Organ donation and utilization in the United States, 1999-2008

Disturbed sleep after lung transplantation is associated with worse patient-reported outcomes and chronic lung allograft dysfunction

Many lung transplant recipients fail to derive the expected improvements in functioning, HRQL, or long-term survival. Sleep may represent an important, albeit rarely examined, factor influencing lung transplant outcomes. Within a larger cohort study, 141 lung transplant recipients completed the Medical Outcomes Study (MOS) Sleep Scale along with a broader survey of patient-reported outcome (PRO) measures and frailty assessment. MOS Sleep yields the Sleep Problems Index (SPI); we also derived an insomnia-specific subscale. Potential perioperative predictors of disturbed sleep and time to chronic lung allograft dysfunction (CLAD) and death were derived from medical records. We investigated associations between perioperative predictors on SPI and Insomnia and associations between SPI and Insomnia on PROs and frailty by linear regressions, adjusting for age, sex, and lung function. We evaluated the associations between SPI and Insomnia on time to CLAD and death using Cox models, adjusting for age, sex, and transplant indication. Post-transplant hospital length of stay >30 days was associated with worse sleep by SPI and insomnia (SPI: p=0.01; Insomnia p=0.02). Worse sleep by SPI and insomnia was associated with worse depression, cognitive function, HRQL, physical disability, health utilities, and Fried Frailty Phenotype frailty (all p<0.01). Those in the worst quartile of SPI and insomnia exhibited increased risk of CLAD (HR 2.18; 95%CI: 1.22-3.89 ; p=0.01 for SPI and HR 1.96; 95%CI 1.09-3.53; p=0.03 for insomnia). Worsening in SPI but not insomnia was also associated with mortality (HR: 1.29; 95%CI: 1.05-1.58; p=0.01). Poor sleep after lung transplant may be a novel predictor of patient reported outcomes, frailty, CLAD, and death with potentially important screening and treatment implications.

Awareness, Attitude, and Beliefs Regarding Organ Donation Among the General Public in Saudi Arabia

Background

Organ donation is a lifesaving option to rescue many patients with end-stage organ failure from possible morbidities and mortalities. Unfortunately, due to a shortage of donors, many patients suffering from their illnesses are waiting for an organ. This study aimed to determine the awareness, attitude, and beliefs toward organ donation among the Saudi population.

Patients and Methods

This is an online cross-sectional survey that was conducted in Saudi Arabia between July and September 2022. A self-administered questionnaire was distributed to the general public using an online platform. The questionnaire consists of two sections: the first is about demographic data, and the second is about questions to assess awareness, attitude, and beliefs regarding organ donation. The Chi-squared test was used to examine the differences in participants' awareness, attitude, and beliefs towards organ donation. A binary logistic regression analysis was used to identify predictors of a positive attitude towards organ donation.

Results

A total of 3507 individuals participated in this study. Around 68.1% were aged between 18 and 30 years. Twenty-four percent of them knew of the legislative body for organ donation; 58.5% believed that organ donation should be promoted; and 66.1% had a positive attitude toward donating body organs. Younger age (31-50 years), male gender, being unemployed or working in a government job, and being married were factors that decreased the likelihood of having a positive attitude towards organ donation.

Conclusion

Although there was a positive attitude and belief about organ donation, awareness was suboptimal. Younger age, male gender, being unemployed or working in a government job, and being married were factors that decreased the likelihood of having a positive attitude towards organ donation. It is necessary to address the gaps in knowledge, and social media as well as mass media may have an important role in bridging the gaps.

Two Decades of Liver Transplants for Primary Biliary Cholangitis: A Comparative Study of Living Donors vs. Deceased Donor Liver Transplantations

Primary biliary cholangitis (PBC) prompts liver transplantation (LT) due to cholestasis, cirrhosis, and liver failure. Despite lower MELD scores, recent studies highlight higher PBC waitlist mortality, intensifying the need for alternative transplantation strategies. Living donor liver transplant (LDLT) has emerged as a solution to the organ shortage. This study compares LDLT and deceased donor liver transplant (DDLT) outcomes in PBC patients via retrospective analysis of the UNOS database (2002-2021). Patient survival, graft failure, and predictors were evaluated through Kaplan-Meier and Cox-proportional analyses. Among 3482 DDLTs and 468 LDLTs, LDLT showed superior patient survival (92.3%, 89.1%, 87.6%, 85.0%, 77.2% vs. 91.5%, 88.3%, 86.3%, 82.2%, 71.0%; respectively; p = 0.02) with no significant graft survival difference at 1-, 2-, 3-, 5-, and 10-years post-LT (91.0%, 88.0%, 85.7%, 83.0%, 75.4% vs. 90.5%, 87.4%, 85.3%, 81.3%, 70.0%; respectively; p = 0.06). Compared to DCD, LDLT showed superior patient and graft survival (p < 0.05). Younger male PBC recipients with a high BMI, diabetes, and dialysis history were associated with mortality and graft failure (p < 0.05). Our study showed that LDLT had superior patient survival to DDLT. Predictors of poor post-LT outcomes require further validation studies.

Systematic review and meta-analysis of open versus laparoscopy-assisted versus pure laparoscopic versus robotic living donor hepatectomy

The value of minimally invasive approaches for living donor hepatectomy remains unclear. Our aim was to compare the donor outcomes after open versus laparoscopy-assisted versus pure laparoscopic versus robotic living donor hepatectomy (OLDH vs. LALDH vs. PLLDH vs. RLDH). A systematic literature review of the MEDLINE, Cochrane Library, Embase, and Scopus databases was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement (up to December 8, 2021). Random-effects meta-analyses were performed separately for minor and major living donor hepatectomy. The risk of bias in nonrandomized studies was assessed using the Newcastle-Ottawa Scale. A total of 31 studies were included. There was no difference in donor outcomes after OLDH versus LALDH for major hepatectomy. However, PLLDH was associated with decreased estimated blood loss, length of stay (LOS), and overall complications versus OLDH for minor and major hepatectomy, but also with increased operative time for major hepatectomy. PLLDH was associated with decreased LOS versus LALDH for major hepatectomy. RLDH was associated with decreased LOS but with increased operative time versus OLDH for major hepatectomy. The scarcity of studies comparing RLDH versus LALDH/PLLDH did not allow us to meta-analyze donor outcomes for that comparison. There seems to be a marginal benefit in estimated blood loss and/or LOS in favor of PLLDH and RLDH. The complexity of these procedures limits them to transplant centers with high volume and experience. Future studies should investigate self-reported donor experience and the associated economic costs of these approaches.

Sociodemographic Variables in Canadian Organ Donation Organizations: A Health Information Survey

Health systems must collect equity-relevant sociodemographic variables to measure and mitigate health inequities. The specific variables collected by organ donation organizations (ODOs) across Canada, variable definitions, and processes of the collection are not defined. We undertook a national health information survey of all ODOs in Canada. These results will inform the development of a standard national dataset of equity-relevant sociodemographic variables.

Methods

We conducted an electronic, self-administered cross-sectional survey of all ODOs in Canada from November 2021 to January 2022. We targeted key knowledge holders familiar with the data collection processes within each Canadian ODO known to Canadian Blood Services. Categorical item responses are presented as numbers and proportions.

Results

We achieved a 100% response rate from 10 Canadian ODOs. Most data were collected by organ donation coordinators. Only 2 of 10 ODOs reported using scripts explaining why sociodemographic data are being collected or incorporated training in cultural sensitivity for any given variable. A lack of cultural sensitivity training was endorsed by 50% of respondents as a barrier to the collection of sociodemographic variables by ODOs, whereas 40% of respondents identified a lack of training in sociodemographic variable collection as a significant barrier.

