THE ROLE OF CDX2 IN TROPHOBLAST DIFFERENTIATION FROM HUMAN PLURIPOTENT TSEM

s / Placenta 34 (2013) A1–A99 A22 [1] Stanley et al 2012. Hypertension. 59(5): 1021-8. [2] Constancia et al 2002. Nature. 417, 945-8. http://dx.doi.org/10.1016/j.placenta.2013.06.065 P1.29. THE ROLE OF CDX2 IN TROPHOBLAST DIFFERENTIATION FROM HUMAN PLURIPOTENT TSEM Chi-Wei Lu, Yasunari Seita Rutgers University, New Brunswick, NJ, USA Objective The unique requirement for Cdx2 in the development of mouse placental trophoblasts has been well-studied, in genetic models and through manipulating its expression in embryonic stem cells. The role of CDX2 in human trophoblast differentiation remains elusive. MethodsWe studied the involvement of CDX2 in trophoblast differentiation fromhumanembryonic and induced pluripotent stem cells (ESCs and iPSCs). Results From BMP4-induced trophoblast differentiation, we observed that CDX2 expressed in nearly 100% of cells, and largely overlapping with OCT4 expression, suggesting the model of their mutual transcription repression seen in the mouse is not conserved in humans. We tested whether CDX2 expression alone is associated with a trophoblast progenitor fate, through generating iPS cell lines with ectopic CDX2 expression. Two CDX2 expressing cell lines were analyzed, both expressing telomerase activity and capable of differentiation into syncytiotrophoblast after switching into serum containing media. However, in the cell line expressing CDX2 at a very high level, differentiation into mesoderm and endoderm lineages was also observed, suggesting the effect of CDX2 for trophoblast differentiation is dose dependent. Repressing CDX2 expression by shRNA does not blockade BMP4-induced trophoblast differentiation. Conclusion Altogether, our results suggest that while the mechanism of transcription regulation is different from the mouse, CDX2 in the human plays a conservative role in trophoblast development as being not necessary for differentiation, but sufficient for inducing a trophoblastic-stem cell like phenotype from pluripotent stem cells. http://dx.doi.org/10.1016/j.placenta.2013.06.066 P1.30. ENDOTHELIAL DYSFUNCTION OF THE FETOPLACENTAL CIRCULATION CONTRIBUTES TO THE INCREASED VASCULAR RESISTANCE OBSERVED IN FETAL GROWTH RESTRICTION Sarah Jones, Helen Bischof, Edward Johnstone, Sue Greenwood, Mark Wareing, Colin Sibley, Paul Brownbill University of Manchester, Manchester, UK Fetal growth restriction (FGR) affects 3-8% of pregnancies and is associated with increased risk of neonatalmorbidityandmortality. A hallmark of severe FGR is increased vascular resistance identified clinically using umbilical arteryDopplermeasurements. However, the sites andunderlyingmechanisms of increased vascular resistance in the fetoplacental circulation remain unclear. In this studywe tested the hypothesis that endothelial dysfunction and altered nitric oxide (NO) production in placental vessels contribute to the pathology of FGR. Dual perfusion was performed on placental cotyledons from normal pregnancies and those complicated by idiopathic FGR ( 5th centile). Vascular resistance and shear stress-induced vasodilatation of the fetal vasculaturewasmeasured in response to increasingflow rates (2-12ml/ min), and the role of NOwas examined using the NO synthase inhibitor Nunitro-L-arginine (L-NNA). Incremental increases in fetoplacental flow (212ml/min) in normal placentas elevated vascular resistance in a stepwise manner. This was significantly amplified in perfused cotyledons from FGR pregnancy, compared to those fromnormal pregnancy, particularly at higher flow rates (76.5 9mmHg versus 45.4 6mmHg at 12ml/min respectively; mean sem; n1⁄410 per group). Inhibition of eNOS by L-NNA moderately increased the resistance at high flow rates in normal placentas. In contrast, steady state vascular resistance in FGRplacentaswas augmentedby L-NNAat all flow rates. We propose that this effect of L-NNA may relate to increased levels of NO being produced to compensate for the increased resistance; a theory supported by our work on isolated endothelial cells (see separate abstract). In normal placentas increases in fetal-side flow ratewere followed by significant shear-induced vasodilatationwhichwas inhibited by L-NNA. In FGR placentas responses to shear-mediated vasodilatation were absent. In conclusion, placental vessels from pregnancies complicated by fetal growth restriction exhibit endothelial dysfunction and fail to adapt to increases in flow, resulting in increased vascular resistance. http://dx.doi.org/10.1016/j.placenta.2013.06.067 P1.31. MATERNAL ADMINISTRATION OF SILDENAFIL CITRATE ALTERS FETAL VASCULAR FUNCTION IN A MOUSE MODEL OF FETAL GROWTH RESTRICTION Lewis Renshall, Elizabeth Cowley, Susan Greenwood, Mark Dilworth, Mark Wareing Maternal and Fetal Research Centre, The University of Manchester,