Design, Analysis, and Pitfalls of Clinical Trials Using Ex Situ Liver Machine Perfusion: The International Liver Transplantation Society Consensus Guidelines.

BACKGROUND: Recent trials in liver machine perfusion (MP) have revealed unique challenges beyond those seen in most clinical studies. Correct trial design and interpretation of data are essential to avoid drawing conclusions that may compromise patient safety and increase costs. METHODS: The International Liver Transplantation Society, through the Special Interest Group "DCD, Preservation and Machine Perfusion," established a working group to write consensus statements and guidelines on how future clinical trials in liver perfusion should be designed, with particular focus on relevant clinical endpoints and how different techniques of liver perfusion should be compared. Protocols, abstracts, and full published papers of clinical trials using liver MP were reviewed. The use of a simplified Grading of Recommendations Assessment, Development, and Evaluation working group (GRADE) system was attempted to assess the level of evidence. The working group presented its conclusions at the International Liver Transplantation Society consensus conference "DCD, Liver Preservation, and Machine Perfusion" held in Venice, Italy, on January 31, 2020. RESULTS: Twelve recommendations were proposed with the main conclusions that clinical trials investigating the effect of MP in liver transplantation should (1) make the protocol publicly available before the start of the trial, (2) be adequately powered, and (3) carefully consider timing of randomization in function of the primary outcome. CONCLUSIONS: There are issues with using accepted primary outcomes of liver transplantation trials in the context of MP trials, and no ideal endpoint could be defined by the working group. The setup of an international registry was considered vital by the working group.

The Impact of Portal Vein Thrombosis on Liver Transplant Outcomes: Does Grade or Flow Rate Matter?

BACKGROUND: Portal vein thrombosis (PVT) makes the technical aspect of liver transplantation challenging and also affects outcomes. Our aim was to study impact of PVT grade and postreperfusion portal flow on posttransplant outcomes. METHODS: Patients who underwent transplantation with PVT between January 2007 and May 2017 were selected (n = 126). Data on grade of PVT and portal vein flow were collected. Patients were classified into 2 groups; low grade (Yerdel Grade I, n = 73) and high grade (Yerdel Grade II or III, n = 53). Using portal flow rate, patients were divided into high flow (≥1000 mL/min, n = 95) and low flow (<1000 mL/min, n = 31). Additional analyses of flow by graft weight and complications were performed. RESULTS: Postoperatively, incidence of biliary strictures were significantly greater in high-grade PVT compared with low grade (P = 0.02). Incidence of postoperative portal vein thrombosis was higher in low flow after reperfusion compared with high flow (P = 0.02), as was bile leak (P = 0.02). On identifying factors associated with graft loss, moderate to severe ascites preoperatively, high PVT grade and bile leak were associated with worse graft survival. Subanalysis performed combining grade and flow showed that low grade, high flow had the highest graft survival while high grade, low flow had the lowest (P = 0.006). High-grade PVT with low flow also appeared to be an independent risk factor for biliary complications (P = 0.01). CONCLUSIONS: In conclusion, biliary complications, especially strictures are more common in high-grade PVT and graft survival is worse in high-grade PVT and low portal flow.

Factors associated with low graft regeneration in the early phase after living donor liver transplantation.

Appropriate graft regeneration after living donor liver transplantation (LDLT) is crucial to avoid small-for-size syndrome. We enrolled 44 recipients who underwent ABO-identical/compatible LDLT from December 2007 to August 2016 and determined possible factors associated with low graft regeneration after LDLT. Liver regeneration was calculated by the ratio of the graft size on postoperative day (POD) 7 ± 1 day (calculated by CT volumetry) to the size of the donated liver at implant. Postoperative outcomes were compared between the low and high regeneration groups. Median regeneration rate was 1.65-fold. Regeneration rate was negatively correlated with graft-to-recipient weight ratio. Postoperative morbidity rates on POD 14-90 were significantly higher in the low group compared with the high group (63% vs 18%, P = .03). Graft and patient survival in the low group were significantly worse than the high group (1-year graft survival 73% vs 100%, P = .002; patient survival 82% vs 100%, P = .01). Cold ischemia time (CIT; per 10 minute; odds ratio [OR] =1.37) and platelet count <60 000/µL on POD 5 (OR = 14.32) were independently associated with low regeneration. In conclusion, longer CIT and postoperative thrombocytopenia were associated with low graft regeneration in the early phase after LDLT, which could consequently lead to poor graft and patient survival.

