Cobalt chloride improves angiogenic potential of CD133+ cells.

Umbilical cord blood-derived CD133+ cells exhibit the ability to differentiate into endothelial cells and induce new blood vessel growth. Hypoxia-inducible factor-1 (HIF-1), a regulator of hypoxia or the hypoxia-mimetic agent response, actives the SDF-1/CXCR4 signaling pathway and thus plays an important role in angiogenesis in-vivo. In this study we aim to investigate whether CD133+ cells enhance angiogenic ability through hypoxia or CoCl2 in vitro. The CD133+ cells were cultured in normoxia (20 Percent O2), hypoxia (10 Percent O2, 3 Percent O2), or in various concentrations of CoCl2 (50 microM/L, 100 microM/L, 200 microM/L) and subjected to in vitro flow cytometric analysis, tubule formation, as well as migration and proliferation assays. The results demonstrate that both environmental hypoxia and CoCl2 induced hypoxia result in significantly increased CD133+ cell migration, proliferation, and tubule-like structure formation compared with normoxia culture conditions. The HIF-1a, SDF-1, and VEGF protein and gene expression level in conditions of hypoxia is higher than that found in normaxia conditions. Collectively, these data suggest that angiogenic potential of CD133+ cells is influenced by hypoxia or a hypoxia mimetic agent in vitro.