OPTN/SRTR 2013 Annual Data Report: lung

Survival outcomes following urgent lung transplantation in France and the USA

INTRODUCTION

Lung graft allocation can be based on a score (Lung Allocation Score) as in the USA or sequential proposals combined with a discrete priority model as in France. We aimed to analyse the impact of allocation policy on the outcome of urgent lung transplantation (LT).

METHODS

US United Network for Organ Sharing (UNOS) and French Cristal databases were retrospectively reviewed to analyse LT performed between 2007 and 2017. We analysed the mortality risk of urgent LT by fitting Cox models and adjusted Restricted Mean Survival Time. We then compared the outcome after urgent LT in the UNOS and Cristal groups using a propensity score matching.

RESULTS

After exclusion of patients with chronic obstructive pulmonary disease/emphysema and redo LT, 3775 and 12 561 patients underwent urgent LT and non-urgent LT in the USA while 600 and 2071 patients underwent urgent LT and non-urgent LT in France. In univariate analysis, urgent LT was associated with an HR for death of 1.24 (95% CI 1.05 to 1.48) in the Cristal group and 1.12 (95% CI 1.05 to 1.19) in the UNOS group. In multivariate analysis, the effect of urgent LT was attenuated and no longer statistically significant in the Cristal database (HR 1.1 (95% CI 0.91 to 1.33)) while it remained constant and statistically significant in the UNOS database (HR 1.12 (95% CI 1.05 to 1.2)). Survival comparison of urgent LT patients between the two countries was significantly different in favour of the UNOS group (1-year survival rates 84.1% (80.9%-87.3%) vs 75.4% (71.8%-79.1%) and 3-year survival rates 66.3% (61.9%-71.1%) vs 62.7% (58.5%-67.1%), respectively).

CONCLUSION

Urgent LT is associated with adverse outcome in the USA and in France with a better prognosis in the US score-based system taking post-transplant survival into account. This difference between two healthcare systems is multifactorial.

A new method for evaluating lung volume: AI-3D reconstruction

Objective: This study aims to explore the clinical application of an AI-3D reconstruction system in measuring lung volume and analyze its practical value in donor-recipient size matching in lung transplantation. Methods: The study retrospectively collected data from 75 subjects who underwent a plethysmography examination and lung CT at the First Hospital of Jilin University. General data and information related to lung function, and imaging results were collected. The correlation between actual total lung volume (aTLV), predicted total lung volume (pTLV), and artificial intelligence three-dimensional reconstruction CT lung volume (AI-3DCTVol) was analyzed for the overall, male, and female groups. The correlation coefficient and the absolute error percentage with pTLV and AI-3DCTVol were obtained. Results: In the overall, male, and female groups, there were statistical differences (p <0.05) between the pTLV formula and AI-3D reconstruction compared to the plethysmography examination value. The ICC between pTLV and aTLV for all study participants was 0.788 (95% CI: 0.515-0.893), p <0.001. Additionally, the ICC value between AI-3D reconstruction and aTLV was 0.792 (95% CI: 0.681-0.866), p <0.001. For male study participants, the ICC between pTLV and aTLV was 0.330 (95% CI: 0.032-0.617), p = 0.006. Similarly, the ICC value between AI-3D reconstruction and aTLV was 0.413 (95% CI: 0.089-0.662), p = 0.007. In the case of female research subjects, the ICC between pTLV and aTLV was 0.279 (95% CI: 0.001-0.523), p = 0.012. Further, the ICC value between AI-3D reconstruction and aTLV was 0.615 (95% CI: 0.561-0.870), p <0.001. Conclusion: The AI-3D reconstruction, as a convenient method, has significant potential for application in lung transplantation.

Dynamic logistic state space prediction model for clinical decision making

Prediction modeling for clinical decision making is of great importance and needed to be updated frequently with the changes of patient population and clinical practice. Existing methods are either done in an ad hoc fashion, such as model recalibration or focus on studying the relationship between predictors and outcome and less so for the purpose of prediction. In this article, we propose a dynamic logistic state space model to continuously update the parameters whenever new information becomes available. The proposed model allows for both time-varying and time-invariant coefficients. The varying coefficients are modeled using smoothing splines to account for their smooth trends over time. The smoothing parameters are objectively chosen by maximum likelihood. The model is updated using batch data accumulated at prespecified time intervals, which allows for better approximation of the underlying binomial density function. In the simulation, we show that the new model has significantly higher prediction accuracy compared to existing methods. We apply the method to predict 1 year survival after lung transplantation using the United Network for Organ Sharing data.

Lung transplantation and concomitant cardiac surgical procedures: A systematic review and meta-analysis

BACKGROUND

Lung transplantation is an effective treatment option for end-stage lung diseases. In some cases, these patients may also have underlying cardiac disease which may require surgical intervention before or during transplantation. Concomitant cardiac surgery may often be preferred, as reduced lung function precludes these patients from pre-transplant surgery. Our meta-analysis sought to examine the impact of lung transplantation paired with concomitant cardiac surgery on long-term mortality.

METHODS

We conducted a systematic review of the MEDLINE, Embase, and Cochrane databases. Our primary outcome was overall mortality. Secondary outcomes included length of stay (LOS) in hospital and serious postoperative complication rates. We used a meta-analytic model to determine the differences in the above outcomes between patients who underwent lung transplantation with or without concomitant cardiac surgery.

RESULTS

Out of the 1876 articles screened, 7 met our pre-determined inclusion criteria. Lung transplantation with concomitant cardiac surgery was not associated with increased mortality compared to lung transplantation alone (hazard ratio = 1.02; 95% confidence interval [CI] = 0.80-1.31; I²  = 0%; p = .99). LOS in hospital was not significantly different between groups (standardized mean difference = 0.32; 95% CI = -0.91 to 1.55). Postoperative complication rates were also reported but not analyzed due to missing data.

CONCLUSIONS

There was no significant difference in mortality rates in patients undergoing lung transplantation with or without concomitant cardiac surgery at 1, 3, and 5 years. However, postoperative complication rates were higher in the concomitant group. The decision to perform concomitant procedures should be tailored to each patient's clinical condition.

Outcomes of patients awaiting lung transplantation after the implementation of donation after brain death at a single Chinese center

Voluntary contribution has become the only source of donor lungs in China since 2015. To elaborate the outcomes of patients awaiting lung transplantation (LTx) after the implementation of donation after brain death, we performed a retrospective study that encompassed 205 patients with end-stage lung disease who registered for LTx at Shanghai Pulmonary Hospital from January 1, 2015 to January 1, 2021. A total of 180 patients were enrolled in the study. The median waiting time was 1.25 months. Interstitial lung disease (ILD) (103/180, 57.2%) and chronic obstructive pulmonary disease (COPD) (56/180, 31.1%) were the most common diseases in our study population. The mean pulmonary artery pressure (mPAP) of patients in the died-waiting group was higher than that of the survivors (53.29±21.71 mmHg vs. 42.11±18.58 mmHg, P=0.002). The mortality of patients with ILD (34/103, 33.00%) was nearly twice that of patients with COPD (10/56, 17.86%) while awaiting LTx (P=0.041). In the died-waiting group, patients with ILD had a shorter median waiting time than patients with COPD after being listed (0.865 months vs. 4.720 months, P=0.030). ILD as primary disease and mPAP > 35 mmHg were two significant independent risk factors for waitlist mortality, with hazard ratios (HR) of 3.483 (95% CI 1.311-9.111; P=0.011) and 3.500 (95% CI 1.435-8.536; P=0.006). Hence, LTx is more urgently needed in patients with ILD and pulmonary hypertension.

