Pegylated-Catalase is Protective in Lung Ischemic Injury and Oxidative Stress.

ABSTRACT Background Lung transplant ischemia-reperfusion injury (IRI) is typified by toxic metabolites and oxygen free radicals leading to worse graft function. Catalase is an enzyme involved in oxidative-stress detoxification. We hypothesize that direct delivery of highly concentrated polyethylene glycol-catalase (PEG-CAT) during normothermic ex-vivo lung perfusion (EVLP) significantly reduces IRI. Methods To demonstrate protection, primary culture porcine endothelial cells were treated with PEG-CAT (0–1250U/mL) in model of oxidative stress (400μM H2O2). In-vivo, rat lungs were subjected to 0h or 1h of warm ischemic injury and 2h of EVLP with or without PEG-CAT. Perfusate was collected throughout the perfusion duration and tissue was collected at the end. Tissue and perfusate underwent analysis for markers of apoptosis and a biometric signature of lung health. Results Uptake of PEG-CAT into primary endothelial cells was demonstrated with AF488-labeled PEG-CAT. Oxidatively stressed cells pretreated with PEG-CAT had significantly decreased cytotoxicity and caspase 3/7 activity and increased cell viability and cell membrane integrity. In a rat model of warm ischemia with EVLP, PEG-CAT improved allograft viability as measured by indications of cell membrane integrity (LDH and HA), presence of vasoconstrictive peptides (ET-1 and Big ET-1) released from endothelial cells, and reduced apoptosis (TUNEL). Conclusions In-vitro and ex-vivo, PEG-CAT protects against oxidative stress-induced cytotoxicity, maintains cellular metabolism, and PEG-CAT mitigates lung IR in an experimental model. Together, these data suggest that PEG-CAT is a potential therapeutic target for donor organs at risk for IRI.