hiPSC-derived cardioids to study the impact of RASopathy mutations on human cardiogenesis

RASopathies that are caused by germ-line mutations affecting genes residing along the canonical MAPKinase signaling pathway. They constitute the second most common cause of congenital heart defects (CHDs) after Down syndrome. Although 2D cardiac-directed differentiation of hiPSCs can provide invaluable insight into cardiogenesis mechanisms, they lack spatial context in a sense that they do not form 3D structures and therefore are not ideal to model CHDs. Recently, 3D self-organizing cardiac organoids called cardioids have been generated in our lab. They have the early features of the left ventricular chamber and comprise various cell types found in the developing heart. Considering the early defects observed in our RASopathy 2D model and the CHDs observed in infants with RASopathies, we postulated that the cardioid system may be valuable to further understand the cellular and molecular defects of the NS embryonic heart. Hence, this project aims to investigate the underlying molecular causes of cardiogenesis defects in RASopathies using hiPSC-derived cardioids. Cardioid differentiation using our RASopathy hiPSC lines will be performed in combination with flow cytometry, immunofluorescence as well as bulk and single cell RNA-seq. We anticipate that 3D cardioids will help uncovering the impact of RASopathies on early cardiac morphogenesis.