The impact of time to death in donors after circulatory death on recipient outcome in simultaneous pancreas-kidney transplantation

The time to arrest donors after circulatory death is unpredictable and can vary. This leads to variable periods of warm ischemic damage prior to pancreas transplantation. There is little evidence supporting procurement team stand-down times based on donor time to death (TTD). We examined what impact TTD had on pancreas graft outcomes following donors after circulatory death (DCD) simultaneous pancreas-kidney transplantation. Data were extracted from the UK transplant registry from 2014 to 2022. Predictors of graft loss were evaluated using a Cox proportional hazards model. Adjusted restricted cubic spline models were generated to further delineate the relationship between TTD and outcome. Three-hundred-and-seventy-five DCD simultaneous kidney-pancreas transplant recipients were included. Increasing TTD was not associated with graft survival (adjusted hazard ratio HR 0.98, 95% confidence interval 0.68-1.41, P = .901). Increasing asystolic time worsened graft survival (adjusted hazard ratio 2.51, 95% confidence interval 1.16-5.43, P = .020). Restricted cubic spline modeling revealed a nonlinear relationship between asystolic time and graft survival and no relationship between TTD and graft survival. We found no evidence that TTD impacts pancreas graft survival after DCD simultaneous pancreas-kidney transplantation; however, increasing asystolic time was a significant predictor of graft loss. Procurement teams should attempt to minimize asystolic time to optimize pancreas graft survival rather than focus on the duration of TTD.

Multi-Centre UK Analysis of Simultaneous Pancreas and Kidney (SPK) Transplant in Recipients With Type 2 Diabetes Mellitus

90% of the UK diabetic population are classified as T2DM. This study aims to compare outcomes after SPK transplant between recipients with T1DM or T2DM. Data on all UK SPK transplants from 2003-2019 were obtained from the NHSBT Registry (n = 2,236). Current SPK transplant selection criteria for T2DM requires insulin treatment and recipient BMI < 30 kg/m2. After exclusions (re-transplants/ambiguous type of diabetes) we had a cohort of n = 2,154. Graft (GS) and patient (PS) survival analyses were conducted using Kaplan-Meier plots and Cox-regression models. Complications were compared using chi-squared analyses. 95.6% of SPK transplants were performed in recipients with T1DM (n = 2,060). Univariate analysis showed comparable outcomes for pancreas GS at 1 year (p = 0.120), 3 years (p = 0.237), and 10 years (p = 0.196) and kidney GS at 1 year (p = 0.438), 3 years (p = 0.548), and 10 years (p = 0.947). PS was comparable at 1 year (p = 0.886) and 3 years (p = 0.237) and at 10 years (p = 0.161). Multi-variate analysis showed comparable outcomes in pancreas GS (p = 0.564, HR 1.221, 95% CI 0.619, 2.406) and PS(p = 0.556, HR 1.280, 95% CI 0.563, 2.911). Comparable rates of common complications were demonstrated. This is the largest series outside of the US evaluating outcomes after SPK transplants and shows similar outcomes between T1DM and T2DM recipients. It is hoped dissemination of this data will lead to increased referral rates and assessment of T2DM patients who could benefit from SPK transplantation.

O007 Pancreas and islet transplantation in the United Kingdom during the COVID-19 era

Introduction

Methods

Results

Conclusion

Take-home message

O002 Diabetes-associated HLA donor genotypes and pancreas transplant outcomes

Introduction

The genotypes HLA DR3/DR4, DR3/DR3, DR4/DR4 are associated with a predisposition to diabetes. This study evaluated UK recipient outcomes after pancreas transplantation from donors with a diabetes-associated genotypes.

Methods

Data on all UK pancreas transplants from 2004–2019 was obtained from the NHSBT-UK Registry, n=2,938. HLA-DR type was recorded for all organ donors. Re-transplants and those missing patient (PS) or graft (GS) survival were excluded, resulting in a final cohort of n=2,661. We further delineated our categories into SPK, PTA and PAK as a previous study suggested different recipient categories may be adversely affected. Univariate analyses were conducted using Kaplan-Meier plots and multi-variate analysis using Cox-regression models. Complications were analysed using chi-squared analyses.

