Peripheral blood-derived eEPC and OECs have distinctive transcriptomes. Normalised data from Illumina WG-6 v3.0 Expression Beadchip were imported into NIA array for analysis. Numbers of upregulated transcripts are shown in red and downregulated transcripts in green. There were minimal differences (<50 transcripts) among technical replicates as shown by the log-ratio chart for pairwise comparison of eEPC replicates(A), and the log-ratio chart for pairwise comparison of OEC replicates(B); however there were extensive differences (> 5000 differentially expressed transcripts) when eEPCs were compared to OECs as shown by the log-ratio chart for pairwise comparison of eEPCs vs. OECs(C). Prinicipal component analysis (PCA) segregates eEPCs from OECs(D) using one single component (PC1). Biplot analysis on PCA graph identifies transcripts specifically expressed in each EPC subtype(E).