Managing pulmonary arterial hypertension: how to select and facilitate successful transplantation

PURPOSE OF REVIEW

Despite improvements in available medical therapies, pulmonary arterial hypertension (PAH) remains a progressive, ultimately fatal disorder. Lung transplantation is a viable treatment option for PAH patients with advanced disease.

RECENT FINDINGS

Recent guidelines from the International Society of Heart and Lung Transplantation (ISHLT) have updated recommendations regarding time of referral and listing for lung transplantation in PAH. The new guidelines emphasize earlier referral for transplant evaluation to ensure adequate time for proper evaluation and listing. They also incorporate objective risk stratification criteria to assist in decision-making regarding timing of referral and listing. With regards to the transplant procedure, bilateral lung transplantation has largely supplanted heart-lung transplantation as the procedure of choice for transplantation for advanced PAH. Exceptions to this include patients with PAH because of congenital heart disease and those with concurrent LV dysfunction. Use of mechanical support via venoarterial ECMO initiated before transplantation and continued into the early postoperative period is emerging as a standard of care and may help to reduce early posttransplant mortality in this population. There has been increased recognition of the importance of WHO Group 3 pulmonary hypertension. Many of the lessons learned from PAH may be applied when transplanting patients with severe WHO Group 3 pulmonary hypertension.

SUMMARY

Patients with PAH present unique challenges with regards to transplantation that require a therapeutic approach distinct from other lung disorders. Lung transplantations for PAH are high-risk endeavors best performed at centers with expertise in management of both PAH and extracorporeal support.

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.

Prevalence, Clinical Characteristics, and Outcomes Among Lung Transplant Recipients of Donors With Cocaine Use

INTRODUCTION

There is limited data regarding lung transplant (LT) outcomes among recipients of donors with a history of cocaine use. We sought to assess the burden of cocaine abuse among LT donors, describe their characteristics, and evaluate the association with post-transplant outcomes.

METHODS

From the United Network for Organ Sharing database, we included adult patients (age ≥18 years) who underwent LT between 1996 and 2014 (N = 20,106; mean age 53.7 ± 13 years; male: 57%). Study groups were divided based on the donor history of recent cocaine abuse (last 6 months). Donor and recipient characteristics were compared between the 2 groups. With 1-year survival as the primary endpoint, multivariate logistic regression analysis was conducted to assess for an independent association with the donor history of cocaine use.

RESULTS

The overall frequency of donors with any history of cocaine use was 10.9% (n = 2189), although less than half were current users (n = 1001, 4.98%). Unadjusted 1-year survival was worse among recipients of donors with current cocaine use, although it did not achieve statistical significance (84.4% vs 82.2%; odds ratio 1.17, 95% confidence interval 0.99-1.38; P = .07). After adjusting for potential confounders, the current use of cocaine was not associated with 1-year survival (adjusted OR 1.06, 95% CI 0.95-1.18; P = .29).

CONCLUSIONS

A significant proportion of lung donors have a history of cocaine abuse. Although unadjusted early outcomes appear to worsen among recipients of active cocaine users, an independent association was not seen with 1-year survival. The current analysis supports the continued use of donors with a history of cocaine abuse, assuming they meet other criteria for organ quality.

Lung transplantation disparities based on diagnosis for patients bridging to transplant on extracorporeal membrane oxygenation

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) is increasingly utilized as a bridge to lung transplantation, but ECMO status is not explicitly accounted for in the Lung Allocation Score (LAS). We hypothesized that among waitlist patients on ECMO, patients with pulmonary arterial hypertension (PAH) would have lower transplantation rates.

METHODS

Using United Network for Organ Sharing data, we conducted a retrospective cohort study of patients who were ≥12 years old, active on the lung transplant waitlist, and required ECMO support from June 1, 2015 through June 12, 2020. Multivariable competing risk analysis was used to examine waitlist outcomes.

RESULTS

1064 waitlist subjects required ECMO support; 40 (3.8%) had obstructive lung disease (OLD), 97 (9.1%) had PAH,138 (13.0%) had cystic fibrosis (CF), and 789 (74.1%) had interstitial lung disease (ILD). Ultimately, 671 (63.1%) underwent transplant, while 334 (31.4%) died or were delisted. The transplant rate per person-years on the waitlist on ECMO was 15.41 for OLD, 6.05 for PAH, 15.66 for CF, and 15.62 for ILD. Compared to PAH patients, OLD, CF, and ILD patients were 78%, 69%, and 62% more likely to undergo transplant throughout the study period, respectively (adjusted SHRs 1.78 p = 0.007, 1.69 p = 0.002, and 1.62 p = 0.001). The median LAS at waitlist removal for transplantation, death, or delisting were 75.1 for OLD, 79.6 for PAH, 91.0 for CF, and 88.3 for ILD (p < 0.001).

CONCLUSIONS

Among patients bridging to transplant on ECMO, patients with PAH had a lower transplantation rate than patients with OLD, CF, and ILD.

The Surplus Transplant Lung Allocation System in Italy: An Evaluation of the Allocation Process via Stochastic Modeling

Background: Lung transplantation is a specialized procedure used to treat chronic end-stage respiratory diseases. Due to the scarcity of lung donors, constructing fair and equitable lung transplant allocation methods is an issue that has been addressed with different strategies worldwide. This work aims to describe how Italy’s “national protocol for the management of surplus organs in all transplant programs” functions through an online app to allocate lung transplants. We have developed two probability models to describe the allocation process among the various transplant centers. An online app was then created. The first model considers conditional probabilities based on a protocol flowchart to compute the probability for each area and transplant center to receive each n-th organ in the period considered. The second probability model is based on the generalization of the binomial distribution to correlated binary variables, which is based on Bahadur’s representation, to compute the cumulative probability for each transplant center to receive at least nth organs. Our results show that the impact of the allocation of a surplus organ depends mostly on the region where the organ was donated. The discrepancies shown by our model may be explained by a discrepancy between the northern and southern regions in relation to the number of organs donated.

The Cellular and Physiological Basis for Lung Repair and Regeneration: Past, Present, and Future

The respiratory system, which includes the trachea, airways, and distal alveoli, is a complex multi-cellular organ that intimately links with the cardiovascular system to accomplish gas exchange. In this review and as members of the NIH/NHLBI-supported Progenitor Cell Translational Consortium, we discuss key aspects of lung repair and regeneration. We focus on the cellular compositions within functional niches, cell-cell signaling in homeostatic health, the responses to injury, and new methods to study lung repair and regeneration. We also provide future directions for an improved understanding of the cell biology of the respiratory system, as well as new therapeutic avenues.

N-myc-interactor mediates microbiome induced epithelial to mesenchymal transition and is associated with chronic lung allograft dysfunction

BACKGROUND

Recent evidence suggests a role for lung microbiome in occurrence of chronic lung allograft dysfunction (CLAD). However, the mechanisms linking the microbiome to CLAD are poorly delineated. We investigated a possible mechanism involved in microbial modulation of mucosal response leading to CLAD with the hypothesis that a Proteobacteria dominant lung microbiome would inhibit N-myc-interactor (NMI) expression and induce epithelial to mesenchymal transition (EMT).

