SS-31 Peptide Protects Heart Cells from Iron-Induced Cell Death After Oxygen Deprivation

Myocardial ischemia-reperfusion (I/R) injury is a major cause of morbidity and mortality, occurring when blood flow returns to heart tissue after a period of deprivation. This process can lead to significant cell damage, including a recently recognized form of programmed cell death called ferroptosis, characterized by iron-dependent lipid peroxidation. Understanding how to mitigate ferroptosis in cardiomyocytes following hypoxia/reoxygenation (H/R) stress, especially in the presence of potential stressors like superparamagnetic iron oxide nanoparticles (SPIONs), remains a critical knowledge gap.

The combination of H/R and SPIONs (50 µg/mL) significantly induced ferroptosis in cardiomyocytes, resulting in a 45% reduction in cell viability and a 2.8-fold increase in lipid peroxidation (MDA levels) compared to untreated control cells (p<0.001). Pre-treatment with SS-31 demonstrated a clear dose-dependent protective effect, with the highest dose (10 µM) substantially mitigating these detrimental changes. Specifically, SS-31 (10 µM) restored cell viability by 38% (from 55% to 93% of control levels) and significantly reduced lipid peroxidation by 62% (p<0.001) compared to the H/R + SPION group. > The most significant finding was that SS-31 (10 µM) effectively reversed SPION-induced intracellular iron accumulation, decreasing iron levels by 3.1-fold and restoring GPX4 (glutathione peroxidase 4) protein expression by 2.5-fold compared to the H/R + SPION group (p<0.001), indicating a direct counteraction of a core ferroptosis mechanism. Furthermore, SS-31 treatment significantly suppressed the upregulation of pro-ferroptotic markers ACSL4 and SLC7A11 by 50% and 40% respectively (p<0.01), demonstrating its ability to modulate the ferroptosis pathway at multiple points. These protective effects were also associated with SS-31's known capacity to preserve mitochondrial membrane potential and reduce excessive reactive oxygen species (ROS) generation, which are critical drivers of ferroptosis.