Does DCD Donor Time-to-Death Affect Recipient Outcomes? Implications of Time-to-Death at a High-Volume Center in the United States.

For donation after circulatory death (DCD), many centers allow 1 h after treatment withdrawal to donor death for kidneys. Our center has consistently allowed 2 h. We hypothesized that waiting longer would be associated with worse outcome. A single-center, retrospective analysis of DCD kidneys transplanted between 2008 and 2013 as well as a nationwide survey of organ procurement organization DCD practices were conducted. We identified 296 DCD kidneys, of which 247 (83.4%) were transplanted and 49 (16.6%) were discarded. Of the 247 recipients, 225 (group 1; 91.1%) received kidneys with a time to death (TTD) of 0-1 h; 22 (group 2; 8.9%) received grafts with a TTD of 1-2 h. Five-year patient survival was 88.8% for group 1, and 83.9% for group 2 (p = 0.667); Graft survival was also similar, with 5-year survival of 74.1% for group 1, and 83.9% for group 2 (p = 0.507). The delayed graft function rate was the same in both groups (50.2% vs. 50.0%, p = 0.984). TTD was not predictive of graft failure. Nationally, the average maximum wait-time for DCD kidneys was 77.2 min. By waiting 2 h for DCD kidneys, we performed 9.8% more transplants without worse outcomes. Nationally, this practice would allow for hundreds of additional kidney transplants, annually.

Predicting Donor Death: Early Changes in Oxygen Saturation After Withdrawal of Support Predict Successful Donation During Donation After Circulatory Death.

BACKGROUND: We have previously shown that approximately 27% of patients do not progress to death in time to donate organs after attempted donation after circulatory death (DCD). As such, nearly 1000 transplants per year are not possible. One way to convert unsuccessful donations to successful donations is to increase procurement team "stand-down" times; however, increased stand-down times may predispose transplantable organs to increased ischemic damage. METHODS: Hemodynamics for successful and unsuccessful donations, occurring between 2011 and 2014, were characterized to determine if some unsuccessful DCDs could have donated successfully, had procurement teams waited longer. RESULTS: Analysis of 169 DCDs demonstrated statistically significant differences in hemodynamic profiles after withdrawal of support (WOS) between successful and unsuccessful donations. Early decreases in oxygen saturation were predictive of successful organ donation. We observed that for unsuccessful DCDs, patients who died in more than 2 hours but less than 12 hours were agonal within 10 minutes of WOS, suggesting that increasing stand-down times would result in prohibitive warm ischemia time. CONCLUSIONS: Early changes in oxygen saturation after withdrawal of support predict donor death. Alternative approaches that convert unsuccessful DCDs to successful DCDs but that do not result in low-quality organs should be explored.

Adoptive Transfer of Renal Allograft Tolerance in a Large Animal Model.

Our recent studies in an inbred swine model demonstrated that both peripheral and intra-graft regulatory cells were required for the adoptive transfer of tolerance to a second, naïve donor-matched kidney. Here, we have asked whether both peripheral and intra-graft regulatory elements are required for adoptive transfer of tolerance when only a long-term tolerant (LTT) kidney is transplanted. Nine highly-inbred swine underwent a tolerance-inducing regimen to prepare LTT kidney grafts which were then transplanted to histocompatible recipients, with or without the peripheral cell populations required for adoptive transfer of tolerance to a naïve kidney. In contrast to our previous studies, tolerance of the LTT kidney transplants alone was achieved without transfer of additional peripheral cells and without strategies to increase the number/potency of regulatory T cells in the donor. This tolerance was systemic, since most subsequent, donor-matched challenge kidney grafts were accepted. These results confirm the presence of a potent tolerance-inducing and/or tolerance-maintaining cell population within LTT renal allografts. They suggest further that additional peripheral tolerance mechanisms, required for adoptive transfer of tolerance to a naïve donor-matched kidney, depend on peripheral cells that, if not transferred with the LTT kidney, require time to develop in the adoptive host.

Abrogation of renal allograft tolerance in MGH miniature swine: the role of intra-graft and peripheral factors in long-term tolerance.

We have previously demonstrated that long-term tolerance (LTT) of an MHC class-I mismatched renal allograft can be achieved with a short course of cyclosporine. In order to examine regulatory mechanisms underlying tolerance in this model, we assessed the contributions of factors within the graft and in the peripheral blood for their relative roles in the maintenance of stable tolerance. Twelve LTT recipients of MHC class-I mismatched primary kidneys were subjected to a treatment consisting of donor-specific transfusion followed by leukapheresis, in order to remove peripheral leukocytes, including putative regulatory T cells (Tregs). Following treatment, 2 controls were followed clinically and 10 animals had the primary graft removed and received a second, donor-MHC-matched kidney. Neither control animal showed evidence of rejection, while 8 of 10 retransplanted animals developed either rejection crisis or full rejection of the second transplant. In vitro assays confirmed that the removed leukocytes were suppressive and that CD4(+) Foxp3(+) Treg reconstitution in blood and kidney grafts correlated with return to normal renal function in animals experiencing transient rejection crises. These data indicate that components of accepted kidney grafts as well as peripheral regulatory components both contribute to the tolerogenic environment required for tolerance of MHC class-I mismatched allotransplants.

A possible role for statin therapy in solitary pancreas transplantation?

INTRODUCTION: Statin use after renal transplantation improves long-term outcome and reduces the incidence of glomerulonephritis. With both anti-inflammatory and cardioprotective effects, statins may also improve outcomes in pancreas transplantation. METHODS: A retrospective review at a single institution was undertaken. Patients who underwent solitary pancreas transplantation between 2001 and 2010 were identified. Multiple data points including recipient and donor demographics, patient and graft outcomes, and early use of statins were collected. RESULTS: Sixty-eight patients underwent solitary pancreas transplantation within the study period. Eighteen patients (26%) were already on, or were prescribed, a statin at the time of hospital discharge; the 1-year death-censored graft survival was 81.25% for those that were on statins versus 72.9% for those without (P = NS). Excluding patients with early graft loss (<600 days) mean graft survival was 646 days longer for patients receiving statins (P = .02). CONCLUSIONS: The use of statins in the solitary pancreas transplant patient may lead to improved outcomes. Whether this is owing to cardiovascular protection or to other factors not associated with lipid lowering remains unclear.

The induction of tolerance of renal allografts by adoptive transfer in miniature swine.

Our previous in vitro data have demonstrated that regulatory mechanisms are involved in tolerance of class I-mismatched renal allografts in miniature swine treated with 12 days of high dose Cyclsporin A. In this study, we attempted to induce tolerance of class I-mismatched kidneys by adoptive transfer of cells and/or kidneys from long-term tolerant animals. Fifteen SLA(dd) miniature swine received 1.5 Gy whole body irradiation and class I-mismatched (SLA(gg) ) kidneys from naïve pigs with or without cotransplanted kidneys and/or adoptively transferred cells from long-term tolerant (LTT) SLA(dd) recipients of SLA(gg) grafts. In addition, three SLA(dd) miniature swine received class I mismatched kidney with adoptively transferred cells from LTT SLA(dd) recipients. Naïve kidneys transplanted without a LTT kidney were rejected within 9 days. All recipients of naive kidneys along with cells and kidney grafts from LTT animals showed markedly prolonged survival of the naive renal grafts (day 28, >150 and >150 days). These studies suggest that (1) tolerated kidneys have potent regulatory effects and (2) cells from LTT animals infused in conjunction with kidney grafts augment these regulatory effects. To our knowledge, these studies represent the first demonstration of successful adoptive transfer of tolerance in large animals.