PPARdelta signaling induces metabolic maturation in human pluripotent stem cell-derived cardiomyocytes

Pluripotent stem cell-derived cardiomyocytes (PSC-CMs) provide an unprecedented opportunity to study human heart development and disease. A major caveat however is that they remain functionally and structurally immature in culture, limiting their potential for disease modeling and regenerative approaches. Here we address the question of how different metabolic pathways can be modulated in order to induce efficient cardiac maturation of hPSC-CMs. We show that PPAR signaling acts in an isoform-specific manner to balance the glycolysis and fatty acid oxidation (FAO) pathways. PPARd activation or inhibition results in efficient respective up- or down-regulation of the gene regulatory networks underlying FAO in hPSC-CMs. PPARd induction further increases mitochondrial and peroxisome content, enhances mitochondrial cristae formation and augments FAO flux. Lastly PPARd activation results in enhanced myofibril organization and increased numbers of bi-nucleated hPSC-CMs. Transient lactate exposure, commonly used in hPSC-CM purification protocols, induces an independent program of cardiac maturation, but when combined with PPARd activation equally results in a metabolic switch to FAO. In summary, we identify multiple axes of metabolic modifications of hPSC-CMs including a role for PPARdelta signaling in inducing the metabolic switch to FAO in hPSC-CMs. Our findings provide new opportunities to generate and use metabolically mature hPSC-CMs including for disease modeling and regenerative therapy. Overall design: 105 total samples were analyzed, consisting of 34 treatment conditions with a minimum of 3 biological replicates each. Control samples are included for monolayers (Samples 1-3), EHTs (Samples 88-90) and Ebs (Samples 103-105).