Fig. 1.

Endothelial colony forming cells (ECFCs) develop a cobblestone-like morphology in culture and express endothelial cell surface markers. A: image of typical preterm ECFCs [magnification: low-power, ×40; high-power (inset), ×100]. B: flow cytometry of preterm ECFCs. Each single-stain result (gray) was compared with the appropriate isotype control (white). Preterm ECFCs were strongly positive for endothelial cell lineage makers, CD31, CD105, and CD146, weakly positive for CD34 and negative for CD133, a marker of cell immaturity. Cells were negative for the hematopoietic makers CD38 and CD45 and the fibroblast marker CD90. C: preterm ECFCs in an in vitro tube formation assay.