Fig. 4: Modeling cardiac injury in cardiac organoids.

A Protocol to induce cardiac injury in the cardiac organoids. B RT-qPCR expression analyses of the heart failure marker (BNP) and metabolic-related genes (GAPDH, LDHA, GLUT1, CPT1B) in the cardiomyocyte populations isolated from the control (non-treated) and CI organoids (N = 6 biologically independent samples). C Left; Representative immunostaining of CX43 in the control and CI-treated organoids. Scale bar; 20um. Right; Quantification of CX43 expression in the two organoid populations (N = 27 from 3 independent biological replicates). D Quantification of CK release from the indicated CI-treated and control populations (N = 3 biologically independent samples). E Analyses of the oxygen consumption rate (OCR) in the indicated populations using the Seahorse fatty acid oxidation (FAO) assay (N = 3 biologically independent samples each). F RT-qPCR expression analyses of extracellular matrix (COL1A1, COL3A1, ELN, COL5A3), cytoskeleton (ACTA2, PALLD, CNN1), fibrosis-related (TNC, LOX), and matrifibrocyte-related (CHAD, COMP, CILP2) genes in the FACS isolated CD90⁺ cardiac fibroblast populations from the control and CI organoids (N = 3 biologically independent samples for matrifibrocyte genes, N = 6 biologically independent samples for others). Adult and fetal CF RNA was included as a reference (N = 3 each). G Representative immunostaining of fibronectin (FN) in the control and CI organoids at 5 weeks of culture. Scale bar; 20 μm. (N = 5 biologically independent samples). Statistical analysis was performed by one-way ANOVA with Tukey’s multiple comparisons in (D), (E) and by two-sided unpaired t-test in (B), (C), (F). All error bars represent SEM. CF cardiac fibroblasts, CI organoid cardiac injury organoid, VCM ventricular cardiomyocytes, CKM Creatine Kinase Muscle. Source data are provided as a Source Data file.