Cf dna cf rna preservative tubes

Patients provided blood at 11 different time points: 1 h before the first fraction of radiation (at baseline), immediately after the first fraction (time 0), and 1, 3, 6, 12, 24, 36, 48, 72 and 96 h after the first fraction (Figure 2). Ten milliliters of blood were collected into PAXgene Blood ccfDNA Tubes (Qiagen) or cf-DNA/cf-RNA Preservative Tubes (Norgen). Plasma samples were separated from the cellular fraction within 2-8 h after the blood-draw by two-step centrifugation (400 g for 10 min at room temperature followed by 14400 g for 10 min at 4 °C). The supernatants were aliquoted into 2 mL tubes and stored at −70 °C until further use. Cell-free DNA was extracted with the QIAmp Circulating Nucleic Acid Kit (Qiagen) as recommended by Diefenbach et al[22 (link)]. Isolated DNA was subsequently diluted in sterile distilled water and frozen at −24 °C until further analysis.

The study was approved by the institutional review board of Seoul National University Hospital Clinical Research Institute (# 1606-051-770). All individuals gave written informed consent for the use of sample and clinical information for research purposes. In this prospective cohort study, singleton pregnant women who delivered by cesarean at Seoul National University Hospital between November 2018 and June 2021 were included. We collected maternal peripheral blood, fetal umbilical cord blood, and placental tissues at the time of cesarean delivery. Maternal and matched cord blood was collected in EDTA bottles or cf-DNA/cf-RNA Preservative Tubes (Norgen Biotek Corp., Thorold, Ontario, Canada). After removing the fetal membrane, several 2-cm mid-layer tissue biopsies were collected from the fetal side of the placenta adjacent to the cord insertion site. Tissue samples were placed in RNALater (Invitrogen, Thermo Fisher Scientific, Waltham, Massachusetts, USA) for 12–24 h at 4°C, washed with PBS, and frozen in liquid nitrogen until RNA extraction.