METHODS

Explant CLAD, non-CLAD, and healthy nontransplant lung tissue were collected, as well as bronchoalveolar lavage from 14 CLAD and matched non-CLAD subjects, which were followed by 16S rRNA amplicon sequencing and quantitative polymerase chain reaction (PCR) analysis. Pseudomonas aeruginosa (PsA) or PsA-lipopolysaccharide was cocultured with primary human bronchial epithelial cells (PBEC). Western blot analysis and quantitative reverse transcription (qRT) PCR was performed to evaluate NMI expression and EMT in explants and in PsA-exposed PBECs. These experiments were repeated after siRNA silencing and upregulation (plasmid vector) of EMT regulator NMI.

RESULTS

16S rRNA amplicon analyses revealed that CLAD patients have a higher abundance of phyla Proteobacteria and reduced abundance of the phyla Bacteroidetes. At the genera level, CLAD subjects had an increased abundance of genera Pseudomonas and reduced Prevotella. Human CLAD airway cells showed a downregulation of the N-myc-interactor gene and presence of EMT. Furthermore, exposure of human primary bronchial epithelial cells to PsA resulted in downregulation of NMI and induction of an EMT phenotype while NMI upregulation resulted in attenuation of this PsA-induced EMT response.

CONCLUSIONS

CLAD is associated with increased bacterial biomass and a Proteobacteria enriched airway microbiome and EMT. Proteobacteria such as PsA induces EMT in human bronchial epithelial cells via NMI, demonstrating a newly uncovered mechanism by which the microbiome induces cellular metaplasia.

Clinical Application of Human Induced Pluripotent Stem Cell-Derived Organoids as an Alternative to Organ Transplantation

Transplantation is essential and crucial for individuals suffering from end-stage organ failure diseases. However, there are still many challenges regarding these procedures, such as high rates of organ rejection, shortage of organ donors, and long waiting lines. Thus, investments and efforts to develop laboratory-grown organs have increased over the past years, and with the recent progress in regenerative medicine, growing organs in vitro might be a reality within the next decades. One of the many different strategies to address this issue relies on organoid technology, a miniaturized and simplified version of an organ. Here, we address recent progress on organoid research, focusing on transplantation of intestine, retina, kidney, liver, pancreas, brain, lung, and heart organoids. Also, we discuss the main outcomes after organoid transplantation, common challenges faced by these promising regenerative medicine approaches, and future perspectives on the field.

Catheter ablation of atrial arrhythmias following lung transplant: Electrophysiological findings and outcomes

INTRODUCTION

Data on the mechanisms of atrial arrhythmias (AAs) and outcomes of catheter ablation (CA) in lung transplantation (LT) patients are insufficient. We evaluated the electrophysiologic features and outcomes of CA of AAs in LT patients. METHODS AND RESULTS: We conducted a retrospective study of all the LT patients who underwent CA for AAs at our institution between 2004 and 2019. A total of 15 patients (43% males, age: 61 ± 10 years) with a history of LT (60% bilateral and 40% unilateral) were identified. All patients had documented organized AA on surface electrocardiogram and seven patients also had atrial fibrillation (AF; 47% with >1 clinical arrhythmia). At electrophysiological study, 19 organized AAs were documented (48% focal and 52% macro-re-entrant). Focal atrial tachycardias/flutters were targeted along the pulmonary vein (PV) anastomotic site at the left inferior PV (n = 2), ridge and carina of the left superior PV (n = 2), left atrium (LA) posterior wall (n = 3), LA roof (n = 1), and tricuspid annulus (n = 1). Macro-re-entrant AAs included cavotricuspid isthmus-dependent flutter (n = 2), incisional LA flutter (n = 4), LA roof-dependent flutter (n = 1), and mitral annular flutter (n = 3). In patients with LA mapping (n = 13), PV reconnection on the side of the LT was found in six patients (40%, all with clinically documented AF), with a mean of 2.1 ± 0.9 PVs reconnected per patient. Patients with AF underwent successful PV isolation. After a median follow-up of 19 months (range: 6-86 months), 75% of patients remained free from recurrent AAs. No procedural major complications occurred.

CONCLUSION

In patients with prior LT, recurrent AAs are typically associated with substrate surrounding the surgical anastomotic lines and/or chronically reconnected PVs. CA of AAs in this population is safe and effective to achieve long-term arrhythmia control.

Functional, Metabolic and Morphologic Results of Ex Vivo Donor Lung Perfusion with a Perfluorocarbon-Based Oxygen Carrier Nanoemulsion in a Large Animal Transplantation Model

Background: Ex vivo lung perfusion (EVLP) is a technology that allows the re-evaluation of questionable donor lung before implantation and it has the potential to repair injured donor lungs that are otherwise unsuitable for transplantation. We hypothesized that perfluorocarbon-based oxygen carrier, a novel reconditioning strategy instilled during EVLP would improve graft function. Methods: We utilized perfluorocarbon-based oxygen carrier (PFCOC) during EVLP to recondition and improve lung graft function in a pig model of EVLP and lung transplantation. Lungs were retrieved and stored for 24 h at 4 °C. EVLP was done for 6 h with or without PFCOC. In the transplantation groups, left lung transplantation was done after EVLP with or without PFCOC. Allograft function was assessed by means of pulmonary gas exchange, lung mechanics and vascular pressures, histology and transmission electron microscopy (TEM). Results: In the EVLP only groups, physiological and biochemical markers during the 6-h perfusion period were comparable. However, perfusate lactate potassium levels were lower and ATP levels were higher in the PFCOC group. Radiologic assessment revealed significantly more lung infiltrates in the controls than in the PFCOC group (p = 0.04). In transplantation groups, perfusate glucose consumption was higher in the control group. Lactate levels were significantly lower in the PFCOC group (p = 0.02). Perfusate flavin mononucleotide (FMN) was significantly higher in the controls (p = 0.008). Post-transplant gas exchange was significantly better during the 4-h reperfusion period in the PFCOC group (p = 0.01). Plasma IL-8 and IL-12 levels were significantly lower in the PFCOC group (p = 0.01, p = 0.03, respectively). ATP lung tissue levels at the end of the transplantation were higher and myeloperoxidase (MPO) levels in lung tissue were lower in the PFCOC group compared to the control group. In the PFCOC group, TEM showed better tissue preservation and cellular viability. Conclusion: PFCOC application is safe during EVLP in lungs preserved 24 h at 4 °C. Although this strategy did not significantly affect the EVLP physiology, metabolic markers of the donor quality such as lactate production, glucose consumption, neutrophil infiltration and preservation of mitochondrial function were better in the PFCOC group. Following transplantation, PFCOC resulted in better graft function and TEM showed better tissue preservation, cellular viability and improved gas transport.

FK506 induces lung lymphatic endothelial cell senescence and downregulates LYVE-1 expression, with associated decreased hyaluronan uptake

BACKGROUND

Therapeutic lymphangiogenesis in an orthotopic lung transplant model has been shown to improve acute allograft rejection that is mediated at least in part through hyaluronan drainage. Lymphatic vessel endothelial hyaluronan receptor (LYVE-1) expressed on the surface of lymphatic endothelial cells plays important roles in hyaluronan uptake. The impact of current immunosuppressive therapies on lung lymphatic endothelial cells is largely unknown. We tested the hypothesis that FK506, the most commonly used immunosuppressant after lung transplantation, induces lung lymphatic endothelial cell dysfunction.

METHODS

Lung lymphatic endothelial cells were cultured in vitro and treated with FK506. Telomerase activity was measured using the TRAP assay. Protein expression of LYVE-1 and senescence markers p21 and β-galactosidase was assessed with western blotting. Matrigel tubulation assay were used to investigate the effects of FK506 on TNF-α-induced lymphangiogenesis. Dual luciferase reporter assay was used to confirm NFAT-dependent transcriptional regulation of LYVE-1. Flow cytometry was used to examine the effects of FK506 on LYVE-1 in precision-cut-lung-slices ex vivo and on hyaluronan uptake in vitro.

