Metabolic Maturation of Differentiating Cardiosphere-Derived Cells

Abstract

Cardiosphere-derived cells (CDCs) can be expanded in vitro and induced to differentiate along the cardiac lineage. To recapitulate the phenotype of an adult cardiomyocyte, differentiating progenitors need to upregulate mitochondrial glucose and fatty acid oxidation. Here we cultured and differentiated CDCs using protocols aimed to maintain stemness or to promote differentiation, including triggering fatty acid oxidation using an agonist of peroxisome proliferation receptor α (PPARα). Metabolic changes were characterised as the CDCs differentiated towards a cardiac phenotype. CDCs from rat atria were expanded on fibronectin or collagen IV via cardiosphere formation. Differentiation was characterised using flow cytometry and qPCR and substrate metabolism was measured using radiolabelled substrates. Collagen IV promoted proliferation of CDCs, with a greater proportion of cells expressing progenitor-cell markers, whereas fibronectin primed cells for differentiation towards a cardiac phenotype. In both populations, differentiation induced a switch towards oxidative metabolism, as shown by changes in gene expression, decreased glycolytic flux and increased oxidation of glucose and palmitate. Addition of a PPARα agonist increased both glucose and fatty acid oxidation and expression of cardiac genes. We conclude that oxidative metabolism and cell differentiation act in partnership with increases in one driving an increase in the other.