Illumina HiSeq 2000 paired end sequencing; RNA-seq of human first and second trimester placenta
RNA-seq of human first and second trimester placenta
First and second trimester tissue samples were collected with informed written patient consent and approval of the Joint University College London/University College London Hospital Committees on the Ethics of Human Research (05/Q0505/82) from 7-8 wGA (n=8) and 13-14 wGA (n=6) uncomplicated pregnancies. Gestational age was confirmed by ultrasound measurement of the crown-rump length of the embryo. All samples were collected from patients undergoing surgical pregnancy termination under general anaesthesia for psycho-social reasons. Villous samples were obtained under transabdominal ultrasound guidance from the central region of the placenta using a chorionic villus sampling (CVS) technique. All samples were snap-frozen immediately in liquid nitrogen and stored at −80 °C until analysis. RNA was extracted from human first-trimester placental villi using the RNeasy Plus Universal Mini Kit (catalog no. 73404; Qiagen).  Libraries were made using the Illumina TruSeq Stranded mRNA Library Kit according to the manufacturer's instructions.