Endothelial Stabilization Reduces the Effects of Brain Death Induced Acute Lung Injury Post-Transplant

Purpose Donor Brain death (BD) provokes activation of inflammatory pathways resulting in acute lung injury (BD-ALI), characterized by the breakdown of endothelial and epithelial barrier function. These injuries are further propagated in the early transplant period by ischemia reperfusion injury (IRI) which together adversely affect post-transplant outcomes. We have developed and characterized a novel small molecule gap/tight junction stabilizer, aCT1, which we have shown to improve cellular communication and integrity. Herein we explored the use of aCT1 as a pretreatment therapeutic to protect donor lungs from the effects of BD-ALI. Methods A mouse model of BD and orthotopic left lung transplant (LTx) were utilized to examine the effects of aCT1 on barrier function stabilization in BD and subsequent impact on LTx outcomes. Following BD induction donors were nebulized with aCT1 or vehicle and ventilated for a further 3 hours. Lungs were then removed to be flushed with and stored in Perfadex solution at 4°C. After 18 hours of cold storage the right lung was processed for histological analysis and the left lung transplanted into CD45.1 B6 mice. Transplanted lungs were then harvested 6 hours post-Tx for analysis of graft injury via histopathology and protein quantification. For controls a standard living donor (LD) model was used for comparison. Results After 3 hrs of BD induction and 18 hours cold ischemia, lungs had BD-ALI features which included significant increases in immune cell infiltration, edema, and endothelial activation. Treatment with aCT1 had no impact on BD-ALI features. 6 hrs post-Tx lungs from BD donors had significantly increased IRI as compared to LD controls, as determined by increased immune cell infiltration and pathological assessment of injury. Treatment of BD donors with aCT1 significantly reduced this BD injury profile, with pathological injury not dissimilar to that seen in LD controls (BD+aCT1 3 vs. BD 8.25, BD+aCT1 3 vs. LD 3, respectively. p Conclusion These data support gap junction stabilization as a viable option for protecting donor lungs against BD-ALI exacerbated ischemia reperfusion injury.