Department of Anatomy and Embryology, Leiden University Medical Centre, 2333 ZC Leiden, The Netherlands.
Leiden University Medical Center hiPSC Hotel, Leiden University Medical Centre, 2333 ZC Leiden, The Netherlands.
Cells. 2021 Sep 13;10(9):2400. doi: 10.3390/cells10092400.
Human pluripotent stem cells (hPSCs) are not only a promising tool to investigate differentiation to many cell types, including the germline, but are also a potential source of cells to use for regenerative medicine purposes in the future. However, current in vitro models to generate human primordial germ cell-like cells (hPGCLCs) have revealed high variability regarding differentiation efficiency depending on the hPSC lines used. Here, we investigated whether differences in X chromosome inactivation (XCI) in female hPSCs could contribute to the variability of hPGCLC differentiation efficiency during embryoid body (EB) formation. For this, we first characterized the XCI state in different hPSC lines by investigating the expression of and H3K27me3, followed by differentiation and quantification of hPGCLCs. We observed that the XCI state did not influence the efficiency to differentiate to hPGCLCs; rather, hPSCs derived from cells isolated from urine showed an increased trend towards hPGCLCs differentiation compared to skin-derived hPSCs. In addition, we also characterized the XCI state in the generated hPGCLCs. Interestingly, we observed that independent of the XCI state of the hPSCs used, both hPGCLCs and soma cells in the EBs acquired expression, indicative of an inactive X chromosome. In fact, culture conditions for EB formation seemed to promote expression. Together, our results contribute to understanding how epigenetic properties of hPSCs influence differentiation and to optimize differentiation methods to obtain higher numbers of hPGCLCs, the first step to achieve human in vitro gametogenesis.
人类多能干细胞（hPSCs）不仅是研究向包括生殖细胞在内的多种细胞类型分化的有前途的工具，而且也是未来用于再生医学目的的细胞的潜在来源。然而，目前生成人类原始生殖细胞样细胞（hPGCLCs）的体外模型显示，由于所使用的 hPSC 系的不同，分化效率存在很大的可变性。在这里，我们研究了女性 hPSC 中的 X 染色体失活（XCI）差异是否会导致在胚胎体（EB）形成过程中 hPGCLC 分化效率的可变性。为此，我们首先通过研究和 H3K27me3 的表达来表征不同 hPSC 系中的 XCI 状态，然后进行 hPGCLC 的分化和定量。我们观察到 XCI 状态不会影响分化为 hPGCLCs 的效率；相反，与皮肤来源的 hPSCs 相比，源自尿液分离的细胞的 hPSCs 显示出向 hPGCLCs 分化的增加趋势。此外，我们还对生成的 hPGCLCs 中的 XCI 状态进行了表征。有趣的是，我们观察到，独立于所用 hPSC 的 XCI 状态，EB 中的 hPGCLCs 和体细胞都获得了表达，表明 X 染色体失活。事实上，EB 形成的培养条件似乎促进了表达。总之，我们的结果有助于了解 hPSC 的表观遗传特性如何影响分化，并优化分化方法以获得更多数量的 hPGCLCs，这是实现人类体外配子发生的第一步。
