The relationship between amniotic fluid miRNAs and congenital obstructive nephropathy.

Exosomes are small membrane vesicles with size of 30-100 nm, which were found in bodily fluids including amniotic fluid and saliva. The biological materials in exosomes, such as proteins and RNA, can be used as novel potential biomarkers for diagnostic assays. The purpose of this study was to assess whether exosomal microRNAs (miRNAs) could be used as biomarkers to prenatally diagnose congenital hydronephrosis and to evaluate fetal kidney function. Transmission electron microscopy (TEM), flow cytometry (FACS), and western-blot were applied to identify exosomes in the amniotic fluid from fetuses with congenital hydronephrosis and healthy controls. Exosomal miRNA was extracted according to the manufacturer's protocol and used for microarray. The differentially expressed miRNAs were selected for further study. The miRNA targets were analyzed to assess their possible function in the pathophysiology of obstructive nephropathy, and the miRNA array results were confirmed by qPCR. Amniotic fluid exosomes were identified based on CD24 and CD9 expression. The has-miR-942, has-miR-4289, has-miRPlus-A1073, and has-miR-195-3p were up-regulated in amniotic fluid exosomes from fetuses with congenital hydronephrosis comparing with those in healthy controls, and 35 had reduced expression levels. These results were confirmed by using qPCR. After integrating the miRNAs targets predicted via three databases and subjecting those target genes to KEGG pathway analysis, we found that the target genes of hsa-miR-300 and hsa-miR-299-5p were determined to be part of the Wnt signaling pathway. In addition, DVL2, PP2R5A, SRFP2, and SIAH1 predicted as target genes of has-miR-300 and has-miR-299-5p are informative for further exploration of congenital hydronephrosis pathologies. The reduced expression of hsa-miR-300 and hsa-miR-299-5p in the amniotic fluid of congenital hydronephrosis could be a biomarker for kidney fibrosis associated with congenital obstructive nephropathy.