Results

The majority of grafts were from donors not associated with diabetes genotypes (90.1%, n=2397) whereas 5.4%(n=145) came from HLA DR3/DR4 donors, 1.6%(n=43) from DR3/DR3 and (n=76)2.9% from DR4/DR4. Comparable outcomes for GS at 1yr (SPK p=0.980, PTA p=0.759, PAK p=0.244) and 3yrs (SPK p=0.708, PTA p=0.744, PAK p=0.275) and PS at 1yr (SPK p=0.553, PTA p=0.527, PAK p=0.756) and 3yrs (SPK p=0.728, PTA p=0.928, PAK p=0.424) were seen. Multivariate analysis also showed no statistically significant difference in GS (p=0.604, HR 1.041, 95%CI 0.895, 1.211) or PS (p=0.623, HR 1.045, 95%CI 0.876, 1.248). There were comparable complication rates.

Conclusion

This multicentre UK study has found comparable survival outcomes and complication rates within our donor-HLA-genotype groups. We do not believe that the presence or absence of a diabetes associated HLA-genotype influences outcomes for any category of pancreas transplant.

Take-home message

We do not believe that the presence or absence of a diabetes-associated HLA-genotype influences outcomes for any category of pancreas transplant.

The impact of islet mass, number of transplants, and time between transplants on graft function in a national islet transplant program

The UK islet allotransplant program is nationally funded to deliver one or two transplants over 12 months to individuals with type 1 diabetes and recurrent severe hypoglycemia. Analyses were undertaken 10 years after program inception to evaluate associations between transplanted mass; single versus two transplants; time between two transplants and graft survival (stimulated C-peptide >50 pmol/L) and function. In total, 84 islet transplant recipients were studied. Uninterrupted graft survival over 12 months was attained in 23 (68%) single and 47 (94%) (p = .002) two transplant recipients (separated by [median (IQR)] 6 (3-8) months). 64% recipients of one or two transplants with uninterrupted function at 12 months sustained graft function at 6 years. Total transplanted mass was associated with Mixed Meal Tolerance Test stimulated C-peptide at 12 months (p < .01). Despite 1.9-fold greater transplanted mass in recipients of two versus one islet infusion (12 218 [9291-15 417] vs. 6442 [5156-7639] IEQ/kg; p < .0001), stimulated C-peptide was not significantly higher. Shorter time between transplants was associated with greater insulin dose reduction at 12 months (beta -0.35; p = .02). Graft survival over the first 12 months was greater in recipients of two versus one islet transplant in the UK program, although function at 1 and 6 years was comparable. Minimizing the interval between 2 islet infusions may maximize cumulative impact on graft function.

Outcomes after simultaneous pancreas-kidney transplantation from donation after circulatory death donors: A UK registry analysis

There are concerns that simultaneous pancreas-kidney (SPK) transplants from donation after circulatory death (DCD) donors have a higher risk of graft failure than those from donation after brain death (DBD) donors. A UK registry analysis of SPK transplants between 2005 and 2018 was performed. Pancreas survivals of those receiving organs from DCD or DBD donors were compared. Multivariable analyses were used to adjust for baseline differences between the two groups and to identify factors associated with pancreas graft loss. A total of 2228 SPK transplants were implanted; 403 (18.1%) were from DCD donors. DCD donors were generally younger, slimmer, less likely to have stroke as a cause of death, with lower terminal creatinines and shorter pancreas cold ischemic times than DBD donors. Median (IQR) follow-up was 4.2 (1.6-8.1) years. On univariable analysis, there were no statistically significant differences in 5-year death-censored pancreas graft survival between the two donor types (79.5% versus 80.4%; p = .86). Multivariable analysis showed no statistically significant differences in 5-year pancreas graft loss between transplants from DCD (n = 343) and DBD (n = 1492) donors (hazard ratio 1.26, 95% CI 0.76-1.23; p = .12). The findings from this study support the increased use of SPK transplants from DCD donors.