RESULTS

In vitro, FK506 downregulated telomerase reverse transcriptase expression, resulting in decreased telomerase activity and subsequent induction of p21 expression and cell senescence. Treatment with FK506 decreased LYVE-1 mRNA and protein levels and resulted in decreased LEC HA uptake. Similar result showing reduction of LYVE-1 expression when treated with FK506 was observed ex vivo. We identified a putative NFAT binding site on the LYVE-1 promoter and cloned this region of the promoter in a luciferase-based reporter construct. We showed that this NFAT binding site regulates LYVE-1 transcription, and mutation of this binding site blunted FK506-dependent downregulation of LYVE-1 promoter-dependent transcription. Finally, FK506-treated lymphatic endothelial cells show a blunted response to TNF-α-mediated lymphangiogenesis.

CONCLUSION

FK506 alters lymphatic endothelial cell molecular characteristics and causes lymphatic endothelial cell dysfunction in vitro and ex vivo. These effects of FK506 on lymphatic endothelial cell may impair the ability of the transplanted lung to drain hyaluronan macromolecules in vivo. The implications of our findings on the long-term health of lung allografts merit more investigation.

Pegylated-Catalase Is Protective in Lung Ischemic Injury and Oxidative Stress

BACKGROUND

Lung transplant ischemia-reperfusion injury 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 ischemia-reperfusion injury.

METHODS

To demonstrate protection, primary culture porcine endothelial cells were treated with PEG-CAT (0 to 1250 U/mL) in a model of oxidative stress (400 μM H₂o₂). In vivo, rat lungs were subjected to 0 hours or 1 hour of warm ischemic injury and 2 hours 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 Alexa Fluor 488-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 (lactate dehydrogenase and hyaluronic acid), presence of vasoconstrictive peptides (endothelin-1 and big endothelin-1) released from endothelial cells, and reduced apoptosis (terminal deoxynucleotidyl transferase dUTP nick-end labeling).

CONCLUSIONS

In vitro and ex vivo, PEG-CAT protects against oxidative stress-induced cytotoxicity, maintains cellular metabolism, and mitigates lung ischemia-reperfusion in an experimental model. Together, these data suggest that PEG-CAT is a potential therapeutic target for donor organs at risk for ischemia-reperfusion injury.

The impact of systemic innovations for transforming transplant systems. Lessons learned from the German lung transplantation system. A qualitative study

The aim of this paper is to demonstrate the potential of the systemic innovations approach for transforming transplantation systems. It explores potential leverage points for intervening in the LTx-system as well as possible paths of transformation. We present possible transition pathways giving the example of the German Lung transplantation system that teeters on the brink of collapse due to system failures and organ scarcity and illustrate systemic innovations as core mechanisms for systems change in health systems. Desk research and semi-structured experts interviews provided qualitative data for a deductive-inductive coding and a rigorous qualitative content analysis of the data. Depending on the systemic innovations chosen to achieve systems change, transplant systems follow different transformational paths: from a collapse to a leapfrogging towards a non-human transplantation system. Thus, global health areas like transplantation benefit from analysis on systemic innovations as these support researchers, public policy and regulators by developing transformative strategies in healthcare systems.

SPECT imaging of lung ischemia-reperfusion injury using [99mTc]cFLFLF for molecular targeting of formyl peptide receptor 1

Primary graft dysfunction after lung transplantation, a consequence of ischemia-reperfusion injury (IRI), is a major cause of morbidity and mortality. IRI involves acute inflammation and innate immune cell activation, leading to rapid infiltration of neutrophils. Formyl peptide receptor 1 (FPR1) expressed by phagocytic leukocytes plays an important role in neutrophil function. The cell surface expression of FPR1 is rapidly and robustly upregulated on neutrophils in response to inflammatory stimuli. Thus, we hypothesized that use of [^99mTc]cFLFLF, a selective FPR1 peptide ligand, would permit in vivo neutrophil labeling and noninvasive imaging of IRI using single-photon emission computed tomography (SPECT). A murine model of left lung IRI was utilized. Lung function, neutrophil infiltration, and SPECT imaging were assessed after 1 h of ischemia and 2, 12, or 24 h of reperfusion. [^99mTc]cFLFLF was injected 2 h before SPECT. Signal intensity by SPECT and total probe uptake by gamma counts were 3.9- and 2.3-fold higher, respectively, in left lungs after ischemia and 2 h of reperfusion versus sham. These values significantly decreased with longer reperfusion times, correlating with resolution of IRI as shown by improved lung function and decreased neutrophil infiltration. SPECT results were confirmed using Cy7-cFLFLF-based fluorescence imaging of lungs. Immunofluorescence microscopy confirmed cFLFLF binding primarily to activated neutrophils. These results demonstrate that [^99mTc]cFLFLF SPECT enables noninvasive detection of lung IRI and permits monitoring of resolution of injury over time. Clinical application of [^99mTc]cFLFLF SPECT may permit diagnosis of lung IRI for timely intervention to improve outcomes after transplantation.

Mucormycosis in lung transplant recipients: A systematic review of the literature and a case series

BACKGROUND

Mucormycosis is a rare infection in lung transplant recipients (LTR). Our objective was to better define the clinical presentation and optimal management of this frequently lethal infection.

METHODS

A systematic review of the literature was performed to identify all published cases of mucormycosis in LTR using PubMed/MEDLINE. These cases were analyzed together with a new case series from our clinic.

RESULTS

Literature search yielded 44 articles matching the inclusion criteria, describing 121 cases. Six additional cases were identified from our clinic. Data regarding infection site and outcome were available for a total of 53 patients. The lungs were the most common site of infection (62%), followed by rhinocerebral and disseminated disease. Most cases (78%) developed in the first post-transplant year, with over 40% of them in the first month. Additional risk factors for mucormycosis were identified in over half of the patients. Surgical debridement was uncommon in pulmonary infection (9%). Posaconazole therapy was used in 35% of cases, mostly in combination with amphotericin B. Overall mortality was 32% but varied according to site of infection.

CONCLUSION

Mucormycosis in LTRs tends to be an early post-surgical infection, associated with additional risk factors and intensified immunosuppressive states, and most often affects the lungs, where surgical debridement is rarely feasible. Posaconazole as first-line therapy should be further explored.

Need for tracheostomy after lung transplant predicts decreased mid- and long-term survival

BACKGROUND

Tracheostomy is an important adjunct for lung transplant patients requiring prolonged ventilation. We explored the effects of post-transplant tracheostomy on survival and bronchiolitis obliterans syndrome after lung transplant.

METHODS

A retrospective, single center analysis was performed on all lung transplant recipients during the Lung Allocation Score (LAS) era. Risk factors for post-transplant tracheostomy or death within 30 days were assessed. Kaplan-Meier estimates and Cox proportional hazards models were used to examine the association between tracheostomy within 30 days after transplant and survival at 1 and 3 years. A total of 403 patients underwent single or bilateral lung transplant between May 2005 and February 2016 with complete data for 352 cases, and 35 patients (9.9%) underwent tracheostomy or died (N = 10, 2.8%) within 30 days.

