Donor Lungs For Transplantation Research Articles

Long-Term Persisting Donor-Derived Human Leukocyte Antigen Antibody as a Possible Passenger Lymphocyte Syndrome Following Lung Transplantation: A Case Report

Herein, we reported the transfer of donor-derived antihuman leukocyte antigen (HLA) antibodies in 2 recipients after lung transplantation. Case 1: A 39-year-old woman with pleuroparenchymal fibroelastosis underwent a single brain-dead donor lung transplantation. Antibody screening 36 days after transplantation demonstrated high levels of de novo nondonor HLA class I-specific antibodies. The antibody screening in the donor serum revealed that the donor demonstrated a largely overlapping antibody profile. Importantly, the donor serum also included high-level HLA-specific antibodies against the recipient HLA-specific antigens, which were not detected in the recipient sera after transplantation. Donor-derived anti-HLA antibodies were still detected in the recipient 39 months after transplantation, without causing any complications such as graft-vs-host disease. Case 2: A 47-year-old woman underwent living-donor lobar lung transplantation for pulmonary complications after bone marrow transplantation with a right lower lobe from her husband and the left lower lobe from her sister. On postoperative day 39, the recipient's anti-HLA-class I antibody profile was found to be similar to that of the highly sensitized left lung donor. These donor-derived anti-HLA antibodies remained to be produced in the recipient 66 months after transplantation, without the development of complications.

Donor and Recipient Adipose-Derived Mesenchymal Stem Cell Therapy for Rat Lung Transplantation

Mesenchymal stem cells (MSCs) are beginning to be proven as immunosuppressant in the field of organ transplantation. However, the effects of MSC origin (donor or recipient) on immunosuppression are not clear. Hence, we investigated the effects of recipient and donor adipose-derived MSCs (ADMSCs) on immunosuppression in a rat lung transplantation model. Subjects were divided into no treatment, tacrolimus administration, recipient ADMSC administration, donor ADMSC administration, and mixed donor and recipient ADMSC administration groups. ADMSC-administered groups were also treated with tacrolimus. Histologic study, immunofluorescence, immunohistochemistry, enzyme-linked immunosorbent assay, and polymerase chain reaction were used for various analyses. Fluorescently labeled ADMSCs were predominant in the grafted donor lung, but not in the recipient lung, on day 5. On day 7, the pathologic rejection grades of the grafted donor lung were significantly lower in the ADMSC-administered groups (P < .05) and did not differ among these groups. Although serum hepatocyte growth factor and vascular endothelial growth factor levels did not differ among the groups, interleukin 10 level was slightly higher in the ADMSC-administered groups. The numbers of infiltrating regulatory T cells in the grafted lung were significantly higher in the ADMSC-administered groups (P < .05) but did not differ with cell origin. Transcriptional analysis suggested interleukin 6 suppression to be the main overlapping immunosuppressive mechanism, regardless of origin. Therefore, a donor or recipient origin may not influence the immunosuppressive efficacy of ADMSCs in our rat lung transplantation model. Collectively, the results indicate that allogenic ADMSCs, regardless of their origin, may exert similar immunosuppressive effects in clinical organ transplantation.

Hyperammonemia syndrome in immunosuppressed individuals.

Hyperammonemia syndrome is an increasingly recognized and often fatal condition that occurs in immunosuppressed individuals, most commonly lung transplant recipients. Growing evidence suggests hyperammonemia syndrome is associated with systemic infections caused by urease-producing organisms, namely Ureaplasma spp., an organism unable to grow with routine culturing techniques. This review will summarize the epidemiology and clinical manifestations of hyperammonemia syndrome, as well as diagnostic and management strategies once hyperammonemia syndrome is suspected. Hyperammonemia syndrome is being described in increasing frequency in the solid organ transplant population. Morbidity and mortality, even with treatment, is high once hyperammonemia syndrome occurs. Surveillance studies indicate the prevalence of lung donor colonization with Ureaplasma spp. is high, suggesting screening and treatment may be of benefit. Antibiotic resistance is common, and rapid diagnostics can facilitate appropriate antimicrobial therapy in the peri-transplant period. Hyperammonemia syndrome is most commonly seen in lung transplant recipients and has a high mortality rate once it occurs. Screening for Ureaplasma spp. should be considered in all lung transplant donors.

Clinical significance of donor lung weight at procurement and during ex vivo lung perfusion.

Elevated donor lung weight may adversely affect donor lung transplant suitability and post-transplant outcomes. The objective of this study is to investigate the impact of lung weight after procurement and ex vivo lung perfusion (EVLP) on transplant suitability, post-transplant graft dysfunction, and clinical outcomes and define the donor lung weight range most relevant to clinical outcomes. From February 2016 to August 2020, 365 human lung donors to a single transplant center were retrospectively reviewed. 239 were transplanted without EVLP, 74 treated with EVLP (50 went on to transplant), and 52 declined for transplant without EVLP consideration. Donor lung weights were measured immediately after procurement and, when performed, after EVLP. Lung weights were adjusted by donor height and divided into 4 quartiles. Donor lungs in the highest weight quartile at donor hospital had a significantly lower transplant suitability rate after EVLP, higher rates of primary graft dysfunction grade 3 at 72 hours, and longer intensive care unit/hospital stay. For lungs treated with lung perfusion, the highest lung weight quartile at the end of lung perfusion was associated with a significantly lower transplant suitability rate, higher incidence of primary graft dysfunction grade 3 at 72 hours, and longer intensive care unit/hospital stay, compared to the other categories. Donor lung weight stratified by quartile categories can assist decision-making regarding need for EVLP at the donor hospital as well as during EVLP evaluation. Caution should be used when considering donor lungs in the highest weight quartile for transplantation.

