Purpose: Our group reported an ex vivo ABO antigen removal technique that converts donor lung of ABO-A1 blood type to universal O type, which may allow safe ABO incompatible (ABOi) lung transplant (Wang A, Sci Transl Med 2022). The present study investigates the ABO-A1 genotype in its relation to the expression and regeneration of ABO antigen. We hypothesize that the heterozygous genotype is associated with lower antigen generating activity, thereby represent a lower risk patient group for future ABOi lung transplantation.

Purpose: Donation after uncontrolled cardiac death (uDCD) offers a potential solution to the organ shortage for transplantation. Clinical series on uDCD reported successful transplantation but low utilization rates due to concerns over the associated warm ischemia injury (WII). Recent reports have shown lung storage at 10°C leads to improved preservation, however, this preservation temperature has not been studied in the context of WII. This study investigates whether increasing the hypothermic preservation temperature to 10°C can improve allograft function for donor lungs subjected to WII in a porcine model.

Purpose: Improving lung preservation solutions is a current challenge in transplantation. Itaconate (ITA) has been investigated as an immunoprotective metabolite in ischemia-reperfusion injury (IRI) models. Our group previously demonstrated higher expression of ITA in lungs preserved at 10ºC vs standard ice storage (Ali A, Sci Transl Med, 2021). This study aims to explore ITA in a lung cell IRI model, select the best ITA variant, and evaluate adding ITA to the lung preservation solution in a large animal model of Ex Vivo Lung Perfusion (EVLP).

Purpose: We hypothesize that reducing exposure of biological perfusate to artificial surfaces such as the membrane oxygenator is beneficial for prolonged EVLP. This study explores the feasibility of removing the gas exchange membrane from the EVLP system and investigates its effect on cellular and acellular perfusion.

OBJECTIVES:Hypothermic lung preservation at 10 °C has been recently shown to enhance quality of healthy donor lungs during ischemia. This study aims to show generalizability of the 10 °C lung preservation using an endotoxin-induced lung injury with specific focus on the benefits of post-transplant lung function and mitochondrial preservation. METHODS:Lipopolysaccharide (3 mg/kg) was injected intratracheally in rats to induce lung injury. Injured lungs were flushed with preservation solution and allocated to 3 groups (n = 6 each): minimum cold storage, 6-hour storage on ice (ice), and 6-hour storage at 10 °C (10 °C). Left lungs were transplanted and reperfused for 2 hours. After storage, lung tissue was used to evaluate the effects of hypothermic storage on the mitochondrial function: mitochondrial membrane potential was assessed by JC-1 staining; mitochondrial oxygen consumption was assessed using high-resolution respirometry. RESULTS:Two hours after reperfusion, the oxygen tension/inspired oxygen fraction ratio from the graft was significantly greater in the 10 °C group than in the Ice group (P = .015), whereas the wet-to-dry weight ratio was significantly lower (P = .041). Levels of interleukin-8 in lung tissues were significantly lower in the 10 °C group than in the Ice group (P = .004). Mechanistically, we noted greater mitochondrial membrane potential and elevated state III respiration in the 10 °C group than in the Ice group (P = .015 and P = .002, respectively), implying higher metabolic activities may be maintained during 10 °C preservation. CONCLUSIONS:Favorable metabolism during 10 °C preservation prevented ischemia-induced mitochondrial damages in injured lungs, leading to better post-transplant outcomes.

Purpose This study explores feasibility and safety of using enzymes (FpGalNAc deacetylase & FpGalNase) to remove ABO-A antigens from donor lungs during ex vivo lung perfusion (EVLP). The enzymes have been reported to efficiently convert ABO-A blood to O (Withers, Nat Microbiol, 2019). Methods Human lungs (ABO-A1, n=5), declined for transplant, were treated with the enzymes during EVLP. Tissues were sampled before and after. The distribution and expression level of ABO antigens were analyzed by immunohistochemistry and flow cytometry. Lung function was monitored for side-effects. Immediate post-transplant immune response was simulated in an ex vivo model of hyperacute lung rejection, with introduction of ABO-O plasma (carrying ABO antibodies) as the surrogate for the recipient circulation (Fig.1H, n=1). The physiology and histology of lungs were analyzed for anti-A-induced immune responses. Results The histo-blood type A (BTA) antigens in the A1 lungs are observed primarily on endothelial and epithelial cells. BTA were cleared remarkably well from treated lungs (Fig.1A). The enzymes convert vascular BTA to the blood group H (BTH) antigens found in ABO-O tissue (Fig.1B). Over 97% of endothelial BTA antigens were removed within the typical 4h clinical EVLP timeframe using very low dose (1 µg/mL) enzymes (Fig.1C). No acute side-effects were seen (Fig.1D-G). The rejection model showed that the 3-hour treatment of human lung with low dose enzymes prevented the damage triggered by type O plasma (presumably due to anti-A antibodies) as observed in the physiology and histology of the control lung (Fig.1I-J). Conclusion Ex vivo enzymatic treatment can efficiently remove ABO-A antigen in donor lungs without acute side-effects. Preliminary results show that the treatment can prevent ABO mismatch-induced early damages. The treatment can potentially allow expansion of ABO-incompatible lung transplantation, leading to significant improvements in logistics and fairness of organ allocation.