Brincidofovir as Salvage Therapy for Adenovirus Disease in Intestinal Transplant Recipients.

BACKGROUND: Adenoviruses are double-stranded DNA viruses that typically cause mild self-limiting respiratory, ocular, and gastrointestinal infections. In immunocompromised patients, especially transplant recipients, the infection can be severe, with dissemination and multiorgan failure. In intestinal transplant recipients, the incidence is as high as 57%. To our knowledge, no standardized guidelines or U.S. Food and Drug Administration-approved medications exist for the treatment of adenovirus disease. AIMS: We describe two isolated intestinal transplant recipients who developed adenovirus disease (viremia with viral enteritis) that was managed with a new experimental drug, brincidofovir (an oral lipid conjugate prodrug of cidofovir), as salvage therapy. RESULTS: The first patient was a 44-year-old woman who developed adenoviral enteritis 1 month after transplantation, which resolved with ribavirin therapy. Two weeks later, the infection recurred, and brincidofovir was initiated. While receiving this therapy for 3 months, she developed severe acute rejection, which was managed with rabbit antithymocyte globulin followed by infliximab. Eventually, complete resolution of the rejection and adenoviral enteritis was achieved. At 12 months posttransplantation, the patient was healthy and tolerating enteral feeding. The second patient was a 28-year-old man who had undergone isolated intestinal transplantation 6 years before he presented with generalized weakness and an increased ostomy output; he was diagnosed with adenoviral enteritis. Maintenance immunosuppression was reduced, and brincidofovir was started. The infection resolved with a month of therapy. Six months after the infection, he was healthy and tolerating enteral feeding. CONCLUSION: This is the first publication, to our knowledge, to describe two cases in which brincidofovir was used to successfully treat adenovirus infection in intestinal transplant recipients. Thus, these cases demonstrate that brincidofovir appears to be a safe and effective option in the management of adenoviral enteritis in these patients.

Prediction of biliary anastomotic stricture after deceased donor liver transplantation: the impact of platelet counts - a retrospective study.

Biliary stricture is a common cause of morbidity after liver transplantation (LT). This study aimed to determine the risk factors for post-transplant biliary anastomotic strictures (BAS), focusing on perioperative platelet counts. We enrolled 771 consecutive recipients who underwent ABO-identical/compatible deceased donor LT with duct-to-duct biliary reconstruction from January 2000 to June 2012. BAS was identified in 142 cases. The median time for stricture development was 176 days. Preoperative and postoperative platelet counts within 5 days after LT were significantly lower in patients with BAS than those without BAS. Using cutoff values acquired by the receiver operating characteristic curve analysis, persistent postoperative thrombocytopenia was defined as platelet counts <41 × 1000/µl and <53 × 1000/µl on postoperative day (POD) 3 and POD 5, respectively. Multivariate analysis indicated persistent postoperative thrombocytopenia (OR = 2.38) was the only independent risk factor for BAS. No significant associations were observed in terms of donor and surgical factors. Multivariate analysis demonstrated estimated blood loss (OR = 1.01, per 100 ml) was an independent contributing factor for persistent postoperative thrombocytopenia. We demonstrated low platelet count was associated with progression of post-transplant BAS. Minimizing intraoperative blood loss potentially contributes to maintain post-transplant platelet count, which may reduce incidence of BAS.

Prognostic impact of postoperative low platelet count after liver transplantation.

