Role of NETRIN-4 on placental angiogenesis

Abstract

s / Placenta 35 (2014) A1eA112 A16 stillbirths, such as the Relevant Condition at time of Death (ReCoDe) incorporate evidence of placental causes. Even using a modern classification system 15-20% of stillbirths remain “unexplained”; the role of the placenta in these cases is uncertain. Methods: A retrospective analysis of all cases (n1⁄4126) of singleton stillbirth in a tertiary UK obstetric unit from 2010-2013. Centiles for placental weight and birthweight:placental weight (BW:PW) were determined using population-based, gender and gestational-age-specific centile curves [1]. Cases of stillbirth were grouped according to ReCoDe classification for comparison. Result: The placental weight was 90th centile in 65/126 cases (52%). Respectively, the incidence of placental weight 90th centile for different stillbirth classifications was 79% and 58% for known FGR or placental insufficiency, 46% and 57% for other identified causes of stillbirth, and 49% and 47% for stillbirths of unknown cause. Conclusion: The incidence of placental weight and BW:PW ratio at the extremes of population-based centiles exceeded those anticipated; this persisted even in the absence of a clear diagnosis of FGR or placental insufficiency. The extreme of BW:PW ratio could be interpreted as “placental insufficiency” such that the placenta cannot meet the demand of the fetus. This provides further evidence of the presence of placental dysfunction in stillbirth. [1] Thompson et al. BJOG. 2007. 114(6):715-20. P1.18. ROLE OF NETRIN-4 ON PLACENTAL ANGIOGENESIS Mbarka Dakouane-Giudicelli , Guillaume Vallat , Sammy Si Nacer , Antoine Torre , Marion Vall ee , Jean-Jacque Feige , Nadia Alfaidy , Philippe de Mazancourt a Universit e de Versailles-St-Quentin en Yvelines, Versailles, France; b INSERM U1036 iRTSV /LAPV, Grenoble, France Objectives: Netrin-4 is a molecule involved in axon guidance, differentiation, cell growth and morphogenesis. Recently, netrin-4 was identified to play a key role in angiogenesis. These effects are mediated by Neogenin and UNC5B receptors. Recently, we have characterized netrin-4 and its receptors Neogenin and UNC5B expression in the human placenta. Netrin4 was observed in villous and extravillous cytotrophoblasts (EVT), syncytiotrophoblast (ST) and intravilli human placental endothelial cells (HPEC). The Neogenin receptor was localized to the ST and HPEC. UNC5B was observed in the villous cytotrophoblasts and HPEC. Considering the endothelial localisations of netrin 4 and ist receptors in the human placenta, we hypothezized that this systemmight play a role in the human placental angiogenesis. Methods: We isolated microvascular endothelial cells (HPEC) from term human placenta. Their endothelial origin was characterized using endothelial cells markers CD31, CD34, and vWF . First, we have demonstrated that HPEC cells express netrin-4, UNC5B and neogenin both at the mRNA and protein levels. Isolated HPEC cells were used to determine the effect of netrin4 on their proliferation, tube-like structure formation in matrigel, migration and endothelial cell spheroid sprouting in collagen. All these assayswere used as in vitromodel of angiogenesis andHPECwas incubated with different doses of netrin-4 (50-100-200-500ng/ml) added to the culture medium. Tube formation was quantified by counting the number of connections between endothelial cells after 6 hours (h), spheroid sprouting by counting outgrowth after 12h, migration by using wound healing after 12h and proliferation by counting cells after 24h treatment by netrin-4. Results:Netrin 4-mediated angiogenic processes in HPEC showed that this protein inhibits their proliferation, tubes formation, migration and spheroid sprouting, suggesting a potential role of netrin-4 in regulating placental angiogenesis. Conclusion: This is the first report of an anti-angiogenic activity of netrin4 in human placenta. This study will bring new insights into possible role of netrin-4 in placental angiogenesis-related pathologies of pregnancy such as intrauterine growth retardation and preeclampsia.