Abstract
Isolation of endothelial progenitors from human umbilical cord blood generated great hope in vascular tissue engineering. However, before clinical use, progenitor derived endothelial cells (PDECs) have to be compared with mature endothelial cells (ECs). The aim of this study was to explore the behavior of PDECs exposed to a proinflammatory cytokine (interleukin-1α; IL-1α) according to the mitogen-activated protein (MAP) kinase and nuclear factor (NF)-κB signal transduction pathways as well as procoagulant activity (PCA). CD34+ mononuclear cells were isolated using magnetic beads, cultured, and compared with human saphenous vein ECs (HSVECs). PDECs express endothelial markers: CD31, VE-cadherin, von Willebrand factor, KDR, and incorporate acetylated low-density lipoprotein (Dil-Ac-LDL). IL-1α similarly activates c-Jun N-terminal protein kinase (JNK) and p38 pathways in HSVECs and PDECs, whereas extracellular signal-related kinase (ERK)1/2 phosphorylation is lower in PDECs than in HSVECs. Low ERK1/2 phosphorylation in PDECs was specific to IL-1α as vascular endothelial growth factor (VEGF) similarly stimulated ERK1/2 pathway. With respect to inhibitor of NF-κ B (Iκ B) degradation, NF-κ B translocation and phosphorylation, the NF-κ B pathway is comparable in HSVECs and PDECs after stimulation. PCA and tissue factor level induced by IL-1α are lower in PDECs than in HSVECs. Thus, our data show that PDECs display the characteristics of functional mature ECs under IL-1α stimulation. However, we observed significant differences between PDECs and HSVECs related to both ERK1/2 pathway activation and tissue factor production.