Impact of ex vivo lung perfusion on brain-dead donor lung utilization: The French experience

Ex vivo lung perfusion (EVLP) is a valuable method for expanding the lung donor pool. Its indications currently differ across centers. This national retrospective cohort study aimed to describe the profile of donors with lungs transplanted after EVLP and determine the effectiveness of EVLP on lung utilization. We included brain-dead donors with at least one lung offered between 2012 and 2019 in France. Lungs transplanted without or after EVLP were compared with those that were rejected. Donor group phenotypes were determined with multiple correspondence analysis (MCA). The association between donor factors and lung transplantation was assessed with a multivariable multinomial logistic regression. MCA revealed that donors whose lungs were transplanted after EVLP had profiles similar to the donors whose lungs were declined and quite different from those of donors with lungs transplanted without EVLP. Donor predictors of graft nonuse included age ≥50years, smoking history, PaO2 /FiO2 ratio ≤300mmHg, abnormal chest imaging, and purulent secretions. EVLP increased utilization of lungs from donors with a smoking history, PaO2 /FiO2 ratio ≤300mmHg, and abnormal chest imaging.

Emerging Paradigms in Bioengineering the Lungs.

In end-stage lung diseases, the shortage of donor lungs for transplantation and long waiting lists are the main culprits in the significantly increasing number of patient deaths. New strategies to curb this issue are being developed with the help of recent advancements in bioengineering technology, with the generation of lung scaffolds as a steppingstone. There are various types of lung scaffolds, namely, acellular scaffolds that are developed via decellularization and recellularization techniques, artificial scaffolds that are synthesized using synthetic, biodegradable, and low immunogenic materials, and hybrid scaffolds which combine the advantageous properties of materials in the development of a desirable lung scaffold. There have also been advances in the design of bioreactors in terms of providing an optimal regenerative environment for the maturation of functional lung tissue over time. In this review, the emerging paradigms in the field of lung tissue bioengineering will be discussed.

Thoracic mediastinal-occupying ratio predicts recovery and prognosis after lung transplantation.

OBJECTIVESEven after transplantation of favourable donor lungs, some recipients require prolonged weaning from mechanical ventilation, indicating a poor prognosis. We investigated the effects of prolonged mechanical ventilation (PMV) for >14 days on the recovery and survival of patients who underwent cadaveric lung transplantation in relation to their physical traits.METHODSWe retrospectively reviewed patients who underwent cadaveric lung transplantation (age ≥15 years) at a single centre between April 2015 and December 2020 and classified them into PMV and non-PMV groups (>14 and ≤14 days of mechanical ventilation postoperatively, respectively). The factors predicting PMV comprised clinical factors (e.g. marginal donor) and physical features, namely flat chest, narrow fourth intercostal space (length, <5 mm), mediastinal shift, thoracic mediastinal-occupying ratio (TMOR) >40% and sarcopenia, according to the logistic regression analysis. The log-rank test was used to examine the association between TMOR >40% and 3-year prognosis.RESULTSThe PMV group comprised 17 (33%) of 51 recipients. Multivariable logistic analysis showed that the TMOR >40% (odds ratio, 7.3; 95% confidence interval, 1.3–40.1; P = 0.023) was an independent preoperative predictive factor for PMV postoperatively. Stepwise analysis revealed intraoperative extracorporeal membrane oxygenation and reoperation as postoperative predictive factors in addition to TMOR >40%. Recipients with TMOR >40% had significantly worse 3-year survival than other recipients (71.2% vs 100.0%, respectively; P = 0.008).CONCLUSIONSRecipients with a TMOR >40% may be long-term ventilator dependent and have a poor prognosis.

Standardized Radiographic Evaluation of Human Donor Lungs During Ex Vivo Lung Perfusion Predicts Lung Injury and Lung Transplant Outcomes

