Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, College of Medicine and the Hospital, National Taiwan University, Taipei, Taiwan.
Tissue Eng Part A. 2010 Sep;16(9):2901-13. doi: 10.1089/ten.tea.2009.0722.
Hypoxic environment is theoretically more physiological for the growth of human embryonic stem (hES) cells. It has been reported that hypoxic culture maintained better undifferentiation of hES cells, but the effects on differentiation are less well established. The hES cells were thus cultured and compared in hypoxia (2% oxygen [O2]) and normoxia (21% O2). The data showed that the undifferentiated state of hES cells was maintained more favorably in hypoxia during prolonged culture. Most tested genes belonging to FGF, TGF-beta/GMP, and Wnt signaling pathways were enriched in undifferentiated hES cells and downregulated upon differentiation, accompanied with differential expression of FGFR1, FGFR2, and FRAT2 between hypoxia and normoxia. Higher P-Smad2/3 level was identified in hypoxia, favoring the maintenance of hES cells in undifferentiation. Bisulfite sequencing showed similar imprinting status between different O2 tensions at H19 differentially methylated region (DMR) and KvDMR loci. Embryoid body formation was enhanced in hypoxia accompanied with suppressed Sox17, Desmin, Gata4, Brachyury, and Cdx2 expression. We concluded that hypoxia improved self-renewal of hES cells through modulation of major signaling pathways and was also more efficient for differentiation to embryoid bodies, though they might present with suppressed expression of some lineage-specific genes across all the three embryonic germ layers and trophectoderm.
缺氧环境在理论上更有利于人类胚胎干细胞（hES）的生长。据报道，低氧培养能更好地维持 hES 细胞的未分化状态，但对分化的影响则不太明确。因此，将 hES 细胞在低氧（2%氧气[O2]）和常氧（21% O2）中进行培养和比较。数据表明，在长时间培养过程中，hES 细胞在低氧环境下更有利于保持未分化状态。大多数属于 FGF、TGF-beta/GMP 和 Wnt 信号通路的测试基因在未分化的 hES 细胞中富集，并在分化时下调，伴随着 FGFR1、FGFR2 和 FRAT2 在低氧和常氧之间的差异表达。在低氧条件下，P-Smad2/3 水平较高，有利于 hES 细胞保持未分化状态。亚硫酸氢盐测序显示，在 H19 差异甲基化区域（DMR）和 KvDMR 基因座，不同氧张力之间的印迹状态相似。低氧条件下胚状体的形成增强，同时 Sox17、Desmin、Gata4、Brachyury 和 Cdx2 的表达受到抑制。我们得出结论，低氧通过调节主要信号通路改善了 hES 细胞的自我更新能力，并且对于向胚状体的分化也更有效，尽管它们可能表现出所有三个胚胎生殖层和滋养外胚层中某些谱系特异性基因的表达受到抑制。
