Endothelial progenitor cells and plasma vascular endothelial growth factor and stromal cell-derived factor-1 during ranibizumab treatment for neovascular age-related macular degeneration

PURPOSE: To evaluate endothelial progenitor cell [late outgrowth endothelial progenitor cells (OECs)], vascular endothelial growth factor (VEGF), and stromal cell-derived factor 1α (SDF-1α) plasma levels as potential biomarkers before and during ranibizumab (Lucentis(®)) treatment for neovascular age-related macular degeneration (nvAMD).

METHODS: Thirty-one patients with untreated nvAMD presenting for 3 consecutive intravitreal ranibizumab injections and a follow-up visit at 4 weeks intervals were enrolled. Peripheral blood was collected before each injection and at the follow-up visit and OEC clusters were cultured and evaluated according to previously published protocols. VEGF and SDF-1α plasma levels were measured by enzyme-linked immunosorbent assay and compared to values from healthy young and old control.

RESULTS: Patients with a high OEC count before treatment presented significantly more often with a short symptom duration and a smaller choroidal neovascularization size. VEGF plasma levels were significantly higher in nvAMD (282.4±195.2 pg/mL) compared to young (45.5±6.8 pg/mL) and old control (46.1±8.5 pg/mL). OEC levels decreased nonsignificantly during ranibizumab treatment, returning to baseline levels after the third injection. VEGF and SDF-1α plasma levels decreased significantly during treatment toward control values. Patients needing retreatment after 3 ranibizumab injections had significantly higher VEGF plasma levels at pretreatment compared to patients not needing further treatment.

CONCLUSIONS: The results presented here suggest that VEGF plasma levels may warrant further evaluation regarding biological, therapeutical, and predictive implications in nvAMD.