Continuous high dose gNO at 200 ppm is effective towards reducing common respiratory pathogens in vitro. Inhaled high-dose gNO appears to be safe during 12h EVLP. We are further exploring this treatment using infected human lungs. If successful high dose gNO could be part of EVLP clinical protocols.

Ex vivo enzymatic treatment can efficiently remove blood type antigen in donor lungs without acute side effects. This treatment has potential to be developed as an adjuvant therapy in ABO-incompatible organ transplantation, minimizing the need for recipient antibody removal procedures or augmented immunosuppression.

Purpose Extracorporeal membrane oxygenation, veno-venous configuration (VV-ECMO) is an effective intervention to improve gas exchange in patients with severe respiratory failure, refractory to conventional treatments, or as a bridge to lung transplantation. However, optimal mechanical ventilation (MV) strategies during VV-ECMO to minimize ventilator-induced lung injury are undetermined. While there is general consensus in minimizing tidal ventilation, the potential benefit of high positive end-expiratory pressure (PEEP) strategies in optimizing cardiopulmonary interaction and reducing the severity of lung injury remains unclear.We hypothesize that PEEP-induced alveolar recruitment will reduce lung injury during VV-ECMO for ARDS, in comparison to atelectatic lungs. Methods Yorkshire pigs weresedated, paralyzed, mechanically ventilated,and cannulated for VV-ECMO support. Lung injury was done by two serial bronchoscopic instillations of gastric juice to achieve a P/F ratio < 100 mmHg. ECMO blood flow and sweep gas were then titrated to achieve normal gas exchange . The animals were randomized to receive MV with PEEP 20 cmH2O(HP group, n=4) or 5 cmH2O(LP group, n=5). Driving pressure was reduced to 5 cmH2O, respiratory rate to 10/min, and FiO2 to 50%.Lung and cardiac function were monitored for 5 hours, and sample were collected for tissue wet-to-dry ratio (W/D) measurements from dependent and non-dependent areas of the lung. Cytokines IL6, IL8, TNFα, I1RA and RAGE will also be measured in the lung. Results During VV-ECMO, gas exchange and hemodynamic parameters remained stable and comparable in the two groups, despite the very low tidal volume delivered (HP 54 ml ±; LP 41 ml ±11). Lung volume was higher in the HP compared with the LP group, and remained unchanged during the 5 hours of VV-ECMO support. At the end of the 5 hours of ECMO support, in the dependent lung areas the W/D was significantly higher in the HP compared to LP group (HP 11.1, 95% CI: 10.5-11.7; LP 9.2, 95% CI: 8.2-10.3); in the non-dependent areas the W/D was significantly higher in the LP compared to HP group (LP 6.3, 95% CI: 5.6-6.9; HP 5.3, 95% CI: 4.9-5.8). Conclusion VV-ECMO for severe acute respiratory failure MV with very low tidal volume and LP reduces regional lung edema in the dependent areas, while HP reduces edema.More studies are required to characterize the mechanisms of these findings.

About 40% of controlled donation after cardiac death (cDCD) are declined because death does not occur in a suitable time after withdrawal of life support. Improved strategies to preserve lungs may enable mobilization of the recovery team after death occurs to recover the lungs in all cDCDs independent of the interval. Prone positioning in ARDS patients has been shown to provide a more homogeneous distribution of alveolar distending pressure and improved outcomes. We hypothesized prone positioning during warm ischemia time (WIT) could decrease atelectasis and homogeneously distribute alveolar inflation leading to improved function during ex vivo lung perfusion (EVLP).

Lung transplant is a life-saving therapy for patients suffering from end-stage lung diseases. Ex vivo lung perfusion (EVLP) is used for organ preservation and for lung infection treatment prior to transplant. Ultraviolet-C light (UVC) irradiation is an effective bactericidal treatment used for blood products. In this study, we examine the effects of UVC light irradiation and antibiotic therapy on common bacterial pathogens in a miniaturized EVLP model.