<h3>Purpose</h3> Ex vivo lung perfusion (EVLP) is increasingly used to evaluate marginal donor lungs for transplantation. A commonly used component of donor lung assessment during EVLP is a lung radiograph taken after 1h and 3h of perfusion. The purpose of our study was to systematically evaluate EVLP radiographic findings and define their association with observed lung injury and EVLP outcomes. <h3>Methods</h3> We retrospectively evaluated all EVLP cases from 2020-21 (n=113). Radiographs were scored by a thoracic radiologist blinded to donor lung outcome. Each ex vivo lung lobe was scored for five radiographic features (consolidation, infiltrates, atelectasis, nodules, and interstitial lines) on a scale of 0 to 3 by severity for a maximum radiographic lung score (RLS) of 18 per feature. The RLS was correlated with markers of lung injury (PaO₂/FiO₂ and edema) using Spearman's correlation. Logistic regression was used to generate receiver operating curves to derive the performance of RLS in predicting transplantation outcome following EVLP. <h3>Results</h3> Consolidation and infiltrates after 1h of EVLP were the most frequent findings (RLS 2.5±3.4 and 4.4±4.3). Interstitial lines were less frequent (RLS 1.76±3.53), with nodules and atelectasis being uncommon (RLS 0.60±1.30 and 0.41±0.65). At the first and third hours of perfusion, consolidation (r=-0.536 and -0.608, p<0.0001) and infiltrates (r=-0.492 and -0.616, p<0.0001) were inversely correlated with oxygenation (PaO₂/FiO₂), whereas interstitial lines were correlated with increased perfusate loss in the circuit reflecting increased edema (r=0.244, p=0.019, and r=0.309, p=0.0047). First-hour consolidation, infiltrates, atelectasis, nodules, and interstitial line RLS predicted the decision to transplant the lungs with area under the curve of 87%, 88%, 52%, 58%, and 56%, respectively. First- and third-hour RLS from all five features predicted the decision to transplant with an area under the curve of 90% and 88%, respectively, and when combined, the value increased to 92%. <h3>Conclusion</h3> Consolidation and infiltrates were the most frequent findings in lungs undergoing ex vivo lung perfusion. The Radiographic Lung Score (RLS) predicted the suitability of donor lungs for transplant. Radiographic ex vivo lung images provide key information for the clinical evaluation of donor lungs for transplantation.

Lung Transplantation from Donors with a History of Substance Use

<h3>Purpose</h3> Substance use is common among lung transplant donors, but the implications have not been well studied aside from donor smoking. Stimulant drugs such as cocaine and methamphetamine can induce pulmonary arterial hypertension while smoked products such as cannabis and crack cocaine can produce airways and parenchymal lung diseases. We sought to characterize donor substance use at our center and evaluate the associations with overall survival as well as post-transplant graft function. <h3>Methods</h3> We studied all double lung transplants in our program between 2004-2016. We reviewed donor substance use histories for the following: heavy smoking, heavy drinking, regular cannabis smoking, ecstasy, benzodiazepines, cocaine, crack cocaine, methamphetamine, crystal methamphetamine, and opiates. We used proportional hazards modelling to evaluate the association between each drug and overall survival as well as chronic lung allograft dysfunction (CLAD) development. We used Fisher's Exact test to evaluate the association between drug use and grade 3 primary graft dysfunction (PGD3) in addition to baseline lung allograft dysfunction (BLAD), defined as failure to achieve both FEV1 and FVC ≥80% predicted on 2 consecutive tests ≥3 weeks apart. <h3>Results</h3> Of 473 recipients studied, 186 (39%) received lungs from a donor with a history of drug use in at least one of the 9 categories defined previously. Donor heavy smoking (n=65) was associated with lower overall survival (hazard ratio [HR]: 1.47; 95% confidence interval [CI]: 1.03-2.10; p=0.032) and an increased risk of PGD3 (odds ratio [OR]: 2.13; 95% CI: 1.15-3.84; p=0.014) and BLAD (OR: 2.56; 95% CI: 1.47-4.53; p<0.001). Donor crack cocaine use (n=24) was also associated with impaired overall survival both unadjusted (HR: 2.02; 95% CI: 1.15-3.55; p=0.015) and adjusted for donor heavy smoking (HR: 1.99; 95% CI: 1.13-3.50; p=0.017). No other history of donor substance use was associated with post-transplant survival, CLAD, PGD3, or BLAD. <h3>Conclusion</h3> History of substance use was common in our cohort of lung donors. Donor crack cocaine use in addition to donor heavy smoking were associated with impaired post-transplant survival while donor use of other substances does not appear to affect survival and lung function outcomes post-transplant.

Evaluating the Use of CT-Derived Lung Volumes in Donor-Recipient Lung Size Matching for Lung Transplantation

