miRNA Expression profiling in formalin-fixed and paraffin-embedded placental tissue samples from pregnancies with severe preeclampsia

Aims: Micro RNAs (miRNAs) are small, single-strand RNAs, playing an important role in post-transcriptional gene regulation. The placenta is considered to play a key role in pathogenesis of preeclampsia. The purpose of this study was to demonstrate deregulation of miRNAs in placentas with preeclampsia using formalin-fixed and paraffin-embedded (FFPE) tissues. Methods: Expression levels of 162 miRNAs were measured in FFPE placental tissues (5 with severe preeclampsia, 5 from a control group) using a quantitative qPCR based technique. Results: Six miRNAs were more than 2-fold over-expressed in severe preeclampsia: let-7b, miRNA-302^*, miRNA-104, miRNA-128a, miRNA-182^* and miRNA-133b. Gene ontology analyses were performed using the algorithms "TargetScanS", "microRNA", and "PicTar". Conclusions: Two of the up-regulated miRNAs (miRNA-182^* and miRNA-133b) are putative regulators of the transcript variants 1 and 2 of the BCL2-like gene, which controls apoptosis. miRNA-182^* is also a probable angiogenesis regulator via angiogenin and VEGF-B. Apoptosis and angiogenesis are major mechanisms presumed to be involved in the pathogenesis of preeclampsia. Moreover, usability of qPCR technique based miRNA profiling for FFPE tissues was proofed. Hence FFPE tissue is the most widely used material for retrospective clinical studies, this method has a great property for future investigations in placenta research.