RESULTS

In adjusted analyses, primary graft dysfunction grade 3 (PGD3) was associated with a composite end point of tracheostomy or death within 30 days (HR 3.11 (1.69, 5.71), P-value < .001). Tracheostomy within 30 days was associated with decreased survival at 1(HR 4.25 [1.75, 10.35] P-value = .001) and 3 years (HR 2.74 [1.30, 5.76], P-value = .008), as well as decreased bronchiolitis obliterans (BOS)-free survival at 1 (HR 1.87 [1.02, 3.41] P-value = .042) and 3 years (HR 2.15 [1.33, 3.5], P-value = .002).

CONCLUSION

Post-transplant tracheostomy is a marker for advanced lung allograft dysfunction with significant reduction in long-term overall and BOS-free survival.

Ex vivo perfusion induces a time- and perfusate-dependent molecular repair response in explanted porcine lungs

Ex vivo lung perfusion (EVLP) shows promise in ameliorating pretransplant acute lung injury (ALI) and expanding the donor organ pool, but the mechanisms of ex vivo repair remain poorly understood. We aimed to assess the utility of gene expression for characterizing ALI during EVLP. One hundred sixty-nine porcine lung samples were collected in vivo (n = 25), after 0 (n = 11) and 12 (n = 11) hours of cold static preservation (CSP), and after 0 (n = 57), 6 (n = 8), and 12 (n = 57) hours of EVLP, utilizing various ventilation and perfusate strategies. The expression of 53 previously described ALI-related genes was measured and correlated with function and histology. Twenty-eight genes were significantly upregulated and 6 genes downregulated after 12 hours of EVLP. Aggregate gene sets demonstrated differential expression with EVLP (P < .001) but not CSP. Upregulated 28-gene set expression peaked after 6 hours of EVLP, whereas downregulated 6-gene set expression continued to decline after 12 hours. Cellular perfusates demonstrated a greater reduction in downregulated 6-gene set expression vs acellular perfusate (P < .038). Gene set expression correlated with relevant functional and histologic parameters, including P/F ratio (P < .001) and interstitial inflammation (P < .005). Further studies with posttransplant results are warranted to evaluate the clinical significance of this novel molecular approach for assessing organ quality during EVLP.

Cell replacement in human lung bioengineering

BACKGROUND

As the number of patients with end-stage lung disease continues to rise, there is a growing need to increase the limited number of lungs available for transplantation. Unfortunately, attempts at engineering functional lung de novo have been unsuccessful, and artificial mechanical devices have limited utility as a bridge to transplant. This difficulty is largely due to the size and inherent complexity of the lung; however, recent advances in cell-based therapeutics offer a unique opportunity to enhance traditional tissue-engineering approaches with targeted site- and cell-specific strategies.

METHODS

Human lungs considered unsuitable for transplantation were procured and supported using novel cannulation techniques and modified ex-vivo lung perfusion. Targeted lung regions were treated using intratracheal delivery of decellularization solution. Labeled mesenchymal stem cells or airway epithelial cells were then delivered into the lung and incubated for up to 6 hours.

RESULTS

Tissue samples were collected at regular time intervals and detailed histologic and immunohistochemical analyses were performed to evaluate the effectiveness of native cell removal and exogenous cell replacement. Regional decellularization resulted in the removal of airway epithelium with preservation of vascular endothelium and extracellular matrix proteins. After incubation, delivered cells were retained in the lung and showed homogeneous topographic distribution and flattened cellular morphology.

CONCLUSIONS

Our findings suggest that targeted cell replacement in extracorporeal organs is feasible and may ultimately lead to chimeric organs suitable for transplantation or the development of in-situ interventions to treat or reverse disease, ultimately negating the need for transplantation.

Inactivating hepatitis C virus in donor lungs using light therapies during normothermic ex vivo lung perfusion

Availability of organs is a limiting factor for lung transplantation, leading to substantial mortality rates on the wait list. Use of organs from donors with transmissible viral infections, such as hepatitis C virus (HCV), would increase organ donation, but these organs are generally not offered for transplantation due to a high risk of transmission. Here, we develop a method for treatment of HCV-infected human donor lungs that prevents HCV transmission. Physical viral clearance in combination with germicidal light-based therapies during normothermic ex-vivo Lung Perfusion (EVLP), a method for assessment and treatment of injured donor lungs, inactivates HCV virus in a short period of time. Such treatment is shown to be safe using a large animal EVLP-to-lung transplantation model. This strategy of treating viral infection in a donor organ during preservation could significantly increase the availability of organs for transplantation and encourages further clinical development.

Organs from donors with transmissible viral infections, such as hepatitis C virus (HCV), are not offered for transplantation due to a high risk of transmission. Here, Galasso et al. develop a method for treatment of HCV-infected human donor lungs that is safe and prevents HCV transmission in the pig model.

Incidence and variables associated with 30-day mortality after lung transplantation

BACKGROUND

With the introduction of the lung allocation score (LAS), sicker patients are prioritized for lung transplantation (LT). There is a lack of data regarding variables independently associated with 30-day mortality after LT.

METHODS

We queried the UNOS database for adult patients undergoing LT between 1989 and 2014. Patients with dual organ or previous transplantation and those with missing survival data were excluded. Mortality during the first 30 days after LT was the primary outcome variable.

RESULTS

The yearly trends indicate a statistically significant reduction in the 30-day mortality during the study period (P < 0.001, overall mortality: 5.5%) which has continued in the post-LAS era (P = 0. 014, overall mortality: 3.6%). Among patients with 30-day mortality, "primary non-function" (n = 118, 72.8%) was reported as the most common etiology. Transplant indication of vascular diseases, history of non-transplant cardiac or lung surgery, mean pulmonary pressures >35 mm Hg, disabled functional status, ECMO support, high LAS, ischemic time >6 hours, and blunt injury as the mechanism of donor death are independently associated with 30-day mortality.

CONCLUSION

The incidence of early mortality after LT continues to decline in the post-LAS era. Apart from the mechanism of donor death and ischemic time, early mortality appears to be primarily driven by the recipient characteristics.

National Heart, Lung, and Blood Institute and American Association for Thoracic Surgery Workshop Report: Identifying collaborative clinical research priorities in lung transplantation

This report summarizes the discussion and recommendations from the June 2017 NHLBI-AATS Workshop on Identifying Collaborative Clinical Research Priorities in Lung Transplantation.

Critical Care before Lung Transplantation

Lung transplantation is widely accepted as the only viable treatment option for patients with end-stage lung disease. However, the imbalance between the number of suitable donor lungs available and the number of possible candidates often results in intensive care unit (ICU) admission for the latter. In the ICU setting, critical care is essential to keep these patients alive and to successfully bridge to lung transplantation. Proper management in the ICU is also one of the key factors supporting long-term success following transplantation. Critical care includes the provision of respiratory support such as mechanical ventilation (MV) and extracorporeal life support (ECLS). Accordingly, a working knowledge of the common critical care issues related to these unique patients and the early recognition and management of problems that arise before and after transplantation in the ICU setting are crucial for long-term success. In this review, we discuss the management and selection of candidates for lung transplantation as well as existing respiratory support strategies that involve MV and ECLS in the ICU setting.

Lung Transplantation in Germany Since the Introduction of the Lung Allocation Score

BACKGROUND

The allocation of donor lungs for transplantation in Germany was changed on 10 December 2011 to a system based on the Lung Allocation Score (LAS). The aim of the present study is to determine whether this change has prolonged the survival of patients on the transplant waiting list and of those who have undergone lung transplantation (LTx).

METHODS

We retrospectively compared data from the three-year periods before and after the change to an LAS-based allocation system (2009-2011 vs. 2012-2014).

