Characterization of Angiogenic Potential of Late Endothelial Progenitor Cells on Human Cord Blood and Bone Marrow

Background: The identification of circulating endothelial progenitor cells (EPCs) has revolutionized approaches to cell-based therapy for injured and ischemic tissues. Recently, we have demonstrated that there are 2 distinct types of EPCs from UCB having different biologic properties for angiogenic capabilities in vitro and in vivo. In present study, the aim is to directly compare umbilical cord blood (UCB)- and BM-derived late EPC surface phenotypes and in vitro functional capacity.

Methods: Mononuclear cells from UCB and BM cultured using EGM-2 medium with VEGF, IGF-1 and FGF for 21 days. Late outgrowing endothelail cells(late OECs) which were in peak growth at third weeks of culture were analyzed for expression of various surface markers by flow cytometry/RT-PCR/IF, tube formation in Matrigel plates, proliferation assay, endothelial colony assay and the role of SDF-1/VEGF on migration.

Results: The adherent cells after culture of 7 days exhibited a fibroblast like shape in BM and a cobblestone shaped cells in UCB. Although two sources of OECs were comparable in expression of endothelial and various adhesion molecule markers, BM-derived OECs contained higher proportion of cells expressing smooth muscle cell markers(SMMHC), several adhesion molecule(CD49d, CD62L and VCAM-1), whereas the expression of CXCR-4, PECAM-1 and CD62E and expression of mRNA on endothelial marker genes were higher in UCB-derived OECs. UCB-OECS stained positive for uptake of acetylated low-density lipoprotein and had more migratory ability in the presence of SDF-1 and VEGF compared with BM-OECs. Both sources OECs effectively formed capillary tubes in Matrigel plates.

Conclusion: We directly compared OECs derived from UCB and BM and two source of OECs differ in aspect of several adhesion molecule and angiogenic potential in vitro. These difference of UCB render it potentially advantageous for human therapeutic OECs applications for potential applications for a “cell therapy” in the situations on vascular injuries when compared with patients-derived BM.