OPTN/SRTR 2011 Annual Data Report: kidney

Metabolic biomarkers for chronic kidney disease

Chronic kidney disease (CKD) is an increasingly recognized burden for patients and health care systems with high (and growing) global incidence and prevalence, significant mortality, and disproportionately high treatment costs. Yet, the available diagnostic tools are either impractical in clinical routine or have serious shortcomings impeding a well-informed disease management although optimized treatment strategies with proven benefits for the patients have become available. Advances in bioanalytical technologies have facilitated studies that identified genomic, proteomic, and metabolic biomarker candidates, and confirmed some of them in independent cohorts. This review summarizes the CKD-related markers discovered so far, and focuses on compounds and pathways, for which there is quantitative data, substantiating evidence from translational research, and a mechanistic understanding of the processes involved. Also, multiparametric marker panels have been suggested that showed promising diagnostic and prognostic performance in initial analyses although the data basis from prospective trials is very limited. Large-scale studies, however, are underway and will provide the information for validating a set of parameters and discarding others. Finally, the path from clinical research to a routine application is discussed, focusing on potential obstacles such as the use of mass spectrometry, and the feasibility of obtaining regulatory approval for targeted metabolomics assays.

Changing organ allocation policy for kidney transplantation in the United States

The new kidney allocation scheme (KAS) in effect since December 4^th 2014 was designed to overcome the shortcomings of previous system. A key feature of the new KAS is preferential allocation of best quality organs to wait-list candidates with the longest predictive survival in a concept called longevity matching. Highly sensitized recipients would get extra points and enjoy widespread sharing of organs in order to increase accessibility to transplant. Wait-list candidates with blood group B will be offered organs from donors with A2 and A2B blood type in order to shorten their wait-list time. Time on the wait list will start from day of listing or date of initiation of dialysis whichever comes first which should benefit candidates with limited resources who might be late to get on the transplant list. Pay back system has been eliminated in the new KAS. These changes in organ allocation policy may lead to increase in median half-life of the allograft and increase the number of transplants; thus resulting in better utilization of a scarce resource. There could be unintended negative consequences which may become evident over time.

Sirolimus effects on cancer incidence after kidney transplantation: a meta-analysis

Sirolimus, an immunosuppressant option for kidney transplant recipients, may reduce cancer risk by interrupting the mammalian target of rapamycin pathway. However, studies of sirolimus and cancer incidence in kidney recipients have not been definitive, and have had limited ability to examine specific cancer types. The literature was systematically reviewed to identify randomized controlled trials (RCTs) and observational studies of kidney recipients that compared sirolimus users to sirolimus nonusers. Meta-analytic methods were used to obtain pooled estimates of the association between sirolimus use and incidence of total cancer and specific cancer types. Estimates were stratified by study type (RCT vs. observational) and use of cyclosporine (an immunosuppressant that affects DNA repair). Twenty RCTs and two observational studies were eligible for meta-analysis, including 39,039 kidney recipients overall. Sirolimus use was associated with lower overall cancer incidence (incidence rate ratio [IRR] = 0.71, 95% CI = 0.56-0.90), driven by a reduction in incidence of nonmelanoma skin cancer (NMSC, IRR = 0.49, 95% CI = 0.32-0.76). The protective effect of sirolimus on NMSC risk was most notable in studies comparing sirolimus against cyclosporine (IRR = 0.19, 95% CI = 0.04-0.84). After excluding NMSCs, there was no overall association between sirolimus and incidence of other cancers (IRR = 1.06, 95% CI = 0.69-1.63). However, sirolimus use had associations with lower kidney cancer incidence (IRR = 0.40, 95% CI = 0.20-0.81), and higher prostate cancer incidence (IRR = 1.85, 95% CI = 1.17-2.91). Among kidney recipients, sirolimus users have lower NMSC risk, which may be partly due to removal of cyclosporine. Sirolimus may also reduce kidney cancer risk but did not appear protective for other cancers, and it may actually increase prostate cancer risk.

Kidney Transplantation in the Diabetic Patient

Diabetes mellitus is one of the most important causes of chronic kidney disease (CKD). In patients with advanced diabetic kidney disease, kidney transplantation (KT) with or without a pancreas transplant is the treatment of choice. We aimed to review current data regarding kidney and pancreas transplant options in patients with both type 1 and 2 diabetes and the outcomes of different treatment modalities. In general, pancreas transplantation is associated with long-term survival advantages despite an increased short-term morbidity and mortality risk. This applies to simultaneous pancreas kidney transplantation or pancreas after KT compared to KT alone (either living donor or deceased). Other factors as living donor availability, comorbidities, and expected waiting time have to be considered whens electing one transplant modality, rather than a clear benefit in survival of one strategy vs. others. In selected type 2 diabetic patients, data support cautious utilization of simultaneous pancreas kidney transplantation when a living kidney donor is not an option. Pancreas and kidney transplantation seems to be the treatment of choice for most type 1 diabetic and selected type 2 diabetic patients.

