Chromosome silencing in vitro reveals trisomy 21 causes cell-autonomous deficits in angiogenesis and early dysregulation in Notch signaling

Abstract

Despite the prevalence and clinical importance of Down syndrome, little is known as to the specific cell pathologies that underlie this multi-system disorder. To understand which cell types and pathways are more directly impacted by trisomy 21, we used an inducible-XIST system to silence the extra chromosome 21 in a panel of patient-derived iPSCs. Transcriptomic analysis showed significant dysregulation of Notch signaling occurring as early as pluripotent stem cells, potentially impacting programming of multiple cell-types. Unbiased analysis from iPSCs revealed prominent dysregulation in two major cell type processes: neurogenesis and angiogenesis. Angiogenesis is important for many systems impacted in Down syndrome but has been understudied; therefore, we focused on investigating whether trisomy 21 impacts endothelial cells. An in vitro assay for microvasculature formation used in a tightly controlled system reveals a novel cellular pathology involving delays in angiogenic response during tube formation. Results demonstrate that this is a cell-autonomous effect of trisomy 21, and transcriptomic analysis of differentiated endothelial cells shows deficits in known angiogenesis regulators. This study reveals a major unknown cell pathology caused by trisomy 21 and highlights the importance of endothelial cell function for Down syndrome comorbidities, with wide reaching implications for development and disease progression.