PhD Student University Health Network, Ontario, Canada
Abstract: The development of the human heart is complex, requiring the cooperation of multiple progenitors undergoing coordinated morphological events in a time-dependent manner. Abnormalities in cardiogenesis result in congenital heart defects impacting 1 in 100 newborns, highlighting the need for a better understanding of this process. Current human pluripotent stem cell (hPSC)-based models do not fully recapitulate these spatiotemporal events of heart development. We propose that gastruloids, a self-organizing hPSC-based model of gastrulation, can establish a 3D model of human cardiogenesis. We hypothesize that extended culture of gastruloids will allow the formation of a cardiac crescent-like structure with corresponding cardiac progenitors. This will provide a model to dissect the spatiotemporal and morphological processes during cardiac progenitor specification as well as the multilineage cell interactions that are essential for human cardiogenesis. We have generated gastruloids that form anterior-posterior axes based on the polarized expression of GATA6 (anterior) and CDX2 (posterior). The posterior pole contained distinct clusters of cells expressing markers of all three germ layers (TBXT, SOX17, SOX2). After extending the cultures to day 20, spontaneously beating regions were observed in some of the gastruloids. Importantly, 25% of these gastruloids contained cTNT+, suggesting a cardiomyocyte phenotype. We are currently further characterizing these cTNT+ cells. In parallel, we are modulating the gastruloid protocol to improve the efficiency of cardiogenesis. Once optimized, this new model will allow us to dissect the spatiotemporal aspects of early stages of human heart development and thereby advance our understanding of congenital heart defects.
