Modelling cardiac hypertrophy in multicellular human cardiac organoids

The increasing prevalence of cardiovascular diseases (CVDs) highlights the urgent need for sophisticated in vitro models that accurately mimic the intricate human cardiac physiology, especially for advancing drug discovery in conditions such as hypertrophic cardiomyopathy (HCM) or myocardial infarction (MI). In order to facilitate improved translational research and to circumvent the use of animal models, three-dimensional cardiac platforms have emerged as a versatile system that allows the incorporation of multiple cardiac cell types within an interactive environment. This environment enables the recapitulation of nutrient and oxygen gradients, paracrine signaling, and interactions with extracellular matrix-like surroundings. Here, we developed a multicellular human cardiac organoid (hCO) platform using human induced pluripotent stem cell-derived cardiomyocytes alongside fibroblasts, endothelial cells, and mesenchymal stem cells, resulting in the formation of spontaneously contracting hCOs. By employing a disease modelling approach, we generated HCM-specific hCOs and conducted an initial assessment of Mavacamten, which is the first-in-class small inhibitor of the cardiac myosin ATPase approved for the treatment of HCM patients with hypercontractility. Both short-term and long-term treatments altered the organoids’ contractile function, with a notable reduction in contraction amplitude. Furthermore, we demonstrated the suitability of this platform for investigating circular RNA candidates such as circZFPM2 [1]. In addition to modelling genetically inherited cardiac hypertrophy, wild-type hCOs were stimulated with the known compounds phenylepinephrine-isoprenaline (PE-Iso), endothelin 1 (ET1) and leukemia inhibitory factor (LIF) in order to induce a hypertrophic phenotype. A comparative analysis revealed that all three stimulations resulted in an increase in the size of the hCOs concomitant with enlarged cardiomyocytes. Furthermore, marked increases in myosin content and hypertrophy-associated gene expression were observed for ET1, which were not observed to the same extent for the other compounds. Moreover, treatment with PE-Iso and LIF resulted in the development of a hypercontractile phenotype. Interestingly, ET1 on the other hand, led to a decreased contractile performance accompanied by an increase occurrence of arrhythmic events. We currently aim to explore the distinct effects of various compounds more comprehensively, with a particular focus on the multicellular complexity of hCOs using single-nuclei sequencing. In summary, the preliminary findings highlight the versatility of multicellular hCOs as effective platforms for drug screening and investigating cardiovascular pathophysiology, particularly cardiac hypertrophy.

[1] Neufeldt D, Schmidt A, Mohr E, Lu D, Chatterjee S, Fuchs M, Xiao K, Pan W, Cushman S, Jahn C, Juchem M, Hunkler HJ, Cipriano G, Jürgens B, Schmidt K, Groß S, Jung M, Hoepfner J, Weber N, Foo R, Pich A, Zweigerdt R, Kraft T, Thum T, Bär C. Circular RNA circZFPM2 regulates cardiomyocyte hypertrophy and survival. Basic Res Cardiol. 2024 Aug;119(4):613-632. doi: 10.1007/