Conclusions

Few programs routinely collect sufficient data to examine health inequities with an intersectional lens. Most data collection occurs midway through the ODO interaction, creating a missed opportunity to better understand differences in social identities of patients who register their intention to donate in advance or who decline the donation. National standardization of equity-relevant data collection definitions and processes of the collection is needed.

Immune characterization of a xenogeneic human lung cross-circulation support system

Improved approaches to expanding the pool of donor lungs suitable for transplantation are critically needed for the growing population with end-stage lung disease. Cross-circulation (XC) of whole blood between swine and explanted human lungs has previously been reported to enable the extracorporeal recovery of donor lungs that declined for transplantation due to acute, reversible injuries. However, immunologic interactions of this xenogeneic platform have not been characterized, thus limiting potential translational applications. Using flow cytometry and immunohistochemistry, we demonstrate that porcine immune cell and immunoglobulin infiltration occurs in this xenogeneic XC system, in the context of calcineurin-based immunosuppression and complement depletion. Despite this, xenogeneic XC supported the viability, tissue integrity, and physiologic improvement of human donor lungs over 24 hours of xeno-support. These findings provide targets for future immunomodulatory strategies to minimize immunologic interactions on this organ support biotechnology.

Declining Medicare reimbursement in abdominal transplantation from 2000 to 2021

BACKGROUND

The Centers for Medicare and Medicaid Services is a major payer for abdominal transplant services. Reimbursement reductions could have a major impact on the transplant surgical workforce and hospitals. Yet government reimbursement trends in abdominal transplantation have not been fully characterized.

METHODS

We performed an economic analysis to characterize changes in inflation-adjusted trends in Medicare surgical reimbursement for abdominal transplant procedures. Using the Medicare Fee Schedule Look-Up Tool, we performed a procedure code-based surgical reimbursement rate analysis. Reimbursement rates were adjusted for inflation to calculate overall changes in reimbursement, overall year-over-year, 5-year year-over-year, and compound annual growth rate from 2000 to 2021.

RESULTS

We observed declines in adjusted reimbursement of common abdominal transplant procedures, including liver (-32.4%), kidney with and without nephrectomy (-24.2% and -24.1%, respectively), and pancreas transplant (-15.2%) (all, P < .05). Overall, the yearly average change for liver, kidney with and without nephrectomy, and pancreas transplant were -1.54%, -1.15%, -1.15%, and -0.72%. Five-year annual change averaged -2.69%, -2.35%, -2.64%, and -2.43%, respectively. The overall average compound annual growth rate was -1.27%.

CONCLUSION

This analysis depicts a worrisome reimbursement pattern for abdominal transplant procedures. Transplant surgeons, centers, and professional organizations should note these trends to advocate sustainable reimbursement policy and to preserve continued access to transplant services.

A new approach to predicting mortality in dialysis patients using sociodemographic features based on artificial intelligence

One of the main problems that affect patients in dialysis therapy who are on the waiting list to receive a kidney transplant is predicting their survival time if they do not receive a transplant. This paper proposes a new approach to survival prediction based on artificial intelligence techniques combined with statistical methods to study the association between sociodemographic factors and patient survival on the waiting list if they do not receive a kidney transplant. This new approach consists of a first stage that uses the clustering techniques that are best suited to the data structure (K-Means, Mini Batch K-Means, Agglomerative Clustering and K-Modes) used to identify the risk profile of dialysis patients. Later, a new method called False Clustering Discovery Reduction is performed to determine the minimum number of populations to be studied, and whose mortality risk is statistically differentiable. This approach was applied to the OPTN medical dataset (n = 44,663). The procedure started from 11 initial clusters obtained with the Agglomerative technique, and was reduced to eight final risk populations, for which their Kaplan-Meier survival curves were provided. With this result, it is possible to make predictions regarding the survival time of a new patient who enters the waiting list if the sociodemographic profile of the patient is known. To do so, the predictive algorithm XGBoost is used, which allows the cluster to which it belongs to be predicted and the corresponding Kaplan-Meier curve to be associated with it. This prediction process is achieved with an overall Multi-class AUC of 99.08 %.

L-alanyl-L-glutamine modified perfusate improves human lung cell functions and extend porcine ex vivo lung perfusion

BACKGROUND

The clinical application of normothermic ex vivo lung perfusion (EVLP) has increased donor lung utilization for transplantation through functional assessment. To develop it as a platform for donor lung repair, reconditioning and regeneration, the perfusate should be modified to support the lung during extended EVLP.

METHODS

Human lung epithelial cells and pulmonary microvascular endothelial cells were cultured, and the effects of Steen solution (commonly used EVLP perfusate) on basic cellular function were tested. Steen solution was modified based on screening tests in cell culture, and further tested with an EVLP cell culture model, on apoptosis, GSH, HSP70, and IL-8 expression. Finally, a modified formula was tested on porcine EVLP. Physiological parameters of lung function, histology of lung tissue, and amino acid concentrations in EVLP perfusate were measured.

RESULTS

Steen solution reduced cell confluence, induced apoptosis, and inhibited cell migration, compared to regular cell culture media. Adding L-alanyl-L-glutamine to Steen solution improved cell migration and decreased apoptosis. It also reduced cold preservation and warm perfusion-induced apoptosis, enhanced GSH and HSP70 production, and inhibited IL-8 expression on an EVLP cell culture model. L-alanyl-L-glutamine modified Steen solution supported porcine lungs on EVLP with significantly improved lung function, well-preserved histological structure, and significantly higher levels of multiple amino acids in EVLP perfusate.

CONCLUSIONS

Adding L-alanyl-L-glutamine to perfusate may provide additional energy support, antioxidant, and cytoprotective effects to lung tissue. The pipeline developed herein, with cell culture, cell EVLP, and porcine EVLP models, can be used to further optimize perfusates to improve EVLP outcomes.

Clinical Phenotypes of Dual Kidney Transplant Recipients in the United States as Identified through Machine Learning Consensus Clustering

Background and Objectives: Our study aimed to cluster dual kidney transplant recipients using an unsupervised machine learning approach to characterize donors and recipients better and to compare the survival outcomes across these various clusters. Materials and Methods: We performed consensus cluster analysis based on recipient-, donor-, and transplant-related characteristics in 2821 dual kidney transplant recipients from 2010 to 2019 in the OPTN/UNOS database. We determined the important characteristics of each assigned cluster and compared the post-transplant outcomes between clusters. Results: Two clinically distinct clusters were identified by consensus cluster analysis. Cluster 1 patients was characterized by younger patients (mean recipient age 49 ± 13 years) who received dual kidney transplant from pediatric (mean donor age 3 ± 8 years) non-expanded criteria deceased donor (100% non-ECD). In contrast, Cluster 2 patients were characterized by older patients (mean recipient age 63 ± 9 years) who received dual kidney transplant from adult (mean donor age 59 ± 11 years) donor with high kidney donor profile index (KDPI) score (59% had KDPI ≥ 85). Cluster 1 had higher patient survival (98.0% vs. 94.6% at 1 year, and 92.1% vs. 76.3% at 5 years), and lower acute rejection (4.2% vs. 6.1% within 1 year), when compared to cluster 2. Death-censored graft survival was comparable between two groups (93.5% vs. 94.9% at 1 year, and 89.2% vs. 84.8% at 5 years). Conclusions: In summary, DKT in the United States remains uncommon. Two clusters, based on specific recipient and donor characteristics, were identified through an unsupervised machine learning approach. Despite varying differences in donor and recipient age between the two clusters, death-censored graft survival was excellent and comparable. Broader utilization of DKT from high KDPI kidneys and pediatric en bloc kidneys should be encouraged to better address the ongoing organ shortage.

