Luft Sabine, Arrizabalaga Onetsine, Kulish Ireen, Nasonova Elena, Durante Marco, Ritter Sylvia, Schroeder Insa S
1 Department of Biophysics, GSI Helmholtz Center for Heavy Ion Research , Darmstadt, Germany .
2 Technical University Darmstadt , Darmstadt, Germany .
Stem Cells Dev. 2017 Mar 1;26(5):341-352. doi: 10.1089/scd.2016.0277. Epub 2016 Dec 22.
Exposure of the embryo to ionizing radiation (IR) is detrimental as it can cause genotoxic stress leading to immediate and latent consequences such as functional defects, malformations, or cancer. Human embryonic stem (hES) cells can mimic the preimplantation embryo and help to assess the biological effects of IR during early development. In this study, we describe the alterations H9 hES cells exhibit after X-ray irradiation in respect to cell cycle progression, apoptosis, genomic stability, stem cell signaling, and their capacity to differentiate into definitive endoderm. Early postirradiation, hES cells responded with an arrest in G2/M phase, elevated apoptosis, and increased chromosomal aberrations. Significant downregulation of stem cell signaling markers of the TGF beta-, Wnt-, and Hedgehog pathways was observed. Most prominent were alterations in the expression of activin receptors. However, hES cells responded differently depending on the culture conditions chosen for maintenance. Enzymatically passaged cells were less sensitive to IR than mechanically passaged ones showing fewer apoptotic cells and fewer changes in the stem cell signaling 24 h after irradiation, but displayed higher levels of chromosomal aberrations. Even though many of the observed changes were transient, surviving hES cells, which were differentiated 4 days postirradiation, showed a lower efficiency to form definitive endoderm than their mock-irradiated counterparts. This was demonstrated by lower expression levels of SOX17 and microRNA miR-375. In conclusion, hES cells are a suitable tool for the IR risk assessment during early human development. However, careful choice of the culture methods and a vigorous monitoring of the stem cell quality are mandatory for the use of these cells. Exposure to IR influences the stem cell properties of hES cells even when immediate radiation effects are overcome. This warrants consideration in the risk assessment of radiation effects during the earliest stages of human development.
胚胎暴露于电离辐射（IR）是有害的，因为它会导致基因毒性应激，从而引发诸如功能缺陷、畸形或癌症等即时和潜在后果。人类胚胎干细胞（hES）可以模拟植入前胚胎，并有助于评估早期发育过程中IR的生物学效应。在本研究中，我们描述了H9 hES细胞在X射线照射后，在细胞周期进程、细胞凋亡、基因组稳定性、干细胞信号传导以及它们分化为定形内胚层的能力方面所表现出的变化。照射后早期，hES细胞表现为G2/M期阻滞、细胞凋亡增加以及染色体畸变增多。观察到TGF-β、Wnt和Hedgehog信号通路的干细胞信号标志物显著下调。最显著的是激活素受体表达的改变。然而，hES细胞根据所选择的维持培养条件而有不同反应。酶消化传代的细胞比机械传代的细胞对IR更不敏感，照射后24小时显示凋亡细胞更少，干细胞信号变化也更少，但染色体畸变水平更高。尽管观察到的许多变化是短暂的，但照射后4天分化的存活hES细胞形成定形内胚层的效率低于 mock 照射的对应细胞。这通过SOX17和微小RNA miR-375较低的表达水平得到证明。总之，hES细胞是早期人类发育过程中IR风险评估的合适工具。然而，使用这些细胞时必须谨慎选择培养方法并严格监测干细胞质量。即使克服了即时辐射效应，暴露于IR仍会影响hES细胞的干细胞特性。这在人类发育最早阶段辐射效应的风险评估中值得考虑。
