Prediction of severe preeclampsia and intrauterine growth restriction based on serum placental exosome miR-520a-5p levels during the first-trimester

Abstract

Background: To assess the predictive capabilities of serum exosomal levels of micro-RNA-520a-5p (miR-520a-5p) concerning the occurrence of severe preeclampsia (sPE) and fetal growth restriction (FGR) during the first trimester of pregnancy.

Methods: During the period spanning from October 2020 to October 2021, serum samples were procured from the first trimester and subsequently preserved by freezing at -80 ℃. These samples were obtained from 105 pregnant women in a nested case-control study. This cohort consisted of individuals who later developed sPE (sPE group, n = 35) and FGR (FGR group, n = 35) during the third trimester. Additionally, 35 women with normal blood pressure were denoted as normal pregnancy group. Serum samples from the first trimester were retrieved from all groups for further analysis after thawing. Exosomes were extracted from the serum samples collected during the first trimester and examined using transmission electron microscopy, western blot, and nanoparticle tracking analysis. Additionally, the determination of their placental origin was also established during the course of the study. Exosome miR-520a-5p levels were measured using real-time quantitative polymerase chain reaction assays, primarily involving quantitative reverse transcription polymerase chain reactions. Fetal placental tissues from the 3 groups were collected shortly after birth, and miR-520a-5p expression was measured using real-time quantitative polymerase chain reaction. Serum placental exosomes and fetal placental tissues were compared for miR-520a-5p levels. Placental trophoblasts were identified as the source of serum exosomes in all 3 groups.

Results: It was found that serum placental exosomes exhibited lower levels of miR-520a-5p in both the sPE and FGR groups when compared to the normal pregnancy group. This finding was consistent with observations made in postpartum placental tissues. The predictive accuracy for sPE using miR-520a-5p levels in serum placental exosomes during the first trimester was notably higher (area under the receiver operating characteristic curve = 0.806, P <.05) compared to the prediction of FGR (area under the receiver operating characteristic curve = 0.628, P <.05).

Conclusion: Placenta-derived exosomes can be extracted from maternal serum during the first trimester of pregnancy and miR-520a-5p detected from the exosomes. The downregulation of miR-520a-5p serves as a more predictive indicator for the subsequent development of sPE compared to predicting FGR.

Figure 1.

Experimental process pattern diagram.

Figure 2.

Particle size and distribution of placental exosomes.

Figure 3.

Placental exosome morphology.

Figure 4.

Western blot detection of exosome CD63, CD81, and PLAP expression.

Figure 5.

miR-520a-5p expression in serum placental exosomes (A) and placental tissue (B) in early pregnancy. (A) Serum placental exosome expression of miRNA-520a-5p during early pregnancy. Women with a late-onset of FGR or sPE had lower levels of miR-520a-5p in their serum exosomes compared to the NP group when the test was performed using a nonparametric method (the Kruskal–Wallis test). (B) miR-520a-5p expression in human placenta. A non-parametric test showed that miR-520a-5p was down-regulated in placental tissue during the first trimester of pregnancy in women with late-onset FGR or sPE compared to the NP group (the Kruskal–Wallis test).

Figure 6.

ROC curve of miR-520a-5p predicting sPE (A) and FGR (B). (A) The ROC curve for miR-520a-5p to predict sPE; indicated high accuracy in predicting the development of sPE (AUC 0.806, P < .001); (B) the ROC curve depicting the ability of miR-520a-5p to predict FGR; indicated lower accuracy in predicting the development of FGR (AUC 0.628, P < .05).