Osteogenic Differentiation of Late-Outgrowth CD45-Negative Endothelial Progenitor Cells

Background/Aims: Late-outgrowth CD45-negative endothelial colony-forming cells are implicated to be circulating endothelial progenitor cells (EPCs), as they express endothelial cell markers and can directly form blood vessels. As these cells share characteristics of other progenitor cell phenotypes, late-outgrowth EPCs were assayed for both multilineage differentiation capability and for markers of pluripotency. Methods: Clonal single-colony late-outgrowth EPCs were derived from human cord blood and assayed both for multilineage differentiation capability in vitro and for markers of pluripotency by qPCR. Results: Under osteogenic growth conditions, these EPCs expressed the osteogenic markers RUNX2, COL1A1, ALPL, and osteocalcin and demonstrated calcium deposition and bone mineralization. Endothelial colony-forming cells expressed markers associated with induced pluripotent stem cells, including SOX2, POU5F1, c-MYC, and KLF4. Conclusions: Late-outgrowth EPCs express markers associated with pluripotency and can directly express an osteogenic phenotype under bone differentiation conditions in vitro. (C) 2014 S. Karger AG, Basel