Project description:The mammalian heart undergoes maturation during postnatal life to meet the increased functional requirements of the adult. However, the key drivers of this process remain poorly defined. We developed as 96-well screening platform, using human pluripotent stem cell derived cardiac organoids, to determine the molecular requirements for in vitro cardiomyocyte maturation. Here, we describe gene expression changes resulting from culturing human cardiac organoids in standard cell culture conditions and under optimized maturation conditions. We assessed our maturation conditions by comparing transcriptional changes of human cardiac organoids to RNA isolated from human heart. Interesting, analysis of these data revealed that a switch to fatty acid oxidative metabolism is a key governor of cardiomyocyte maturation and mature cardiac organoids were refractory to mitogenic stimuli.
Project description:The mammalian heart undergoes major transitions during postnatal life to acquire the physiological properties of an adult organ. Postnatal life imposes numerous adaptations including electrophysiological, structural and metabolic maturation of cardiomyocytes1, which occur coincident with loss of proliferative capacity and regenerative potential2,3. The discovery of key upstream drivers of cardiomyocyte maturation and cell cycle arrest remains one of the most important unanswered questions in cardiac biology. Discovery of these drivers would facilitate current attempts to promote cardiomyocyte maturation in vitro for drug discovery and to de-differentiate adult cardiomyocytes in vivo for regenerative medicine. A recent study has suggested that the shift from a low oxygen environment in utero towards a high oxygen environment after birth acts as a key trigger for cardiomyocyte cell cycle exit4. Moreover, it was recently demonstrated that proliferative adult cardiomyocytes reside in a hypoxic niche5 and that exposure of adult mice to gradual hypoxemia is sufficient to drive cell cycle re-entry and regeneration following infarction6. However, it is currently unclear whether postnatal changes in oxygen tension or the associated shifts in cardiomyocyte metabolism are sufficient to promote maturation and cell cycle arrest as human pluripotent stem cell (hPSC)-derived cardiomyocytes fail to mature when cultured at 21% oxygen7,8. There are considerable changes in metabolic substrate provision during early postnatal life. The mammalian heart relies on high concentrations of carbohydrates and the presence of insulin in utero but later switches to fatty acid dominated substrates present in milk and low insulin levels post-birth9. In order to adapt to these changes in substrates, cardiomyocytes upregulate the genes required for fatty acid oxidation after birth10. The importance of these metabolic adaptations for cardiomyocyte maturation has been difficult to study because genetic disruption of fatty acid oxidation components in vivo can have a broad range of negative health impacts11. Therefore, there is a need to develop alternative approaches for studying the impact of cardiomyocyte metabolism on the maturation process. hPSCs are now widely used for the generation of defined human somatic cell types, including cardiomyocytes. These cardiomyocytes have now been used extensively for developmental studies, drug screening, disease modeling, and heart repair. However, lack of maturity and inappropriate responses to pharmacological agents have been identified as limitations in 2D or embryoid body based differentiation strategies12. To improve maturity of hPSC-derived cardiomyocytes, long-term culture can be used13, although long-term cultures may not be amenable to high-throughput screening applications and adult-like maturity is still not achieved14. In an effort to better simulate heart muscle structure and function, cardiac tissue engineering to form 3D engineered heart tissue has been used15-19. However, despite these recent advances in human cardiac tissue engineering, cardiac tissues derived from hPSC still lack many features of fully mature adult heart tissue20. Moreover, engineered heart tissue fabrication, culture, mechanical loading and pacing protocols, and analysis methods using organ baths are costly, labor intensive, and the multiple handling steps induce variability. In order to facilitate higher-throughput experiments, platforms for engineered heart tissue production have been miniaturized, however, screening experiments using semi-automated force of contraction analyses have only been published in 24-well plate formats21. Therefore, we developed a novel 96-well device, the heart dynamometer (Heart-Dyno), for high-throughput functional screening of human cardiac organoids (hCOs) to facilitate screening on a larger scale. The Heart-Dyno is designed to facilitate automated formation of dense muscle bundles from minimal cells and reagents while also facilitating culture and automated force of contraction analysis without any tissue handling. Using the Heart-Dyno, we define serum-free 3D culture conditions that promote structural, electrophysiological, metabolic and proliferative maturation of hPSC-derived cardiac organoids. Furthermore, we uncover a metabolic mechanism governing cardiomyocyte cell cycle arrest through repression of a β-catenin and YAP1 dependent signalling.
