Abstract Body: Introduction: Mitochondrial dysregulation is implicated in many complications of type 2 diabetes (T2D). Mitochondrial-targeted therapies SkQ1, AP39 and SS31 limit renal T2D complications. We sought to obtain the first evidence of the cardioprotective potential of SkQ1, AP39 and SS31 in T2D, using a human induced pluripotent stem cell (iPSC)-derived 3D multicellular cardiac organoid model of diabetic cardiomyopathy.
Methods: Human cardiac organoids (foreskin-2 cell-line) generated from human iPSC-derived cardiomyocytes, cardiac fibroblasts and endothelial cells were subjected to 5.55mM glucose (control) or T2D-like conditions (20mM glucose, fatty acids, endothelin-1 and cortisol) for 4 days with supplementation of either SkQ1 (50nM), AP39 (50nM) or SS31 (1µM) on day 2. On day 4, endpoint parameters were evaluated in cardiac organoids, including contractile function (captured via Olympus IX71), mitochondrial superoxide levels (MitoSOX assay), mitochondrial membrane potential (TMRM assay), and cellular injury (lactate dehydrogenase; LDH). Data are expressed as mean±SEM (fold control) with n=4-6 from 2-3 independent experiments. One-way ANOVA with Dunnett`s post hoc analysis was performed with P<0.05 considered significant.
Results: After 4 days, T2D-conditions increased total contraction duration (1.55±0.10-fold control), time-to-peak (1.71±0.11-fold control, indicative of systolic dysfunction) and relaxation duration (1.46±0.13-fold control, indicative of diastolic dysfunction) in cardiac organoids. All 3 functional parameters were attenuated by AP39 (to 1.15±0.06, 1.32±0.09 and 1.04±0.04-fold control, respectively), or by SS31 (to 1.10±0.05, 1.12±0.15 and 1.09±0.12-fold control, respectively; all P<0.05), but not SkQ1. T2D-conditions increased mitochondrial superoxide (2.68±0.16-fold control), which was blunted by all 3 interventions, SkQ1 to 2.00±0.29, AP39 to 1.82±0.16 and SS31 to 1.89±0.17 (all P<0.05). Cellular injury was evident in T2D cardiac organoids (2.07±0.23-fold control), which was again limited by SkQ1 (to 1.06±0.11), AP39 (to 1.18±0.09) or SS31 (to 1.08±0.07), all P<0.05.
Conclusion: These findings in human cardiac organoids highlight the cardioprotective potential of mitochondrial-targeted therapies to limit T2D-induced cardiac dysfunction, mitochondrial dysregulation and cellular injury, potentially facilitating clinical progression of candidates such as AP39 and SS31 as new therapies for patients with diabetic cardiomyopathy.