Autoreactive T cell profiles are altered following allogeneic islet transplantation with alemtuzumab induction and re-emerging phenotype is associated with graft function

Islet transplantation is an effective therapy for life-threatening hypoglycemia, but graft function gradually declines over time in many recipients. We characterized islet-specific T cells in recipients within an islet transplant program favoring alemtuzumab (ATZ) lymphodepleting induction and examined associations with graft function. Fifty-eight recipients were studied: 23 pretransplant and 40 posttransplant (including 5 with pretransplant phenotyping). The proportion with islet-specific T cell responses was not significantly different over time (pre-Tx: 59%; 1-6 m posttransplant: 38%; 7-12 m: 44%; 13-24 m: 47%; and >24 m: 45%). However, phenotype shifted significantly, with IFN-γ-dominated response in the pretransplant group replaced by IL-10-dominated response in the 1-6 m posttransplant group, reverting to predominantly IFN-γ-oriented response in the >24 m group. Clustering analysis of posttransplant responses revealed two main agglomerations, characterized by IFN-γ and IL-10 phenotypes, respectively. IL-10-oriented posttransplant response was associated with relatively low graft function. Recipients within the IL-10⁺ cluster had a significant decline in C-peptide levels in the period preceding the IL-10 response, but stable graft function following the response. In contrast, an IFN-γ response was associated with subsequently decreased C-peptide. Islet transplantation favoring ATZ induction is associated with an initial altered islet-specific T cell phenotype but reversion toward pretransplant profiles over time. Posttransplant autoreactive T cell phenotype may be a predictor of subsequent graft function.

β-Cell and renal transplantation options for diabetes

Despite major advances in structured education, insulin delivery and glucose monitoring, diabetes self-management remains an unremitting challenge. Insulin therapy is inextricably linked to risk of dangerous hypoglycaemia and sustained hyperglycaemia remains a leading cause of renal failure. This review sets out to demystify transplantation for diabetes multidisciplinary teams, facilitating consideration and incorporation within holistic overall person-centred management. Deceased and living donor kidney, whole pancreas and isolated islet transplant procedures, indications and potential benefits are described, in addition to outcomes within the integrated UK transplant programme.

Is the increase in DCD organ donors in the United Kingdom contributing to a decline in DBD donors?

INTRODUCTION

Organ donation after brain death (DBD) has declined in the United Kingdom, whereas donation after cardiac death (DCD) has increased markedly. We sought to understand the reasons for the decline in DBD and determine whether the increase in DCD was a major factor.

METHODS

The UK Transplant Registry was analyzed to determine trends in organ donation. Data from the "Potential Donor Audit," an audit of all patients younger than 76 years who died in noncardiothoracic UK intensive care units, was analyzed to identify trends in clinical demographics and management and to determine whether potential donors (DBD and DCD) were identified and appropriate steps were taken to enable organ donation.

RESULTS

There were 7589 (12.8 per million of population [pmp]) deceased organ donors in the United Kingdom from 1999 to 2009. The total number of deceased donors increased by 16% (to 14.9 pmp), but DBD donors decreased from 744 to 612, and the overall increase in donors was due to an 8-fold increase in DCD donors (33 in 1999 to 2000, 288 in 2008 to 2009). Analysis of the Potential Donor Audit over the 5-year period 2004 to 2005 to 2008 to 2009 showed that the number of patients dying in intensive care units who were possibly brain stem dead (comatose, apparently apnoeic with unresponsive pupils) decreased from 1929 in 2004 to 2005 to 1495 in 2008 to 2009 (22.5% reduction). The proportion of potential DBD donors who became donors increased from 45% to 51%.

CONCLUSION

There is no evidence that the increase in DCD donors has contributed directly to the decline in DBD, which reflects a decrease in the number of patients with brain death.

