Peripheral blood mononuclear cells as a novel source for mitochondrial transplantation therapy in peripheral nerve injury repair

Peripheral nerve injury remains a significant clinical challenge, with energy metabolism disorders severely hampering complete nerve regeneration. While mitochondrial transplantation has emerged as a promising therapeutic approach to restore cellular bioenergetics and promote neural repair, current mitochondrial sources from mesenchymal stem cells or skeletal muscles require invasive harvesting procedures. This study investigated peripheral blood mononuclear cells as a novel, minimally invasive source for therapeutic mitochondria in peripheral nerve regeneration.

Functional mitochondria were isolated from both rat and human peripheral blood mononuclear cells and adipose-derived stem cells using standardized protocols. Mitochondrial structure and function were evaluated through transmission electron microscopy, proteomic analysis, and ATP production assays. Therapeutic efficacy was assessed in both a rat sciatic nerve crush injury model and a 10-mm segmental sciatic nerve defect model bridged with an acellular nerve allograft (ANA).

Functional recovery was evaluated by histological, electrophysiological, muscular, and gait analyses. In vitro studies further examined mitochondrial internalization and bioenergetic effects in neuronal cells, while transcriptomic analysis of dorsal root ganglion neurons were performed to explore potential mechanisms underlying mitochondrial-enhanced axonal growth. Successfully isolated peripheral blood mononuclear cell-derived mitochondria demonstrated intact ultrastructure and shared similar protein profiles with adipose-derived stem cell mitochondria, particularly in oxidative phosphorylation pathways.

In the sciatic nerve crush model, sub-epineural injection of peripheral blood mononuclear cell-derived mitochondria significantly improved functional recovery at 21 days post-injury, with enhanced axonal regeneration and reduced muscle atrophy comparable to adipose-derived stem cell mitochondria. In the 10-mm nerve defect model, PBMC-derived mitochondria loaded into ANAs improved CMAP recovery, axonal regeneration, Schwann cell-associated nerve reconstruction, target muscle preservation, and gait function at 12 weeks postoperatively. Human-derived mitochondria did not produce an evident systemic inflammatory response or major-organ injury under the conditions examined.

In vitro studies showed effective mitochondrial internalization within 3 h, significantly enhancing cellular respiratory capacity. Mitochondrial transplantation promoted axon growth in dorsal root ganglia neurons, with transcriptomic analysis implicating axon-guidance-related pathways. PBMCs represent a readily accessible and minimally invasive source of mitochondria for transplantation therapy.

PBMC-derived mitochondria achieved regenerative efficacy comparable to conventional ADSC-derived mitochondria in both crush and segmental nerve defect models, while avoiding the need for additional tissue harvesting and prolonged cell expansion. These findings support the further development of autologous PBMC-derived mitochondrial transplantation as a potential strategy for peripheral nerve repair. Mitochondrial membrane complex subunit 20 Carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone This study was supported by Open Project of Chongqing Engineering Research Center of Organ Intelligent Bio-Manufacturing (CQERC-OIBM20241001).