Perlecan (HSPG2) signalling promotes structural, contractile, and metabolic development during the maturation stage of hPSC-CM differentiation
Perlecan (HSPG2), a multifunctional heparan sulphate proteoglycan (HSPG), is a key player in extracellular matrix maturation and stabilisation. Structurally perlecan is similar to agrin, another HSPG known to contribute to cardiomyocyte phenotype switching by reverting hypertrophy. Although perlecan is crucial for cardiac development, its role in cardiomyocyte phenotypic switching is unknown. Here we show perlecan expression increases over time during the differentiation of pluripotent stem cells to cardiomyocytes (hPSC-CMs). Haploinusuffient hPSCs (HSPG2+/-) differentiate efficiently towards cardiomyocytes with minimal transcriptomic differences seen early in differentiation, but wide-ranging changes seen in late-stage cardiomyocytes. These differences are associated with structural, contractile, metabolic, and ECM genes. In keeping, late-stageHSPG2+/-hPSC-CMs display reduced maximal metabolic capacity and increased extracellular acidification rate, characteristics of reduced maturity. Moreover, engineered heart tissues produced withHSPG2+/-hPSC-CMs exhibit increased ECM remodelling, reduced tissue thickness and force generation. Wild-type hPSC-CMs grown on a substrate coated with a perlecan peptide showed increased cardiomyocyte nucleation typical of hypertrophic growth, suggesting that perlecan plays the opposite role of agrin by promoting cellular maturation rather than hyperplasia and proliferation. These data show that perlecan promotes cardiomyocyte maturity, possibly through hypertrophic growth. Targeting perlecan-dependent signalling may, therefore, reverse the phenotypic switch common to many forms of heart failure, by improving cardiomyocyte functionality. Overall design: Comparative gene expression profiling analysis and comparative transcript analysis of RNA-seq data for human pluripotent stem cell cardiomycocyte lines