Received 2 February 2008; accepted 14 October 2008. published online 10 December 2008.
Background
Multiple measures of endothelial progenitor cells (EPCs) have been described, but there has been limited study of the comparability of these assays. We sought to determine the reproducibility of and correlation between alternative EPC assay methodologies.
Methods
We simultaneously assessed EPC numbers in 140 patients undergoing cardiac catheterization using the 2 most commonly used culture techniques: endothelial cell outgrowth and colony-forming unit (CFU). In the final 77 patients, EPCs were also identified on the basis of cell surface marker expression (CD133, CD34, and vascular endothelial growth factor receptor-2 [VEGFR-2]) and aldehyde dehydrogenase (ALDH) activity.
Results
Endothelial progenitor cell enumeration based on fluorescence activated cell sorting was more precise than culture assays. There was limited correlation between EPC numbers determined using the 2 common culture-based assays; however, endothelial CFUs correlated with VEGFR-2 and CD34/VEGFR-2–expressing cells. Endothelial progenitor cells defined by expression of CD133, CD34, CD133/CD34, and ALDH activity correlated with each other, but not with VEGFR-2+ cells.
Conclusions
Endothelial progenitor cells can be broadly classified into 2 classes: VEGFR-2–expressing cells, which give rise to endothelial CFUs, and CD133/CD34 or ALDHbr cells. These observations underscore the need for better assay standardization and a more precise definition of EPCs in cell therapy research.
aDivision of Cardiology, Duke University Medical Center, Durham, NC
bMiller School of Medicine, University Of Miami, Miami, FL
cDuke Clinical Research Institute, Duke University Medical Center, Durham, NC
Reprint requests: Thomas J. Povsic MD, PhD, Department of Cardiology, Box 3126, Duke University Medical Center, Durham, NC 27710.
This study was funded in part by National Heart, Lung, and Blood Institute (NHLBI) (Bethesda, MD) K-18 HL081419-01A1 to T.J.P, a Society of Geriatric Cardiology Merck Geriatric Cardiology Research Award to T.J.P., and grants from the Duke Clinical Research Institute and Medtronic Inc (Minneapolis, MN), through the Medtronic-Duke Strategic Alliance to T.J.P.
Dr. J. Michael DiMaio served as guest editor for this manuscript.
ABSTRACT