title: GSM4576097: PAC0046_tissue; Homo sapiens; miRNA-Seq
library_construction_protocol: Placental villous tissue was collected from women who were undergoing elective pregnancy terminations (6-23+6 weeks' gestation). All placenta tissue was collected post termination and processed as soon as possible after collection and placed into RNALater (Thermo Fisher) within 15 minutes. Total RNA was isolated using a modified protocol of the RNeasy mini plus kit (Qiagen, Hilden, Germany) whereby the RW1 buffer, a proprietary component of the RNeasy Kit, is replaced with 100% ethanol, that then underwent size fractionation for small RNAs before sequencing. For plasma, samples of peripheral blood (6-9 mL) were collected from the same women into standard EDTA blood tubes at the time of termination and stored on ice until processed. Whole blood underwent centrifugation at 800 x g for 15 minutes at 4°C before plasma removal and then spun for a further 15 minutes. All samples were stored at -80°C until further processing. Micro RNA was isolated from 200 μL plasma samples using the QIAGEN miRNA serum/plasma kit (Qiagen, Hilden, Germany) according to the manufacturer's instructions. Sequencing library preparation and sequencing was performed by Qiagen (Valencia, CA) using the QIAseq miRNA Library Kit and QIAseq miRNA 48 Index IL kits as per manufacturer's instructions. Amplified cDNA libraries underwent single-end sequencing by synthesis (Illumina 1.9).