Description
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.