Safety risks of intratracheal lipid nanoparticle gene delivery to the lung and potential mitigation strategies

Lung transplantation is a life-saving procedure, but graft rejection and ischemia-reperfusion injury remain major clinical challenges. Gene therapy, specifically the upregulation of anti-inflammatory cytokines like interleukin-10 (IL-10), has shown promise in improving graft outcomes. This study investigates whether lipid nanoparticles (LNPs) can serve as a safer, more efficient nonviral alternative to traditional adenoviral vectors (ADVs) for delivering gene therapies to donor lungs.

The researchers synthesized and screened 10 different LNP candidates to identify the most effective formulation for gene delivery. They evaluated transfection efficiency in human lung epithelial and monocytic cell lines, optimized the LNP composition (specifically adjusting the content of the helper lipid DOTAP), and compared the performance of the best candidate against adenoviral vectors in human precision-cut lung slices (PCLS). Finally, they tested the optimized LNP in a rat model to assess in vivo protein expression and potential safety risks, including lung injury and inflammation.

The researchers identified an ionizable lipid, ST-1, which, when formulated with 7.8% DOTAP, achieved high transfection rates (exceeding 88%) in human cells. This optimized LNP formulation demonstrated faster protein expression than adenoviral vectors in PCLS models. In rat models, intratracheal delivery of the LNP resulted in sustained, dose-dependent protein expression localized to the lung. However, high doses (500 μg/kg) caused significant lung injury, characterized by pulmonary hepatization, reduced oxygenation (P/F ratio), and the upregulation of inflammatory markers. Crucially, the researchers found that reducing the dose to 50 μg/kg achieved therapeutic levels of hIL-10 while successfully mitigating the LNP-induced inflammatory response.