<h3>Purpose</h3> Practices for donor and recipient size matching for lung transplantation vary. The objective of this study was to assess the accuracy of CT-derived lung volumes to predict donor-recipient lung size match for bilateral lung transplantation. <h3>Methods</h3> We studied 62 patients who underwent bilateral lung transplantation for Interstitial Lung Disease/Idiopathic Pulmonary Fibrosis during 2018-2019. Recipient data was retrieved from medical records and our transplant database. Donor data was obtained from UNOS DonorNet. Data collected included demographic data, lung heights, estimated donor total lung capacity (TLC) and recipient measured TLC from plethysmography; Computed Tomography (CT) derived lung volumes both pre- and post-transplant in recipients and clinical data. The recipient post-transplant CT-derived lung volume was used as a surrogate for donor lung CT volumes due to unavailable or poor donor data. Techniques included thresholding, region growing and cutting using Computer-Aided Design. Preoperative CT-derived lung volumes in recipients were compared with the plethysmography TLC, Frustum Model, and donor estimated TLC. We studied the ratio of recipient's pre- and post-operative CT-derived volumes, and the ratio of preoperative CT-derived lung volume and donor estimated TLC and correlated with one-year outcomes. <h3>Results</h3> The recipient preoperative CT-derived volume correlated with the recipient preoperative plethysmography TLC (Pearson correlation coefficient (PCC) of 0.688, p-value of 1.75e-07) and with the recipient Frustum model volume (PCC of 0.593, p-value of 2.766e-07). The recipient postoperative CT-derived volume correlated with the recipient postoperative plethysmography TLC (PCC of 0.651, p-value of 9.424e-06). There was no statistical correlation between recipient CT-derived preoperative or postoperative volume with donor estimated TLC. The ratio of preoperative CT-derived volume to donor estimated TLC correlated inversely with length of ventilation (p value: 0.0031). Lung oversizing (post- to preoperative CT lung volume ratio of over 1.2) did not affect outcomes. <h3>Conclusion</h3> CT-derived lung volume is a valid and convenient method for evaluating lung sizing for transplants. Donor estimated TLC should be interpreted cautiously. Matching donor and recipient CT lung volumes will be the scope of further research.

The Combination of Post-Mortem Sevoflurane Ventilation and In Situ Topical Cooling Provides Improved 6h Lung Preservation in an Uncontrolled DCD Porcine Model

Purpose Recent clinical series on donation after uncontrolled cardiac death (uDCD) reported successful transplantation of lungs preserved by pulmonary inflation up to 3h post-mortem. This study aims to investigate the additive effects of in situ lowering of intrathoracic temperature and sevoflurane preconditioning on lung grafts in a porcine uDCD model. Methods After uDCD induction, donor pigs were allocated to one of the following groups: (1) static lung inflation only (SLI); (2) SLI + continuous intrapleural topical cooling (TC); or (3) sevoflurane preconditioning (30 min) + SLI + TC. Six hours post-asystole, lungs were retrieved and evaluated via ex vivo lung perfusion (EVLP) for 6 hours. The group with best performance on EVLP was then evaluated by transplantation in the 2nd phase of the study. Grafts were reperfused for 4h, followed by right pulmonary hilar clamping to evaluate graft oxygenation and ventilatory mechanics. Results A target intrathoracic temperature < 15°C was achieved within 1 hour of chest filling in groups 2 and 3. All lungs in group 1 failed - i.e., met EVLP termination criteria in 1h (Fig.1A). At 1h lungs from group 3 presented lower PVR, lower airway pressures, higher compliances and a higher P/F ratio compared to group 1 (Fig.1B). Despite similar early performance of groups 2 and 3, group 3 showed lower airway pressures and higher pulmonary compliances at the final hour (Fig.1C). Post-EVLP lung weight (edema) was higher in group 1 compared to groups 2 and 3 (Fig.1B). Post-transplant graft assessment in group 3 showed good oxygenation throughout the post-reperfusion observation period (Fig.1D). Conclusion Preservation of uDCD lungs with sevoflurane + static lung inflation + topical cooling maintains good pulmonary function up to 6h post-mortem with excellent early post-lung transplant function. These interventions could potentially help expand the clinical utilization of uDCD donor lungs for transplantation. Recent clinical series on donation after uncontrolled cardiac death (uDCD) reported successful transplantation of lungs preserved by pulmonary inflation up to 3h post-mortem. This study aims to investigate the additive effects of in situ lowering of intrathoracic temperature and sevoflurane preconditioning on lung grafts in a porcine uDCD model. After uDCD induction, donor pigs were allocated to one of the following groups: (1) static lung inflation only (SLI); (2) SLI + continuous intrapleural topical cooling (TC); or (3) sevoflurane preconditioning (30 min) + SLI + TC. Six hours post-asystole, lungs were retrieved and evaluated via ex vivo lung perfusion (EVLP) for 6 hours. The group with best performance on EVLP was then evaluated by transplantation in the 2nd phase of the study. Grafts were reperfused for 4h, followed by right pulmonary hilar clamping to evaluate graft oxygenation and ventilatory mechanics. A target intrathoracic temperature < 15°C was achieved within 1 hour of chest filling in groups 2 and 3. All lungs in group 1 failed - i.e., met EVLP termination criteria in 1h (Fig.1A). At 1h lungs from group 3 presented lower PVR, lower airway pressures, higher compliances and a higher P/F ratio compared to group 1 (Fig.1B). Despite similar early performance of groups 2 and 3, group 3 showed lower airway pressures and higher pulmonary compliances at the final hour (Fig.1C). Post-EVLP lung weight (edema) was higher in group 1 compared to groups 2 and 3 (Fig.1B). Post-transplant graft assessment in group 3 showed good oxygenation throughout the post-reperfusion observation period (Fig.1D). Preservation of uDCD lungs with sevoflurane + static lung inflation + topical cooling maintains good pulmonary function up to 6h post-mortem with excellent early post-lung transplant function. These interventions could potentially help expand the clinical utilization of uDCD donor lungs for transplantation.

