Transcriptomic signatures in trophectoderm and inner cell mass of human blastocysts grouped according to developmental potential

Selection of high-quality embryos is important to achieve successful pregnancy in assisted reproductive technology (ART). Recently, it has been debated whether RNA-sequencing (RNA-seq) should be applied to ART to predict embryo quality. However, the information on which genes can serve as markers for pregnant expectancy is limited. Furthermore, there is no information on which transcriptome of trophectoderm (TE) or inner cell mass (ICM) is more highly correlated with pregnant expectancy. Here we performed RNA-seq analysis for TE and ICM, respectively, in human blastocysts of which the expectation of pregnancy was retrospectively determined by the clinical outcomes of 1,890 cases of frozen-thawed blastocyst transfer. We identified dozens of genes that were correlated with the expected pregnancy rate in ICM and TE, respectively, with a larger number of genes identified in TE. Importantly, downregulated genes in TE of blastocysts classified as having lower expectation of pregnancy included tight junction-related genes, such as CXADR, CLDN10, and ATP1B1, which were implicated in peri-implantation development. Additionally, we showed that aneuploidy estimation by RNA-seq datasets does not correlate with pregnancy expectation. Our study thus provide an expanded list of candidate genes for prediction of pregnancy in human blastocyst embryos. Overall design: RNAseq were performed in trophectoderm (TE) and inner cell mass (ICM) from human blastocysts of which the expectation of pregnancy was retrospectively determined by the clinical outcomes of 1,890 cases of frozon-thawed blastocyst transfer.

在辅助生殖技术（assisted reproductive technology, ART）中，优质胚胎的筛选对于实现成功妊娠至关重要。近年来，RNA测序（RNA-sequencing, RNA-seq）是否可应用于辅助生殖技术以预测胚胎质量，学界尚存争议。然而，目前可作为妊娠预后标志物的基因相关信息仍较为匮乏，且尚不明确滋养外胚层（trophectoderm, TE）与内细胞团（inner cell mass, ICM）的转录组，哪一类与妊娠预后的相关性更强。本研究针对1890例冻融胚泡移植的临床结局，回溯确定了人类胚泡的妊娠预后，并分别对其滋养外胚层与内细胞团开展RNA测序分析。我们分别鉴定出了与内细胞团、滋养外胚层妊娠预期率相关的数十个基因，其中滋养外胚层中鉴定出的基因数量更多。值得注意的是，被归类为低妊娠预后的胚泡滋养外胚层中，下调的基因包含紧密连接相关基因，如CXADR、CLDN10及ATP1B1，这些基因已被证实参与围植入期发育。此外，本研究表明，基于RNA测序数据集的非整倍体评估与妊娠预后并无相关性。综上，本研究为人类胚泡胚胎的妊娠预测提供了更多候选基因。整体实验设计：本研究对通过1890例冻融胚泡移植临床结局回溯确定妊娠预后的人类胚泡的滋养外胚层与内细胞团进行了RNA测序。