Tachikawa Saoko, Nishimura Toshinobu, Nakauchi Hiromitsu, Ohnuma Kiyoshi
Department of Bioengineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata, 940-2188, Japan.
Division of Stem Cell Therapy, Center for Stem Cell Biology and Regenerative Medicine, Institute of Medical Science, University of Tokyo, Tokyo, 108-8639, Japan.
In Vitro Cell Dev Biol Anim. 2017 Oct;53(9):841-851. doi: 10.1007/s11626-017-0192-8. Epub 2017 Aug 28.
Thalidomide, which was formerly available commercially to control the symptoms of morning sickness, is a strong teratogen that causes fetal abnormalities. However, the mechanism of thalidomide teratogenicity is not fully understood; thalidomide toxicity is not apparent in rodents, and the use of human embryos is ethically and technically untenable. In this study, we designed an experimental system featuring human-induced pluripotent stem cells (hiPSCs) to investigate the effects of thalidomide. These cells exhibit the same characteristics as those of epiblasts originating from implanted fertilized ova, which give rise to the fetus. Therefore, theoretically, thalidomide exposure during hiPSC differentiation is equivalent to that in the human fetus. We examined the effects of thalidomide on undifferentiated hiPSCs and early-differentiated hiPSCs cultured in media containing bone morphogenetic protein-4, which correspond, respectively, to epiblast (future fetus) and trophoblast (future extra-embryonic tissue). We found that only the number of undifferentiated cells was reduced. In undifferentiated cells, application of thalidomide increased the number of apoptotic and dead cells at day 2 but not day 4. Application of thalidomide did not affect the cell cycle. Furthermore, immunostaining and flow cytometric analysis revealed that thalidomide exposure had no effect on the expression of specific markers of undifferentiated and early trophectodermal differentiated cells. These results suggest that the effect of thalidomide was successfully detected in our experimental system and that thalidomide eliminated a subpopulation of undifferentiated hiPSCs. This study may help to elucidate the mechanisms underlying thalidomide teratogenicity and reveal potential strategies for safely prescribing this drug to pregnant women.
沙利度胺曾在市场上用于控制孕吐症状，它是一种会导致胎儿畸形的强致畸剂。然而，沙利度胺致畸性的机制尚未完全明确；沙利度胺对啮齿动物无明显毒性，且使用人类胚胎在伦理和技术上都不可行。在本研究中，我们设计了一个以人诱导多能干细胞（hiPSC）为特色的实验系统来研究沙利度胺的作用。这些细胞表现出与源自着床受精卵的上胚层相同的特征，而上胚层会发育成胎儿。因此，从理论上讲，hiPSC分化过程中接触沙利度胺等同于人类胎儿接触沙利度胺。我们研究了沙利度胺对在含有骨形态发生蛋白-4的培养基中培养的未分化hiPSC和早期分化hiPSC的影响，这两种细胞分别对应上胚层（未来的胎儿）和滋养层（未来的胚外组织）。我们发现只有未分化细胞的数量减少了。在未分化细胞中，沙利度胺在第2天增加了凋亡和死亡细胞的数量，但在第4天没有。沙利度胺的应用不影响细胞周期。此外，免疫染色和流式细胞术分析表明，接触沙利度胺对未分化和早期滋养外胚层分化细胞的特异性标志物表达没有影响。这些结果表明，在我们的实验系统中成功检测到了沙利度胺的作用，并且沙利度胺消除了未分化hiPSC的一个亚群。这项研究可能有助于阐明沙利度胺致畸性的潜在机制，并揭示安全地给孕妇开这种药的潜在策略。
