Interaction network analysis as a framework for the interpretation of EPC biology. (A) Cord blood mononuclear cells were isolated and plated on fibronectin-coated culture dishes for four days. Adherent early EPCs are shown. Twenty-one days after plating, late EPCs with a cobblestone-like morphology were selected, reseeded, and grown to confluence. (B) Expression of progenitor, endothelial and hematopoietic markers on EPCs and HUVEC by flow cytometry analysis. Cyan: fluorescent signal using indicated antibodies; Red: isotype control. (C) Tube formation (upper) and Transwell (lower) assays of late EPC and HUVEC. Right panels: quantitative results of the two assays (n = 3) *: p < 0.05. (D) The analysis pipeline for identification of known miRNAs from smRNA-seq data. Reads or sequences pass each filtration process were indicated. (E) Venn diagram of expressed known miRNAs (RPM > 100). (F) Heat maps of known miRNA expression profiles. Left: EC > late EPC > early EPC at a 1.5 fold change (FC); Middle: FC between late EPC and EC < 1.5, which between late EPC and early EPC > 1.5; Right: early EPC > late EPC > HUVEC at a 1.5 fold change. Blue, downregulated; Red, upregulated. (G) RT-qPCR confirmation of selected miRNAs. White bars: early EPC; grey: late EPC; black: mature EC. Histograms of qPCR results were graphed as mean ± standard deviation (n = 3) *: p < 0.05, **: p < 0.01, ***: p < 0.001.