Xenogeneic support for the recovery of human donor organs

Perfusate Exchange Does Not Improve Outcomes in 24-hour Ex Situ Lung Perfusion

BACKGROUND

Reliable 24-hour preservation is required to optimize the rehabilitation potential of Ex Situ Lung Perfusion (ESLP). Other ESLP protocols include fresh perfusate replacement to counteract an accumulation of deleterious by-products. We describe the results of our reliable 24-hour negative pressure ventilation (NPV)-ESLP protocol with satisfactory acute post-transplant outcomes and investigate perfusate exchange (PE) as a modification to enhance prolonged ESLP.

METHODS

Twelve pig lungs underwent 24 hours of NPV-ESLP using 1.5L of cellular perfusate (500 mL packed red blood cells and 1 L buffered perfusate). The Control (n = 6) had no PE; the PE (n = 6) had 500 mL replaced after 12 hours of NPV-ESLP with 1000 mL fresh perfusate. Three left lungs per group were transplanted.

RESULTS

Results are reported as Control vs PE (mean ± SEM). Both groups demonstrated stable and acceptable oxygenation during 24 hours of ESLP with final PF ratios of 527.5 ± 42.19 and 488.4 ± 35.38 (P = .25). Final compliance measurements were 20.52 ± 3.59 and 18.55 ± 2.91 (P = .34). There were no significant differences in pulmonary artery pressure after 24 hours of ESLP (10.02 ± 2.69 vs 14.34 ± 1.64, P = .10), and pulmonary vascular resistance only differed significantly at T12 (417.6 ± 53.06 vs 685.4 ± 81.19, P = .02). Percentage weight gain between groups was similar (24.32 ± 8.4 and 45.33 ± 7.76, P = .07). Post-transplant left lung oxygenation was excellent (327.3 ± 14.62 and 313.3 ± 15.38, P = .28). There was no significant difference in % weight gain of lungs post-transplant (22.20 ± 7.22 vs 14.36 ± 9.96, P = .28).

CONCLUSION

Acceptable lung function was maintained during 24-hour NPV-ESLP and post-transplant regardless of PE.

Innovation and disruptive science determine the future of cardiothoracic surgery

One of the currently most asked questions in the field of medicine is how any specialty in the future will evolve to ensure better health for the patients by using current, unparalleled developments in all areas of science. This article will give an overview of new and evolving strategies for cardiothoracic (CT) surgery that are available today and will become available in the future in order to achieve this goal. In the founding era of CT surgery in the 1950s and 1960s, there was tremendous excitement about innovation and disruptive science, which eventually resulted in a completely new medical specialty, i.e. CT surgery. Entirely new treatment strategies were introduced for many cardiovascular diseases that had been considered incurable until then. As expected, alternative techniques have evolved in all fields of science during the last few decades, allowing great improvements in diagnostics and treatment in all medical specialties. The future of CT surgery will be determined by an unrestricted and unconditional investment in innovation, disruptive science and our own transformation using current achievements from many other fields. From the multitude of current and future possibilities, I will highlight 4 in this review: improvements in our current techniques, bringing CT surgery to low- and middle-income countries, revolutionizing the perioperative period and treating as yet untreatable diseases. These developments will allow us a continuation of the previously unheard-of treatment possibilities provided by ingenious innovations based on the fundamentals of CT surgery.

Lung Xenotransplantation

Although efforts have been made to expand the pool of donor lung allografts for human lung transplantation, a shortage remains. Lung xenotransplantation has been proposed as an alternative approach, but lung xenotransplantation in humans has not yet been reported. In addition, significant biological and ethical barriers will have to be addressed before clinical trials can be undertaken. However, significant progress has been made toward addressing biological incompatibilities that present a barrier, and recent advances in genetic engineering tools promise to accelerate further progress.

Diagnostic and Therapeutic Implications of Ex Vivo Lung Perfusion in Lung Transplantation: Potential Benefits and Inherent Limitations

Ex vivo lung perfusion (EVLP), a technique in which isolated lungs are continually ventilated and perfused at normothermic temperature, is emerging as a promising platform to optimize donor lung quality and increase the lung graft pool. Over the past few decades, the EVLP technique has become recognized as a significant achievement and gained much attention in the field of lung transplantation. EVLP has been demonstrated to be an effective platform for various targeted therapies to optimize donor lung function before transplantation. Additionally, some physical parameters during EVLP and biological markers in the EVLP perfusate can be used to evaluate graft function before transplantation and predict posttransplant outcomes. However, despite its advantages, the clinical practice of EVLP continuously encounters multiple challenges associated with both intrinsic and extrinsic limitations. It is of utmost importance to address the advantages and disadvantages of EVLP for its broader clinical usage. Here, the pros and cons of EVLP are comprehensively discussed, with a focus on its benefits and potential approaches for overcoming the remaining limitations. Directions for future research to fully explore the clinical potential of EVLP in lung transplantation are also discussed.

Exploring predisposing factors and pathogenesis contributing to injuries of donor lungs

INTRODUCTION

Lung transplantation (LTx) remains the only therapeutic strategy for patients with incurable lung diseases. However, its use has been severely limited by the narrow donor pool and potential concerns of inferior quality of donor lungs, which are more susceptible to external influence than other transplant organs. Multiple insults, including various causes of death and a series of perimortem events, may act together on donor lungs and eventually culminate in primary graft dysfunction (PGD) after transplantation as well as other poor short-term outcomes.

AREAS COVERED

This review focuses on the predisposing factors contributing to injuries to the donor lungs, specifically focusing on the pathogenesis of these injuries and their impact on post-transplant outcomes. Additionally, various maneuvers to mitigate donor lung injuries have been proposed.

EXPERT OPINION

The selection criteria for eligible donors vary and may be poor discriminators of lung injury. Not all transplanted lungs are in ideal condition. With the rapidly increasing waiting list for LTx, the trend of using marginal donors has become more apparent, underscoring the need to gain a deeper understanding of donor lung injuries and discover more donor resources.

Novel approaches for long-term lung transplant survival

Allograft failure remains a major barrier in the field of lung transplantation and results primarily from acute and chronic rejection. To date, standard-of-care immunosuppressive regimens have proven unsuccessful in achieving acceptable long-term graft and patient survival. Recent insights into the unique immunologic properties of lung allografts provide an opportunity to develop more effective immunosuppressive strategies. Here we describe advances in our understanding of the mechanisms driving lung allograft rejection and highlight recent progress in the development of novel, lung-specific strategies aimed at promoting long-term allograft survival, including tolerance.