Abstract
Purpose::
Neovascular age-related macular degeneration (AMD) is a leading cause of irreversible blindness in developed countries. The mechanism and the factors that influence choroidal neovascularization (CNV) have not been fully understood. Recently, hematopoietic stem cells (HSCs) including endothelial progenitor cells (EPCs) have been shown to contribute to experimental CNV. However, the potential role of these cells remains unclear. The purpose of this study is to investigate the potential role of circulating HSCs/EPCs in the progression of CNV.
Methods::
The numbers of HSCs/EPCs in the peripheral blood of neovascular AMD patients (n=81), age matched controls (n=21) and young healthy volunteers (n=10) were analyzed using flow cytometry. We also measured the functions of EPCs using colony forming units of endothelial cells (CFU-EC) and the migration activities of EPCs in ex vivo culture system. CNV activity was judged by the period from the last sign of progression. CNV severity was judged by CNV size and laterality of CNV.
Results::
The number of circulating HSCs/EPCs were increased with the activity of CNV (CD34+HSCs; control: 3.8±0.4cells/µl, stable AMD group: 4.0±0.2cells/µl, active AMD group: 5.3±0.5 cells/µl, control vs. active P=0.02, stable vs. active P=0.01) but not related to the severity of CNV. In contrast, the functions of EPCs did not change with activity of CNV but significantly decreased in severer CNV cases (CFU-EC; large CNV: 21.5±4.4 vs. small CNV: 37.3±6.3, P=0.02, bilateral CNV: 18.8±4.8 vs. unilateral CNV: 33.2±5.0, P=0.02).
Conclusions::
Bone marrow derived cells may have an important role in the formation and progression of CNV in AMD patients. Controlling the circulating HSCs/EPCs may be a new therapeutic strategy for preventing progression of CNV.
Keywords: age-related macular degeneration • choroid: neovascularization • flow cytometry