Comparing the Paragonix LUNGguard Donor Lung Preservation System to Traditional Ice Storage

Purpose For decades, static cold storage (SCS) has been the standard for preserving donor lungs for transplant (LTx). However, questions and concerns have been raised regarding organ temperature on ice. A new preservation system (Paragonix LUNGguard; LG) was developed to maintain consistent temperatures between 4-8°C. Here, we compare short-term outcomes of recipients using LG for human LTx at a single, high-volume center to a matched SCS control group. Methods Perioperative outcomes for patients who received lungs stored via LG at our institution were collected and matched 1:2 to a contemporary cohort of patients who received lungs stored with SCS. Patients were matched based on age at LTx, lung allocation score, disease group, ischemic time, previous LTx, and pre-operative ECMO. Descriptive statistics compared perioperative outcomes between LG and SCS groups. Results 18 LG and 36 matched SCS recipients were included. Age (LG vs SCS: 61.5 vs 62.0 years, p = 0.65), lung allocation score (41.9 vs 43.6, p = 0.73), and proportion of restrictive lung disease (14, 77.8% vs 28, 77.8%, p = 1.00) were similar for recipients between cohorts. Donor age (32.0 vs 34.0 years, p = 0.67), PaO2/FiO2 ratio (423 vs 475, p = 0.24), and proportion of donation after circulatory death (3, 16.7% vs 7, 19.4%, p = 1.00) were also similar between cohorts. Median ischemic time did not differ significantly between cohorts (394 vs 395 minutes, p = 0.84). With the LG device, the median of the average allograft storage temperatures was 4.7°C (range: -0.4 - 6.1°C). During the index transplant hospitalization, LG and SCS recipients had similar rates of acute rejection (3, 16.7% vs 1, 2.8%, p = 0.10). Rates of any grade 3 primary graft dysfunction (PGD3) within 72 hours post-transplant (7, 38.9% vs 14, 38.9%, p = 1.00), PGD3 at 48 or 72 hours (3, 16.7% vs 7, 19.4%, p = 1.00), postoperative ECMO (4, 22.2% vs 6, 16.7%, p = 0.72), hospital length of stay (30.0 vs 29.0 days, p = 0.81), and 90-day mortality (1, 2.8% vs 1, 5.6%, p = 1.00) were similar between cohorts. Conclusion Compared to traditional cold storage, the LG storage system appears to be an effective alternative for lung preservation, with similar short-term perioperative outcomes after LTx. For decades, static cold storage (SCS) has been the standard for preserving donor lungs for transplant (LTx). However, questions and concerns have been raised regarding organ temperature on ice. A new preservation system (Paragonix LUNGguard; LG) was developed to maintain consistent temperatures between 4-8°C. Here, we compare short-term outcomes of recipients using LG for human LTx at a single, high-volume center to a matched SCS control group. Perioperative outcomes for patients who received lungs stored via LG at our institution were collected and matched 1:2 to a contemporary cohort of patients who received lungs stored with SCS. Patients were matched based on age at LTx, lung allocation score, disease group, ischemic time, previous LTx, and pre-operative ECMO. Descriptive statistics compared perioperative outcomes between LG and SCS groups. 18 LG and 36 matched SCS recipients were included. Age (LG vs SCS: 61.5 vs 62.0 years, p = 0.65), lung allocation score (41.9 vs 43.6, p = 0.73), and proportion of restrictive lung disease (14, 77.8% vs 28, 77.8%, p = 1.00) were similar for recipients between cohorts. Donor age (32.0 vs 34.0 years, p = 0.67), PaO2/FiO2 ratio (423 vs 475, p = 0.24), and proportion of donation after circulatory death (3, 16.7% vs 7, 19.4%, p = 1.00) were also similar between cohorts. Median ischemic time did not differ significantly between cohorts (394 vs 395 minutes, p = 0.84). With the LG device, the median of the average allograft storage temperatures was 4.7°C (range: -0.4 - 6.1°C). During the index transplant hospitalization, LG and SCS recipients had similar rates of acute rejection (3, 16.7% vs 1, 2.8%, p = 0.10). Rates of any grade 3 primary graft dysfunction (PGD3) within 72 hours post-transplant (7, 38.9% vs 14, 38.9%, p = 1.00), PGD3 at 48 or 72 hours (3, 16.7% vs 7, 19.4%, p = 1.00), postoperative ECMO (4, 22.2% vs 6, 16.7%, p = 0.72), hospital length of stay (30.0 vs 29.0 days, p = 0.81), and 90-day mortality (1, 2.8% vs 1, 5.6%, p = 1.00) were similar between cohorts. Compared to traditional cold storage, the LG storage system appears to be an effective alternative for lung preservation, with similar short-term perioperative outcomes after LTx.