Effect of donor age and parent-to-child transplant on living-related donor kidney transplantation: a single center's experience of 236 cases

To study the impact of parent-to-child transplant and older donor age on recipients' post-transplant creatinine levels, a total of 236 patients who received living donor kidney transplantation were evaluated for kidney viability based on creatinine (Cr) level. Of the 236 pairings, 113 (48%) were parent-to-child followed by sibling transplants (66, 30%). Recipient Cr levels were significantly higher at 6 months and 3 years post-transplant in the parent-to-child transplants compared to other donor-recipient relationships. In addition, donor age (average age: 44.1 ± 11.5; range: 19-66) contributed to higher recipient post-transplant Cr levels (p < 0.01). Pre-transplant donor and recipient Cr levels tended to result in higher post-transplant Cr levels in recipients (p < 0.05). Multivariate logistic regression analysis revealed that the presence of both parent-to-child transplant and older donor significantly increased the risk of elevated post-transplant Cr levels in recipients with an estimated odds ratios ranging from 3.46 (95% CI: 1.71-6.98) at 6 months to 8.04 (3.14-20.56) at 3 years post-transplant. Donor age significantly affected transplant survival as measured by higher recipient post-transplant Cr levels. In addition, parent-to-child transplant pairings, along with older donor age, significantly increased the risk of elevated post-transplant Cr levels in recipients.

Kidney transplantation threshold in patients with hepatitis C: a decision analysis model

BACKGROUND

There are no standard guidelines for the permissible degree of liver fibrosis in patients with chronic hepatitis C virus prohibiting cadaveric renal transplantation (CRT).

METHODS

A decision analysis model was constructed to compare 5-year patient survival using three strategies for patients on hemodialysis. The probabilities of pretransplant and posttransplant survival, progression of liver fibrosis, CRT, and sustained viral response were obtained from a systematic review of the literature. Sensitivity analyses were performed.

RESULTS

Kidney transplantation was associated with improved 5-year survival for patients with fibrosis stages 1 to 3, but not stage 4 (cirrhosis). Antiviral therapy was associated with improvement in survival in patients with stage 3 fibrosis. The 5-year survival was similar for patients with stage 4 irrespective of the option of antiviral therapy. The model was sensitive to varying the probability of both pretransplant and posttransplant survival.

CONCLUSION

There appears to be no overall 5-year survival benefit in treating S1 and S2 fibrosis patients with hepatitis C virus antiviral therapy before CRT. There is no benefit in overall 5-year survival in patients with cirrhosis and thus should not be candidates for CRT.

African-American race modifies the influence of tacrolimus concentrations on acute rejection and toxicity in kidney transplant recipients

STUDY OBJECTIVE

To determine the effect of tacrolimus trough concentrations on clinical outcomes in kidney transplantation, while assessing if African-American (AA) race modifies these associations.

DESIGN

Retrospective longitudinal cohort study of solitary adult kidney transplants.

SETTING

Large tertiary care transplant center.

PATIENTS

Adult solitary kidney transplant recipients (n=1078) who were AA (n=567) or non-AA (n=511).

EXPOSURE

Mean and regressed slope of tacrolimus trough concentrations. Subtherapeutic concentrations were lower than 8 ng/ml.

MEASUREMENTS AND MAIN RESULTS

AA patients were 1.7 times less likely than non-AA patients to achieve therapeutic tacrolimus concentrations (8 ng/ml or higher) during the first year after kidney transplant (35% vs 21%, respectively, p<0.001). AAs not achieving therapeutic concentrations were 2.4 times more likely to have acute cellular rejection (ACR) as compared with AAs achieving therapeutic concentrations (20.8% vs 8.5%, respectively, p<0.01) and 2.5 times more likely to have antibody-mediated rejection (AMR; 8.9% vs 3.6%, respectively, p<0.01). Rates of ACR (8.3% vs 6.7%) and AMR (2.0% vs 0.9% p=0.131) were similar in non-AAs compared across tacrolimus concentration groups. Multivariate modeling confirmed these findings and demonstrated that AAs with low tacrolimus exposure experienced a mild protective effect for the development of interstitial fibrosis/tubular atrophy (IF/TA; hazard ratio [HR] 0.78, 95% confidence interval [CI] 0.47-1.32) with the opposite demonstrated in non-AAs (HR 2.2, 95% CI 0.90-5.1).

