Distinct gene expression patterns in endothelial cells of different postnatal differentiation stages. (A) A principal component analysis (PCA) plot using genes differentially expressed between CD133+ stem cells and matured endothelial cells (8880 probe sets, q < 10-4). GSE12891: early and late EPCs from GEO data set GSE12891. Each spot represents a single array sample. (B) A heat map showing genes unique in each endothelial lineage cell type. Columns represent human tissue and stem cell samples, while rows represent probe sets. Genes in red: increased expression; in blue: decreased. (C-D) Cell membrane proteins specifically expressed in early (C) or late (D) EPCs according to the “Cellular Component” ontology in the GO database. (E-F) Mean gene expression levels of early (E) or late (F) EPC surface proteins (compared to GAPDH control; n = 3). Results are expressed as the mean ± standard deviation. ND: not detectable. *: P < 0.05 by analysis of variance (ANOVA).