Donor Airway Bile Acid as a Biomarker of Aspiration and Predictor of Post Lung Transplant Outcomes

<h3>Purpose</h3> Emesis and aspiration contribute to donor lung damage and may promote allograft dysfunction. Currently, there is no clinical tool to detect occult aspiration and objectively assess its severity in donor lungs. A previous study by our group identified that aspirated total bile acids (TBA) in donor bronchial wash (BW) was associated with acceptability of donor lungs for transplant. Herein, we seek to validate this finding in a large retrospective cohort and assess the association between donor TBA and recipient outcomes. <h3>Methods</h3> TBA was measured in available BW samples of 605 consecutive lung donors from 2012 to 2018. 90% specificity threshold was used to derive a TBA cut-off that identified donor lungs unsuitable for transplant. We further assessed associations between BW TBA concentrations and performance of donor lungs undergoing ex vivo lung perfusion (EVLP), as well as post-transplant recipient outcomes. <h3>Results</h3> Donor TBA was higher in lungs deemed unsuitable for transplant compared to those suitable for direct transplant and those requiring further assessment on EVLP (Figure A; Mann-Whitney U test). In lungs assessed on EVLP, higher TBA concentration in donor BW correlated with lower pH, higher lactate levels, and higher pro-inflammatory cytokines in EVLP perfusate. In lungs not assessed on EVLP, TBA cut-off of 1245nM was able to differentiate donor lungs suitable for transplantation vs declined with 90% specificity. Based on this cut-off, high donor TBA was associated with worse post-transplant recipient outcomes: longer time to extubation (p<0.001) (Figure B; log-rank test) and shorter time to chronic lung allograft dysfunction (p=0.01). <h3>Conclusion</h3> In a large retrospective cohort we observed that high TBA in donor bronchial wash was associated with suitability of donor lungs for transplant, performance on EVLP, and adverse recipient outcomes. TBA measurement may be useful to triage donor lungs for further assessment on EVLP and potential pre-transplant therapeutic interventions.

Long-Term Results of the OCS Lung Expand International Trial Using Organ Care System Lung Perfusion System (OCS) in Extended-Criteria Donor (ECD) and Donation After Circulatory Death (DCD) Donor Lungs

Purpose To evaluate short and long-term clinical outcomes after lung transplantation of ECD and DCD lungs that were preserved, recruited and assessed using the OCS Lung System. Methods OCS Lung EXPAND targeted double lungs donors with one or more risk factors: age ≥55, PaO2/FiO2 (PF) ≤ 300 mmHg, expected ischemic time > 6 hours, or DCD donors. Lungs were perfused and ventilated on OCS from procurement until time of transplantation. Lungs were transplanted after OCS perfusion if: PF > 300mmHg, vascular resistance, pulmonary artery pressures or peak airway pressures were within 20% of starting values. Patients were followed for 4 years post-transplant and assessed for incidence of BOS and survival. To benchmark the outcomes, we assessed the relative risk for the development of BOS grade 3 between the EXPAND patients and patients in the control arm of the INSPIRE trial who were transplanted with standard-criteria donor (SCD) lungs using ice preservation without OCS perfusion (N=184). Results 79 out of 91 eligible donor lungs were transplanted in the EXPAND Trial for a utilization rate of 87%. Donor inclusion risk factors for the transplanted patients were as follows: 39% age ≥55, 33% DCD, 32% expected ischemic time > 6 hours, 25% PF ≤ 300 mmHg, and 27% with multiple categories. The incidence of BOS Grade 3 is summarized in the table below. Overall graft survival at 4 years was 87.6% for EXPAND vs. 84.9% for the INSPIRE Control cohort. Patient survival at 4 years was 72.0% for EXPAND vs. 71.9% for the INSPIRE Control cohort. Conclusion OCS Lung resulted in a high utilization rate for ECD and DCD donor lungs for transplantation with similar or better long-term post-transplant clinical outcomes compared to SCD lung transplants preserved on ice. These results provide strong clinical evidence supporting the use of the OCS Lung System in extended-criteria donor lungs to increase donor lung utilization for transplantation. To evaluate short and long-term clinical outcomes after lung transplantation of ECD and DCD lungs that were preserved, recruited and assessed using the OCS Lung System. OCS Lung EXPAND targeted double lungs donors with one or more risk factors: age ≥55, PaO2/FiO2 (PF) ≤ 300 mmHg, expected ischemic time > 6 hours, or DCD donors. Lungs were perfused and ventilated on OCS from procurement until time of transplantation. Lungs were transplanted after OCS perfusion if: PF > 300mmHg, vascular resistance, pulmonary artery pressures or peak airway pressures were within 20% of starting values. Patients were followed for 4 years post-transplant and assessed for incidence of BOS and survival. To benchmark the outcomes, we assessed the relative risk for the development of BOS grade 3 between the EXPAND patients and patients in the control arm of the INSPIRE trial who were transplanted with standard-criteria donor (SCD) lungs using ice preservation without OCS perfusion (N=184). 79 out of 91 eligible donor lungs were transplanted in the EXPAND Trial for a utilization rate of 87%. Donor inclusion risk factors for the transplanted patients were as follows: 39% age ≥55, 33% DCD, 32% expected ischemic time > 6 hours, 25% PF ≤ 300 mmHg, and 27% with multiple categories. The incidence of BOS Grade 3 is summarized in the table below. Overall graft survival at 4 years was 87.6% for EXPAND vs. 84.9% for the INSPIRE Control cohort. Patient survival at 4 years was 72.0% for EXPAND vs. 71.9% for the INSPIRE Control cohort. OCS Lung resulted in a high utilization rate for ECD and DCD donor lungs for transplantation with similar or better long-term post-transplant clinical outcomes compared to SCD lung transplants preserved on ice. These results provide strong clinical evidence supporting the use of the OCS Lung System in extended-criteria donor lungs to increase donor lung utilization for transplantation.

