ABSTRACT: **Objective:** Peripheral nerve injury (PNI) often results in sensory and motor dysfunction, severely affecting patients' quality of life. Autologous nerve transplantation remains the clinical "gold standard" for treatment, but it has limitations such as limited donor availability and size mismatch. Actively exploring new strategies for treating PNI is crucial. Mitochondrial transplantation (MT) is an emerging regenerative medicine technique that can improve mitochondrial function, promote ATP production, reduce ROS, and modulate inflammatory responses, thereby facilitating tissue repair. This study aims to investigate the therapeutic effects and mechanisms of mitochondria derived from different human cell sources (iPSCs and iMSCs) on the repair of peripheral nerve defects. Methods: A rat sciatic nerve defect model (10 mm gap) was established. Mitochondria derived from iPSCs or iMSCs (iP-MT and iM-MT groups) were injected locally, while the control group received PBS injections. At 12 weeks post-operation, functional recovery of the sciatic nerve was assessed using gait analysis and electrophysiology (nerve conduction velocity and latency). The promotion of nerve regeneration by mitochondrial transplantation was evaluated through gastrocnemius muscle weighing, Masson staining, S100/NF200 immunofluorescence staining of regenerated nerves, toluidine blue staining, and transmission electron microscopy. RNA-seq was used to explore related molecular mechanisms. *In vitro* experiments: Both types of mitochondria were co-cultured with normal and oxidative stress-injured Schwann cells (SCs) to assess effects on proliferation, migration, ATP production, apoptosis, and ROS release. Seahorse assay and RT-PCR were used to measure cellular energy metabolism characteristics and molecular gene expression levels, respectively. Results: The findings revealed: (1) iPSCs and iMSCs exhibit distinct metabolic patterns: iPSCs showed more prominent oxidative phosphorylation characteristics, while iMSCs displayed stronger glycolytic features; (2) Both iP-MT and iM-MT promoted ATP production in SCs, with iM-MT having a more significant effect; (3) Both iP-MT and iM-MT enhanced SC proliferation, but without a significant difference between them; (4) Both iP-MT and iM-MT upregulated the expression of BDNF and Mn-SOD, enhanced mitochondrial biogenesis in SCs, with iM-MT showing a more pronounced effect; (5) Both iP-MT and iM-MT improved the survival rate and ATP production of SCs after oxidative damage, reduced ROS generation and apoptosis, with iM-MT being more effective; (6) Both iP-MT and iM-MT promoted the recovery of nerve conduction and motor function in rats after PNI, with iM-MT demonstrating superior effects compared to iP-MT. Conclusion:iPSCs and iMSCs possess distinct energy metabolic characteristics, and the mitochondria derived from them differently enhance the energy metabolism of SCs. iMSC-derived mitochondria outperformed iP-MT in promoting SC proliferation, neurotrophic factor expression, and resistance to oxidative damage. *In vivo*, iMSC-derived mitochondria exhibited better efficacy in promoting motor function recovery after PNI in rats, indicating greater clinical therapeutic potential. This study provides a theoretical foundation for mitochondrial transplantation in the repair of peripheral nerve injury.
