MitoQ Protects Against Oxidative Stress-Induced Mitochondrial Dysregulation in Human Cardiomyocytes

The overproduction of reactive oxygen species (ROS) and mitochondrial dysregulation are regarded as key mechanisms in the progression of cardiac remodelling in cardiometabolic diseases including heart failure. Conventional treatments are often ineffective as they do not specifically target the underlying pathological mechanisms. Mitoquinone mesylate (MitoQ), a mitochondrial-targeted antioxidant has been reported to be protective against vascular dysfunction in hypertension, diabetic kidney disease and alcohol-induced liver damage. However, the cardioprotective potential of MitoQ to limit oxidative stress-induced mitochondrial remodelling in cardiomyocytes has not been fully resolved. We sought to investigate the effect of MitoQ and its mitochondrial-targeting moiety dodecyl-triphenylphosphonium (dTPP) on hydrogen peroxide-induced overproduction of ROS, mitochondrial dysregulation and cell death in H9C2 rat cardiomyoblasts (H9C2-rCM) and human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM). Cardiomyocytes were exposed to acute or chronic treatment (5-60 min or 48 h) of vehicle control (0.0001 % Ultrapure Milli-Q water), hydrogen peroxide (100 μM) ± MitoQ (1 μM) or dTPP (1 μM) control. Hydrogen peroxide-induced overproduction of ROS, extracellular superoxide, mitochondrial ROS, mitochondrial hyperpolarisation and cell death were significantly blunted by MitoQ, but not dTPP, suggesting that the coenzyme Q₁₀ moiety of MitoQ is protective under these conditions. Interestingly, both MitoQ and dTPP exhibited a pro-mitochondrial fusion effect by preserving mitochondrial network and reducing mitochondrial fragmentation in oxidative stress conditions. Overall, our findings confirm the cytoprotective potential of MitoQ to limit oxidative stress-induced adverse mitochondrial remodelling and dysregulation that is clinically observed in cardiometabolic-induced cardiac dysfunction in the failing heart.