Preservation solutions for static cold storage in donation after circulatory death and donation after brain death liver transplantation in the United States

Static cold preservation remains the cornerstone for storing donor livers following procurement; however, the choice between University of Wisconsin solution (UW) and histidine-tryptophan-ketoglutarate solution (HTK) remains controversial. Recent International Liver Transplantation Society (ILTS) guidelines have recommended avoiding HTK for donation after circulatory death (DCD) grafts based on older reports. We studied the latest US adult graft outcomes in three recent eras (2006-2010, 2011-2015, 2016-2020) comparing HTK and UW among 5956 DCD LTs: 3873 (65.0%) used UW and 1944 (32.7%) used HTK. In a total of 82,679 donation after brain death (DBD) liver transplantations (LTs), 63,511 (76.8%) used UW and 15,855 (19.2%) used HTK. The HTK group had higher 1-year and 5-year graft survival rates of 89.7% and 74.3%, respectively, compared with 85.9% and 70.8% in the UW group in the 2016-2020 era (p = 0.005). This difference remained when adjusted for important potential confounders (hazard ratio, 0.78; 95% confidence interval: 0.60, 0.99). There were no differences between groups among DCD LTs in the earlier eras or among DBD LTs in all eras (all p values > 0.05). The latest US data suggest that HTK is at least noninferior to UW for preserving DCD livers. These data support HTK use in DCD LT and contradict ILTS guidance.

Electrical Impedance as a Noninvasive Metric of Quality in Allografts Undergoing Normothermic Ex Vivo Lung Perfusion

Ex vivo lung perfusion (EVLP) increases the pool of suitable organs for transplant by facilitating assessment and repair at normothermia, thereby improving identification of quality of marginal organs. However, there exists no current objective approach for assessing total organ edema. We sought to evaluate the use of electrical impedance as a metric to assess total organ edema in lungs undergoing EVLP. Adult porcine lungs (40 kg) underwent normothermic EVLP for 4 hours. To induce varying degrees of lung injury, the allografts were perfused with either Steen, a modified cell culture media, or 0.9% normal saline. Physiologic parameters (peak airway pressure and compliance), pulmonary artery and left atrial blood gases, and extravascular lung water measurements were evaluated over time. Wet-to-dry ratios were evaluated postperfusion. Modified Murray scoring was used to calculate lung injury. Impedance values were associated with lung injury scores ( p = 0.007). Peak airway pressure ( p = 0.01) and PaO 2 /FiO 2 ratios ( p = 0.005) were both significantly associated with reduced impedance. Compliance was not associated with impedance ( p = 0.07). Wet/dry ratios were significantly associated with impedance and Murray Scoring within perfusion groups of Steen, Saline, and Modified Cell Culture ( p = 0.0186, 0.0142, 0.0002, respectively). Electrical impedance offers a noninvasive modality for measuring lung quality as assessed by tissue edema in a porcine model of normothermic EVLP. Further studies evaluating the use of impedance to assess organ edema as a quality marker in human clinical models and abdominal organs undergoing ex vivo perfusion warrant investigation.

Primary Graft Dysfunction: The Role of Aging in Lung Ischemia-Reperfusion Injury

Transplant centers around the world have been using extended criteria donors to remedy the ongoing demand for lung transplantation. With a rapidly aging population, older donors are increasingly considered. Donor age, at the same time has been linked to higher rates of lung ischemia reperfusion injury (IRI). This process of acute, sterile inflammation occurring upon reperfusion is a key driver of primary graft dysfunction (PGD) leading to inferior short- and long-term survival. Understanding and improving the condition of older lungs is thus critical to optimize outcomes. Notably, ex vivo lung perfusion (EVLP) seems to have the potential of reconditioning ischemic lungs through ex-vivo perfusing and ventilation. Here, we aim to delineate mechanisms driving lung IRI and review both experimental and clinical data on the effects of aging in augmenting the consequences of IRI and PGD in lung transplantation.

A systematic review and meta-analysis of coronary artery disease and revascularization in lung transplant patients

Coronary artery disease (CAD) is common in candidates for lung transplantation (LTx) and has historically been considered a relative contraindication to transplantation. We look to review the outcomes of LTx in patients with CAD and determine the optimum revascularization strategy in LTx candidates. PubMed, Medline and Web of Science were systematically searched by three authors for articles comparing the outcomes of LTx in patients with CAD and receiving coronary revascularization. In total 1668 articles were screened and 12 were included in this review.Preexisting CAD in LTx recipients was not associated with significantly increased postoperative morbidity or mortality. The pooled estimates of mortality rate at 1, 3 and 5 years indicated significantly inferior survival in LTx recipients with a prior history of coronary artery bypass grafting (CABG) [odds ratio (OR), 1.84; 95% confidence interval (CI), 1.53-2.22; P < 0.00001; I2 = 0%; OR, 1.52; 95% CI, 1.21-1.91; P = 0.0003; I2 = 0%; OR, 1.62; 95% CI, 1.13-2.33; P = 0.008; I2 = 71%, respectively). However, contemporary literature suggests that survival rates in LTx recipients with CAD that received revascularization either by percutaneous coronary intervention (PCI), previous or concomitant CABG, are similar to patients who did not receive revascularization. Trends in postoperative morbidity favored CABG in the rates of myocardial infarction and repeat revascularization, whereas rates of stroke favored PCI. The composite results of this study support the consideration of patients with CAD or previous coronary revascularization for LTx. Prospective, randomized controlled trials with consistent patient populations and outcomes reporting are required to fully elucidate the optimum revascularization strategy in LTx candidates.

International Population Study in Spain, Cuba, and the United States of Attitudes Toward Organ Donation Among the Cuban Population

Cuban immigrants constitute an important group in both the United States and Spain, with different behaviors toward organ donation having been described among the different Latin American nationalities. We analyzed the attitude toward organ donation among the Cuban populations in Cuba, Spain, and Florida. The study population was Cuban immigrants over 15 years of age residing in Cuba, Spain, and Florida, with samples randomly stratified by age and sex. A validated questionnaire on psychosocial aspects of organ donation (PCID-DTO Rios) was used. Census was used as the sampling base in all 3 countries; however, additionally, in Spain and the United States (Florida), we sought the support of immigration support associations to determine the Cuban population without legal documentation. The questionnaire was completed anonymously and self-administered. The completion rate of the study was 74% (4123/5574) among 424 surveyed in Spain, 1224 in Florida, and 2475 in Cuba. The attitude in favor of donating their own organs upon death was 60.6% of those surveyed in Spain, 37.6% in Florida, and 68.9% in Cuba, or 58% of the global sample. Multivariate analysis showed that country of residence was an independent factor associated with attitude toward organ donation (odds ratio, 1.929). Other factors associated with attitude were sex, educational level, performance of prosocial activities, knowledge of the brain death concept, religion, the couple's opinion toward donation, fear of mutilation after donation, and attitude toward manipulation of the body after death. The attitude toward organ donation among Cubans in their country of origin and immigrants in Spain was similar, being significantly different from those who emigrate to Florida, where the attitude is much less favorable.

