Stem Cell-Derived Mitochondria-Enriched Preservation Solutions as Organelle-Based Therapeutic Strategy for Cold...

Organ preservation remains a critical challenge in transplantation, primarily due to hypothermia-induced oxidative stress and metabolic dysfunction. Here, we report a mitochondria-enriched, cell-free preservation strategy by supplementing standard preservation solutions with freshly isolated mitochondria derived from human induced pluripotent stem cell-mesenchymal stem cells (MSC-mt). MSC-mt retained intact ultrastructure and functional biophysical properties. In vitro, MSC-mt were internalized by hepatocyte- and kidney-derived cells, reduced oxidative stress, preserved ATP levels, and attenuated apoptosis under cold stress. Ex vivo, MSC-mt improved liver preservation in University of Wisconsin (UW) solution, reducing sinusoidal edema, apoptosis, ALT/AST release, MDA accumulation, and oxidative DNA damage while enhancing SOD activity and preserving mitochondrial content. Human-specific mitochondrial signals remained detectable within preserved hepatic tissue. In a warm reoxygenation model, MSC-mt enhanced ATP recovery and reduced tissue injury and oxidative damage following cold storage. In kidneys, MSC-mt provided stronger protection than fibroblast- or adipose-derived mitochondria across both HC-A and UW solutions. Mechanistically, MSC-mt showed higher total and phosphorylated PINK1 levels and greater Parkin co-localization than fibroblast-derived mitochondria, while mitophagy inhibition partially reversed their antioxidant effects. These findings establish MSC-mt as a cell-free mitochondrial strategy for improving hypothermic organ preservation.