Lung transplantation from donors after circulatory death using portable ex vivo lung perfusion

Cold but not too cold: advances in hypothermic and normothermic organ perfusion

Transplantation is the method of choice and, in many cases, the only method of treatment for patients with end-stage organ disease. Excellent results have been achieved, and the main focus today is to extend the number of available donors. The use of extended-criteria donors or donors after circulatory death is standard, but is accompanied by an increased risk of ischemia reperfusion injury. This review presents newly developed machine perfusion techniques using hypothermic, subnormothermic, or normothermic conditions, with or without oxygenation. Possibilities for treatment and quality assessment in decision-making about organ acceptability are also discussed.

Mesenchymal Stromal/Stem Cells and Their Products as a Therapeutic Tool to Advance Lung Transplantation

Lung transplantation (LTx) has become the gold standard treatment for end-stage respiratory failure. Recently, extended lung donor criteria have been applied to decrease the mortality rate of patients on the waiting list. Moreover, ex vivo lung perfusion (EVLP) has been used to improve the number/quality of previously unacceptable lungs. Despite the above-mentioned progress, the morbidity/mortality of LTx remains high compared to other solid organ transplants. Lungs are particularly susceptible to ischemia-reperfusion injury, which can lead to graft dysfunction. Therefore, the success of LTx is related to the quality/function of the graft, and EVLP represents an opportunity to protect/regenerate the lungs before transplantation. Increasing evidence supports the use of mesenchymal stromal/stem cells (MSCs) as a therapeutic strategy to improve EVLP. The therapeutic properties of MSC are partially mediated by secreted factors. Hence, the strategy of lung perfusion with MSCs and/or their products pave the way for a new innovative approach that further increases the potential for the use of EVLP. This article provides an overview of experimental, preclinical and clinical studies supporting the application of MSCs to improve EVLP, the ultimate goal being efficient organ reconditioning in order to expand the donor lung pool and to improve transplant outcomes.

Ex Vivo Lung Perfusion: A Platform for Donor Lung Assessment, Treatment and Recovery

Lung transplantation offers a lifesaving therapy for patients with end-stage lung disease but its availability is presently limited by low organ utilization rates with donor lungs frequently excluded due to unsuitability at assessment. When transplantation does occur, recipients are then vulnerable to primary graft dysfunction (PGD), multitudinous short-term complications, and chronic lung allograft dysfunction. The decision whether to use donor lungs is made rapidly and subjectively with limited information and means many lungs that might have been suitable are lost to the transplant pathway. Compared to static cold storage (SCS), ex vivo lung perfusion (EVLP) offers clinicians unrivalled opportunity for rigorous objective assessment of donor lungs in conditions replicating normal physiology, thus allowing for better informed decision-making in suitability assessments. EVLP additionally offers a platform for the delivery of intravascular or intrabronchial therapies to metabolically active tissue aiming to treat existing lung injuries. In the future, EVLP may be employed to provide a pre-transplant environment optimized to prevent negative outcomes such as primary graft dysfunction (PGD) or rejection post-transplant.

Conditioned Medium from Human Amnion-Derived Mesenchymal Stromal/Stem Cells Attenuating the Effects of Cold Ischemia-Reperfusion Injury in an In Vitro Model Using Human Alveolar Epithelial Cells

The clinical results of lung transplantation (LTx) are still less favorable than other solid organ transplants in both the early and long term. The fragility of the lungs limits the procurement rate and can favor the occurrence of ischemia-reperfusion injury (IRI). Ex vivo lung perfusion (EVLP) with Steen Solution^TM (SS) aims to address problems, and the implementation of EVLP to alleviate the activation of IRI-mediated processes has been achieved using mesenchymal stromal/stem cell (MSC)-based treatments. In this study, we investigated the paracrine effects of human amnion-derived MSCs (hAMSCs) in an in vitro model of lung IRI that includes cold ischemia and normothermic EVLP. We found that SS enriched by a hAMSC-conditioned medium (hAMSC-CM) preserved the viability and delayed the apoptosis of alveolar epithelial cells (A549) through the downregulation of inflammatory factors and the upregulation of antiapoptotic factors. These effects were more evident using the CM of 3D hAMSC cultures, which contained an increased amount of immunosuppressive and growth factors compared to both 2D cultures and encapsulated-hAMSCs. To conclude, we demonstrated an in vitro model of lung IRI and provided evidence that a hAMSC-CM attenuated IRI effects by improving the efficacy of EVLP, leading to strategies for a potential implementation of this technique.

Ex vivo lung perfusion prior to transplantation: an overview of current clinical practice worldwide

Lung transplantation is a lifesaving treatment in numerous forms of end-stage lung disease but organ shortage remains nowadays his biggest issue. Ex vivo lung perfusion (EVLP) has recently emerged as a solution to this problem and begins to be accepted is clinical practice. In this review, we will focus on his experience worldwide. We would like to describe the technique and the criteria used to select the donors and the transplantable lungs. We will also browse the acceptance rate described in literature as well as numerous other aspects of this new tool.

