Modifications of the endometrial transcriptome at day 7 of the estrus cycle are crucial to maintain gestation after transfer of in vitro-produced (IVP) embryos, although these changes are still largely unknown. The aim of this study was to identify genes, and their related biological mechanisms, important for pregnancy establishment based on the endometrial transcriptome of recipient lactating dairy cows that become pregnant in the subsequent estrus cycle, upon transfer of IVP embryos. Endometrial biopsies were taken from Holstein Friesian cows on day 6-8 of the estrus cycle followed by embryo transfer in the following cycle. Animals were classified retrospectively as pregnant (PR, n = 8) or nonpregnant (non-PR, n = 11) cows, according to pregnancy status at 26-47 days. Extracted mRNAs from endometrial samples were sequenced with an Illumina platform to determine differentially expressed genes (DEG) between the endometrial transcriptome from PR and non-PR cows. There were 111 DEG (false discovery rate < 0.05), which were mainly related to extracellular matrix interaction, histotroph metabolic composition, prostaglandin synthesis, transforming growth factor-β signaling as well as inflammation and leukocyte activation. Comparison of these DEG with DEG identified in two public external data sets confirmed the more fertile endometrial molecular profile of PR cows. In conclusion, this study provides insights into the key early endometrial mechanisms for pregnancy establishment, after IVP embryo transfer in dairy cows.

中文翻译：

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转移体外产生的胚胎后，早期雌激素中子宫内膜转录组的特征影响了奶牛的怀孕状态。

发情周期第7天子宫内膜转录组的修饰对于体外产生（IVP）胚胎移植后维持妊娠至关重要，尽管这些变化仍然未知。这项研究的目的是基于受体的泌乳奶牛的子宫内膜转录组，在随后的发情周期中怀孕，并转移IVP胚胎，从而确定对建立怀孕至关重要的基因及其相关的生物学机制。在发情周期的第6-8天从荷斯坦黑白花奶牛取子宫内膜活检，随后在下一个周期进行胚胎移植。根据26-47天的妊娠状况，将动物回顾性分为怀孕（PR，n = 8）或未怀孕（non-PR，n = 11）母牛。使用Illumina平台对从子宫内膜样品中提取的mRNA进行测序，以确定PR和非PR母牛的子宫内膜转录组之间的差异表达基因（DEG）。有111 DEG（假发现率<0.05），主要与细胞外基质相互作用，组织营养代谢组成，前列腺素合成，转化生长因子β信号转导以及炎症和白细胞激活有关。将这些DEG与两个公开的外部数据集中确定的DEG进行比较，证实了PR奶牛的子宫内膜分子分子更加肥沃。总之，本研究提供了对奶牛IVP胚胎移植后怀孕建立的关键早期子宫内膜机制的见解。