Ogawa M, Kizumoto M, Nishikawa S, Fujimoto T, Kodama H, Nishikawa S I
Department of Molecular Genetics, Faculty of Medicine, Kyoto University, Kyoto, Japan.
Blood. 1999 Feb 15;93(4):1168-77.
Embryonic stem cells can differentiate in vitro into hematopoietic cells through two intermediate stages; the first being FLK1(+) E-cadherin- proximal lateral mesoderm and the second being CD45(-) VE-cadherin+ endothelial cells. To further dissect the CD45(-) VE-cadherin+ cells, we have examined distribution of alpha4-integrin on this cell population, because alpha4-integrin is the molecule expressed on hematopoietic stem cells. During culture of FLK1(+) E-cadherin- cells, CD45(-) VE-cadherin+ alpha4-integrin- cells differentiate first, followed by alpha4-integrin+ cells appearing in both CD45(-) VE-cadherin+ and CD45(-) VE-cadherin- cell populations. In the CD45(-) VE-cadherin+ cell population, alpha4-integrin+ subset but not alpha4-integrin- subset had the potential to differentiate to hematopoietic lineage cells, whereas endothelial cell progenitors were present in both subsets. The CD45(-) VE-cadherin- alpha4-integrin+ cells also showed hematopoietic potential. Reverse transcription-polymerase chain reaction analyses showed that differential expression of the Gata2 and Myb genes correlated with the potential of the alpha4-integrin+ cells to give rise to hematopoietic cell differentiation. Hematopoietic CD45(-) VE-cadherin+ alpha4-integrin+ cells were also present in the yolk sac and embryonic body proper of 9.5 day postcoitum mouse embryos. Our results suggest that the expression of alpha4-integrin is a marker of the earliest precursor of hematopoietic cell lineage that was diverged from endothelial progenitors.
胚胎干细胞在体外可通过两个中间阶段分化为造血细胞；第一个阶段是FLK1(+)E-钙黏蛋白近端外侧中胚层，第二个阶段是CD45(-)VE-钙黏蛋白+内皮细胞。为了进一步剖析CD45(-)VE-钙黏蛋白+细胞，我们检测了α4整合素在该细胞群体上的分布，因为α4整合素是造血干细胞上表达的分子。在FLK1(+)E-钙黏蛋白-细胞培养过程中，CD45(-)VE-钙黏蛋白+α4整合素-细胞首先分化，随后α4整合素+细胞出现在CD45(-)VE-钙黏蛋白+和CD45(-)VE-钙黏蛋白-细胞群体中。在CD45(-)VE-钙黏蛋白+细胞群体中，α4整合素+亚群而非α4整合素-亚群具有分化为造血谱系细胞的潜力，而两个亚群中均存在内皮细胞祖细胞。CD45(-)VE-钙黏蛋白-α4整合素+细胞也表现出造血潜力。逆转录-聚合酶链反应分析表明，Gata2和Myb基因的差异表达与α4整合素+细胞产生造血细胞分化的潜力相关。造血性CD45(-)VE-钙黏蛋白+α4整合素+细胞也存在于妊娠9.5天小鼠胚胎的卵黄囊和胚胎体中。我们的结果表明，α4整合素的表达是造血细胞谱系最早前体的标志物，该前体与内皮祖细胞不同。
