Impact of Portable Normothermic Machine Perfusion for Liver Transplantation From Adult Deceased Donors.

OBJECTIVE: To assess how liver allografts preserved using portable normothermic machine perfusion (NMP) compare against those that underwent ischemic cold storage (ICS) in the setting of donation after brain death (DBD) and donation after circulatory death (DCD) liver transplantation (LT). BACKGROUND: Compared with conventional ICS, NMP may offer more homeostatic preservation, permit physiological assessment of organ function, and provide opportunities for graft improvement/modification. We report a single-center US experience of liver NMP. METHODS: A single-center, retrospective analysis of collected data on 541 adult whole LTs from 469 DBD donors [NMP (n = 58) vs ICS (n = 411)] and 72 DCD donors [NMP (n = 52) vs ICS (n = 20)] between January 2016 and December 2022. RESULTS: In DBD LT, male sex [odds ratio (95% CI): 1.83 (1.08-3.09)] and >10% macrosteatosis of the donor liver [1.85 (1.10-3.10)] were statistically significant independent risk factors of early allograft dysfunction (EAD). Donor age >40 years and cold ischemia time >7 hours were independent risk factors of reperfusion syndrome (RPS). One-year, 3-year, and 5-year incidences of ischemic cholangiopathy (IC) did not differ significantly in DBD cases between the NMP and ICS cohorts. In DCD LT, NMP was an independent protective factor against EAD [0.11 (0.03-0.46)] and RPS [0.04 (0.01-0.25)]. The incidence of IC in the DCD cases at 1-year and 3-year time points was significantly lower in the NMP cohort (1.9% compared with 20% in the ICS group). CONCLUSIONS: Compared with conventional ICS, NMP can significantly reduce the incidence of EAD, RPS, and IC after DCD LT.

Donor antigen-specific regulatory T cell administration to recipients of live donor kidneys: A ONE Study consortium pilot trial.

Regulatory T cells (Tregs) can inhibit cellular immunity in diverse experimental models and have entered early phase clinical trials in autoimmunity and transplantation to assess safety and efficacy. As part of the ONE Study consortium, we conducted a phase I-II clinical trial in which purified donor antigen reactive (dar)-Tregs (CD4+CD25+CD127lo) were administered to 3 patients, 7 to 11 days after live donor renal transplant. Recipients received a modified immunosuppression regimen, without induction therapy, consisting of maintenance tacrolimus, mycophenolate mofetil, and steroids. Steroids were weaned off over 14 weeks. No rejection was seen on any protocol biopsy. Therefore, all patients discontinued mycophenolate mofetil 11 to 13 months posttransplant, per protocol. An early for-cause biopsy in 1 patient, 5 days after dar-Treg infusion, revealed absence of rejection and accumulation of Tregs in the kidney allograft. All patients had Treg-containing lymphoid aggregates evident on protocol biopsies performed 8 months posttransplant. The patients are now all >6 years posttransplant on tacrolimus monotherapy with excellent graft function. None experienced rejection episodes. No serious adverse events were attributable to Treg administration. These results support a favorable safety profile of dar-Tregs administered early after renal transplant, suggest early biopsy might be an instructive research endpoint and provide preliminary evidence of potential immunomodulatory activity.

Ex vivo generation of regulatory T cells from liver transplant recipients using costimulation blockade.

The potential of adoptive cell therapy with regulatory T cells (Tregs) to promote transplant tolerance is under active exploration. However, the impact of specific transplant settings and protocols on Treg manufacturing is not well-delineated. Here, we compared the use of peripheral blood mononuclear cells (PBMCs) from patients before or after liver transplantation to the use of healthy control PBMCs to determine their suitability for Treg manufacture using ex vivo costimulatory blockade with belatacept. Despite liver failure or immunosuppressive therapy, the capacity for Treg expansion during the manufacturing process was preserved. These experiments did not identify performance or quality issues that disqualified the use of posttransplant PBMCs-the currently favored protocol design. However, as Treg input correlated with output, significant CD4-lymphopenia in both pre- and posttransplant patients limited Treg yield. We therefore turned to leukapheresis posttransplant to improve absolute yield. To make deceased donor use feasible, we also developed protocols to substitute splenocytes for PBMCs as allostimulators. In addition to demonstrating that this Treg expansion strategy works in a liver transplant context, this preclinical study illustrates how characterizing cellular input populations and their performance can both inform and respond to clinical trial design and Treg manufacturing requirements.

