Abstract P3087: Single-cell Transcriptomics Reveals Cell-type Specific Transcriptional Responses In Murine Embryonic Hearts Exposed To Maternal Hyperglycemia

Abstract

Congenital heart disease (CHD) is a significant pediatric health burden in the United States and a leading non-infectious cause of mortality in the infants. According to CDC, ~1 in 4 babies born with cardiac defects develop critical CHD and require medical interventions during first year of their lives. Despite the strong heritable basis of CHD, genetic variations explain nearly 30% of cases. The phenotypic heterogeneity and incomplete penetrance of the disease implies a vital role of environmental factors as non-genetic contributors of CHD. Women with pregestational diabetes mellitus (PGDM) are about four times more likely to have a pregnancy affected by CHD compared to women without diabetes. Previous studies have established that maternal hyperglycemia (matHG) before pregnancy and in first trimester profoundly increases the risk of CHD among the offspring, with a preponderance of conotruncal and septal defects. However, the cell-type-specific sensitivity to matHG responsible for such cardiac malformations remains unclear. Using a chemically induced murine PGDM model, we first demonstrated increased incidence of CHD in matHG-exposed embryos compared to control (CNTRL) embryos. To evaluate the underlying cellular basis of CHD risk in diabetic pregnancies, we performed in vivo single-cell RNA-sequencing in CNTRL and matHG-exposed embryonic hearts. The transcriptomic data revealed cardiac cell-type-specific molecular changes associated matHG. Bioinformatics analysis showed significant gene expression differences in Isl1+ multipotent progenitor cells, Tnnt2+ cardiomyocytes, Tbx18+ epicardial cells, Sox9+ fibromesenchymal cells, Cdh5+ endocardial/endothelial cells, and in Dlx5+ neural crest cell populations. Pseudotime trajectory analysis suggested HG-induced impairments in genes critical for cardiomyocyte differentiation. Furthermore, in vivo Isl1-derived cell fate mapping studies suggested matHG-mediated perturbations in cardiomyocyte proliferation and differentiation at critical stages of cardiac development. In combination with our scRNA-seq and cell fate mapping data, future mechanistic studies will delineate cell-type-specific gene regulatory network perturbed in matHG environment. Early diagnosis and treatment of diabetes in pregnancy is of great clinical significance and more in-depth studies will enable the development of preventative therapeutic measures to ameliorate PGDM associated CHD.