Abstract
Purpose: :
As previous studies have demonstrated a relationship between hyperglycemia and proliferative diabetic retinopathy, and as pigment epithelium-derived factor (PEDF) inhibits blood vessel growth, this study investigated the effect of PEDF on glucose-stimulated angiogenic factor erythropoietin (Epo) in human retinal pigment epithelial (hRPE) cells.
Methods: :
Human RPE specimens were obtained from postmortem non-pathological eyes and culture in vitro. Cellular proliferation in the presence of increasing concentrations of FBS, glucose, and glucose with PEDF was measured by 3H-thymidine incorporation; trypan blue exclusion studies verified cell viability. Under the same experimental conditions, synthesis of Epo was measured utilizing 14C-methionine immunoprecipitation and immunocytochemical methods.
Results: :
FBS stimulated hRPE cell number in a dose-dependent manner, as measured by trypan blue exclusion and 3H-thymidine incorporation in hRPE cells. Glucose did not show any stimulatory effect on hRPE cell number. Glucose stimulated 14C-Epo synthesis in hRPE cells in a dose-dependent manner, as demonstrated by 14C-methionine immunoprecipitation. PEDF (10 ng/mL) suppressed the stimulatory effect of glucose (20 mM) on immunoprecipitated 14C-Epo in hRPE cells (741.13±48.29 vs. 924.65±96.85, CPM±SEM, p<0.05,N=16). This data was qualitatively confirmed by immunocytochemical studies.
Conclusions: :
PEDF inhibits glucose-stimulated Epo synthesis in hRPE cells and may have therapeutic value in treating proliferative diabetic retinopathy.
Keywords: diabetic retinopathy • retinal pigment epithelium • neovascularization