BACKGROUND: The positive impact of platelets has been recently implicated in liver transplantation (LT). The aim of this study was to determine the risk factors for graft loss and mortality after LT, focusing on perioperative platelet counts. METHODS: We reviewed all deceased donor LT from 2000 to 2012 and enrolled 975 consecutive recipients. The risk factors for graft loss and mortality were analyzed by multivariate analysis, using Cox's regression model. RESULTS: Using cutoff values acquired by receiver operating characteristics curve analysis, multivariate analyses determined that viral hepatitis C (hazard ratio [HR]=1.32), donor age >40 (HR=1.33), higher peak serum alanine aminotransferase (HR=1.01), reoperation within 30 days (HR=1.51), and platelet count <72 500/µL on postoperative day (POD) 5 (HR=1.30) were independent risk factors for graft loss. Viral hepatitis C (HR=1.33), reoperation within 30 days (HR=1.35), and platelet count <72 500/µL on POD 5 (HR=1.38) were independent risk factors for mortality. CONCLUSION: A low platelet count on POD 5 was associated with graft loss and mortality after LT. Platelet count <72 500/µL on POD 5 can be a predictor of poor graft and overall survival. Maintaining higher postoperative platelet counts could potentially improve graft and overall survival rates.

Continuous Quadrupole Magnetic Separation of Islets during Digestion Improves Purified Porcine Islet Viability.

Islet transplantation (ITx) is an emerging and promising therapy for patients with uncontrolled type 1 diabetes. The islet isolation and purification processes require exposure to extended cold ischemia, warm-enzymatic digestion, mechanical agitation, and use of damaging chemicals for density gradient separation (DG), all of which reduce viable islet yield. In this paper, we describe initial proof-of-concept studies exploring quadrupole magnetic separation (QMS) of islets as an alternative to DG to reduce exposure to these harsh conditions. Three porcine pancreata were split into two parts, the splenic lobe (SPL) and the combined connecting/duodenal lobes (CDL), for paired digestions and purifications. Islets in the SPL were preferentially labeled using magnetic microparticles (MMPs) that lodge within the islet microvasculature when infused into the pancreas and were continuously separated from the exocrine tissue by QMS during the collection phase of the digestion process. Unlabeled islets from the CDL were purified by conventional DG. Islets purified by QMS exhibited significantly improved viability (measured by oxygen consumption rate per DNA, p < 0.03) and better morphology relative to control islets. Islet purification by QMS can reduce the detrimental effects of prolonged exposure to toxic enzymes and density gradient solutions and substantially improve islet viability after isolation.

When Do DCD Donors Die?: Outcomes and Implications of DCD at a High-volume, Single-center OPO in the United States.

OBJECTIVE: The objective of this study was to determine the fate of patients who attempted to donate organs after circulatory death (DCD) using a standardized DCD protocol. BACKGROUND: Successful donation is not always possible after attempted DCD. METHODS: Data were collected for all DCD donors between 1/2011 and 9/2014. DCDs were carried out using a uniform protocol at a single-center organ procurement organization. RESULTS: During the timeframe considered, DCD donation was attempted in 169 patients. In 46 patients (27.2%), no organs were recovered because the patients did not die within 2 hours. Successful donation was more likely if withdrawal of support occurred in the operating room versus the intensive care unit (P = 0.006). Time from extubation to death was available for 161/169 donors (95.3%). Of 161 donors, 111 (66.9%) died in under 1 hour. The mean time from withdrawal of support to patient death for unsuccessful donations was 33 hours, 37 minutes (range, 24 minutes-242 hours) versus 29 minutes (range, 5 minutes-2 hours, 4 minutes) for successful donations. Twenty-seven patients who unsuccessfully donated (67.5%) died within 24 hours. Were unsuccessful donations converted to successful donations, as many as 837 abdominal transplants could have been carried out in the United States, during the study period. CONCLUSIONS: DCD is an important form of organ donation. A large number of abdominal transplants are not possible due to unsuccessful DCD organ donation. It may be useful to explore DCD donor family satisfaction to identify other options for improving DCD donation.

Temperature profiles of different cooling methods in porcine pancreas procurement.

