Transplantation of Mitochondria isolated from iPSC-MSCs mitigates doxorubicin-induced cardiomyopathy by inhibiting cardiomyocyte senescence

BACKGROUND: Mitochondrial dysfunction plays an important role in the development of doxorubicin-induced cardiomyopathy (DIC). Mitochondrial transplantation (MT) exerts beneficial effects on multiple cardiovascular diseases. OBJECTIVE: This study aimed to determine whether transplantation of exogenous mitochondria derived from induced pluripotent stem cell-derived mesenchymal stem cells (iPSC-MSC-Mito) could protect against DIC in mice and explore the potential molecular mechanisms. METHODS: Mitochondria were isolated from iPSC-MSCs using ultracentrifugation, then characterized by transmission electron microscopy and Western blotting. The cellular senescence of neonatal mouse cardiomyocytes (NMCMs) was examined by senescence-associated-β-galactosidase assay. Mitochondrial function in doxorubicin (DOX)-treated NMCMs exposed to different treatments was evaluated by seahorse assay. A mouse model of DIC was induced by intraperitoneal injection of DOX followed by intraperitoneal injection of iPSC-MSC-Mito. Cardiac function, fibrosis and cardiomyocyte senescence in each group was examined. RESULTS: The isolated iPSC-MSC-Mito exhibited intact mitochondrial morphology and quality. In vitro, iPSC-MSC-Mito could be internalized by NMCMs under DOX challenge. Administration of iPSC-MSC-Mito improved the respiratory capacity of cardiomyocytes under DOX challenge, due to downregulated lactate level, leading to inhibition of cardiomyocyte senescence. This effect was partially abrogated by exogenous lactate. Utilizing molecular docking and site-directed mutation assays, we found that lactate regulated SIRT2 expression by binding to the ARG97 and HIS187 residues in the PH domain of SIRT2. In vivo, transplantation of iPSC-MSC-Mito functionally attenuated DIC, manifested as improved cardiac function and decreased cardiac fibrosis and cardiomyocyte senescence. CONCLUSIONS: Transplantation of mitochondria isolated from iPSC-MSCs improved cardiac function in a mouse model of DIC by alleviating cardiomyocyte senescence via improved metabolic function. This may offer a novel therapeutic strategy for DIC.