Self-assembling human pluripotent stem cell-derived heart organoids for the study of heart development and congenital heart disease

Congenital heart defects (CHD) constitute the most common birth defect in humans, affecting approximately 1% of all live births. Our ability to understand how these disorders originate is hindered by our limited ability to model the complexity of the human heart in vitro. There is a pressing need to develop more representative organ-like platforms recapitulating complex in vivo phenotypes to study human development and disease in vitro. This dissertation outlines a novel method to generate physiologically relevant human heart organoids by self-assembly using pluripotent stem cells. This method is fully defined, highly efficient, scalable, exhibits high reproducibility, and is compatible with screening and high-content approaches. Human heart organoids (hHOs) are generated through a three-step Wnt signaling modulation strategy using a combination of chemical inhibitors and growth factors in completely defined culture conditions. hHOs recapitulate aspects of human cardiac development and are comparable to age-matched fetal cardiac tissues at the transcriptomic, structural, and cellular levels. hHOs develop sophisticated internal chambers with well-organized multi-lineage cell type regional identities reminiscent of the heart fields and the atrial and ventricular chambers, as well as the epicardium, endocardium, and vasculature, and exhibit robust functional activity. Finally, hHOs can recreate complex metabolic disorders associated with CHD by establishing the first in vitro human heart organoid model of pregestational diabetes (PGD) to study embryonic CHD. Our heart organoid model constitutes a powerful novel tool for translational studies in human cardiac development and disease.