Assessing accuracy of estimated dry weight in dialysis patients post transplantation: the kidney knows best.

INTRODUCTION: Estimated dry weight is used to guide fluid removal during outpatient hemodialysis sessions. Errors in estimated dry weight can result in intradialytic hypotension and interdialytic fluid overload. The goal of this study was to assess the accuracy of estimated dry weight by comparing it to the 2-week post-transplant weight in two cohorts of hemodialysis patients. METHODS: This observational, multi-center, retrospective cohort study included maintenance hemodialysis patients who underwent kidney transplantation at two medical centers in Massachusetts. The relationship between estimated dry weight pre-transplant and weight at week 2 post-transplant in patients with good allograft function (serum creatinine ≤ 1.5 mg/dL) was analyzed. Estimated dry weight was considered accurate if it was within ± 2% of the week 2 post-transplant weight. RESULTS: Fifty seven patients with good allograft function were identified: mean age 54 ± 14 years, 32 (58%) from deceased donors, 22 (38.6%) females. 38 were Caucasian (66.7%), 11 Hispanic (19.3%), 3 black (5.3%), and 5 others (8.8%). 2-week mean post transplantation serum creatinine was 1.2 ± 0.2 mg/dL. Mean (SD) estimated dry weight was 71.4 ± 15.9. Before transplantation, only 14 (24.6%) patients were within ± 2% of the 2-week post-transplant weight; 23 (40.3%) were above and 20 (35.1%) were below. CONCLUSIONS: Our point of view, based on the assumption that the weight of patients with good allograft function at 2 weeks post-transplant approaches their accurate dry weight, is that a majority of maintenance hemodialysis patients (75.4%) are hypervolemic or hypovolemic prior to renal transplantation. This highlights the importance of finding novel tools to achieve euvolemia in patients undertaking dialysis. Timely feedback regarding achieved weight 2 weeks post-transplant to treating nephrologists and dialysis centers may be a starting point for assessing accuracy of dry weight.

Peritransplant Energy Changes and Their Correlation to Outcome After Human Liver Transplantation.

BACKGROUND: The ongoing shortage of donor livers for transplantation and the increased use of marginal livers necessitate the development of accurate pretransplant tests of viability. Considering the importance energy status during transplantation, we aimed to correlate peritransplant energy cofactors to posttransplant outcome and subsequently model this in an ex vivo setting. METHODS: Sequential biopsies were taken from 19 donor livers postpreservation, as well as 30 minutes after portal venous reperfusion and hepatic arterial reperfusion and analyzed by liquid chromatography-mass spectrometry for energetic cofactors (adenosine triphosphate [ATP]/adenosine diphosphate [ADP]/adenosine monophosphate [AMP], nicotinamide adenine dinucleotide /NAD, nicotinamide adenine dinucleotide phosphate / nicotinamide adenine dinucleotide phosphate , flavin adenine dinucleotide , glutathione disulfide/glutathione). Energy status was correlated to posttransplant outcome. In addition, 4 discarded human donation after circulatory death livers were subjected to ex vivo reperfusion, modeling reperfusion injury and were similarly analyzed for energetic cofactors. RESULTS: A rapid shift toward higher energy adenine nucleotides was observed following clinical reperfusion, with a 2.45-, 3.17- and 2.12-fold increase in ATP:ADP, ATP:AMP and energy charge after portal venous reperfusion, respectively. Seven of the 19 grafts developed early allograft dysfunction. Correlation with peritransplant cofactors revealed a significant difference in EC between early allograft dysfunction and normal functioning grafts (0.09 vs 0.31, P < 0.05). In the simulated reperfusion model, a similar trend in adenine nucleotide changes was observed. CONCLUSIONS: A preserved energy status appears critical in the peritransplant period. Levels of adenine nucleotides change rapidly after reperfusion and ratios of ATP/ADP/AMP after reperfusion are significantly correlated to graft function. Using these markers as a viability test in combination with ex vivo reperfusion may provide a useful predictor of outcome that incorporates donor, preservation, and reperfusion factors.