Porcine islet xenotransplantation is a promising alternative to human islet allotransplantation. Porcine pancreas cooling needs to be optimized to reduce the warm ischemia time (WIT) following donation after cardiac death, which is associated with poorer islet isolation outcomes. This study examines the effect of four different cooling Methods on core porcine pancreas temperature (n = 24) and histopathology (n = 16). All Methods involved surface cooling with crushed ice and chilled irrigation. Method A, which is the standard for porcine pancreas procurement, used only surface cooling. Method B involved an intravascular flush with cold solution through the pancreas arterial system. Method C involved an intraductal infusion with cold solution through the major pancreatic duct, and Method D combined all three cooling Methods. Surface cooling alone (Method A) gradually decreased core pancreas temperature to <10 °C after 30 min. Using an intravascular flush (Method B) improved cooling during the entire duration of procurement, but incorporating an intraductal infusion (Method C) rapidly reduced core temperature 15-20 °C within the first 2 min of cooling. Combining all methods (Method D) was the most effective at rapidly reducing temperature and providing sustained cooling throughout the duration of procurement, although the recorded WIT was not different between Methods (P = 0.36). Histological scores were different between the cooling Methods (P = 0.02) and the worst with Method A. There were differences in histological scores between Methods A and C (P = 0.02) and Methods A and D (P = 0.02), but not between Methods C and D (P = 0.95), which may highlight the importance of early cooling using an intraductal infusion. In conclusion, surface cooling alone cannot rapidly cool large (porcine or human) pancreata. Additional cooling with an intravascular flush and intraductal infusion results in improved core porcine pancreas temperature profiles during procurement and histopathology scores. These data may also have implications on human pancreas procurement as use of an intraductal infusion is not common practice.

Antihypertensive pharmacotherapy and long-term outcomes in pediatric kidney transplantation.

Hypertension (HTN) is common in pediatric recipients following kidney transplantation (KT). We retrospectively assessed the impact of HTN on long-term (>10-yr) outcomes in pediatric KT recipients (aged < 18 yr) at our center. Two hundred and ninety-three pediatric KT recipients (83% living donor [LD]) with graft survival (GS) for ≥5 yr were studied. HTN was defined by antihypertensive medication use at five yr post-KT. One hundred and sixty (55%) recipients did not have HTN, and 133 (45%) had HTN at five yr post-KT. There were no differences in actuarial patient survival between cohorts. Actuarial GS at 15 and 20 yr was 68% and 53% for recipients without HTN, and 53% and 33% for recipients with HTN (p = 0.006). Among LD recipients using one antihypertensive, GS at 15 yr was 100% for those using an angiotensin-converting enzyme inhibitor (ACEI) and 44% for those not using an ACEI (p = 0.04). Among these recipients, HTN treated with no ACEI was a significant risk factor for graft failure at >5 yr (hazard ratio [HR] = 2.5, p = 0.02), but HTN treated with an ACEI was not (HR = 0.6, p = 0.7). HTN at five yr post-KT is associated with poorer long-term GS in pediatric recipients, but ACEI therapy may enable better outcomes and should be studied further.

Persufflation (gaseous oxygen perfusion) as a method of heart preservation.

Persufflation (PSF; gaseous oxygen perfusion) is an organ preservation technique with a potential for use in donor heart preservation. Improved heart preservation with PSF may improve outcomes by maintaining cardiac tissue quality in the setting of longer cold ischemia times and possibly increasing the number of donor hearts available for allotransplant. Published data suggests that PSF is able to extend the cold storage times for porcine hearts up to 14 hours without compromising viability and function, and has been shown to resuscitate porcine hearts following donation after cardiac death. This review summarizes key published work on heart PSF, including prospective implications and future directions for PSF in heart transplantation. We emphasize the potential impact of extending preservation times and expanding donor selection criteria in heart allotransplant. Additionally, the key issues that need to be addressed before PSF were to become a widely utilized preservation strategy prior to clinical heart transplantation are summarized and discussed.

Energetic recovery in porcine grafts by minimally invasive liver oxygenation.