Feasibility of Lung Transplantation From Donation After Circulatory Death Donors Following Portable Ex Vivo Lung Perfusion: A Pilot Study

BACKGROUND

Donation after circulatory death (DCD) has the potential to significantly alleviate the shortage of transplantable lungs. We report our initial experience with the use of portable ex vivo lung perfusion (EVLP) with the Organ Care System Lung device for evaluation of DCD lungs.

METHODS

We performed a retrospective review of the DCD lung transplantation (LTx) experience at a single institution through the use of a prospective database.

RESULTS

From 2011 to 2015, 208 LTx were performed at the University of Alberta, of which 11 were DCD LTx with 7 (64%) that underwent portable EVLP. DCD lungs preserved with portable EVLP had a significantly shorter cold ischemic time (161 ± 44 vs 234 ± 60 minutes, P = .045), lower grade of primary graft dysfunction at 72 hours after LTx (0.4 ± 0.5 vs 2.1 ± 0.7, P = .003), similar mechanical ventilation time (55 ± 44 vs 103 ± 97 hours, P = .281), and hospital length of stay (29 ± 11 vs 33 ± 10 days, P = .610). All patients were alive at 1-year follow-up after LTx with improved functional outcomes and acceptable quality of life compared with before LTx, although there were no intergroup differences.

CONCLUSIONS

In our pilot cohort, portable EVLP was a feasible modality to increase confidence in the use of DCD lungs with validated objective evidence of lung function during EVLP that translates to acceptable clinical outcomes and quality of life after LTx. Further studies are needed to validate these initial findings in a larger cohort.

Machine perfusion of thoracic organs

This article summarizes recent knowledge and clinical advances in machine perfusion (MP) of thoracic organs. MP of thoracic organs has gained much attention during the last decade. Clinical studies are investigating the role of MP to preserve, resuscitate, and assess heart and lungs prior to transplantation. Currently, MP of the cardiac allograft is essential in all type DCD heart transplantation while MP of the pulmonary allograft is mandatory in uncontrolled DCD lung transplantation. MP of thoracic organs also offers an exciting platform to further investigate downregulation of the innate and adaptive immunity prior to reperfusion of the allograft in recipients. MP provides a promising technology that allows pre-transplant preservation, resuscitation, assessment, repair, and conditioning of cardiac and pulmonary allografts outside the body in a near physiologic state prior to planned transplantation. Results of ongoing clinical trials are awaited to estimate the true clinical value of this new technology in advancing the field of heart and lung transplantation by increasing the total number and the quality of available organs and by further improving recipient early and long-term outcome.

Devices for ex vivo heart and lung perfusion

INTRODUCTION

The number of organs available for heart and lung transplantation is far short of the number that is needed to meet demand. Perfusion and ventilation of donor organs after procurement has led to exciting advances in the field of cardiothoracic transplantation. The clinical implications of this technology allows for techniques to evaluate the quality of an organ, active rehabilitation of organs after procurement and prior to implantation, and increased time between organ procurement and implantation. This ex-vivo perfusion technique has also been referred to in the lay press as the 'heart in a box' or 'lung in a box.'

AREAS COVERED

This review includes information from case reports, case series, and clinical trials on ex vivo heart and lung perfusion. The focus is on the devices, ventilation and perfusion techniques, outcomes, and application of the technology.

EXPERT COMMENTARY

Ex vivo perfusion of donor hearts and lungs prior to transplantation has proven to be a viable alternative to standard cold-preservation strategies. Its use has allowed for ongoing expansion of the donor pool. The biggest barriers to expansion of this technology are access, cost, and lack of evidence which clearly supports superior outcomes.

Current state of ex-vivo lung perfusion

PURPOSE OF REVIEW

The purpose of the current report is to review the ex-vivo peer-reviewed literature published in the last 5 years and to summarize the findings.

RECENT FINDINGS

Encouraging data have been published by several centers utilizing ex-vivo lung perfusion (EVLP) as a means to identify viable grafts from the high-risk donor pool. The outcomes of transplanted lungs that were initially declined because of poor quality, but reevaluated with ex-vivo perfusion, are equivalent to standard criteria donor lungs. Further, research reports have emphasized the role of ex-vivo perfusion as a platform to improve graft quality and reduce the injurious effects of ischemia-reperfusion.

SUMMARY

Over the last 10 years, EVLP has proved its value as a reassessment tool to increase donor utilization. As short- and long-term data demonstrate the safety of EVLP, its use as a therapeutic platform is emerging, along with the promise of a new era in lung transplantation.

The evolving potential for pediatric ex vivo lung perfusion

Despite the rise in the number of adult lung transplantations performed, rates of pediatric lung transplantation remain low. Lung transplantation is an accepted therapy for pediatric end-stage lung disease; however, it is limited by a shortage of donor organs. EVLP has emerged as a platform for assessment and preservation of donor lung function. EVLP has been adopted in adult lung transplantation and has successfully led to increased adult lung transplantations and donor lung utilization. We discuss the future implications of EVLP utilization, specifically, its potential evolving role in overcoming donor shortages in smaller children and adolescents to improve the quality and outcomes of lung transplantation in pediatric patients.