No abstract

Background-Prior reports on patients with ARVC/D focused on individuals with advanced forms of the disease. There are limited data regarding diagnostic performance of various testing modalities in newly identified individuals suspected of having ARVC/D.

Human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) have been widely used for disease modeling and drug cardiotoxicity screening. To this end, we recently developed human cardiac organoids (hCOs) for modeling human myocardium. Here, we perform a transcriptomic analysis of various in vitro hiPSC-CM platforms (2D iPSC-CM, 3D iPSC-CM and hCOs) to deduce the strengths and limitations of these in vitro models. We further compared iPSC-CM models to human myocardium samples. Our data show that the 3D in vitro environment of 3D hiPSC-CMs and hCOs stimulates the expression of genes associated with tissue formation. The hCOs demonstrated diverse physiologically relevant cellular functions compared to the hiPSC-CM only models. Including other cardiac cell types within hCOs led to more transcriptomic similarities to adult myocardium. hCOs lack matured cardiomyocytes and immune cells, which limits a complete replication of human adult myocardium. In conclusion, 3D hCOs are transcriptomically similar to myocardium, and future developments of engineered 3D cardiac models would benefit from diversifying cell populations, especially immune cells.

Cardiac fibroblasts (CFBs) support heart function by secreting extracellular matrix (ECM) and paracrine factors, respond to stress associated with injury and disease, and therefore are an increasingly important therapeutic target. We describe how developmental lineage of human pluripotent stem cell‐derived CFBs, epicardial (EpiC‐FB), and second heart field (SHF‐FB) impacts transcriptional and functional properties. Both EpiC‐FBs and SHF‐FBs exhibited CFB transcriptional programs and improved calcium handling in human pluripotent stem cell‐derived cardiac tissues. We identified differences including in composition of ECM synthesized, secretion of growth and differentiation factors, and myofibroblast activation potential, with EpiC‐FBs exhibiting higher stress‐induced activation potential akin to myofibroblasts and SHF‐FBs demonstrating higher calcification and mineralization potential. These phenotypic differences suggest that EpiC‐FBs have utility in modeling fibrotic diseases while SHF‐FBs are a promising source of cells for regenerative therapies. This work directly contrasts regional and developmental specificity of CFBs and informs CFB in vitro model selection.

Acute cardiac injuries occur in 20%–25% of hospitalized COVID‐19 patients. Herein, we demonstrate that human cardiac organoids (hCOs) are a viable platform to model the cardiac injuries caused by COVID‐19 hyperinflammation. As IL‐1β is an upstream cytokine and a core COVID‐19 signature cytokine, it was used to stimulate hCOs to induce the release of a milieu of proinflammatory cytokines that mirror the profile of COVID‐19 cytokine storm. The IL‐1β treated hCOs recapitulated transcriptomic, structural, and functional signatures of COVID‐19 hearts. The comparison of IL‐1β treated hCOs with cardiac tissue from COVID‐19 autopsies illustrated the critical roles of hyper‐inflammation in COVID‐19 cardiac insults and indicated the cardioprotective effects of endothelium. The IL‐1β treated hCOs thus provide a defined and robust model to assess the efficacy and potential side effects of immunomodulatory drugs, as well as the reversibility of COVID‐19 cardiac injuries at baseline and simulated exercise conditions.