BACKGROUND: Gaseous insufflation of oxygen via the venous vascular system has proven to be an effective tool for preventing anoxic tissue injury after extended time periods of ischemic liver preservation. Most experimental studies so far have been undertaken in rat models and include a series of pinpricks into postsinusoidal venules as an outlet for the insufflated gas. Here, we describe a simplified technique for minimally invasive liver oxygenation in porcine grafts, representing a hassle-free access to organ oxygenation without vascular lesions. METHODS: We retrieved livers from Landrace pigs and cold-stored them in histidine-tryptophan-ketoglutarate solution. Subsequent to 18 h preservation, we treated some livers for an additional 2 h with gaseous oxygen, insufflated via silicone tubing inserted into the suprahepatic caval vein. Gas pressure was limited to 18 mm Hg. We occluded the infrahepatic caval vein with a bulldog clamp. Gas bubbles left the graft via the portal vein. We assessed liver integrity by energetic tissue status and by controlled in vitro reperfusion with autologous blood. RESULTS: Magnetic resonance imaging demonstrated homogeneous gas distribution in the persufflated tissue without major shunting. Biochemical analyses revealed effective and homogeneous restoration of energetic homeostasis in the ischemic graft before reperfusion. Sinusoidal endothelial clearance of hyaluronic acid was significantly improved upon reperfusion, as was hepatic arterial flow. Parenchymal enzyme loss was concordantly mitigated after minimally invasive liver oxygenation. CONCLUSIONS: Our results indicate that gaseous oxygen persufflation of the porcine liver is possible without tissue trauma, and significantly enhances post-preservation recovery of the graft.

Persufflation (or gaseous oxygen perfusion) as a method of organ preservation.

Improved preservation techniques have the potential to improve transplant outcomes by better maintaining donor organ quality and by making more organs available for allotransplantation. Persufflation, (PSF, gaseous oxygen perfusion) is potentially one such technique that has been studied for over a century in a variety of tissues, but has yet to gain wide acceptance for a number of reasons. A principal barrier is the perception that ex vivo PSF will cause in vivo embolization post-transplant. This review summarizes the extensive published work on heart, liver, kidney, small intestine and pancreas PSF, discusses the differences between anterograde and retrograde PSF, and between PSF and other conventional methods of organ preservation (static cold storage, hypothermic machine perfusion). Prospective implications of PSF within the broader field of organ transplantation, and in the specific application with pancreatic islet isolation and transplant are also discussed. Finally, key issues that need to be addressed before PSF becomes a more widely utilized preservation strategy are summarized and discussed.

Ten-year outcome after rapid discontinuation of prednisone in adult primary kidney transplantation.

BACKGROUND AND OBJECTIVES: Rapid discontinuation of prednisone after kidney transplantation potentially allows for minimization of steroid-related side effects. Although intermediate-term data with rapid discontinuation of prednisone have been promising, concern still exists regarding long-term outcomes. The 10-year experience is reported herein. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Between October 1, 1999 and December 31, 2010, 1241 adult primary kidney transplants (791 living donor and 450 deceased donor) were performed using a protocol in which prednisone is discontinued after postoperative day 5. The 10-year actuarial recipient and graft survival rates and prednisone-related side effects were studied. RESULTS: Ten-year actuarial patient survival was 71% for living donor transplants and 62% for deceased donor transplants; 10-year graft survival was 61% for living donor transplants and 51% for deceased donor transplants, and was comparable to 10-year Scientific Registry of Transplant Recipients national data. Ten-year death-censored graft survival was 79% for living donor transplants and 80% for deceased donor transplants. Ten-year acute rejection rates were 25% for deceased donor transplants and 31% for living donor transplants; 10-year chronic rejection (interstitial fibrosis/tubular atrophy) rates were 39% for deceased donor transplants and 47% for living donor transplants. For nondiabetic recipients of living donor or deceased donor allografts, the incidence of new-onset diabetes was significantly lower than in historical controls on prednisone (P<0.001). We also found significantly reduced rates of cataracts, avascular necrosis, and cytomegalovirus infection in some subgroups. CONCLUSIONS: Prednisone-related side effects can be minimized in a protocol incorporating rapid discontinuation of prednisone for maintenance immunosuppression. Ten-year patient and graft outcomes remain acceptable.

Outcome of living kidney donors left with multiple renal arteries.