RESULTS

The number of patients on the active waiting list declined from 606 on 12/31/2011 to 432 on 12/31/2014, a 29% decrease. The number of patients who died while on the waiting list fell from 306 in 2009-2011 to 226 in 2012-2014 (-26%, p = 0.04). Waiting-list mortality declined across all disease groups. Meanwhile, the number of lung transplantation procedures per year increased by 21% over the period of observation, from 865 to 1045. During the period in which the LAS was used, the proportion of transplant recipients with restrictive lung disease (46% vs. 31%; p<0.001) surpassed the proportion of those with a diagnosis of obstructive lung disease (33% vs. 40%; p = 0.003). The percentage of transplantations in patients treated with mechanical ventilation or extracorporeal respiratory support before transplantation rose from 9% to 13%. The one-year survival rate after lung transplantation was 76% in 2009-2011 and 81% in 2012-2014.

CONCLUSION

The introduction of the LAS in Germany was associated with a decrease in the number of patients on the waiting list, and also in the number of deaths among patients on the waiting list. The distribution of primary diagnoses among transplant recipients shifted away from obstructive and toward restrictive lung diseases. In the future, additional parameters of patients on the waiting list should be considered to enable further improvement of the allocation model.

Cutaneous Complications in Recipients of Lung Transplants: A Pictorial Review

Lung transplant is now an established modality for a broad spectrum of end-stage pulmonary diseases. According to the International Society for Heart and Lung Transplantation Registry, more than 50,000 lung transplants have been performed worldwide, with nearly 11,000 recipients of lung transplants alive in the United States. With the increasing use of lung transplant, pulmonologists must be cognizant of the common as well as the unique posttransplant dermatologic complications. Immunosuppression, infections, and a variety of medications and environmental exposures can contribute to these complications. This review aims to provide representative pictures and describe the pathogenesis, epidemiologic characteristics, and clinical manifestations of dermatologic complications encountered among recipients of lung transplants.

The Future of Lung Transplantation

The field of lung transplant has made significant advances over the last several decades. Despite these advances, morbidity and mortality remain high when compared with other solid organ transplants. As the field moves forward, the speed by which progress can be made will in part be determined by our ability to overcome several stumbling blocks, including donor shortage, proper selection of candidates, primary graft dysfunction, and chronic lung allograft dysfunction. The advances and developments surrounding these factors will have a significant impact on shaping the field within the coming years. In this review, we look at the current climate (ripe for expanding the donor pool), new technology (ex vivo lung perfusion and bioengineered lungs), cutting-edge innovation (novel biomarkers and new ways to treat infected donors), and evidence-based medicine to discuss current trends and predict future developments for what we hope is a bright future for the field of lung transplantation.

Early in vivo experience with the pediatric continuous-flow total artificial heart

BACKGROUND

Heart transplantation in infants and children is an accepted therapy for end-stage heart failure, but donor organ availability is low and always uncertain. Mechanical circulatory support is another standard option, but there is a lack of intracorporeal devices due to size and functional range. The purpose of this study was to evaluate the in vivo performance of our initial prototype of a pediatric continuous-flow total artificial heart (P-CFTAH), comprising a dual pump with one motor and one rotating assembly, supported by a hydrodynamic bearing.

METHODS

In acute studies, the P-CFTAH was implanted in 4 lambs (average weight: 28.7 ± 2.3 kg) via a median sternotomy under cardiopulmonary bypass. Pulmonary and systemic pump performance parameters were recorded.

RESULTS

The experiments showed good anatomical fit and easy implantation, with an average aortic cross-clamp time of 98 ± 18 minutes. Baseline hemodynamics were stable in all 4 animals (pump speed: 3.4 ± 0.2 krpm; pump flow: 2.1 ± 0.9 liters/min; power: 3.0 ± 0.8 W; arterial pressure: 68 ± 10 mm Hg; left and right atrial pressures: 6 ± 1 mm Hg, for both). Any differences between left and right atrial pressures were maintained within the intended limit of ±5 mm Hg over a wide range of ratios of systemic-to-pulmonary vascular resistance (0.7 to 12), with and without pump-speed modulation. Pump-speed modulation was successfully performed to create arterial pulsation.

CONCLUSION

This initial P-CFTAH prototype met the proposed requirements for self-regulation, performance, and pulse modulation.

Patient characteristics and outcome of end-stage lung diseases referred for lung transplantation in North India

Objective:

Most countries worldwide have transplant registries for patients with end-stage lung diseases (ESLD) requiring lung transplantation. There is no such lung transplant registry in India. Herein, we describe the demographic profile and clinical outcomes among patients referred for lung transplantation at a tertiary care center in North India.

Materials and Methods:

This was a prospective, observational study of consecutive patients with chronic respiratory diseases who were referred for lung transplantation between July 2013 and December 2016. Patients were evaluated using standard criteria for listing for lung transplantation.

Results:

Of the 176 patients assessed for lung transplantation, 167 were included in the study. The mean (standard deviation [SD]) age of the study population (52.1% females) was 53.2 (14.7) years. Interstitial lung disease (ILD, 46.7%), chronic obstructive pulmonary disease (COPD, 25.7%), and bronchiectasis (10.2%) were the most common diseases in this population. The median (interquartile range, IQR) survival was worst for patients with bronchiolitis (78.5 [9–208] days) and idiopathic pulmonary fibrosis (IPF, 93.5 [19–239] days) and best for patients with idiopathic pulmonary arterial hypertension (757 [340–876] days) and COPD (578 [184–763] days). Only 13% of the patients expressed willingness for lung transplantation. Patients willing for transplantation died earlier than those unwilling (median [IQR], 102 [36-224] days vs. 310 [41-713] days, P < 0.001).

Conclusion:

ILD was the most common cause of ESLD in patients referred for lung transplantation. The waitlist mortality was highest for patients with bronchiolitis and IPF. Despite having ESLD, very few patients were willing for lung transplantation. Patients willing for lung transplantation died earlier than those who were unwilling.

The Management of Patients With Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF), the most common form of fibrosing idiopathic interstitial pneumonia, is an inexorably progressive disease with a 5-year survival of ~20%. In the last decade, our understanding of disease pathobiology has increased significantly and this has inevitably impacted on the approach to treatment. Indeed, the paradigm shift from a chronic inflammatory disorder to a primarily fibrotic one coupled with a more precise disease definition and redefined diagnostic criteria have resulted in a massive increase in the number of clinical trials evaluating novel candidate drugs. Most of these trials, however, have been negative, probably because of the multitude and redundancy of cell types, growth factors and profibrotic pathways involved in disease pathogenesis. As a consequence, until recently IPF has lacked effective therapies. Finally, in 2014, two large phase 3 clinical trials have provided robust evidence that pirfenidone, a compound with anti-fibrotic, anti-oxidant and anti-inflammatory properties, and nintedanib, a tyrosine kinase inhibitor with selectivity for vascular endothelial growth factor, platelet-derived growth factor and fibroblast growth factor receptors are able to slow down functional decline and disease progression with an acceptable safety profile. While this is a major achievement, neither pirfenidone nor nintedanib cures IPF and most patients continue to experience disease progression and/or exacerbation despite treatment. Therefore, in recent years increasingly more attention has been paid to preservation of quality of life and, in the advanced phase of the disease, palliation of symptoms. Lung transplantation, the only curative treatment, remains a viable option for only a minority of highly selected patients. The unmet medical need in IPF remains high, and more efficacious and better tolerated drugs are urgently needed. However, a truly effective therapeutic approach should also address quality of life and highly prevalent concomitant conditions and complications of IPF.

