Organisational alteration of cardiac myofilament proteins by hyperglycaemia in mouse embryonic stem cell-derived cardiomyocytes.

The exposure of the developing foetal heart to hyperglycaemia in mothers with diabetes mellitus is a major risk factor for foetal cardiac complications that lead to heart failure. We studied the effects of hyperglycaemia on the layout of cardiac myofilament proteins in stem cell-derived cardiomyocytes and their possible underlying mechanisms. Mouse embryonic stem cells (mESCs) were differentiated into cardiac-like cells and cultured in media containing baseline- or high glucose concentrations. Cellular biomarkers were detected using Western blot analysis, immunocytochemistry, 5-ethynyl-2'-deoxyuridine (EdU) cell proliferation assay, and terminal deoxynucleotidyl transferase dUTP nick-end labelling (TUNEL) assay. High glucose decreased the proportion of cardiac troponin T and α-actinin 2 positive mESCs as well as disrupted the α-actinin 2 striated pattern and the distribution of the cardiac myosin heavy chain α- and β isoforms. However, there was no alteration of the cellular EdU uptake nor the expression of the receptor of advanced glycation end-product (RAGE). High glucose also increased the presence of the oxidative stress marker nitrotyrosine as well as the number of TUNEL-stained nuclei in cardiac-like cells. Treatment with the antioxidant N-acetyl cysteine decreased the number of TUNEL-stained cells in high glucose and improved the α-actinin 2 striated pattern. Hyperglycaemia negatively impacted the expression and cellular organisation of cardiac myofilament proteins in mESC-derived cardiomyocytes through oxidative stress. The results add further insights into the pathophysiological mechanisms of cardiac contractile dysfunction in diabetic cardiac developmental disease.