Derepression of the IL-10 Gene by CRISPR-Cas Genome Editing as a Therapeutic Strategy for Persistent Immunomodulation of Donor Lungs for Transplantation

<h3>Purpose</h3> Anti-rejection immunosuppression is a persistent challenge in lung transplantation. We envisioned creating less immunogenic donor organs to obviate or reduce the need for immunosuppression. To induce persistent expression of the immunomodulatory cytokine IL-10, we aimed to harness CRISPR-Cas-mediated genome editing. We hypothesized that mutating the regulatory region of the IL-10 could induce persistent IL-10 upregulation with practicality in organ modification. To prove our concept, we investigate the efficacy and persistence of this approach in vitro. <h3>Methods</h3> Plasmids encoding Streptococcus pyogenes Cas9 (SpCas9), a puromycin cassette, and a single guide RNA (gRNA), designed to bind the promoter of the rat IL-10 gene, were delivered into a rat lung epithelial cell line. Transfected cells were enriched using puromycin and assessed for mutations and gene expressions after 14 and 28 days. The treatment group (targeting gRNA group) was compared to a no gRNA group and a non-targeting gRNA group. <h3>Results</h3> Insertions/deletions at the target site were detected in 77±20 % of alleles at day 14 and 87±11% at day 28 in the treatment group (Fig. 1A). The treatment group showed enhanced rat IL-10 expression while other groups showed mostly undetectable IL-10 expression (457±338- and 865+573- fold increase compared to negative control at day 14 and 28 respectively, Fig.1B). Importantly, IL-10 upregulation lasted for 28 days despite a decline in SpCas9 expression (Fig. 1C) suggesting an effective and persistent expression after one round of genome editing. <h3>Conclusion</h3> We have demonstrated that CRISPR-Cas9-mediated genome editing at the promoter region induces stable IL-10 expression. Targeted editing outside of the coding region potentially leads to a safer application of whole organ gene editing. Our findings expand the potential of genome editing towards engineering optimized donor organs for transplantation.

HCV-Viremic Lung Transplantation Does Not Confer Higher Rejection Rates Compared to HCV-Negative Transplant

<h3>Purpose</h3> There is increasing utilization of hepatitis C virus (HCV)-infected organ donors for lung transplantation. Non-infectious outcomes are not clearly investigated in the literature. We aimed to assess acute and/or chronic rejection rates at one year following lung transplantation from HCV-infected donors. <h3>Methods</h3> After obtaining IRB approval, we retrospectively reviewed electronic medical records of patients that underwent lung transplant from 4/1/2017-10/1/2020 at our institution. Following data were abstracted - demographics, transplant details including surgery and immunosuppression, HCV management, outcomes including acute and chronic rejection as defined by ISHLT, and mortality. <h3>Results</h3> Among 76 patients transplanted during the study period, 15 received HCV-viremic allografts and 61 were from HCV-negative donors; details are noted in Table 1. Standard immunosuppression consisted of basiliximab induction followed by maintenance with tacrolimus, prednisone, and mycophenolate mofetil. We found no difference in the rate of acute or chronic rejection between the two groups. All 15 patients receiving HCV-viremic organs were treated with 12 weeks of DAA started at a median of 20 days (range 11-30) from surgery. The most prevalent genotype was 1/1a/1b (13/15, 84%). Most patients were treated with glecaprevir/pibrentasvir (12/15, 80%). All patients achieved sustained virological response at 12 weeks, indicative of a cure. There were no cases of HCV-related serious adverse events including fulminant hepatitis or death. Median lung allocation score at time of HCV+ transplant was 41 (IQR 34.6-62.6). <h3>Conclusion</h3> We report successful single-center experience using HCV-viremic organs for lung transplant with low rates of allograft rejection between the 2 groups though a small data set is a limitation. As experience using such organs for transplant continues to increase, longer term follow-up and multicenter data is needed.

Pulmonary Dead Space Fraction: A Predictive Factor for Transplant Suitability in Clinical Ex Vivo Lung Perfusion