Positive Impact of a Pilot Pharmacist-Run Diabetes Pharmacotherapy Clinic in Solid-Organ Transplant Recipients

PURPOSE

Post-transplant diabetes mellitus (PTDM) can lead to significant morbidity and cardiovascular death with a functioning graft. A paucity of literature exists regarding glycemic control in solid-organ transplant (SOT) recipients, including pharmacist management of PTDM. This study aimed to assess the impact of pharmacist interventions on diabetes management in a pharmacist-run PTDM clinic.

METHODS

This was a single-center, prospective, observational study of 24 adult SOT recipients enrolled in a pilot pharmacist-managed PTDM clinic from 1 January to 30 June 2015.

RESULTS

Improvements were realized in markers of glycemic control, including changes in A1C, average daily self-monitoring of blood glucose (SMBG) results, fasting SMBG results, and pre-lunch SMBG results from enrollment through at least 3 months of follow-up. Median A1C decreased significantly from 8.05% (interquartile range [IQR] 6.33-11.75) at baseline to 6.45% (IQR 6.05-7.3) at the last follow-up encounter (P = 0.0010). Average daily SMBG results decreased significantly from a median of 191 mg/dL (IQR 138-232 mg/dL) at baseline to 125 mg/dL (IQR 111-167 mg/dL) at the final encounter (P = 0.0023). Median fasting and pre-lunch SMBG results decreased significantly from 153 mg/dL (IQR 117-208 mg/dL) at baseline to 120 mg/dL (IQR 102-134 mg/dL) (P = 0.0064) and from 212 mg/dL (IQR 159-258 mg/dL) to 122 mg/dL (IQR 110-169 mg/dL) (P = 0.0161), respectively. Changes from baseline in other SMBG values, lipid levels, and BMI were not statistically significant.

CONCLUSION

The results of our study demonstrate that a pharmacist-managed PTDM clinic can significantly affect glycemic control in SOT recipients.

Recent advances in extracorporeal life support as a bridge to lung transplantation

INTRODUCTION

Invasive mechanical respiratory support in candidate bridging to transplant (BTT) has become common practice in recent years. This usually consists of mechanical ventilation, extracorporeal life support (ECLS) or a combination of both techniques. Areas covered: This review covers epidemiology, technical considerations, indications and outcome of ELCS as BTT. Published literature was identified by searching the MEDLINE bibliographic database (1946-present) and appropriate papers were reviewed. In a retrospective analysis of the period 2010-2016 (n = 92 cases of ECLS bridging, 62% ECLS only) at our institution, bridging success was 73%, with 1-year survival among patients surviving to transplant 78%, surpassing our previously published results between 2005-2009 (bridging success 58%, 1-year survival 58%, p = 0.002 and p = 0.02, respectively). Expert commentary: While ECLS success has influenced lung transplant selection criteria, bridging remains technically and ethically challenging. Candidate selection and organ allocation are crucial to achieving acceptable results.

Effect of Transplant Center Volume on Cost and Readmissions in Medicare Lung Transplant Recipients

RATIONALE

Although lung transplant recipient survival is better at higher volume centers, the effect of center volume on admission cost and early hospital readmission is unknown.

OBJECTIVES

To understand the association between transplant center volume and recipient risk-adjusted transplant admission cost, in-hospital mortality, and early hospital readmission in lung transplant recipients.

METHODS

Medicare lung transplant recipients from May 4, 2005 to December 31, 2011 were identified through linkage of transplant registry and Medicare administrative claims. Transplant admission cost was extracted, adjusted for regional price variation, and compared across low-, intermediate-, and high-volume centers. A multivariable hierarchical generalized linear regression model was used to assess the effect of transplant center volume on recipient adjusted cost. Modified Poisson regression models were used to assess adjusted in-hospital mortality and early hospital readmission by transplant center volume.

MEASUREMENTS AND MAIN RESULTS

There were 3,128 Medicare lung transplant recipients identified. Unadjusted transplant cost was lower at high-volume centers (mean, $131,352 [SD, ±$106,165]; median, $90,177; interquartile range [IQR], $79,165-$137,915) than at intermediate-volume (mean, $138,792 [SD, ±$106,270]; median, $93,024; IQR, $82,700-$154,857) or low-volume (mean, $143,609 [SD, ±$123,316]; median, $95,234; IQR, $83,052-$152,149) centers (P < 0.0001). After adjusting for recipient health risk, low-volume centers had an 11.66% greater transplant admission cost (P = 0.040), a 41% greater risk for in-hospital mortality (P = 0.015), and a 14% greater risk for early hospital readmission (P = 0.033) compared with high-volume centers. There was no significant difference in transplant cost, in-hospital mortality, or early hospital readmission between intermediate- and high-volume centers.

CONCLUSIONS

Lung transplant admission cost, in-hospital mortality, and early hospital readmission rate are lower at high-volume centers compared with low-volume centers.

Advanced pulmonary arterial hypertension: mechanical support and lung transplantation

The development of targeted therapies has transformed the outlook for patients with pulmonary arterial hypertension (PAH); however, some patients fail to achieve an adequate clinical response despite receiving maximal treatment. For these patients, lung transplantation remains an important therapeutic option, and recommendations for transplantation are included in the current European Society of Cardiology/European Respiratory Society guidelines for the diagnosis and treatment of pulmonary hypertension. Although lung transplantation is not without risk, overall long-term survival rates are good and substantial improvements in quality of life have been reported for lung transplant recipients. In this review, we describe the important considerations prior to, during and after transplantation, including the role of mechanical support, in patients with advanced PAH.

Lung transplantation and mechanical support play key therapeutic roles in patients with advanced PAHhttp://ow.ly/mqfG30gMcMd

High emergency organ allocation rule in lung transplantation: a simulation study

The scarcity of suitable organ donors leads to protracted waiting times and mortality in patients awaiting lung transplantation. This study aims to assess the short- and long-term effects of a high emergency organ allocation policy on the outcome of lung transplantation.

We developed a simulation model of lung transplantation waiting queues under two allocation strategies, based either on waiting time only or on additional criteria to prioritise the sickest patients. The model was informed by data from the United Network for Organ Sharing. We compared the impact of these strategies on waiting time, waiting list mortality and overall survival in various situations of organ scarcity.

The impact of a high emergency allocation strategy depends largely on the organ supply. When organ supply is sufficient (>95 organs per 100 patients), it may prevent a small number of early deaths (1 year survival: 93.7% against 92.4% for waiting time only) without significant impact on waiting times or long-term survival. When the organ/recipient ratio is lower, the benefits in early mortality are larger but are counterbalanced by a dramatic increase of the size of the waiting list. Consequently, we observed a progressive increase of mortality on the waiting list (although still lower than with waiting time only), a deterioration of patients’ condition at transplant and a decrease of post-transplant survival times.

High emergency organ allocation is an effective strategy to reduce mortality on the waiting list, but causes a disruption of the list equilibrium that may have detrimental long-term effects in situations of significant organ scarcity.

High emergency organ allocation is effective to reduce waiting list mortality when organ supply is sufficienthttp://ow.ly/KD1930fPs8I

Racial and ethnic disparities in lung transplant listing and waitlist outcomes

BACKGROUND

The United States lung transplant registry data demonstrate differences in adult waitlist mortality by race/ethnicity. It is unknown whether these differences persist after risk adjustment or occur secondary to disparities in disease severity at the time of listing.