Project description:The physiological adaptation of the heart to the postnatal environment is one of the most critical developmental transitions in the life of mammals. Despite in depth knowledge of the molecular mechanisms controlling embryonic heart development, little is known about the signals that govern postnatal maturation of the heart in humans. Here, we analyse the transcriptome of more than 50,000 single cells in the developing human heart from early gestation to adulthood, which enabled mapping of developmental trajectories across 7 main classes of cardiac cells over time. Striking sex-specific differences in cardiomyocyte maturation were identified and subsequently confirmed via deep RNA sequencing of purified cardiomyocytes. To identify transcriptional drivers of these changes, ATAC-seq was used to assay the open chromatin landscape, which unveiled the progesterone receptor as a key mediator of sex-dependent transcriptional changes during cardiomyocyte maturation. Functional studies in mice, as well as human pluripotent stem cell-derived cardiomyocytes and organoids, validated the progesterone receptor as a mediator of sex-specific metabolic programs and as a cardiac inotrope, consistent with a role in developmental maturation. These datasets provide a blueprint for understanding sex-specific mechanisms governing human heart development and unveil an important role for the progesterone receptor in cardiomyocyte maturation.
Project description:The physiological adaptation of the heart to the postnatal environment is one of the most critical developmental transitions in the life of mammals. Despite in depth knowledge of the molecular mechanisms controlling embryonic heart development, little is known about the signals that govern postnatal maturation of the heart in humans. Here, we analyse the transcriptome of more than 50,000 single cells in the developing human heart from early gestation to adulthood, which enabled mapping of developmental trajectories across 7 main classes of cardiac cells over time. Striking sex-specific differences in cardiomyocyte maturation were identified and subsequently confirmed via deep RNA sequencing of purified cardiomyocytes. To identify transcriptional drivers of these changes, ATAC-seq was used to assay the open chromatin landscape, which unveiled the progesterone receptor as a key mediator of sex-dependent transcriptional changes during cardiomyocyte maturation. Functional studies in mice, as well as human pluripotent stem cell-derived cardiomyocytes and organoids, validated the progesterone receptor as a mediator of sex-specific metabolic programs and as a cardiac inotrope, consistent with a role in developmental maturation. These datasets provide a blueprint for understanding sex-specific mechanisms governing human heart development and unveil an important role for the progesterone receptor in cardiomyocyte maturation.
Project description:The physiological adaptation of the heart to the postnatal environment is one of the most critical developmental transitions in the life of mammals. Despite in depth knowledge of the molecular mechanisms controlling embryonic heart development, little is known about the signals that govern postnatal maturation of the heart in humans. Here, we analyse the transcriptome of more than 50,000 single cells in the developing human heart from early gestation to adulthood, which enabled mapping of developmental trajectories across 7 main classes of cardiac cells over time. Striking sex-specific differences in cardiomyocyte maturation were identified and subsequently confirmed via deep RNA sequencing of purified cardiomyocytes. To identify transcriptional drivers of these changes, ATAC-seq was used to assay the open chromatin landscape, which unveiled the progesterone receptor as a key mediator of sex-dependent transcriptional changes during cardiomyocyte maturation. Functional studies in mice, as well as human pluripotent stem cell-derived cardiomyocytes and organoids, validated the progesterone receptor as a mediator of sex-specific metabolic programs and as a cardiac inotrope, consistent with a role in developmental maturation. These datasets provide a blueprint for understanding sex-specific mechanisms governing human heart development and unveil an important role for the progesterone receptor in cardiomyocyte maturation.
