Circulating endothelial and progenitor cells in age-related macular degeneration

Purpose: To evaluate circulating endothelial and circulating progenitor cells as biomarkers in age-related macular degeneration (AMD) patients (both exudative and atrophic forms) in order to establish the possible clinical implication of their assessment. Methods: We have enrolled 44 AMD patients: 22 patients with a recently diagnosed exudative (neovascular) form (nvAMD - group A) and 22 patients with an atrophic (dry) form (drAMD – group B). The control group consisted of 22 age and sex-matched healthy subjects (group C). The number of circulating endothelial progenitor cells (EPC: CD34+/KDR+; CD133+/KDR+; CD34+/KDR+/CD133+), circulating progenitor cells (CPC: CD34+; CD133+; CD34+/CD133+) and circulating endothelial cells (CEC) were determined in the peripheral venous blood samples by flow cytometry. NvAMD patients were evaluated at baseline and 4 weeks after a loading phase of three consequent intravitreal injections of ranibizumab. Results: Comparing AMD patients with the control group, EPCs and CPCs levels were not significantly different, while AMD patients showed significantly higher levels of CECs (p=0.001). Anti-VEGF treatment with intravitreal ranibizumab was associated with a significant reduction of EPC levels, with no significant influence on CPC and CEC. Conclusion: We reported higher levels of CEC in AMD patients in comparison with the control group thereby supporting the hypothesis of an involvement of endothelial dysregulation in the AMD and a reduction of the EPC level in nvAMD patients after three intravitreal injections of ranibizumab.