Aims: During pregnancy, the placenta needs to change through gestation adjusting to fetal needs and controlling maternal physiology adaptations to the cardiovascular system. However, the underlying mechanism of maternal adaptation is unclear. Placental extracellular vesicles (EVs) have been well-reported to play an important role in the regulation of maternal adaptation via the RNA, proteins, DNA, and lipids that they carry to maternal cells/organs. In this study, we compared the miRNA profiles in placental EVs derived from first trimester and term placentae, to understand whether the changes of miRNA profiles contribute to, at least in part, maternal physiologic adaptations across gestation.
Methods: placental EVs from first-trimester and term placentae were collected, and the small RNA they contained sequenced. MicroRNAs with differential abundance between the two groups were identified. Literature searches combined with the target gene enrichment analysis identified differentially abundant miRNAs associated with maternal cardiovascular and immune adaptation.
Results: The total number of miRNAs in placental micro-, and nano-EVs derived from the first trimester placentae was significantly higher than that in term placental EVs. Of the miRNAs present in both early gestation and term EVs, 300 (in micro-EVs) or 208 (in nano-EVs) miRNAs were differentially abundant between the two groups. Gene enrichment analysis showed that some of those differentially abundant miRNAs participate in vascular adaptation, including angiogenesis, vasculogenesis, regulation of blood vessel endothelial cell migration and blood vessel morphogenesis. Those differentially abundant miRNAs include miR-15a-5p, miR-193b-3p, miR-27b-3p, miR-200b-3p, miR-3129-5p, miR93-5p and miR-17-5p.
Conclusion: Significant differences in the numbers and the abundance of miRNAs between placental EVs derived from the two different gestational placentae could participate in maternal adaptation during pregnancy.