Abstract
Purpose: :
To investigate the presence of circulating bone–marrow derived endothelial progenitor cells in patients with choroidal neovascularization (CNV) associated with AMD (neo–AMD).
Methods: :
Peripheral blood mononuclear cells (PBMNC) were collected from patients with neoAMD (n=20), age–matched control (n=20) and young control (n=16). Isolated cells were grown in EGM–2 medium on fibronectin–coated culture vessels. Outgrowth cells were characterized by FACS, Western blot, immunocytochemistry, SA beta–gal staining, angiogenic assays and ELISA for determination of cytokine release.
Results: :
Two different types of cells with endothelial morphology and phenotype and angiogenic potential were cultured from peripheral blood samples: cells appearing early in culture (early EPC) and presenting a limited proliferation potential, and highly–proliferate cell clusters (late outgrowth endothelial cells, OEC) appearing after day 10. Early EPC and OEC presented markedly different cytokine profiles. There was no statistically significant difference in time of OEC appearance, number of clusters and proliferate potential among the studied populations. OEC were grown for a range of 1 to 15 passages until undergoing senescence. Study subjects could be categorized into different groups according to OEC proliferation potential that appeared to be dependent on VEGF–receptor 2 (KDR) expression.
Conclusions: :
Two types of EPC can be derived and cultured from the peripheral blood of patients with neoAMD. Survival of the highly proliferative OEC appears to be responsive to KDR inhibition. Functional differences between patients with neoAMD and unaffected controls as well as the exact role of EPC’s and OEC’s in the formation of neovascular AMD remains to be determined.
Keywords: neovascularization • age-related macular degeneration • growth factors/growth factor receptors