Amniochorionic Membrane Cells in the Maternal Blood as a Biomarker for Preterm Birth

Aim: The aim of the study is 1) to characterize circulating fetal amniochorionic membrane cells (ACM cells) in pregnant women and 2) to investigate if they can function as biomarkers of amniochorionic membrane dysfunction, including risk of preterm birth. Background: Globally, preterm birth (15 mill. per year) is the leading cause of under-5 child mortality (1 mill. per year) and morbidity. Important pathways include preterm labor contractions (PLC), Preterm Prelabor Rupture of the Fetal Membranes (PPROM), and iatrogenic delivery due to preeclampsia and fetal growth restriction. At labor, the fetal amniochorionic membrane undergoes a cellular senescence and shed fetal amniochorionic membrane cells (ACM cells) to the maternal circulation. Similar features are expected to be seen in cases with PPROM. In collaboration with ARCEDI Biotech Aps and the University of Texas Medical Branch at Galveston, Aarhus University has identified specific fetal membrane cell markers, i.e. specific proteins highly expressed by the ACM cells. Commercially available antibodies specific for these identified proteins can be used to isolate ACM cells from the maternal blood. The preliminary studies indicate that circulating ACM cells are present in the second half of pregnancy but not in the first half of pregnancy. The investigators want to confirm by immunohistochemistry that specific antibodies can identify ACM cells in the fetal membranes, and that they can be a platform for isolating ACM cells from the maternal circulation. Materials and Methods: The investigators will isolate ACM cells from maternal blood by Magnetic Activating Cell Sorting (MACS) using different specific antibodies for ACM cells. The enriched ACM cells will be stained using fluorescent-labeled cytokeratin and vimentin antibodies, and sorted individually by Fluorescence Activated Cell Sorting (FACS). The true identification of the fetal derived ACM cells will be done by Short Tandem Repeat (SRT) analysis. The antibodies that perform best will be selected based on pilot studies on pregnant women at term and in gestation week 12, 20, 28 and 34, as well as at labor and post partum. The protein expression and specificity of each antibody will be confirmed by immunohistochemistry and bright field microscopy on biopsies from the fetal membranes, placental tissue, and the placental bed in the uterus. The established protocol will be used to evaluate the number of ACM cells in the maternal blood in normal and pathological pregnancies on cross sectional cohorts of term pregnant women with and without labor contractions and spontaneous rupture of membranes, women with PLC before 34 weeks gestation, women with PPROM before 34 weeks gestation, and a control group at gestational age 25+0 to 37. Perspectives: In the future, the results are expected to improve the diagnostics and treatment of threatening preterm birth, thus preventing mortality and morbidity in millions of children worldwide.