The ability to differentiate human-induced pluripotent stem cells (hiPSCs) efficiently into defined cardiac lineages, such as cardiomyocytes and cardiac endothelial cells, is crucial to study human... Show moreThe ability to differentiate human-induced pluripotent stem cells (hiPSCs) efficiently into defined cardiac lineages, such as cardiomyocytes and cardiac endothelial cells, is crucial to study human heart development and model cardiovascular diseases in vitro. The mechanisms underlying the specification of these cell types during human development are not well understood which limits fine-tuning and broader application of cardiac model systems. Here, we used the expression of ETV2, a master regulator of hematoendothelial specification in mice, to identify functionally distinct subpopulations during the co-differentiation of endothelial cells and cardiomyocytes from hiPSCs. Targeted analysis of single-cell RNA-sequencing data revealed differential ETV2 dynamics in the 2 lineages. A newly created fluorescent reporter line allowed us to identify early lineage-predisposed states and show that a transient ETV2-high-state initiates the specification of endothelial cells. We further demonstrated, unexpectedly, that functional cardiomyocytes can originate from progenitors expressing ETV2 at a low level. Our study thus sheds light on the in vitro differentiation dynamics of 2 important cardiac lineages. Show less
Cao, X.; Mircea, M.; Yakala, G.K.; Hil, F.E. van den; Brescia, M.; Mei, H.; ... ; Orlova, V.V. 2022
Wnt/beta-catenin signaling regulates progenitor cell fate decisions during lung development and in various adult tissues. Ectopic activation of Wnt/beta-catenin signaling promotes tissue repair in... Show moreWnt/beta-catenin signaling regulates progenitor cell fate decisions during lung development and in various adult tissues. Ectopic activation of Wnt/beta-catenin signaling promotes tissue repair in emphysema, a devastating lung disease with progressive loss of parenchymal lung tissue. The identity of Wnt/beta-catenin responsive progenitor cells and the potential impact of Wnt/beta-catenin signaling on adult distal lung epithelial progenitor cell function in emphysema are poorly understood. Here, we used a TCF/Lef:H2B/GFP reporter mice to investigate the role of Wnt/beta-catenin signaling in lung organoid formation. We identified an organoid-forming adult distal lung epithelial progenitor cell population characterized by a low Wnt/beta-catenin activity, which was enriched in club and alveolar epithelial type (AT)II cells. Endogenous Wnt/beta-catenin activity was required for the initiation of multiple subtypes of distal lung organoids derived from the Wnt(low)epithelial progenitors. Further ectopic Wnt/beta-catenin activation specifically led to an increase in alveolar organoid number; however, the subsequent proliferation of alveolar epithelial cells in the organoids did not require constitutive Wnt/beta-catenin signaling. Distal lung epithelial progenitor cells derived from the mouse model of elastase-induced emphysema exhibited reduced organoid forming capacity. This was rescued by Wnt/beta-catenin signal activation, which largely increased the number of alveolar organoids. Together, our study reveals a novel mechanism of lung epithelial progenitor cell activation in homeostasis and emphysema. Show less
Brink, L. van den; Grandela, C.; Mummery, C.L.; Davis, R.P. 2019
Research on mechanisms underlying monogenic cardiac diseases such as primary arrhythmias and cardiomyopathies has until recently been hampered by inherent limitations of heterologous cell systems,... Show moreResearch on mechanisms underlying monogenic cardiac diseases such as primary arrhythmias and cardiomyopathies has until recently been hampered by inherent limitations of heterologous cell systems, where mutant genes are expressed in noncardiac cells, and physiological differences between humans and experimental animals. Human induced pluripotent stem cells (hiPSCs) have proven a game-changer by providing new opportunities for studying the disease in the specific cell type affected, namely the cardiomyocyte. hiPSCs are particularly valuable because not only can they be differentiated into unlimited numbers of these cells, but they also genetically match the individual from whom they were derived. The decade following their discovery showed the potential of hiPSCs for advancing our understanding of cardiovascular diseases, with key pathophysiological features of the patient being reflected in their corresponding hiPSC-derived cardiomyocytes (the past). Now, recent advances in genome editing for repairing or introducing genetic mutations efficiently has enabled the disease etiology and pathogenesis of a particular genotype to be investigated (the present). Finally, we are beginning to witness the promise of hiPSC in personalized therapies for individual patients, as well as their application in identifying genetic variants responsible for or modifying the disease phenotype (the future). In this review we discuss how hiPSCs could contribute to improving the diagnosis, prognosis and treatment of an individual with a suspected genetic cardiac disease, thereby developing better risk stratification and clinical management strategies for these potentially lethal but treatable disorders. Show less
