Endothelial Progenitor Cells and Vascular Health in Dialysis Patients

To the Editor: Patients with end-stage kidney disease (ESKD) are at increased risk for cardiovascular disease (CVD) compared to the general population, because of a number of factors including endothelial dysfunction. Endothelial cells (ECs) arise from progenitors that reside in both the bone marrow and vascular niches, including that of the kidney, and are classified according to specific morphological and functional differences. Endothelial progenitor cells (EPCs) can form “blood-like” islands, which can be measured in a colony-forming unit (CFU) assay in vitro, and late outgrowth ECs (OECs) can home to sites of ischemic injury and contribute to neovascularization. EPCs identified in peripheral blood can be used as indicators of risk of CVD in dialysis patients and play a role in vascular repair by releasing pro-angiogenic growth factors; yet the effect of clinical parameters on OEC appearance in culture has been lacking. OECs have angiogenic properties and as such have been investigated as a source for cell therapy; however, their success has been limited because of their early senescence in culture. In this study, we investigate the effect of patient clinical parameters on OEC appearance as a means of furthering the understanding of OECs as a source of cell therapy for vascular injury.