Nebulized mitochondrial transplantation attenuates inflammation and improves graft function in a murine donation...

Mitochondrial transplantation is a promising therapy for ischemia reperfusion injury (IRI), with efficacy demonstrated in preclinical and early clinical cardiac studies. Its application in lung transplantation (LTx), particularly with donation after cardiac death (DCD) donors, remains unexplored. We hypothesized that nebulized delivery of mitochondria at the time of reperfusion would protect against IRI and engage mitochondrial quality-control pathways.

A murine allogeneic orthotopic LTx model was used with DCD donor lungs subjected to 18 h of cold ischemia. At reperfusion, recipients received nebulized vehicle, Mitochondria-enriched fractions, or heat inactivated mitochondria-enriched fractions. At 24 h, graft oxygenation, histopathology, edema (wet-to-dry ratio, BAL albumin), and immune infiltration were assessed. BAL cytokines were measured by multiplex assay, mitochondrial uptake by flow cytometry, PINK1 expression, and circulating mitochondrial DNA (mtDNA) by qPCR.

Mitochondria-treated recipients had reduced histologic injury and improved graft function as determined by PaO₂ (p < 0.005). Edema was decreased (wet-to-dry 5.0 ± 0.4 vs 7.6 ± 1.1, p < 0.05), as was neutrophil infiltration (44.7 ± 2.2 vs 91.3 ± 8.0 MPO⁺ cells/image). BAL proinflammatory cytokines IL-6, KC, and MCP-1 were significantly reduced in recipients receiving mitochondrial therapy (p < 0.05). PINK1 expression was significantly increased in treated lungs, consistent with mitophagy activation. Serum mtDNA levels were unchanged between groups.

Nebulized mitochondrial transplantation improves oxygenation, reduces IRI, and activates PINK1-dependent quality control without increasing systemic mtDNA. This localized therapy represents a novel strategy to improve outcomes after DCD LTx.