Gene expression patterns of distinct human endothelial precursor cells

Early EPCs (eEPCs) appear at less than 1 week in culture dishes, whereas late EPCs (LEPCs) appear late at 2-4 weeks. Distinct angiogenic properties between these two EPC subpopulations have been disclosed by the angiogenesis assay: late EPCs, but not eEPCs, form vascular networks de novo and are able to incorporate into vascular networks. On the contrary, eEPCs, but not late ones, indirectly augment tubulogenesis even when physically separated by a Transwell membrane, implying the involvement of a cytokine-based paracrine mechanism. Microarrays are great tools to “snapshot” the transcriptome profiles, and thus provide deeper insights into gene expressions and microRNA-gene interactions. Cord blood mononuclear cells (MNCs) were Histopaque-1077 isolated and plated in endothelial growth medium-2 on fibronectin-coated six-well plates at 37°C. After 3 days of culturing, attached eEPCs appeared, and medium and nonadherent cells were removed. Thereafter, the medium were replaced every 2 days, and a certain number of eEPCs continued to grow into the LEPCs colonies, which emerge 2–4 weeks after the start of MNC culture. Total RNA of early and late EPCs were extracted and evaluated with Affymetrix GeneChip Human U133 plus 2.0