Department of Obstetrics and Gynaecology, Faculty of Medicine, the Chinese University of Hong Kong, Shatin, Hong Kong.
Department of Obstetrics and Gynaecology, Faculty of Medicine, the Chinese University of Hong Kong, Shatin, Hong Kong; Reproduction and Development, Li Ka Shing Institute of Health Sciences, the Chinese University of Hong Kong, Shatin, Hong Kong; School of Biomedical Sciences, the Chinese University of Hong Kong, Shatin, Hong Kong.
Placenta. 2020 Mar;92:44-53. doi: 10.1016/j.placenta.2020.02.002. Epub 2020 Feb 6.
Placental-related mechanism of fetal growth restriction (FGR) is still unknown. Here we aimed to profile whole-genome miRNA between selective FGR twin (sFGR-T) and normally larger co-twin (sL-T) in monochorionic (MC) twin pregnancies and to further investigate effect of the miRNA on placental pathogenesis, including angiogenesis and mitochondrial functions.
MC twin pregnancies with or without sFGR were recruited, and their placental miRNAs were profiled (n = 3 vs 5). Ratio of placental miRNAs in the sFGR twin pairs (sFGR-T/sL-T) were calculated and compared to that in the control twin pairs (cS-T/cL-T). Differentially expressed miRNAs and associated markers were validated qRT-PCR, immunohistochemistry staining (n = 8 vs 13) and electron microscopy (n = 3 vs 3).
Placental miR-199a-5p was significantly upregulated in sFGR-T (p = 0.004), which was validated by qRT-PCR (1.03 vs 0.56; p = 0.020). Compared to control twin pairs, ratio of CD31-positive vessels and volume density of vessels in sFGR twin pairs was lower (0.65 vs 0.92 and 18.7% vs 36.3%; both p < 0.001), while that of cyclooxygenase 2 (COX2)-positive trophoblast cells was higher (3.50 vs 2.22; p = 0.001), indicating an impaired angiogenesis and oxidative stress in the sFGR placenta. In addition, ratio of mitochondrial DNA (mtDNA) mitochondrial encoded NADH dehydrogenase 1 (MTND1) copy numbers (2.10 vs 0.90; p = 0.013), H-score ratios of mitochondrial markers citrate synthase (CS) and cytochrome c oxidase subunit 4 isoform 1 (COX4, 0.53 vs 0.95, p < 0.001; 0.29 vs 1.06, p < 0.001) in trophoblast cells of sFGR twin pairs were also altered significantly and correlated with angiogenesis. Furthermore, ratio of mitochondrial numbers per trophoblasts (8.67 vs 18.67; p = 0.006) and percentage of swollen mitochondria (84.33 vs 11.33; p = 0.003) were converted significantly, indicating mitochondrial damage.
Our results suggested miR-199a-5p may play a role in the placental angiogenesis, oxidative stress and mitochondrial damage and dysfunction as an underlying pathogenesis of sFGR.
胎儿生长受限（FGR）的胎盘相关机制仍不清楚。本研究旨在分析单绒毛膜（MC）双胎妊娠中选择性胎儿生长受限（sFGR）的胎儿胎盘与正常较大胎儿胎盘之间的全基因组 miRNA 图谱，并进一步研究 miRNA 对胎盘发病机制的影响，包括血管生成和线粒体功能。
招募了伴有或不伴有 sFGR 的 MC 双胎妊娠，并对其胎盘 miRNA 进行了分析（n=3 对与 5 对）。计算 sFGR 双胞胎中胎盘 miRNA 的比值（sFGR-T/sL-T），并与对照双胞胎（cS-T/cL-T）进行比较。通过 qRT-PCR（n=8 对与 13 对）、免疫组织化学染色（n=8 对与 13 对）和电子显微镜（n=3 对与 3 对）验证差异表达的 miRNA 和相关标志物。
sFGR-T 中 miR-199a-5p 显著上调（p=0.004），通过 qRT-PCR 得到验证（1.03 比 0.56；p=0.020）。与对照双胞胎相比，sFGR 双胞胎的 CD31 阳性血管比例和血管体积密度较低（0.65 比 0.92 和 18.7% 比 36.3%；均 p<0.001），而环氧化酶 2（COX2）阳性滋养层细胞比例较高（3.50 比 2.22；p=0.001），表明 sFGR 胎盘血管生成和氧化应激受损。此外，线粒体 DNA（mtDNA）线粒体编码烟酰胺腺嘌呤二核苷酸脱氢酶 1（MTND1）拷贝数的比值（2.10 比 0.90；p=0.013）、滋养层细胞中线粒体标志物柠檬酸合酶（CS）和细胞色素 c 氧化酶亚基 4 同工型 1（COX4，0.53 比 0.95，p<0.001；0.29 比 1.06，p<0.001）的 H 评分比值也显著改变，并与血管生成相关。此外，滋养层细胞中线粒体数量与滋养层细胞的比值（8.67 比 18.67；p=0.006）和肿胀线粒体的百分比（84.33 比 11.33；p=0.003）也明显转换，表明线粒体损伤。
我们的研究结果表明，miR-199a-5p 可能在胎盘血管生成、氧化应激和线粒体损伤和功能障碍中发挥作用，是 sFGR 的潜在发病机制。