<h3>Purpose</h3> Dead space fraction (DSF) correlates with disease severity in cases of pulmonary embolism (PE) and lung injury, and with mortality in acute respiratory distress syndrome. We sought to determine the relationship between DSF and donor lung transplant suitability during clinical ex vivo lung perfusion (EVLP). <h3>Methods</h3> DSF was calculated in 80 consecutive double lung cases undergoing acellular EVLP from 6/2019 to 8/2021 in our department. 53 cases were judged suitable for transplant. End-tidal CO₂ and CO₂ levels in perfusate were measured, and DSF stratified into quartiles (Q1, lowest; Q4, highest). DSF was calculated using the following formula: (PCO₂ in left atrium - End tidal CO₂) / PCO₂ in left atrium. <h3>Results</h3> Tobacco use history correlated with significantly higher DSF (vs. no tobacco use history, (<i>p</i> < 0.05). Presence of PE also correlated with higher DSF (<i>p</i> < 0.05). Lungs in the highest DSF quartile (Q4) displayed significantly higher peak airway pressure, lower PaO₂/FiO₂, and lower dynamic compliance during EVLP (<i>p</i> < 0.01, each; <b>Figure A-D</b>). The Q4 DSF group also had higher lung weight following EVLP (<i>p</i> < 0.05). Transplant suitability decreased with higher DSF; 85% (17/20 cases) of Q1, 85% (17/20 cases) of Q2, 60% (12/20 cases) of Q3, and 35% (7/20 cases) of Q4 (<i>p</i> < 0.01, <b>Figure E</b>) lungs were suitable for transplant. Of the 53 EVLP cases transplanted, 30-day recipient survival was 98% and the incidence of Grades 0, 1, 2, and 3 primary graft dysfunction at 72 hours was 19%, 57%, 13%, and 6%, respectively with 3 ungradable cases. <h3>Conclusion</h3> In human lungs undergoing acellular EVLP, higher DSF correlates with decreased transplant suitability. Further studies are needed to establish mechanisms by which high DSF contributes to lower transplant suitability.

Outcome After Lung Transplantation From a Donor With Bacterial Pneumonia Under the Japanese Donor Evaluation System

In Japan, a unique medical consultant system for donor evaluation and management has been developed in an effort to maximize the use of extended criteria donor lungs. The aim of this study was to investigate the impact of donor pneumonia (DP) on the outcome after lung transplantation under this system. Clinical data of 85 patients who underwent deceased donor lung transplantation (41 single and 44 bilateral lung transplants) between August 2012 and March 2018 were reviewed. DP was defined as the recognition of pneumonia on imaging with positive bacterial culture in the airway at the time of transplantation. Twenty-three transplanted lung grafts were recognized as having DP (27.1%). Serial chest x-rays at the donor hospital did not show deteriorating infiltration or consolidation. The PaO2/FiO2 ratio at brain death evaluations were similar between the donor pneumonia (DP) negative (-) and donor pneumonia (DP) positive (+) groups. Perioperative antibiotics were effective against 94% of isolated bacteria. The duration of postoperative antibiotics therapy was longer in the DP (+) group (P=.02). The incidence of primary graft dysfunction and acute rejection, intensive care unit stay, chronic lung allograft dysfunction-free survival, and overall survival were similar between the DP (+) and DP (-) groups. Transplantation of donor lung grafts harboring pneumonia but having a similar oxygenation level to those without pneumonia was safely performed and did not affect long-term outcome. Appropriate evaluation of serial imaging at donor hospital and suitable perioperative antibiotic management may be reasons for this outcome.

Left Lung Orthotopic Transplantation in a Juvenile Porcine Model for ESLP

Lung transplantation is the gold-standard treatment for end-stage lung disease, with over 4,600 lung transplantations performed worldwide annually. However, lung transplantation is limited by a shortage of available donor organs. As such, there is high waitlist mortality. Ex situ lung perfusion (ESLP) has increased donor lung utilization rates in some centers by 15%-20%. ESLP has been applied as a method to assess and recondition marginal donor lungs and has demonstrated acceptable short- and long-term outcomes following transplantation of extended criteria donor (ECD) lungs. Large animal (in vivo) transplantation models are required to validate ongoing in vitro research findings. Anatomic and physiologic differences between humans and pigs pose significant technical and anesthetic challenges. An easily reproducible transplant model would permit the in vivo validation of current ESLP strategies and the preclinical evaluation of various interventions designed to improve donor lung function. This protocol describes a porcine model of orthotopic left lung allotransplantation. This includes anesthetic and surgical techniques, a customized surgical checklist, troubleshooting, modifications, and the benefits and limitations of the approach.

Lung transplant to manage end-stage lung disease due to idiopathic pulmonary hemosiderosis: A review of the literature.

Idiopathic pulmonary hemosiderosis (IPH) is a rare immunological disease with a genetic predisposition. It is characterized by recurrent episodes of diffuse alveolar hemorrhage (DAH). Timely use of immunosuppressive medications has significantly improved overall outcomes, including mortality. Still, uncontrolled and frequent episodes of DAH can eventually cause pulmonary fibrosis, leading to end-stage lung disease (ESLD). The objective of the present project was to scrutinize the literature and summarize the demographic, clinical, radiological, and histopathological features, as well as the overall outcomes, in this patient population following lung transplant. The Medline database was searched using the PubMed platform. Articles published in English between 1960 and 2020 were included in the search. Different search terms were used to identify all patients who underwent lung transplantation to manage ESLD due to IPH. Only four cases of lung transplantation have been reported in the literature in patients with IPH. All but one of these underwent deceased donor lung transplant; recurrence was reported in two of these patients and suspected in the third. One patient received living donor lung transplant and had no recurrence during a five-year follow-up. Patients with IPH should not be excluded from lung transplantation because the disease may not recur in all patients, and even when it does recur it can be promptly treated by increasing immunosuppression.