Background: Ferroptosis, an iron-dependent form of cell death driven by lipid peroxidation, contributes to endothelial dysfunction and the progression of atherosclerosis. Moreover, mitochondrial damage leads to ferroptosis through accumulation of reactive oxygen species (ROS). This study aimed to determine whether bone marrow mesenchymal stem cells (BMSCs) protect endothelial cells from ferroptosis through mitochondrial transfer.

Methods: Human umbilical vein endothelial cells (HUVECs) were treated with oxidized low-density lipoprotein (ox-LDL) to induce dysfunction. BMSCs were co-cultured with these damaged HUVECs in a direct system without Transwell inserts. Mitochondrial transfer was evaluated using MitoTracker probes. Key indicators, including adenosine triphosphate (ATP) production, mitochondrial membrane potential, ferroptosis markers (Fe²⁺, ROS, malondialdehyde (MDA), lactate dehydrogenase (LDH)), and ferroptosis-related protein expression (Glutathione Peroxidase 4 (GPX4), Solute Carrier Family 7 Member 11(SLC7A11), Acyl-CoA Synthetase Long Chain Family Member 4 (ACSL4)) were assessed. Furthermore, rescue experiments were performed using ferroptosis activator Rat Sarcoma Viral Oncogene Homolog (RAS)-selective lethal small molecule 3 (RSL3) to validate the underlying mechanisms.

Results: Dual fluorescence microscopy revealed that BMSCs successfully transferred mitochondria to ox-LDL-injured HUVECs. Mitochondrial transfer significantly increased ATP production (1.9-fold, p < 0.01), restored mitochondrial membrane potential (p < 0.01), and enhanced endothelial viability (p < 0.01). Furthermore, ferroptosis-related markers were significantly altered: Fe²⁺, MDA, LDH, and ROS levels decreased (p < 0.05), while glutathione (GSH) levels and anti-ferroptosis protein GPX4 and SLC7A11 increased (p < 0.01), and pro-ferroptosis protein ACSL4 decreased (p < 0.01). RSL3 treatment reversed these protective effects, confirming the role of ferroptosis inhibition.

Conclusion: This study demonstrates that BMSCs can inhibit ferroptosis and restore endothelial cell function via mitochondrial transfer. These findings offer novel therapeutic insights into the treatment of atherosclerosis by targeting ferroptosis.