Ex vivo lung perfusion with perfusate purification for human donor lungs following prolonged cold storage

Background: Ex vivo lung perfusion (EVLP) has developed as the most effective technique for estimating marginal donor lungs. This study attempted to extend the EVLP running time to 12 hours with a dialyzer rather than periodically replacing the perfusate. Methods: Human donor lungs rejected by the clinical lung transplantation (LTx) team were obtained. After cold storage lasting 18-24 hours, lungs were randomly assigned to 2 groups: a control group and a perfusate purification ( PP) group. The control group underwent EVLP in the traditional way, while a dialyzer was added into the circuit as a bypass in the PP group. The effects on lung function, microenvironment, inflammatory response, and cell death were evaluated. Results: A total of 8 rejected donor lungs were obtained and each group was assigned to 4 cases of EVLP. Three cases were prematurely terminated because of serious lung edema and decreased lung function. There were no significant differences in airway pressure, pulmonary artery pressure, and oxygen concentration between the two groups in the first 8 hours. The pH in the control group was significantly lower than that in the PP group, and the levels of potassium and lactate were significantly higher than those in the PP group. Inflammatory markers increased in both groups, while IL-6 and IL-10 were higher in the PP group in the first 6 hours. Hematoxylin and eosin (HE) staining revealed lung injuries in both groups, but no significant difference was noted in the HE-stained slides. There were significantly more TUNEL-positive cells in the control group (69.5%+/- 4.0%) than in the PP group (47.5%+/- 3.9%) (P=0.000). Conclusions: Using the modified method of EVLP reduces the high cost caused by exchanging perfusion fluid per hour and could prolong the normothermic preservation time of donor lungs.