Characterization and reduction of non-endocrine cells accompanying islet-like endocrine cells differentiated from human iPSC

The differentiation of pancreatic endocrine cells from human pluripotent stem cells has been thoroughly investigated for their application in cell therapy against diabetes. Although non-endocrine cells are inevitable contaminating by-products of the differentiation process, a comprehensive profile of such cells is lacking. Therefore, we characterized non-endocrine cells in iPSC-derived pancreatic islet cells (iPIC) using single-cell transcriptomic analysis. We found that non-endocrine cells consist of (1) heterogeneous proliferating cells, and (2) cells with not only pancreatic traits but also liver or intestinal traits marked by FGB or AGR2. Non-endocrine cells specifically expressed FGFR2, PLK1, and LDHB. We demonstrated that inhibition of pathways involving these genes selectively reduced the number of non-endocrine cells in the differentiation process. These findings provide useful insights into cell purification approaches and contribute to the improvement of the mass production of endocrine cells for stem cell-derived cell therapy for diabetes.

Dual kidney transplants from adult marginal donors: Review and perspective

The practice of dual kidney transplantation (DKT) from adult marginal deceased donors (MDDs) dates back to the mid-1990s with initial pioneering experiences reported by the Stanford and Maryland groups, at which time the primary indication was estimated insufficient nephron mass from older donors. Multiple subsequent studies of short and long-term success have been reported focusing on three major aspects of DKT: Identifying appropriate selection criteria and developing scoring systems based on pre- and post-donation factors; refining technical aspects; and analyzing mid-term outcomes. The number of adult DKTs performed in the United States has declined in the past decade and only about 60 are performed annually. For adult deceased donor kidneys meeting double allocation criteria, >60% are ultimately not transplanted. Deceased donors with limited renal functional capacity represent a large proportion of potential kidneys doomed to either discard or non-recovery. However, DKT may reduce organ discard and optimize the use of kidneys from MDDs. In an attempt to promote utilization of MDD kidneys, the United Network for Organ Sharing introduced new allocation guidelines pursuant to DKT in 2019. The purpose of this review is to chronicle the history of DKT and identify opportunities to improve utilization of MDD kidneys through DKT. This article is protected by copyright. All rights reserved.

Xenogeneic stem cell transplantation: Research progress and clinical prospects

Organ transplantation is the ultimate treatment for end-stage diseases such as heart and liver failure. However, the severe shortage of donor organs has limited the organ transplantation progress. Xenogeneic stem cell transplantation provides a new strategy to solve this problem. Researchers have shown that xenogeneic stem cell transplantation has significant therapeutic effects and broad application prospects in treating liver failure, myocardial infarction, advanced type 1 diabetes mellitus, myelosuppression, and other end-stage diseases by replacing the dysfunctional cells directly or improving the endogenous regenerative milieu. In this review, the sources, problems and solutions, and potential clinical applications of xenogeneic stem cell transplantation will be discussed.

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.

Recombinant apoptosis inhibitor of macrophage protein reduces delayed graft function in a murine model of kidney transplantation

Reperfusion injury following cold and warm ischemia (IRI) is unavoidable during kidney transplantation and contributes to delayed graft function (DGF) and premature graft loss. Death of tubular epithelial cells (TECs) by necrosis during IRI releases pro-inflammatory mediators (e.g. HMGB1), propagating further inflammation (necroinflammation) and tissue damage. Kidney Injury Molecule-1 (KIM-1) is a phagocytic receptor upregulated on proximal TECs during acute kidney injury. We have previously shown that renal KIM-1 protects the graft against transplant associated IRI by enabling TECs to clear apoptotic and necrotic cells, and that recognition of necrotic cells by KIM-1 is augmented in the presence of the opsonin, apoptosis inhibitor of macrophages (AIM). Here, we tested whether recombinant AIM (rAIM) could be used to mitigate transplant associated IRI. We administered rAIM or vehicle control to nephrectomised B6 mice transplanted with a single B6 donor kidney. Compared to grafts in vehicle-treated recipients, grafts from rAIM-treated mice exhibited significantly less renal dysfunction, tubular cell death, tissue damage, tubular obstruction, as well as local and systemic inflammation. Both mouse and human rAIM enhanced the clearance of necrotic cells by murine and human TECs, respectively in vitro. These data support testing of rAIM as a potential therapeutic agent to reduce DGF following kidney transplantation.

Transcriptomic investigation reveals donor-specific gene signatures in human lung transplants

INTRODUCTION

Transplantation of lungs from donation after circulatory death (DCD) in addition to donation after brain death (DBD) became routine worldwide to address the global organ shortage. The development of ex vivo lung perfusion (EVLP) for donor lung assessment and repair contributed to the increased use of DCD lungs. We hypothesise that a better understanding of the differences between lungs from DBD and DCD donors, and between EVLP and directly transplanted (non-EVLP) lungs, will lead to the discovery of the injury-specific targets for donor lung repair and reconditioning.

METHODS

Tissue biopsies from human DBD (n=177) and DCD (n=65) donor lungs, assessed with or without EVLP, were collected at the end of cold ischaemic time. All samples were processed with microarray assays. Gene expression, network and pathway analyses were performed using R, Ingenuity Pathway Analysis and STRING. Results were validated with protein assays, multiple logistic regression and 10-fold cross-validation.

RESULTS

Our analyses showed that lungs from DBD donors have upregulation of inflammatory cytokines and pathways. In contrast, DCD lungs display a transcriptome signature of pathways associated with cell death, apoptosis and necrosis. Network centrality revealed specific drug targets to rehabilitate DBD lungs. Moreover, in DBD lungs, tumour necrosis factor receptor-1/2 signalling pathways and macrophage migration inhibitory factor-associated pathways were activated in the EVLP group. A panel of genes that differentiate the EVLP from the non-EVLP group in DBD lungs was identified.

CONCLUSION

The examination of gene expression profiling indicates that DBD and DCD lungs have distinguishable biological transcriptome signatures.

A novel histidine-tryptophan-ketoglutarate formulation ameliorates intestinal injury in a cold storage and ex vivo warm oxygenated reperfusion model in rats

AIM

The present study aims to evaluate protective effects of a novel histidine-tryptophan-ketoglutarate solution (HTK-N) and to investigate positive impacts of an additional luminal preservation route in cold storage-induced injury on rat small bowels.

METHODS

Male Lewis rats were utilized as donors of small bowel grafts. Vascular or vascular plus luminal preservation were conducted with HTK or HTK-N and grafts were stored at 4°C for 8 h followed by ex vivo warm oxygenated reperfusion with Krebs-Henseleit buffer for 30 min. Afterwards, intestinal tissue and portal vein effluent samples were collected for evaluation of morphological alterations, mucosal permeability and graft vitality.

RESULTS

The novel HTK-N decreased ultrastructural alterations but otherwise presented limited effect on protecting small bowel from ischemia-reperfusion injury in vascular route. However, the additional luminal preservation led to positive impacts on the integrity of intestinal mucosa and vitality of goblet cells. In addition, vascular plus luminal preservation route with HTK significantly protected the intestinal tissue from edema.

CONCLUSION

HTK-N protected the intestinal mucosal structure and graft vitality as a luminal preservation solution. Additional luminal preservation route in cold storage was shown to be promising.

