s / Placenta 35 (2014) A1eA112 A7 tissues, ex vivo explants and trophoblast cell culture systems, ADAM12was immunolocalized to the distal ends of EVT columns and to highly-invasive matrix-degrading EVTs. Notably, a specific role for the secreted isoform, ADAM12S, in promoting trophoblast invasion, as well as EVT column outgrowth was demonstrated. ADAM12 gene expression and promoter activity were shown to be in part regulated by cyclic adenosine 30-50monophosphate (cAMP), and this effect was independent of PKA activity. We provide evidence that cAMP-directed induction of ADAM12 is controlled by the guanine nucleotide exchange factor Epac1, where inhibition of Epac1/Rap1a blocks EVT invasion. Our findings demonstrate the importance of ADAM12 in directing EVT column formation and trophoblast cell invasion, and highlight novel upstream factors controlling ADAM12 expression in the early placenta. SIFPAA. EX VIVO DUAL PERFUSION OF A HUMAN PLACENTAL COTELYDON e MODIFICATIONS OF ACCESS TO THE INTERVILLOUS SPACE Henning Schneider Department of Obstetrics and Gynecology, Inselspital eUniversity of Berne, Berne, Switzerland Ex vivo dual perfusion of a human placental cotelydon was first described by M. Panigel in Paris in 1967. After cannulation of a chorionic arterial and venous branch the corresponding segment of the fetal vasculature was perfused. A remnant of a spiral artery of the same cotyledon was catheterized. Imaging by cineradioangiography showed, that the flow picture of the fetal and maternal circuit for that one cotyledon came very close to the in vivo situation, which had been shown in Rhesus monkeys. In an attempt to simplify access to the IVS an adaptationwith penetration of the decidual plate with 3 to 5 cannulae was introduced. Energy dependant functions such as active transport of aminoacids from thematernal to the fetal circuit were still intact inspite of a delay of 20 to 30 min. needed to set up the preparation. This unexpected tolerance of prolonged ischemia may be explained by down regulation of metabolism as had been described for the transitional stage preceding torpor in hibernating animals. With medium with physically dissolved oxygen the supply of oxygen is only a fraction of the in vivo estimate of requirement. The special tolerance of chronic hypoxia of the perfused tissue can partially be explained by metabolic reprogramming with reduction in mitochondrial oxygen consumption and an increase in anaerobic glycolysis. Improving oxygen supply remains a major challenge for ex vivo dual perfusion. Different modes of increasing the oxygen carrying capacity of the medium such as equilibrationwith 95% of oxygen or use of erythrocytes or synthetic oxygen carriers have been unsatisfactory. Recent studies with direct measurement of oxygen content at different sites inside the IVS have shown that by increasing the number of maternal cannulae to 22 a considerable improvement in distribution of perfusate inside the IVS can be achieved. A systematic study to determine the optimal number of cannulae for the maternal perfusion circuit is in progress. THAN. IDENTIFICATION OF PLACENTAL FAILURE e THE KEY TO SAVING BABIES’ LIVES? Alexander Heazell a,b Maternal and Fetal Health Research Centre, University of Manchester, Manchester, UK; b St Mary's Hospital, Manchester Academic Health Science Centre, Manchester, UK In high-income countries approximately 1 in 200 babies are stillborn. Stillbirth is associated with placental disease in up to 65% of cases. Detailed examination of the placenta offers the opportunity to describe processes leading to stillbirth, so that deaths might be prevented. Our research programme focuses on understanding placental abnormalities in stillbirth and applying this knowledge to identify pregnancies at greatest risk. Our systematic review verified that stillbirth is associated with a variety of placental abnormalities ranging from small placental size to specific histopathological entities. However, interpretation of these findings is hampered by variation in classification of “placental causes” of stillbirth and description of lesions. Our morphometric analyses demonstrated that stillbirths associated with fetal growth restriction (FGR) have a specific placental phenotype that is not associated with artefacts of storage or absent fetal circulation. This phenotype is more severe than in live born FGR infants and is evident in some stillbirths currently classified as “unexplained”. A similar analytical approach identified abnormalities of placental structure and dysfunction in groups at increased risk of stillbirth, including women reporting reduced fetal movements (RFM) or advanced maternal age. Thus, some placental causes of stillbirth display a recognisable phenotype, opening the possibility that this dysfunction could be detected antenatally. We therefore tested the hypothesis that adverse pregnancy outcome (APO) can be identified using markers of fetal wellbeing and placental function. In RFM, APO was associated with abnormal fetal heart rate, a small for gestational age fetus and low levels of progesterone, hCG and hPL; low hPL was associated with a 7-fold increase in APO. A pilot randomised controlled trial comparing standard management vs. intervention guided by ultrasound + hPL measurement found a statistically significant reduction in APO, with no increase in maternal anxiety. Thustargeted intervention in women with evidence of placental dysfunction may reduce stillbirths. NIH. HUMAN STEM CELLS FROM SINGLE BLASTOMERES REVEAL PATHWAYS OF EMBRYONIC OR TROPHOBLAST FATE SPECIFICATION Susan Fisher University of California, San Francisco, San Francisco, CA, USA There are major mechanistic differences among species in how initial cell fate decisions are made in embryos. To gain insights into lineage allocation in humans, we derived ten human embryonic stem cell lines from single blastomeres of four 8-cell embryos and one 12-cell embryo from a single couple (UCSFB1-10). Compared to a large panel of lines from blastocysts, they exhibited unique patterns of gene expression and DNA methylation that were highly indicative of trophoblastic competence. At a transcriptional level, UCSFB lines from different embryos were often more closely related than those from the same embryo. As predicted by the transcriptomic data, immunolocalization of eomesodermin and brachyury showed differential expression among blastomeres of 8-12-cell human embryos. The UCSFB lines formed derivatives of the three germ layers. Thus, out data suggested heterogeneity among early-stage blastomeres and that the UCSFB lines had unique properties, suggesting a more immature state than lines derived from blastocysts. Genes controlling extraembryonic or trophoblast development were hypomethylated in the UCSFB lines. Therefore, we investigated their trophoblast potential by forming embryonic bodies. Immunoanalyses of the outgrowths showed that the cultures contained cells with the morphology and antigenic profile of trophoblasts. Next, we asked whether we could derive human trophoblast stem cells from one of the lines. At day 3, trophoblast-like cells were manually dissected from the outgrowths and cultured using ourmethod for establishing lines of trophoblast progenitors from human placentas. The resulting cells could be passaged indefinitely. They immunostained, in a nuclear pattern, for transcription factors that are required for generation of the trophoblast lineage. Wewere also interested in their capacity in terms of forming the mature trophoblast cell types of the human placenta. In this regard, they form invasive cytotrophoblasts and multinucleated syncytiotrophoblasts. Thus, we succeeded in deriving human trophoblast stem cells. NI.1. EXPRESSION OF THE b-ISOFORM OF THE THROMBOXANE A2 RECEPTOR REGULATES MATERNAL AND FETAL DERIVED CHARACTERISTICS OF PRE-ECLAMPSIA Katie L. Powell , Veronica Stevens , Sharon McCracken , Vitomir Tasevski , Jonathan M. Morris , Anthony W. Ashton a Division of Perinatal Research, Kolling Institute of Medical Research, St Leonards NSW