Individuals with kidneys having ≥ 2 arteries appear to have an increased incidence of hypertension. Whether kidney donors in whom the remaining kidney has ≥ 2 arteries are at increased risk of hypertension is unknown. Therefore, we studied 3685 kidney donors to determine whether donors left with a kidney having ≥ 2 arteries were at increased risk of hypertension, impaired renal function, or death. Cohorts were assigned based on our practice pattern and the anatomy of the donated kidney. Of the 3685 donors, 1211 were estimated to have a remaining kidney with ≥ 2 arteries. Mean follow-up time for the single-artery group was 14.1 (± 11.0) yr and 15.3 (± 11.2) yr for the ≥ 2 artery group. Six-month hospital readmission rate was 1.4% and 1.2%, hypertension was noted in 22.4% and 21.8% and proteinuria in 9.7% and 9.6%, and estimated glomerular filtration rate at last follow-up was 62 (± 28) and 62 (± 16) for single vs. ≥ 2 renal artery groups, respectively. Our data suggest no adverse clinical sequelae nor any decrease in long-term survival for donors left with a kidney having ≥ 2 renal arteries.

Paramagnetic microparticles do not elicit islet cytotoxicity with co-culture or host immune reactivity after implantation.

BACKGROUND: Paramagnetic microparticles (MPs) may be useful in pancreatic islet purification, in particular purification of porcine islets as a potential xenotransplantation product. We assessed whether MPs affect islet function or induce an adverse effect following implantation. METHODS: Porcine islets were co-cultured with 0, 500, and 1500 MPs per islet equivalent (IE) for 1 day and with 0 and 1500 MPs/IE for 7 days. Fractional viability was assessed using oxygen consumption rate normalized to DNA content (OCR/DNA) and after 7-day co-culture by perifusion glucose-stimulated insulin secretion (GSIS) and by transplantation under the renal capsule of diabetic nude mice. To assess an inflammatory response or immune reaction, MPs (∼10(7)) were implanted under the renal capsule of C57BL/6 mice. RESULTS: No statistically significant differences were measured in OCR/DNA (mean ± SE) following 1-day co-culture with 0, 500, or 1500 MPs/IE (243.3 ± 4.5, 211.3 ± 8.1, or 230.6 ± 11.3 nmol/min·mgDNA, respectively) or following 7-day co-culture with 0 or 1500 MPs/IE (248.5 ± 1.4 or 252.9 ± 4.7 nmol/min·mgDNA, respectively). GSIS was not affected by the presence of MPs; first- and second-phase insulin area-under-the-curve (mean ± SE) reflected no statistically significant differences after 7-day co-culture between 0 and 1500 MPs/IE (8.36 ± 0.29 and 8.45 ± 0.70 pg/ml·min·ngDNA for first-phase; 69.73 ± 2.18 and 65.70 ± 4.34 pg/ml·min·ngDNA for second-phase, respectively). Islets co-cultured with MPs normalized hyperglycemia in diabetic nude mice, suggesting no adverse effects on in vivo islet function. Implantation of MPs did not elicit tissue injury, inflammatory change or immune reactivity. CONCLUSION: MPs do not adversely affect islet viability or function during co-culture, and MPs are not immune reactive following implantation.

Consideration of donor age and human leukocyte antigen matching in the setting of multiple potential living kidney donors.

BACKGROUND: Defining living donor (LD)-related risk factors affecting kidney transplant outcome will allow better donor selection and more educated informed consent when there is more than one potential donor. We studied risk factors in a large cohort at a single institution. METHODS: We reviewed 1632 recipients who underwent LD kidney transplantation at the University of Minnesota between January 1, 1990, and October 1, 2009. Using Cox regression, we studied the effect of donor and recipient risk factors on patient and graft survival. We specifically examined the effect of donor age and human leukocyte antigen (HLA) matching because these are variables that may help clinical decision making when multiple potential donors exist. RESULTS: Mean donor age was 40.6 years for all transplants; 180 (11%) donors were 55 years or older, and 24 (1.5%) donors were older than 65 years. Mean number of HLA mismatches (per transplant) was 2.9 (29.2% of recipients had one to two HLA mismatches, 39.8% had three to four HLA mismatches, and 25% had five to six HLA mismatches). Donor age more than 65 years, five to six HLA mismatches, delayed graft function, and acute rejection were independent predictors of decreased patient and graft survival. When controlling for recipient age, donor age more than 65 years remained a risk factor for worse outcome. CONCLUSIONS: Our data suggest that advanced donor age (>65 years) and degree of HLA mismatch (≥5) are independent donor-related risk factors associated with worse outcome. When multiple potential LDs exist, it may be ideal to attempt to use a donor younger than 65 years and with less than five HLA mismatches.