A Novel Negative Pressure-Flow Waveform to Ventilate Lungs for Normothermic Ex Vivo Lung Perfusion

Ex vivo lung perfusion (EVLP) is increasingly used to treat and assess lungs before transplant. Minimizing ventilator induced lung injury (VILI) during EVLP is an important clinical need, and negative pressure ventilation (NPV) may reduce VILI compared with conventional positive pressure ventilation (PPV). However, it is not clear if NPV is intrinsically lung protective or if differences in respiratory pressure-flow waveforms are responsible for reduced VILI during NPV. In this study, we quantified lung injury using novel pressure-flow waveforms during normothermic EVLP. Rat lungs were ventilated-perfused ex vivo for 2 hours using tidal volume, positive end-expiratory pressure (PEEP), and respiratory rate matched PPV or NPV protocols. Airway pressures and flow rates were measured in real time and lungs were assessed for changes in compliance, pulmonary vascular resistance, oxygenation, edema, and cytokine secretion. Negative pressure ventilation lungs demonstrated reduced proinflammatory cytokine secretion, reduced weight gain, and reduced pulmonary vascular resistance (p < 0.05). Compliance was higher in NPV lungs (p < 0.05), and there was no difference in oxygenation between the two groups. Respiratory pressure-flow waveforms during NPV and PPV were significantly different (p < 0.05), especially during the inspiratory phase, where the NPV group exhibited rapid time-dependent changes in pressure and airflow whereas the PPV group exhibited slower changes in airflow/pressures. Lungs ventilated with PPV also had a greater transpulmonary pressure (p < 0.05). Greater improvement in lung function during NPV EVLP may be caused by favorable airflow patterns and/or pressure dynamics, which may better mimic human respiratory patterns.

Clinical transplantation using negative pressure ventilation ex situ lung perfusion with extended criteria donor lungs

Lung transplantation remains the best treatment option for end-stage lung disease; however, is limited by a shortage of donor grafts. Ex situ lung perfusion, also known as ex vivo lung perfusion, has been shown to allow for the safe evaluation and reconditioning of extended criteria donor lungs, increasing donor utilization. Negative pressure ventilation ex situ lung perfusion has been shown, preclinically, to result in less ventilator-induced lung injury than positive pressure ventilation. Here we demonstrate that, in a single-arm interventional study (ClinicalTrials.gov number NCT03293043) of 12 extended criteria donor human lungs, negative pressure ventilation ex situ lung perfusion allows for preservation and evaluation of donor lungs with all grafts and patients surviving to 30 days and recovered to discharge from hospital. This trial also demonstrates that ex situ lung perfusion is safe and feasible with no patients demonstrating primary graft dysfunction scores grade 3 at 72 h or requiring post-operative extracorporeal membrane oxygenation.

Brain Death Determination: An Interprofessional Simulation to Determine Brain Death and Communicate with Families Focused on Neurology Residents

INTRODUCTION

Significant variation exists in determining brain death despite an expectation of competence for all neurology residents. In addition, family discussions regarding brain death are challenging and may influence organ donation.

METHODS

We developed two simulations of increasing complexity for PGY 2 and PGY 3 neurology residents. High-fidelity mannequins were used to simulate patients; standardized actors portrayed family members. In the first simulation, residents determined brain death and shared this information with a grieving family. In the second simulation, residents determined brain death in a more complicated scenario, requiring ancillary testing and accurate result interpretation. Following the determination, residents met with a challenging family. The residents worked with an interdisciplinary team and responded to the family's emotions, used active listening skills, and supported the family through next steps.

RESULTS

Twelve residents completed the simulations. Prior to the simulation, three (25%) residents felt comfortable discussing a brain death diagnosis; following the simulation, eight (67%) residents felt comfortable/very comfortable discussing brain death. Prior to the simulation, eight (67%) residents stated they knew prerequisites for performing a brain death examination and seven (58%) agreed they knew indications for ancillary testing; these numbers increased to 100% following the simulation. The number of residents who felt comfortable performing the brain death exam increased from five (42%) to 10 (83%).

DISCUSSION

This simulation of determining brain death and leading difficult family meetings was well-received by neurology residents. Further work should focus on the effects of simulation-based education on practice variation and organ donation consent rates.

Living vs deceased donor liver transplantation in cholestatic liver disease: An analysis of the OPTN database

BACKGROUND

Living donor liver transplantation (LDLT) and donation after circulatory death (DCD) can expand the donor pool for cholestatic liver disease (CLD) patients. We sought to compare the outcomes of deceased donor liver transplant (DDLT) vs LDLT in CLD patients.

METHODS

Retrospective cohort analysis of adult CLD recipients registered in the OPTN database who received primary LT between 2002 and 2018. Cox proportional hazards regression models with mixed effects were used to determine the impact of graft type on patient and graft survival.

RESULTS

Five thousand, nine hundred ninety-nine DDLT (5730 donation after brain death [DBD], 269 DCD) and 912 LDLT recipients were identified. Ten-year patient/graft survival rates were DBD: 73.8%/67.9%, DCD: 74.7%/60.7%, and LDLT: 82.5%/73.9%. Higher rates of biliary complications as a cause of graft failure were seen in DCD (56.8%) than LDLT (30.5%) or DBD (18.7%) recipients. On multivariable analysis, graft type was not associated with patient mortality, while DCD was independently associated with graft failure (P = .046).

CONCLUSION

DBD, DCD, and LDLT were associated with comparable overall patient survival. No difference in the risk of graft failure could be observed between LDLT and DBD. DCD can be an acceptable alternative to DBD with equivalent patient survival, but inferior graft survival likely related to the high rate of biliary complications.

A Systematic Review of Opt-out Versus Opt-in Consent on Deceased Organ Donation and Transplantation (2006-2016)

BACKGROUND

Significant numbers of patients in the USA and UK die while waiting for solid organ transplant. Only 1-2% of deaths are eligible as donors with a fraction of the deceased donating organs. The form of consent to donation may affect the organs available. Forms of consent include: opt-in, mandated choice, opt-out, and organ conscription. Opt-in and opt-out are commonly practiced. A systematic review was conducted to determine the effect of opt-in versus opt-out consent on the deceased donation rate (DDR) and deceased transplantation rate (DTR).

METHODS

Literature searches of PubMed and EMBASE between 2006 and 2016 were performed. Research studies were selected based on certain inclusion criteria which include USA, UK, and Spain; compare opt-in versus opt-out; primary data analysis; and reported DDR or DTR. Modeled effect on US transplant activity was conducted using public data from Organ Procurement and Transplantation Network and Centers for Disease Control WONDER from 2006 to 2015.

RESULTS

A total of 2400 studies were screened and six studies were included. Four studies reported opt-out consent increases DDR by 21-76% over 5-14 years. These studies compared 13-25 opt-out countries versus 9-23 opt-in countries. Three studies reported opt-out consent increases DTR by 38-83% over 11-13 years. These studies compared 22-25 opt-out versus 22-28 opt-in countries. Modeled opt-out activity on the USA resulted in 4753-17,201 additional transplants annually.

CONCLUSION

Opt-out consent increases DDR and DTR and may be useful in decreasing deaths on the waiting list in the USA and other countries.

REGISTRATION NUMBER

PROSPERO CRD42019098759.

Mechano-modulatory synthetic niches for liver organoid derivation

The recent demonstration that primary cells from the liver can be expanded in vitro as organoids holds enormous promise for regenerative medicine and disease modelling. The use of three-dimensional (3D) cultures based on ill-defined and potentially immunogenic matrices, however, hampers the translation of liver organoid technology into real-life applications. We here use chemically defined hydrogels for the efficient derivation of both mouse and human hepatic organoids. Organoid growth is found to be highly stiffness-sensitive, a mechanism independent of acto-myosin contractility and requiring instead activation of the Src family of kinases (SFKs) and yes-associated protein 1 (YAP). Aberrant matrix stiffness, on the other hand, results in compromised proliferative capacity. Finally, we demonstrate the establishment of biopsy-derived human liver organoids without the use of animal components at any step of the process. Our approach thus opens up exciting perspectives for the establishment of protocols for liver organoid-based regenerative medicine.