Effect of tolerance versus chronic immunosuppression protocols on the quality of life of kidney transplant recipients.

BACKGROUND: Kidney transplant patients on tolerance protocols avoid the morbidity associated with the use of conventional chronic immunosuppressive regimens. However, the impact of tolerance versus conventional regimens on the quality of life (QOL) of kidney transplant patients is unknown. METHODS: Five patients who achieved long-term immunosuppression-free renal allograft survival after combined kidney and bone marrow transplantation (tolerant group) were compared with thirty-two comparable kidney transplant recipients on conventional immunosuppression (conventional group). QOL was compared with 16 conventional recipients using the Kidney Disease Quality of Life Short Form 36 (KDQOL SF-36) and the Modified Transplant Symptom Occurrence and Symptom Distress Scale (MTSOSD-59R). RESULTS: Patients in the tolerant group required significantly less treatment after transplant for hypertension and no medications for diabetes (P < 0.01). There was no incidence of diabetes, dyslipidemia, or malignancies in the tolerant group, while these were observed in 12.5%, 40.6%, and 11.8% of the conventional group, respectively. Tolerant patients experienced better overall health (P < 0.01) and scored higher on kidney transplant-targeted scales and healthy survey scales than patients in the conventional group according to the KDQOL SF-36 (P < 0.05). Tolerant patients were less likely to experience depression, dyspnea, excessive appetite/thirst, flatulence, hearing loss, itching, joint pain, lack of energy, muscle cramps, and lack of libido than conventional patients according to the MTSOSD-59R (P < 0.05). CONCLUSION: Kidney transplant recipients who achieved tolerance experience significantly fewer incidences of complications, improved QOL, and fewer comorbid symptoms compared with patients on conventional immunosuppression. These results support the expanded use of tolerance protocols in kidney transplantation.

Mixed chimerism, lymphocyte recovery, and evidence for early donor-specific unresponsiveness in patients receiving combined kidney and bone marrow transplantation to induce tolerance.

BACKGROUND: We have previously reported operational tolerance in patients receiving human leukocyte antigen-mismatched combined kidney and bone marrow transplantation (CKBMT). We now report on transient multilineage hematopoietic chimerism and lymphocyte recovery in five patients receiving a modified CKBMT protocol and evidence for early donor-specific unresponsiveness in one of these patients. METHODS: Five patients with end-stage renal disease received CKBMT from human leukocyte antigen-mismatched, haploidentical living-related donors after modified nonmyeloablative conditioning. Polychromatic flow cytometry was used to assess multilineage chimerism and lymphocyte recovery posttransplant. Limiting dilution analysis was used to assess helper T-lymphocyte reactivity to donor antigens. RESULTS: Transient multilineage mixed chimerism was observed in all patients, but chimerism became undetectable by 2 weeks post-CKBMT. A marked decrease in T- and B-lymphocyte counts immediately after transplant was followed by gradual recovery. Initially, recovering T cells were depleted of CD45RA+/CD45RO(-) "naïve-like" cells, which have shown strong recovery in two patients, and CD4:CD8 ratios increased immediately after transplant but then declined markedly. Natural killer cells were enriched in the peripheral blood of all patients after transplant.For subject 2, a pretransplant limiting dilution assay revealed T helper cells recognizing both donor and third-party peripheral blood mononuclear cells. However, the antidonor response was undetectable by day 24, whereas third-party reactivity persisted. CONCLUSION: These results characterize the transient multilineage mixed hematopoietic chimerism and recovery of lymphocyte subsets in patients receiving a modified CKBMT protocol. The observations are relevant to the mechanisms of donor-specific tolerance in this patient group.