Vitreous Levels of Vascular Endothelial Growth Factor and Stromal-DerivedFactor 1 in Patients With Diabetic Retinopathy and Cystoid Macular Edema Beforeand After Intraocular Injection of Triamcinolone

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Abstract
Background Diffuse macular edema (DME) and/or aberrant neovascularization (NV)can cause vision loss in diabetic retinopathy (DR) and may be modulated bygrowth factors and chemokines. The chemokine stromal-derived factor 1 (SDF-1)is a potent stimulator of vascular endothelial growth factor (VEGF) expression,the main effector of NV, and the key inducer of vascular permeability associatedwith DME. Circulating endothelial cell precursors migrating in response toSDF-1 participate in NV. Objective To investigate the relationship between SDF-1 and (VEGF) in vitreousof patients with varying degrees of DR and DME before and after intraocularinjection of triamcinolone acetonide, used to treat refractory DME. Methods In this prospective study, 36 patients were included and observed for6 months. Vitreous VEGF and SDF-1 levels were measured by enzyme-linked immunosorbentassay in samples obtained immediately before and 1 month after injection oftriamcinolone. Results Both VEGF and SDF-1 were significantly higher (P<.01)in patients with proliferative DR than in patients with nonproliferative DR.Levels of SDF-1 were markedly increased in patients with DME compared withthose without DME. Vascular endothelial growth factor correlated with SDF-1levels and disease severity (r2 = 0.88). Conclusions Triamcinolone administration resulted in dramatic reductions of VEGFand SDF-1 to nearly undetectable levels, eliminated DME, and caused regressionof active NV. Our results support a role for SDF-1 and VEGF in the pathogenesisof the adverse visual consequences of DR and suggest that the eliminationof DME with regression and/or initiation of fibrosis of NV after triamcinoloneinjection may be due to the suppression of VEGF and SDF-1.