3D liver organoids hold great promise for regenerative medicine but the use of ill-defined matrices limits their potential. Here, the authors generate human and mouse liver organoids using a chemically defined matrix, and reveal a link between matrix stiffness and organoid growth that does not require acto-myosin contraction.

A Low-Cost Perfusate Alternative for Ex Vivo Lung Perfusion

BACKGROUND

Normothermic ex vivo lung perfusion (EVLP) has been used successfully to evaluate and recondition marginal donor lungs; however, multiple barriers continue to prevent its widespread adoption. We sought to develop a common hospital ingredient-derived perfusate (CHIP) with equivalent functional and inflammatory characteristics to a standard Krebs-Henseleit buffer with 8% serum albumin-derived perfusate (KHB-Alb) to improve access and reduce costs of ex vivo organ perfusion.

METHODS

Sixteen porcine lungs were perfused using negative pressure ventilation (NPV) EVLP for 12 hours in a normothermic state and were allocated equally to 2 groups: KHB-Alb vs CHIP. Physiological parameters, cytokine profiles, and edema formation were compared between treatment groups.

RESULTS

Perfused lungs in both groups demonstrated equivalent oxygenation (partial pressure of arterial oxygen/fraction of inspired oxygen ratio >350 mm Hg) and physiological parameters. There was equivalent generation of tumor necrosis factor-α and IL-6, irrespective of perfusate solution used, when comparing CHIP vs KHB-Alb. Pig lungs developed equivalent edema formation between groups (CHIP: 15.8 ± 4.8%, KHB-Alb 19.5 ± 4.4%, P > .05).

CONCLUSION

A perfusate derived of common hospital ingredients provides equivalent results to a standard Krebs-Henseleit buffer with 8% serum albumin-based perfusate in NPV-EVLP.

Conjugating homogenized liver-extracellular matrix into decellularized hepatic scaffold for liver tissue engineering

The generation of a transplantable liver scaffold is crucial for the treatment of end-stage liver failure. Unfortunately, decellularized liver scaffolds suffer from lack of bioactive molecules and functionality. In this study, we conjugated homogenized liver-extracellular matrix (ECM) into a decellularized liver in a rat model to improve its structural and functional properties. The homogenized ECM was prepared, characterized, and subsequently perfused into ethyl carbodiimide hydrochloride (EDC)/N-hydroxysuccinimide (NHS) activated liver scaffolds. Various techniques were performed to confirm the improvements that were accomplished through the conjugation process; these included micro/ultra-structural analyses, biochemical analysis of ECM components, DNA quantification, swelling ratio, structural stability, calcification properties, platelet activation study, static and dynamic seeding with EAhy926 endothelial cells and HepG2 hepatocarcinoma cells, subcutaneous implantation and intrahepatic transplantation. The results showed that the conjugated scaffolds have superior micro- and ultrastructural and biochemical characteristics. In addition, DNA contents, swelling ratios, calcification properties, platelet reactions, and host inflammatory reactions were not altered with the conjugation process. The conjugated scaffolds revealed better cellular spreading and popularity compared to the non-conjugated scaffolds. Intrahepatic transplantation showed that the conjugated scaffold had higher popularity of hepatic regenerative cells with better angiogenesis. The conjugation of the decellularized liver scaffold with homogenized liver-ECM is a promising tool to improve the quality of the generated scaffold for further transplantation.

Evaluating Deceased Donor Registries: Identifying Predictive Factors of Donor Designation

The objectives of this study were to evaluate and compare the performance of the deceased donor registries of the 50 states and the District of Columbia and to identify possible predictive factors of donor designation. Data were collected retrospectively by Donate Life America using a questionnaire sent to Donor Designation Collaborative state teams between 2007 and 2010. By the end of 2010, there were 94,669,081 designated donors nationwide. This accounted for 39.8 per cent of the U.S. population aged 18 years and over. The number of designated organ donors and registry-authorized recovered donors increased each year; however, the total number of recovered donors in 2010 was the lowest since 2004. Donor designation rate was significantly higher when license applicants were verbally questioned at the Department of Motor Vehicles (DMV) regarding their willingness to register as a donor and when DMV applicants were not given an option on DMV application forms to contribute money to support organ donation, compared with not being questioned verbally, and being offered an option to contribute money. State registries continue to increase the total number of designated organ donors; however, the current availability of organs remains insufficient to meet the demand. These data suggest that DMV applicants who are approached verbally regarding their willingness to register as a donor and not given an option on DMV application forms to contribute money to support organ donation might be more likely to designate themselves to be a donor.

A Randomized Controlled Trial of Naloxone for Optimization of Hypoxemia in Lung Donors After Brain Death

BACKGROUND

Persistent hypoxemia is the principal reason lungs from otherwise eligible brain dead (BD) organ donors are not transplanted. Experimental models and retrospective studies have suggested that naloxone attenuates neurogenic pulmonary edema and reverses hypoxemia after brain death. We undertook a multisite, randomized, placebo-controlled trial to evaluate whether naloxone is able to improve oxygenation in BD donors with hypoxemia.

METHODS

BD organ donors at 4 organ procurement organizations were randomized in a blinded manner to naloxone 8 mg or saline placebo if lung were being considered for allocation but exhibited hypoxemia (partial pressure of oxygen in arterial blood to fraction of inspired oxygen ratio [PFR] below 300 mm Hg). The primary outcome was change in PFR from baseline to final arterial blood gas. Secondary outcomes included early improvement in PFR and proportion of lungs transplanted.

RESULTS

A total of 199 lung-eligible BD donors were randomized to naloxone (n = 98) or placebo (n = 101). Groups were comparable at baseline. Both groups exhibited similar improvements in oxygenation (median improvement in PFR of 81 with naloxone versus 80 with saline, P = 0.68), with 37 (39%) versus 38 (40%) exhibiting reversal of hypoxemia. There was no difference in the rate of lungs transplanted (19% in both groups, P = 0.97) although it was significantly higher in those with reversal of hypoxemia (32/69 versus 2/111, P < 0.001).

CONCLUSIONS

Naloxone does not improve oxygenation more than placebo in hypoxemic organ donors. However, reversal of hypoxemia was a powerful predictor of lung utilization regardless of drug therapy. Further organ procurement organization-led research is needed to assess optimal interventions to improve oxygenation in BD donors with hypoxemia.

Deceased Brain Dead Donor Liver Transplantation and Utilization in the United States: Nighttime and Weekend Effects

BACKGROUND

Understanding factors that contribute to liver discards and nonusage is urgently needed to improve organ utilization.

METHODS

Using Scientific Registry of Transplant Recipient data, we studied a national cohort of all US adult, deceased brain dead donor, isolated livers available for transplantation from 2003 to 2016, including organ-specific and system-wide factors that may affect organ procurement and discard rates.

