Phenotypic characterization of circulating endothelial cells and CEPs.

Circulating VEGFR-2⁻ endothelial cells express common hematopoietic and endothelial markers, such as C-kit (A), CD13, and PECAM as well as endothelial-specific markers, including E-selectin and VE-cadherin (C). The chemokine receptor for SDF-1, CXCR-4, is expressed on almost all of the CD34⁺VEGFR-2⁺ cells (B). VEGFR-2⁺ cells do not express myelomonocytic specific markers, including CD15 and CD14.