Exposure to microgravity (μg) results in a range of systemic changes in the organism, but may also have beneficial cellular effects. In a previous study we detected increased proliferation capacity and upregulation of genes related to proliferation and survival in boundary cap neural crest stem cells (BC) after MASER14 sounding rocket flight compared to ground-based controls. However, whether these changes were due to μg or hypergravity was not clarified. In the current MASER15 experiment BCs were exposed simultaneously to μg and 1 g conditions provided by an onboard centrifuge. BCs exposed to μg displayed a markedly increased proliferation capacity compared to 1 g on board controls, and genetic analysis of BCs harvested 5 h after flight revealed an upregulation, specifically in μg-exposed BCs, of Zfp462 transcription factor, a key regulator of cell pluripotency and neuronal fate. This was associated with alterations in exosome microRNA content between μg and 1 g exposed MASER15 specimens. Since the specimens from MASER14 were obtained for analysis with 1 week’s delay, we examined whether gene expression and exosome content were different compared to the current MASER15 experiments, in which specimens were harvested 5 h after flight. The overall pattern of gene expression was different and Zfp462 expression was down-regulated in MASER14 BC μg compared to directly harvested specimens (MASER15). MicroRNA exosome content was markedly altered in medium harvested with delay compared to directly collected samples. In conclusion, our analysis indicates that even short exposure to μg alters gene expression, leading to increased BC capacity for proliferation and survival, lasting for a long time after μg exposure. With delayed harvest of specimens, a situation which may occur due to special post-flight circumstances, the exosome microRNA content is modified compared to fast specimen harvest, and the direct effects from μg exposure may be partially attenuated, whereas other effects can last for a long time after return to ground conditions.

中文翻译：

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微重力对神经嵴干细胞的影响

暴露于微重力（μg）会导致生物体发生一系列全身变化，但也可能产生有益的细胞效应。在之前的一项研究中，我们检测到与地面对照组相比，MASER14 探空火箭飞行后，边界帽神经嵴干细胞 (BC) 的增殖能力增加，并且与增殖和存活相关的基因上调。然而，这些变化是由于微克还是超重力引起的尚不清楚。在当前的 MASER15 实验中，BC 同时暴露于机载离心机提供的 μg 和 1 g 条件下。与机载对照中 1 g 相比，暴露于 μg 的 BC 表现出显着增加的增殖能力，飞行后 5 小时收获的 BC 的遗传分析显示，特别是暴露于 μg 的 BC 中，Zfp462 转录因子（细胞多能性的关键调节因子）上调。和神经元的命运。这与暴露的 MASER15 样本中外泌体 microRNA 含量在 μg 和 1 g 之间的变化有关。由于 MASER14 的样本延迟了 1 周才获得进行分析，因此我们检查了基因表达和外泌体含量是否与当前的 MASER15 实验不同，其中样本是在飞行后 5 小时收获的。与直接收获的样本 (MASER15) 相比，MASER14 BC μg 中基因表达的总体模式不同，Zfp462 表达下调。与直接收集的样品相比，延迟收获的培养基中的 MicroRNA 外泌体含量显着改变。总之，我们的分析表明，即使短时间暴露于 μg，也会改变基因表达，导致 BC 增殖和存活能力增加，并在 μg 暴露后持续很长时间。由于飞行后的特殊情况可能会导致标本延迟收获，与快速标本收获相比，外泌体 microRNA 含量会发生变化，μg 暴露的直接影响可能会部分减弱，而其他影响可能会持续一段时间。返回地面条件后很长时间。