RESULTS

Of 73 686 available livers, 65 316 (88.64%) were recovered for transplant, of which 6454 (9.88%) were ultimately discarded. Livers that were not procured or, on recovery, discarded were more frequently from older, heavier, hepatitis B virus (HCV)+, and more comorbid donors (P < 0.001). However, even after adjustment for organ quality, the odds of liver nonusage were 11% higher on the weekend (defined as donor procurements with cross-clamping occurring from 5:00 PM Friday until 11:59 AM Sunday) compared with weekdays (P < 0.001). Nonuse rates were also higher at night (P < 0.001), defined as donor procurements with cross-clamping occurring from 5:00 PM to 5:00 AM; however, weekend nights had significantly higher nonuse rates compared with weekday nights (P = 0.005). After Share 35, weekend nonusage rates decreased from 21.77% to 19.51% but were still higher than weekday nonusage rates (P = 0.065). Weekend liver nonusage was higher in all 11 United Network of Organ Sharing regions, with an absolute average of 2.00% fewer available livers being used on the weekend compared with weekdays.

CONCLUSIONS

Although unused livers frequently have unfavorable donor characteristics, there are also systemic and operational factors, including time of day and day of the week a liver becomes available, that impact the chance of liver nonprocurement and discard.

Potential therapeutic targets for lung repair during human ex vivo lung perfusion

Introduction

The ex vivo lung perfusion (EVLP) technique has been developed to assess the function of marginal donor lungs and has significantly increased donor lung utilisation. EVLP has also been explored as a platform for donor lung repair through injury-specific treatments such as antibiotics or fibrinolytics. We hypothesised that actively expressed pathways shared between transplantation and EVLP may reveal common mechanisms of injury and potential therapeutic targets for lung repair prior to transplantation.

Materials and methods

Retrospective transcriptomics analyses were performed with peripheral tissue biopsies from “donation after brain death” lungs, with 46 pre-/post-transplant pairs and 49 pre-/post-EVLP pairs. Pathway analysis was used to identify and compare the responses of donor lungs to transplantation and to EVLP.

Results

22 pathways were enriched predominantly in transplantation, including upregulation of lymphocyte activation and cell death and downregulation of metabolism. Eight pathways were enriched predominantly in EVLP, including downregulation of leukocyte functions and upregulation of vascular processes. 27 pathways were commonly enriched, including activation of innate inflammation, cell death, heat stress and downregulation of metabolism and protein synthesis. Of the inflammatory clusters, Toll-like receptor/innate immune signal transduction adaptor signalling had the greatest number of nodes and was central to inflammation. These mechanisms have been previously speculated as major mechanisms of acute lung injury in animal models.

Conclusion

EVLP and transplantation share common molecular features of injury including innate inflammation and cell death. Blocking these pathways during EVLP may allow for lung repair prior to transplantation.

Extracorporeal membrane oxygenation as a bridge to lung transplantation: analysis of Korean organ transplantation registry (KOTRY) data

BACKGROUND

The use of extracorporeal membrane oxygenation (ECMO) as a bridge to lung transplantation has greatly increased. However, data regarding the clinical outcomes of this approach are lacking. The objective of this multicenter prospective observational cohort study was to evaluate lung transplantation outcomes in Korean Organ Transplantation Registry (KOTRY) patients for whom ECMO was used as a bridge to transplantation.

METHODS

Between March 2015 and December 2017, a total of 112 patients received lung transplantation and were registered in the KOTRY, which is a prospective, multicenter cohort registry. The entire cohort was divided into two groups: the control group (n = 85, 75.9%) and bridge-ECMO group (n = 27, 24.1%).

RESULTS

There were no significant differences in pre-transplant and intraoperative characteristics except for poorer oxygenation, more ventilator use, and longer operation time in the bridge-ECMO group. The prevalence of primary graft dysfunction at 0, 24, 48, and 72 h after transplantation did not differ between the two groups. Although postoperative hospital stays were longer in the bridge-ECMO group than in the control group, hospital mortality did not differ between the two groups (25.9% vs. 13.3%, P = 0.212). The majority of patients (70.4% of the bridge-ECMO group and 77.6% of the control group) were discharged directly to their homes. Finally, the use of ECMO as a bridge to lung transplantation did not significantly affect overall survival and graft function.

CONCLUSIONS

Short- and long-term post-transplant outcomes of bridge-ECMO patients were comparable to recipients who did not receive ECMO.

Airway bacteria of the recipient but not the donor are relevant to post-lung transplant pneumonia

BACKGROUND

Optimal management of early airway infection is essential for the survival of lung transplant (LTx) recipients during the first 12 months after transplantation. This study aimed to explore the main cause of post-lung transplant pneumonia (PLTP) within 30 days after LTx.

METHODS

Forty LTx patients were retrospectively analyzed. Sputum sampling from donors' and recipients' airways was performed pretransplant and posttransplant daily for the first 30 days after LTx. Organisms in the recipient's and donor's original airways were compared to pathogens responsible for PLTP. Patients with and without PLTP were also compared to identify relevant risk factors.

RESULTS

Seventeen (42.5%) patients developed pneumonia (PLTP group) and 23 had no episode of pneumonia (Non-PLTP group) during the first 30 days. In the PLTP group, median time from LTx to PLTP onset was 6 days. A significantly higher incidence of PLTP was caused by recipient's rather than donor's original airway bacteria (62% vs 13%, p < 0.01). Smoking history of the donor and pretransplant airway bacterial colonization of the recipient were independent risk factors of PLTP which was associated with prolonged posttransplant mechanical ventilation with longer intensive care unit stay and worse survival outcomes.

CONCLUSIONS

The recipient's original airway microflora rather than the donor's, was highly associated with PLTP. A combination of donor smoking history and recipient airway infection should be avoided, while evidence of donor lung infection is not a contraindication for LTx.

Criteria to Identify a Potential Deceased Organ Donor: A Systematic Review

OBJECTIVES

To systematically review the global published literature defining a potential deceased organ donor and identifying clinical triggers for deceased organ donation identification and referral.

DATA SOURCES

Medline and Embase databases from January 2006 to September 2017.

STUDY SELECTION

All published studies containing a definition of a potential deceased organ donor and/or clinical triggers for referring a potential deceased organ donor were eligible for inclusion. Dual, independent screening was conducted of 3,857 citations.

DATA EXTRACTION

Data extraction was completed by one team member and verified by a second team member. Thematic content analysis was used to identify clinical criteria for potential deceased organ donation identification from the published definitions and clinical triggers.

DATA SYNTHESIS

One hundred twenty-four articles were included in the review. Criteria fell into four categories: Neurological, Medical Decision, Cardiorespiratory, and Administrative. Distinct and globally consistent sets of clinical criteria by type of deceased organ donation (neurologic death determination, controlled donation after circulatory determination of death, and uncontrolled donation after circulatory determination of death) are reported.

CONCLUSIONS

Use of the clinical criteria sets reported will reduce ambiguity associated with the deceased organ donor identification and the subsequent referral process, potentially reducing the number of missed donors and saving lives globally through increased transplantation.

Prolonged warm ischemia exacerbated acute rejection after lung transplantation from donation after cardiac death in a mouse

OBJECTIVE

In lung transplantation (LTx) from donation after cardiac death (DCD), the donor lungs are inevitably exposed to warm ischemic time (WIT) between the cardiac arrest and the initiation of cold preservation. We conducted this study to examine the effect of prolonged WIT on lung allograft rejection in a murine model of LTx from DCD.

METHODS

Allogeneic BALB/c → B6 LTx from DCD was performed with a WIT of 15 min (WIT15 group, n = 5) or 60 min (WIT60 group, n = 5). Recipients were immunosuppressed by perioperative costimulatory blockade. The lung allografts were analyzed by histology and flow cytometry on day 7 after the LTx.

RESULTS

Histologically, the rejection grade in the WIT60 group was significantly higher than that in the WIT15 group (3.4 ± 0.4 vs. 2.2 ± 0.2, P = 0.0278). Moreover, the intragraft CD8+ to CD4+ T cell ratio in the WIT60 group was significantly higher than that in the WIT15 group (2.3 ± 0.12 vs. 1.2 ± 0.11, P < 0.0001).

