Proceedings of The Physiological Society
University College Dublin (2009) Proc Physiol Soc 15, PC55
Metabolic Footprint Analysis of Placental Perfusates Investigating Hypoxia and Altered Haemodynamics in Pre-eclampsia
S. Kuruvilla1, W. B. Dunn2, M. Brown2, H. S. Elizabeth1, P. Brownbill1, P. N. Baker1, I. P. Crocker1
1. Maternal and Fetal Health Research Group, The University of Manchester, Manchester, United Kingdom. 2. The Manchester Centre for Integrative Systems Biology, The University of Manchester, Manchester, United Kingdom.
Pre-eclampsia is a vascular complication of human pregnancy, with symptoms of hypertension and proteinuria manifesting from mid-gestation. This multi-system disorder affects 3-5% of pregnancies and is a major cause of maternal and fetal mortality and morbidity. Although its exact cause is unknown, evidence points to placental derived pathogenic factors, liberated in response to placental hypoxia or aberrant utero-placental haemodynamics. In previous studies we have mimicked these placental conditions in an in vitro dual placental perfusion model and have highlighted the liberation of placental factors, which induce both metabolic and apoptotic changes in cultured vascular endothelial cells . In this study we used metabolomic techniques to confirm placental adaptations and identify small molecules in response to these aberrant conditions. Human placenta lobules from uncomplicated term deliveries were dual perfused with Earle’s Bicarbonate Buffer through cannulae, creating a physiological representation of fetal and maternal blood flow in the placenta. Two separate experiments were performed. The first to investigate altered oxygen tensions, in which placentae were perfused under hypoxic (<3%O2, n=5) and normoxic conditions (6%O2, n=4). The second, to determine effects of altered intra-placental haemodynamics, in which maternal flow rates were increased from 14 to 45ml/mins, with a concomitant increase in intra-placental pressures (33±11 to 64±14 mmHg, n=7). The metabolic footprint of the maternal perfusate was analysed by gas chromatography-time of flight-mass spectrometry. Metabolites were identified by comparing the retention time and mass spectral data to libraries of metabolites. Ten metabolites were differentially expressed between high and low flow rate perfusions at a statistically significant level of P<0.01 (Kruskal-Wallis test). Of those chemically identified, hexadecanoic acid, octadecanoic acid and ribitol and/or xylitol, were significantly elevated under high flow conditions. Pyruvic acid was one metabolite significantly decreased in response to hypoxic insult. Throughout these experiments technical precision remained high, indicating that the observed differences were likely to have originated from true biological variance. We conclude that metabolomic analysis provides a novel approach to detecting and identifying placentally-derived low molecular weight compounds. Our experiments were consistent with biology and implied that placental stress can alter energy metabolism through the differential expression and liberation of fatty acids and sugar alcohols. It further remains to discriminate these factors, with the aim of identifying biomarkers or bioactive elements pertinent to the pathogenesis of pre-eclampsia.
Where applicable, experiments conform with Society ethical requirements