Project description:The physiological adaptation of the heart to the postnatal environment is one of the most critical developmental transitions in the life of mammals. Despite in depth knowledge of the molecular mechanisms controlling embryonic heart development, little is known about the signals that govern postnatal maturation of the heart in humans. Here, we analyse the transcriptome of more than 50,000 single cells in the developing human heart from early gestation to adulthood, which enabled mapping of developmental trajectories across 7 main classes of cardiac cells over time. Striking sex-specific differences in cardiomyocyte maturation were identified and subsequently confirmed via deep RNA sequencing of purified cardiomyocytes. To identify transcriptional drivers of these changes, ATAC-seq was used to assay the open chromatin landscape, which unveiled the progesterone receptor as a key mediator of sex-dependent transcriptional changes during cardiomyocyte maturation. Functional studies in mice, as well as human pluripotent stem cell-derived cardiomyocytes and organoids, validated the progesterone receptor as a mediator of sex-specific metabolic programs and as a cardiac inotrope, consistent with a role in developmental maturation. These datasets provide a blueprint for understanding sex-specific mechanisms governing human heart development and unveil an important role for the progesterone receptor in cardiomyocyte maturation.
Project description:The physiological adaptation of the heart to the postnatal environment is one of the most critical developmental transitions in the life of mammals. Despite in depth knowledge of the molecular mechanisms controlling embryonic heart development, little is known about the signals that govern postnatal maturation of the heart in humans. Here, we analyse the transcriptome of more than 50,000 single cells in the developing human heart from early gestation to adulthood, which enabled mapping of developmental trajectories across 7 main classes of cardiac cells over time. Striking sex-specific differences in cardiomyocyte maturation were identified and subsequently confirmed via deep RNA sequencing of purified cardiomyocytes. To identify transcriptional drivers of these changes, ATAC-seq was used to assay the open chromatin landscape, which unveiled the progesterone receptor as a key mediator of sex-dependent transcriptional changes during cardiomyocyte maturation. Functional studies in mice, as well as human pluripotent stem cell-derived cardiomyocytes and organoids, validated the progesterone receptor as a mediator of sex-specific metabolic programs and as a cardiac inotrope, consistent with a role in developmental maturation. These datasets provide a blueprint for understanding sex-specific mechanisms governing human heart development and unveil an important role for the progesterone receptor in cardiomyocyte maturation.
Project description:Human pluripotent stem cells possess the ability to recapitulate key events of mammalian organogenesis in vitro, including heart development. Previously-described human heart organoid protocols elicit early embryonic-like cardiac phenotypes and morphologies. We hypothesized that human heart organoids can be made significantly more complex and physiologically relevant through the implementation of in utero gestational biochemical phenomena. Here, we designed and applied multiple developmental maturation strategies on our human heart organoids for a period of 10 days. Our data reveals the emergence of atrial and ventricular cardiomyocyte populations, valvular cells, epicardial cells, proepicardial-derived cells, endothelial cells, stromal cells, conductance cells, and cardiac progenitors, all of them cell types present in the primitive heart tube.
Project description:Cardiac maturation lays the foundation for postnatal heart development and disease, yet little is known about the contributions of the microenvironment to cardiomyocyte maturation. By integrating single-cell RNA-sequencing data of mouse hearts at multiple postnatal stages, we construct cellular interactomes and regulatory signaling networks. Here we report switching of fibroblast subtypes from a neonatal to adult state and this drives cardiomyocyte maturation. Molecular and functional maturation of neonatal mouse cardiomyocytes and human embryonic stem cell-derived cardiomyocytes are considerably enhanced upon coculture with corresponding adult cardiac fibroblasts. Further, single-cell analysis of in vivo and in vitro cardiomyocyte maturation trajectories identify highly conserved signaling pathways, pharmacological targeting of which substantially delays cardiomyocyte maturation in postnatal hearts, and markedly enhances cardiomyocyte proliferation and improves cardiac function in infarcted hearts. Together, we identify cardiac fibroblasts as a key constituent in the microenvironment promoting cardiomyocyte maturation, providing insights into how the manipulation of cardiomyocyte maturity may impact on disease development and regeneration.
Project description:Transcriptional regulatory circuits that drive cardiomyocyte maturation are poorly understood. Here we found that in ERRa/g KO hiPSC-CMs, cardiac energy metabolic and cardiac structural transcriptional programs are dysregulated.