CONCLUSIONS

Prolonged WIT could exacerbate the severity of lung allograft rejection after LTx from DCD. Minimization of the WIT could improve the outcomes after LTx from DCD.

Transplanting kidneys from donors with small renal masses - a strategy to expand the donor pool

INTRODUCTION

Renal transplantation is the optimal treatment for end-stage renal disease, but organ demand continues to outstrip supply. The transplantation of kidneys from donors with small renal masses (SRMs) represents a potential avenue to expand the donor pool. We reviewed all published cases of transplants from donors with SRMs and we present followup data, best practices, and outline an actionable series of steps to guide the implementation of such transplants at individual centers.

METHODS

A detailed literature search of the MEDLINE/PubMed and SCOPUS databases was performed. Thirty unique data sets met inclusion criteria and described the transplantation of tumor-ectomized kidneys; nine data sets described the transplantation of contralateral kidneys from donors with SRMs.

RESULTS

A total of 147 tumorectomized kidneys have been transplanted. Pathology revealed 120 to be renal cell carcinomas (RCCs), of which 116 were stage T1a (0.3-4 cm). The mean followup time was 44.2 months (1-200). A single suspected tumor recurrence occurred in one patient nine years post-transplantation and it was managed with active surveillance. Twenty-seven kidneys have been transplanted from deceased donors with contralateral renal masses. Pathology revealed 25 to be RCCs, of which 19 were confirmed to be stage T1 (<7 cm). The mean followup time was 46.7 months (0.5-155). One recipient developed an RCC and underwent curative allograft nephrectomy.

CONCLUSIONS

Careful use of kidneys from donors with SRMs is feasible and safe, with an overall recurrence rate of less than 1.5%. The use of such kidneys could help alleviate the organ shortage crisis.

Application of 3-Dimensional Printing in Pediatric Living Donor Liver Transplantation: A Single-Center Experience

Three-dimensional (3D) printing has been used to support organ transplantations. However, whether it helps remains unclear. This study aimed to present and assess the application of 3D-printed liver models in pediatric living donor liver transplantation (LDLT). The 3D images were printed to touchable liver models with transparent liver parenchyma, specifically colored hepatic vessels, and biliary structures. A total of 30 consecutive recipients were enrolled in the study: 10 were operated on with the support of 3D printing (3D-printing group) and 20 (control group) were operated on without it. Detailed photographs and data of the cases in the 3D-printing group were presented. One patient underwent auxiliary partial orthotopic liver transplantation using the left lobe graft, in which the abdominal cavity model was also printed to test whether the planned graft fit the recipient's abdominal cavity. The 3D-printed models facilitated surgical planning and procedures, particularly in the management of hepatic veins and in the prevention of large-for-size syndrome. The operative time of donors in the 3D-printing group was significantly shorter compared with the control group (2.3 ± 0.4 versus 3.0 ± 0.4 hours; P < 0.001). Inpatient costs for donors in the 3D-printing group were 17.1% lower than those in the control group (34.6 ± 6.6 versus 41.7 ± 10.4 thousand ¥; P = 0.03). In conclusion, in small infants and complicated pediatric LDLT patients, 3D-printed models can help minimize the risk of large-for-size syndrome and graft reduction. The 3D-printed models may be conducive to liver graft procurement and intraoperative assistance in pediatric LDLT.

Development of an immunodeficient pig model allowing long-term accommodation of artificial human vascular tubes

Before they are used in the clinical setting, the effectiveness of artificially produced human-derived tissue-engineered medical products should be verified in an immunodeficient animal model, such as severe combined immunodeficient mice. However, small animal models are not sufficient to evaluate large-sized products for human use. Thus, an immunodeficient large animal model is necessary in order to properly evaluate the clinical efficacy of human-derived tissue-engineered products, such as artificial grafts. Here we report the development of an immunodeficient pig model, the operational immunodeficient pig (OIDP), by surgically removing the thymus and spleen, and creating a controlled immunosuppressive protocol using a combination of drugs commonly used in the clinical setting. We find that this model allows the long-term accommodation of artificial human vascular grafts. The development of the OIDP is an essential step towards a comprehensive and clinically relevant evaluation of human cell regeneration strategies at the preclinical stage.

The development of tissue-engineered vascular grafts heavily relies on the availability of large animal models that allow long-term assessment of graft patency. Here Itoh et al. propose a novel model of immunodeficient pigs that allows long-term accommodation of human cell-derived three-dimensional bioprinted vascular tubes.

Introducing of the First DCD Kidney Transplantation Program in Poland

In many countries, including Poland, the main problem with transplantation is the insufficiency of organ donors in relation to the demand for organs. Hence, the common aim globally is to increase the pool of donors. The prolonged survival of patients after transplantation, with respect to the survival time of patients on dialysis, makes the search much more intense. After the recourse of expanded criteria donors (ECD), the next step was obtaining kidneys from donors after irreversible cardiac death (DCD). Therefore, based on Dutch, British, and Spanish experience, it can be hypothesized that the introduction of DCD procedures in countries that have not launched these programs and the improvement of DCD procedures may shorten the waiting time for organ transplantation globally. The legal basis for the procurement of organs after irreversible cardiac arrest came into existence in Poland in 2010. Previously, such organ procurements were not in practice. Since 1984, when Poland published irreversible cardiac arrest as a criterion of brain death, it became the only way to determine death prior to the procurement of organs. The aim of this report was to evaluate the results of the first 19 transplantation cases involving harvested kidneys from donors after cardiac arrest, which was irreversible and clinically confirmed, without any doubt as per the ethical protocol of DCD. Understanding, support, and public perception are essential for this program's initiation and maintenance.

Repopulation of intrahepatic bile ducts in engineered rat liver grafts

Engineered liver grafts for transplantation with sufficient hepatic function have been developed both in small and large animal models using the whole liver engineering approach. However, repopulation of the bile ducts in the whole liver scaffolds has not been addressed yet. In this study, we show the feasibility of repopulating the bile ducts in decellularized rat livers. Biliary epithelial cells were introduced into the bile ducts of the decellularized liver scaffolds with or without hepatocytes in the parenchymal space. The recellularized grafts were cultured under perfusion for up to 2 days and histological analysis revealed that the biliary epithelial cells formed duct-like structures, with the viable hepatocyte mass residing in the parenchymal space, in an arrangement highly comparable to the native tissue. The grafts were viable and functional as confirmed by both albumin and urea assay results and the gene expression analysis of biliary epithelial cells in recellularized liver grafts. This study provides the proof-of-concept results for rat liver grafts co-populated with parenchymal and biliary epithelial cells.

Medical Management of Brain-Dead Organ Donors

With improving healthcare services, the demand for organ transplants has been increasing daily worldwide. Deceased organ donors serve as a good alternative option to meet this demand. The first step in this process is identifying potential organ donors. Specifically, brain-dead patients require aggressive and intensive care from the declaration of brain death until organ retrieval. Currently, there are no specific protocols in place for this, and there are notable variations in the management strategies implemented across different transplant centers. Some transplant centers follow their own treatment protocols, whereas other countries, such as Bangladesh, do not have any protocols for potential organ donor care. In this review, we discuss how to identify brain-dead donors and describe the physiological changes that occur following brain death. We then summarize the management of brain-dead organ donors and, on the basis of a review of the literature, we propose recommendations for a treatment protocol to be developed in the future.