Endothelial-like cells derived from human CD14 positive monocytes

In the present study, we show that endothelial-like cells (ELCs) can develo p from human CD14-positive mononuclear cells (CD14 cells) in the presence o f angiogenic growth factors. The CD14 cells became loosely adherent within 24 h of culture and subsequently underwent a distinct process of morphologi cal transformation to caudated or oval cells with eccentric nuclei. After 1 week in culture the cells showed a clear expression of endothelial cell ma rkers, including von Willebrand factor (vWF), CD144 (VE-cadherin), CD105 (e ndoglin), acetylated low-density lipoprotein (AC-LDL)-receptor, CD36 (throm bospondin receptor), FLT-1, which is vascular endothelial cell growth facto r (VEGF) receptor-1, and, to a weaker extent, KDR (VEGF receptor-2). Furthe rmore, in these cells structures resembling Weibel-Palade bodies at differe nt storage stages were identified by electron microscopy, and upon culturin g on three-dimensional fibrin gels the cells build network-like structures. In addition, cell proliferation and vWF expression was stimulated by VEGF, and the endothelial cell adhesion molecules CD54 (ICAM-1), and CD106 (VCAM -1) became transiently inducible by tumor necrosis factor-alpha (TNF-alpha) . In contrast, the dendritic markers CD1a, and CD83 were not expressed to a ny significant extent. The expression of CD68, CD80 (B7-1), CD86 (B7-2), HL A-DR and CD36 may also suggest that ELCs might be related to macrophages, s inus lining or microvascular endothelial cells. Taken together, our observa tions indicate that ELCs can differentiate from cells of the monocytic line age, suggesting a closer relationship between the monocyte/macrophage- and the endothelial cell systems than previously supposed.