawley
  • Real-Time Polymerase Chain Reaction
  • Receptors, Erythropoietin / genetics
  • Receptors, Vascular Endothelial Growth Factor / genetics
  • Retinal Vessels / drug effects*
  • Vascular Endothelial Growth Factor A / genetics


  • Blood Glucose
  • Collagen Type IV
  • Fluorescent Dyes
  • Plant Lectins
  • RNA, Messenger
  • Receptors, Erythropoietin
  • Vascular Endothelial Growth Factor A
  • tomato lectin
  • vascular endothelial growth factor A, rat
  • Erythropoietin
  • Receptors, Vascular Endothelial Growth Factor