OBJECTIVE To study the use of human embryonic stem cell-derived trophoblastic spheroids (BAP-EB) as human blastocyst surrogates for studying early implantation and trophoblast development. DESIGN Laboratory study. SETTING University research laboratory. PATIENT(S) Infertile in vitro fertilization patients donating endometrial aspirates and human embryonic stem cells (hESCs: VAL3 and H9/WA09). INTERVENTION(S) In BAP-EB derived from hESC, transcriptomes analyzed by next-generation RNA sequencing, effects of Hippo signaling pathway studied by a YAP inhibitor, comparison of attachment of BAP-EB onto primary endometrial epithelial cells (EEC) collected at prereceptive and receptive phases, and antibody blocking assay used to study the molecule(s) involved in BAP-EB attachment. MAIN OUTCOME MEASURE(S) Gene expression profiles and endometrial cell attachment rates. RESULT(S) The BAP-EB differentiation protocol for VAL3 could be used to induce trophoblast differentiation in another hESC line, H9. Transcriptomic analysis showed that the epiblast signature gene expression was reduced while that of the trophoblast was induced during BAP-EB differentiation. Specifically, trophectoderm signature genes were induced in BAP-EB at 48 hours and 72 hours after induction of differentiation. The Hippo signaling pathway was one of the pathways induced during BAP-EB differentiation, and YAP1 inhibitor statistically significantly reduced attachment, outgrowth, and trophoblast gene expressions of BAP-EB. A statistically significantly higher number of BAP-EB derived from both VAL3 and H9 attached onto receptive EEC than prereceptive EEC. The antibody blocking assay demonstrated that endometrial E-cadherin might be critical in early implantation. CONCLUSION(S) The data suggest that BAP-EB possesses a trophectoderm-like signature, which supports the use of BAP-EB as a blastocyst surrogate for the study of trophoblast development and endometrial receptivity.

中文翻译：

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人类胚胎干细胞衍生的囊胚样球体在早期着床过程中类似于人类滋养外胚层

目的 研究使用人胚胎干细胞衍生的滋养层球体 (BAP-EB) 作为人类囊胚替代物研究早期着床和滋养层发育。设计实验室研究。设置大学研究实验室。PATIENT(S) 捐赠子宫内膜抽吸物和人类胚胎干细胞（hESC：VAL3 和 H9/WA09）的体外受精患者。干预（S）在源自 hESC 的 BAP-EB 中，通过下一代 RNA 测序分析的转录组，YAP 抑制剂研究的 Hippo 信号通路的影响，比较 BAP-EB 在接受前收集的原代子宫内膜上皮细胞 (EEC) 上的附着和接受阶段，以及用于研究参与 BAP-EB 附着的分子的抗体阻断试验。主要结果测量基因表达谱和子宫内膜细胞附着率。结果 VAL3 的 BAP-EB 分化方案可用于在另一个 hESC 系 H9 中诱导滋养细胞分化。转录组学分析表明，在 BAP-EB 分化过程中，外胚层特征基因表达减少，而滋养层细胞表达减少。具体而言，在诱导分化后 48 小时和 72 小时，在 BAP-EB 中诱导了滋养外胚层特征基因。Hippo 信号通路是 BAP-EB 分化过程中诱导的通路之一，YAP1 抑制剂在统计学上显着降低了 BAP-EB 的附着、生长和滋养层基因表达。从 VAL3 和 H9 中获得的 BAP-EB 的数量在统计学上显着高于接受性 EEC，而不是接受性 EEC。抗体阻断试验表明子宫内膜 E-钙粘蛋白可能在早期植入中起关键作用。结论(S) 数据表明 BAP-EB 具有滋养外胚层样特征，这支持使用 BAP-EB 作为胚泡替代物来研究滋养层发育和子宫内膜容受性。