microRNA sequencing of human placentae and matched maternal plasma from 6-23 weeks of gestation
microRNAs are increasingly seen as important regulators of placental development and opportunistic biomarker targets. We generated miRNA profiles using 96 placentas from presumed normal pregnancies, across early gestation, in combination with matched profiles from maternal plasma. We identified 637 miRNAs with expression in 86 samples (after removing poor quality samples), showing a clear gestational age gradient and identified 374 differentially expressed (DE) miRNAs across a gestational cut-off of 6-10 weeks' and 11-23 weeks'. We see a clear gestational age group bias in miRNA clusters C19MC, C14MC, miR-17~92 and paralogs, regions that also include many DE miRNAs. Proportional change in expression of placenta-specific miRNA clusters was reflected in maternal plasma, with C19MC miRNAs miR-516b-5p and 517a-3p showing potential as a biomarkers. Chorionic villous samples across early gestation display differential miRNA profiles, particularly in the expression of highly placenta-specific miRNA clusters, and at the presumed introduction of oxygenated maternal blood into the placenta. Data presented here comprise a clinically important reference set for studying early placenta development and enabling development of minimally invasive methods for monitoring placental health. Overall design: smallRNA-seq analysis of placenta tissues and matched maternal plasma between 6-23+6 weeks of gestation