How safe is it to transplant organs from deceased donors with primary intracranial malignancy? An analysis of UK Registry data

Patients dying from primary intracranial malignancy are a potential source of organs for transplantation. However, a perceived risk of tumor transfer to the organ recipient has limited their use. We evaluated the risk of tumor transmission by reviewing the incidence in patients transplanted in the UK. Information from the UK Transplant Registry was combined with that from the national cancer registries of England, Wales and Northern Ireland to identify all organ donors between 1985 and 2001 inclusive with a primary intracranial malignancy and to identify the occurrence of posttransplant malignancy in the recipients of the organs transplanted. Of 11,799 organ donors in the study period, 179 were identified as having had a primary intracranial malignancy, including 33 with high-grade malignancy (24 grade IV gliomas and 9 medulloblastomas). A total of 448 recipients of 495 organs from 177 of these donors were identified. No transmission of donor intracranial malignancy occurred. Organs from patients dying from primary intracranial malignancy, including those with high-grade tumors, should be considered for transplantation and the small risk of tumor transmission should be balanced against the likely mortality for potential recipients who remain on the transplant waiting list.

The MEK pathway is required for stimulation of p21(WAF1/CIP1) by transforming growth factor-beta

Transforming growth factor-beta (TGF-beta)can induce the cyclin-dependent kinase inhibitors p21 and p15 in a variety of cell types. We have shown previously that Smad3 is required for the growth inhibitory activity of TGF-beta, whereas overexpression of Smads is not sufficient to activate the expression of p21 in HaCaT cells. These data suggest that an additional signaling pathway may be involved in stimulating p21 in HaCaT cells. Given the recent finding that the mitogen-activated protein kinase (MAPK) pathway can cause p21 induction and arrest cells, we examined the involvement of this pathway for p21 and p15 induction by TGF-beta. We found that TGF-beta can regulate the MAPK pathway, leading to the increased transactivation ability of transcription factor Elk. Constitutively active components in the MAPK pathway activate p21 expression, and inhibitors or dominant negative constructs for the MAPK pathway significantly decrease p21 induction by TGF-beta. Both constitutively active MEK and inhibitors for MEK have no effect on Smad activity, including DNA binding, localization, and interaction with coactivator p300/CBP. These findings suggest that the MAPK pathway may be an independent pathway that is involved in p21 and p15 induction by TGF-beta.

Characterization of the repeat-tract instability and mutator phenotypes conferred by a Tn3 insertion in RFC1, the large subunit of the yeast clamp loader

The RFC1 gene encodes the large subunit of the yeast clamp loader (RFC) that is a component of eukaryotic DNA polymerase holoenzymes. We identified a mutant allele of RFC1 (rfc1::Tn3) from a large collection of Saccharomyces cerevisiae mutants that were inviable when present in a rad52 null mutation background. Analysis of rfc1::Tn3 strains indicated that they displayed both a mutator and repeat-tract instability phenotype. Strains bearing this allele were characterized in combination with mismatch repair (msh2Delta, pms1Delta), double-strand break repair (rad52), and DNA replication (pol3-01, pol30-52, rth1Delta/rad27Delta) mutations in both forward mutation and repeat-tract instability assays. This analysis indicated that the rfc1::Tn3 allele displays synthetic lethality with pol30, pol3, and rad27 mutations. Measurement of forward mutation frequencies in msh2Delta rfc1:Tn3 and pms1Delta rfc1:Tn3 strains indicated that the rfc1::Tn3 mutant displayed a mutation frequency that appeared nearly multiplicative with the mutation frequency exhibited by mismatch-repair mutants. In repeat-tract instability assays, however, the rfc1::Tn3 mutant displayed a tract instability phenotype that appeared epistatic to the phenotype displayed by mismatch-repair mutants. From these data we propose that defects in clamp loader function result in DNA replication errors, a subset of which are acted upon by the mismatch-repair system.

Telomeres and telomerase in human cancer (review)

Telomerase has recently come into the limelight as one of the most prevalent tumour markers, due to its nearly ubiquitous presence in malignant tissues and absence from most somatic tissues. The essential role of telomeres in unlimited cell proliferation and that of the enzyme in telomere maintenance have suggested that telomerase inhibitors may be effective in cancer therapy. We provide here a compendium and an evaluation of the available data relating to this hypothesis.