Abstract 436: Maternal Pregestational Diabetes Alters Fetal Gene Regulatory Program to Cause Spectrum of Congenital Heart Defects

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Maternal pre-gestational diabetes results in range of congenital malformations with significantpreponderance of congenital heart defects (CHD). We and others have previously demonstratedthat maternal high glucose (HG) acts as primary teratogen in diabetes and in combination withgenetic susceptibility loci, it increases the incidence of CHD ranging from mild ventricular septaldefects (VSD) to complex outflow tract (OFT) abnormalities. However, the underlying cellularand molecular basis of maternal HG dose-response on fetal cardiac development remainselusive. In this study, we have utilized Streptozotocin-induced murine model of maternal type1diabetes and demonstrated that spectrum of CHD in HG exposed developing embryos in utero ,is dose-dependent. We have performed histological analysis of hearts at embryonic (E) day 9.5,11.5, 13.5 and 15.5 exposed to different levels of maternal HG and compared them withuntreated normoglycemic controls. Analysis of E9.5, E11.5 and E13.5 embryos displayedtrabeculation and touchdown defects, thinning of right and left ventricular myocardium, VSD,OFT misalignment, double outlet right ventricle with increasing levels of maternal glucose.Whereas, E15.5 embryos exposed to maternal HG exhibited VSD, cardiac hypertrophy andhyper-trabeculation phenotypes in comparison to normoglycemic controls. To test cell-specificgene-regulatory program in response to hyperglycemia stress, we performed in vivo 10X singlecell transcriptomics and in vitro global RNA-sequencing on murine embryonic cell-lines culturedin normal and increasing doses of HG. RNA-seq analysis revealed differential gene expressionchanges associated with metabolic dysfunction, oxidative stress response, endothelial tomesenchymal transition, cardiomyocytes proliferation and impaired neural crest cell migration.Cardiomyocytes and endothelial cell proliferation (PHH3) and apoptosis (TUNEL) weremeasured using immunohistochemical analysis at E9.5-E15.5 embryonic hearts exposed tomaternal HG. In summary, more in-depth analysis of this study is warranted to indicate howmaternal intrauterine hyperglycemic environment disrupts the fine tuning of fetal cardiogenicgene/epigenetic program to cause CHD.