METHODS

Adult lung transplant waitlist candidates between May 4, 2005 and March 5, 2015 were identified and compared by non-Hispanic white (NHW), non-Hispanic black (NHB), Hispanic and Asian race/ethnicity. A competing risk proportional hazards model was used to assess the association of race/ethnicity with the unadjusted and adjusted risk of waitlist death or removal for too sick, transplant, or removal for other reason. Disease illness severity at transplant listing was compared by race/ethnicity.

RESULTS

There were 20,684 lung transplant candidates identified (82% NHW, 9% NHB, 6% Hispanic, 2% Asian and 1% other). Non-white candidates had higher unadjusted waitlist mortality, which was fully mitigated by adjusting for other risk factors (NHB: hazard ratio [HR] 1.05, 95% confidence interval [CI] 0.93 to 1.18; Hispanic: HR 1.02, 95% CI 0.99 to 1.18; Asian: HR 0.90, 95% CI 0.70 to 1.16). Adjusted waitlist access to transplant was lower in non-white candidates (NHB: HR 0.88, 95% CI 0.83 to 0.94; Hispanic: HR 0.87, 95% CI 0.81 to 0.94; Asian: HR 0.83, 95% CI 0.73 to 0.96). NHW candidates with obstructive lung disease and pulmonary fibrosis were older with less illness severity at listing than non-white candidates.

CONCLUSIONS

Within the current lung allocation system, there is no difference in risk-adjusted waitlist mortality by race/ethnicity, but non-white waitlist candidates have lower risk-adjusted access to lung transplant. Non-white candidates are generally younger with greater disease-specific illness severity at the time of lung transplant listing.

Reconstituting Mouse Lungs with Conditionally Reprogrammed Human Bronchial Epithelial Cells

We developed methods for conditionally reprogramming (CR) primary human bronchial epithelial cells (HBECs) to extend their functional lifespan and permit their differentiation into both upper and lower airway lung epithelium. We also developed a bioreactor to support vascular perfusion and rhythmic breathing of decellularized mouse lungs reconstituted with CR HBECs isolated from patients with and without cystic fibrosis (CF). While conditionally reprogrammed cells only differentiate into an upper airway epithelium after 35 days at the air-liquid interface, in reconstituted lungs these cells differentiate into upper airway bronchial epithelium and lower airway alveolar structures after 12 days. Rapid scale-up and the ability to obtain clonal derivatives of primary patient-derived HBECs without the need for genetic manipulation may permit rapid reconstitution of the lung epithelium; facilitating the study of lung disease in tissue-engineered models.

Selection of Patients for Initial Clinical Trials of Solid Organ Xenotransplantation

Several groups have reported extended survival of genetically engineered pig organs in nonhuman primates, varying from almost 10 months for life-supporting kidney grafts and more than 2 years for non-life-supporting heart grafts to less than 1 month for life-supporting liver and lung grafts. We have attempted to define groups of patients who may not have an option to wait for an allograft. These include kidney, heart, and lung candidates who are highly-allosensitized. In addition, some kidney candidates (who have previously lost at least 2 allografts from rapid recurrence of native kidney disease) have a high risk of further recurrence and will not be offered a repeat allotransplant. Patients with complex congenital heart disease, who may have undergone previous palliative surgical procedures, may be unsuitable for ventricular assist device implantation. Patients dying of fulminant hepatic failure, for whom no alternative therapy is available, may be candidates for a pig liver, even if only as a bridge until an allograft becomes available. When the results of pig organ xenotransplantation in nonhuman primates suggest a realistic potential for success of a pilot clinical trial, highly selected patients should be offered participation.

Clinical characteristics of Japanese candidates for lung transplant for interstitial lung disease and risk factors for early death while on the waiting list

BACKGROUND

Lung transplants have produced very favorable outcomes for patients with interstitial lung disease (ILD) in Japan. However, because of the severe donor lung shortage, patients must wait approximately 2.5 years before they can undergo transplantation and many candidates die before allocation. We reveal the clinical characteristics of Japanese patients with ILD who are candidates for lung transplants and the risk factors for early death while on the waiting list.

METHODS

We retrospectively reviewed the clinical data of patients registered in the Japan Organ Transplant Network from Okayama University Hospital who are candidates for cadaveric lung transplants for ILD between 1999 and 2015.

RESULTS

Fifty-three patients with ILD were included (24 patients with idiopathic pulmonary fibrosis and 29 others). They had severe pulmonary dysfunction and low exercise tolerability. The median waiting time for transplantation was 462 days, and 22 patients died before allocation. Patients who died before 462 days without undergoing transplantation had more severe dyspnea, shorter 6-minute walk distance (6MWD), and lower performance status than those who waited ≥462 days.

CONCLUSIONS

Japanese candidates for cadaveric lung transplants for ILD have severe pulmonary dysfunction. Severe dyspnea, short 6MWD, and low performance status are risk factors for early death while on the waiting list.

Clinical implications of donor age: A single-institution analysis spanning 3 decades

BACKGROUND

We sought to clarify the effect of donor age as a continuous variable on morbidity and mortality in a single-institution experience.

METHODS

From 1986 to 2016, 882 adult lung transplants were performed, including 396 in the lung allocation score era. Kaplan-Meier curves and Cox proportional hazards models were used to evaluate the association of donor age with overall survival and bronchiolitis obliterans syndrome (BOS) score ≥1-free survival. Logistic regression was used to evaluate the association with primary graft dysfunction grade 3. Natural cubic splines were used to explore donor age in a continuous fashion to allow for nonlinear relationships.

RESULTS

In the lung allocation score era, unadjusted 5-year survival was not significantly different between 3 a priori-defined donor age groups: age <40, 40 to 54, and age ≥55 years (64%, 61%, and 69%, P = .8). Unadjusted 5-year freedom from BOS ≥1 was not significantly different (34%, 20%, and 33%, respectively, P = .1). After we adjusted for comorbidities, cubic spline analysis demonstrated no effect between donor age as a continuous variable and hazard for mortality at 5 years. Similarly, no interaction was seen between donor age and risk of BOS or primary graft dysfunction 3. Adjusted analysis of all 882 transplants pre- and postinception of the lung allocation score also showed no effect of age on 10-year survival.

CONCLUSIONS

Long-term survival of lung transplant recipients was not affected by the age of the donor. These findings support the notion that donor age could be relaxed.

The Organ Transplant Imperative

More than 120,000 US patients were listed for solid organ transplants in 2016. Although data are scarce, we suspect that many of these patients will die while awaiting transplant and without engaging in goals-of-care discussions with their physicians. The challenges of addressing goals of care in patients with malignancy, end-stage renal disease, and heart failure have been studied. However, there is sparse literature on addressing goals of care throughout the dynamic process of transplant assessment and listing. We propose the concept of an organ transplant imperative, which is the perceived obligation by patients and health care providers to proceed with organ transplant and to avoid advance care planning and triggered goals-of-care discussions, even in situations in which patients' clinical trajectories have worsened, resulting in poor quality of life and low likelihood of meaningful survival. We situate this concept within the paradigms of clinical inertia and the treatment and technological imperatives. We illustrate this concept by describing a patient with end-stage liver disease (ESLD) who was hoping for a liver transplant, who was caught between the conflicting perspectives of specialist and primary care physicians, and who died of complications of ESLD without experiencing the benefits of advance care planning. Greater awareness of the transplant imperative should generate a shared understanding among specialists, generalists, and patients and will provide opportunities for more formalized involvement of palliative medicine experts in the care of transplant patients.