In vivo- and in vitro-produced bovine embryos have different metabolic profiles and differences in gene transcription patterns. These embryos also have a distinct ability to establish and sustain early pregnancies. Small extracellular vesicles (sEVs) are secreted by embryos and carry bioactive molecules, such as miRNAs. We hypothesize that in vivo or in vitro-produced bovine hatched blastocysts on Day 9 and the sEVs secreted by them have different miRNA profiles. To address this hypothesis, embryos of both groups were placed in in vitro culture on Day 7. After 48 h, hatched embryos and hatched embryo-conditioned media (eCM) of both groups were collected. A total of 210 miRNAs were detected in embryos of both groups, of these 6 miRNAs were downregulated, while 7 miRNAs were upregulated in vitro group when compared to in vivo group. sEVs were isolated from eCM to determine miRNA profile. A total of 106 miRNAs were detected in both groups, including 14 miRNAs upregulated in sEVs from in vivo-eCM, and 2 miRNAs upregulated in sEVs from in vitro-eCM. These miRNAs express in embryos and sEVs secreted by them regulate early embryonic developmental and endometrial pathways, which can modify embryo-maternal communication during early pregnancy and consequently affect pregnancy establishment.

中文翻译：

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来自体内或体外产生的牛胚泡的小细胞外囊泡具有不同的 miRNA 谱——对胚胎-母体识别的意义

体内和体外产生的牛胚胎具有不同的代谢特征和基因转录模式的差异。这些胚胎还具有建立和维持早期妊娠的独特能力。小细胞外囊泡 (sEV) 由胚胎分泌并携带生物活性分子，例如 miRNA。我们假设在第 9 天体内或体外产生的牛孵化的囊胚和它们分泌的 sEV 具有不同的 miRNA 谱。为了解决这一假设，在第 7 天将两组的胚胎置于体外培养中。48 小时后，收集两组的孵化胚胎和孵化胚胎条件培养基 (eCM)。两组胚胎共检测到210个miRNA，其中6个miRNA表达下调，7个miRNA在体外组与体内组相比上调。从 eCM 中分离出 sEV 以确定 miRNA 谱。两组共检测到 106 个 miRNA，包括 14 个在体内-eCM 的 sEV 中上调的 miRNA，2 个在体外-eCM 的 sEV 中上调的 miRNA。这些 miRNA 在胚胎中表达，它们分泌的 sEV 调节早期胚胎发育和子宫内膜通路，这可以改变妊娠早期胚胎与母体的交流，从而影响妊娠的建立。