miRNAs of the largest human miRNA gene cluster at all, i.e., C19MC, are almost exclusively expressed in the placenta. Nevertheless, only little is known about the interindividual variation of their expression and even about possible influence of gestational age, conflicting data is reported as well as for miRNAs of the much smaller miR-371-3 cluster. Our present study aims at the analyses of the expression of miRNAs from both clusters at different times of pregnancy, possible differences between placenta samples obtained from spontaneous or induced abortions in the first trimester, and the possible variation of miRNA expression at different sites within same placentas. miR-371a-3p, miR-372-3p, miR-373-3p, miR-517a-3p, and miR-520c-3p were quantified in 85 samples and miR-371a-3p was quantified in maternal serum samples taken immediately before delivery. While for miRNA-517a-3p and miR-520c-3p the expression increased with increasing gestational age, the present study revealed strong interindividual differences in the expression of miR-371-3 in full-term placental tissue as well as for miRNAs of the C19MC cluster, where the levels differed to a much lesser extent than for the former microRNAs. Also, strong interindividual differences were noted between the serum samples but differences related to the site of the placenta where the sample has been taken from were excluded. For neither of the data from placental tissue, the study revealed differences between the spontaneous and induced abortion group. Thus, the differences do not in general seem to be related to first trimester abortion. It remains to be elucidated whether or not they affect other prenatal processes.

中文翻译：

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C19MC 和 miR-371-3 编码的 miRNA 的表达在个体胎盘之间存在很大差异，但在自然流产和人工流产之间没有差异

最大的人类 miRNA 基因簇的 miRNA，即 C19MC，几乎只在胎盘中表达。然而，关于它们表达的个体间变异，甚至关于孕龄的可能影响知之甚少，报告了相互矛盾的数据以及小得多的 miR-371-3 簇的 miRNA。我们目前的研究旨在分析两个集群在不同怀孕时间的 miRNA 表达，从妊娠早期自然流产或人工流产获得的胎盘样本之间可能存在的差异，以及同一胎盘内不同位点的 miRNA 表达可能变化。 . miR-371a-3p、miR-372-3p、miR-373-3p、miR-517a-3p、和 miR-520c-3p 在 85 个样品中被量化，miR-371a-3p 在分娩前立即采集的母体血清样品中被量化。虽然 miRNA-517a-3p 和 miR-520c-3p 的表达随着胎龄的增加而增加，但本研究揭示了足月胎盘组织中 miR-371-3 的表达以及C19MC 簇，其中的水平差异比以前的 microRNA 小得多。此外，在血清样品之间注意到强烈的个体差异，但排除了与采集样品的胎盘部位相关的差异。对于来自胎盘组织的数据，研究揭示了自然流产组和人工流产组之间的差异。因此，这些差异一般似乎与头三个月的流产无关。它们是否会影响其他产前过程还有待阐明。