CONCLUSION

In contradistinction to non-AAs, AAs who achieve therapeutic tacrolimus concentrations have substantially lower acute rejection rates but are at risk of developing IF/TA. These findings may reflect modifiable time-dependent racial differences in the concentration-effect relationship of tacrolimus. Achievement of therapeutic tacrolimus trough concentrations, potentially through genotyping and more aggressive dosing and monitoring, is essential to minimize the risk of acute rejection in AA kidney transplant recipients.

Explaining the Persistence of Health Disparities: Social Stratification and the Efficiency-Equity Trade-off in the Kidney Transplantation System

Why do health disparities persist when their previous mechanisms are eliminated? Fundamental-cause theorists argue that social position primarily improves health through two metamechanisms: better access to health information and technology. I argue that the general, cumulative, and embodied consequences of social stratification can produce another metamechanism: an efficiency-equity trade-off. A case in point is kidney transplantation, where the mechanisms previously thought to link race to outcomes--ability to pay and certain factors in the kidney allocation system--have been greatly reduced, yet large disparities persist. I show that these current disparities are rooted in factors that directly influence posttransplant success, placing efficiency and racial/ethnic equity at cross-purposes.

Viral surveillance and subclinical viral infection in pediatric kidney transplantation

The more potent immunosuppressive therapy that has successfully reduced the incidence of acute rejection and improved graft outcomes has also resulted in a higher incidence of viral complications. Sensitive molecular methods now allow for the detection of subclinical viral infection, which is increasingly recognized due to the adoption of routine post-transplant viral surveillance protocols. The goal of viral surveillance is the detection of subclinical viral infection that triggers an intervention; one that either prevents progression to viral disease or leads to early diagnosis of viral disease, which is associated with improved outcomes. Knowledge of the epidemiology and natural history of subclinical viral infection and viral disease, as well as patient-specific risk factors, is required to establish the optimal surveillance schedule which achieves the goal of early diagnosis. Evidence that detection of subclinical viral infection can impact viral disease is variable depending on the virus. This review will summarize the current data on the role of viral surveillance for BK virus (BKV), cytomegalovirus (CMV), and the Epstein-Barr virus (EBV) in the pediatric kidney transplant population.

Addressing morbid obesity as a barrier to renal transplantation with laparoscopic sleeve gastrectomy

Morbid obesity is a barrier to renal transplantation and is inadequately addressed by medical therapy. We present results of a prospective evaluation of laparoscopic sleeve gastrectomy (LSG) for patients failing to achieve significant weight loss with medical therapy. Over a 25-month period, 52 obese renal transplant candidates meeting NIH guidelines for metabolic surgery underwent LSG. Mean age was 50.0 ± 10.0 years with an average preoperative BMI of 43.0 ± 5.4 kg/m(2) (range 35.8-67.7 kg/m(2)). Follow-up after LSG was 220 ± 152 days (range 26-733 days) with last BMI of 36.3 ± 5.3 kg/m(2) (range 29.2-49.8 kg/m(2)) with 29 (55.8%) patients achieving goal BMI of <35 kg/m(2) at 92 ± 92 days (range 13-420 days). The mean percentage of excess weight loss (%EWL) was 32.1 ± 17.6% (range 6.7-93.8%). A segmented regression model was used to compare medical therapy versus LSG. This revealed a statistically significant increase in the BMI reduction rate (0.3 kg/m(2)/month versus 1.1 kg/m(2)/month, p < 0.0001). Patients also experienced a 40.9% decrease in anti-hypertensive medications (p < 0.001) and a 49.7% decrease in total daily insulin dose (p < 0.001). LSG is a safe and effective means for addressing obesity in kidney transplant candidates in the context of a multidisciplinary approach.

Coagulation profiles of unexpected DCDD donors do not indicate a role for exogenous fibrinolysis

It has been suggested that vascular stasis during cardio-circulatory arrest leads to the formation of microvascular thrombi and the viability of organs arising from donation after circulatory determination of death (DCDD) donors may be improved through the application of fibrinolytic therapy. Our aim was to comprehensively study the coagulation profiles of Maastricht category II DCDD donors in order to determine the presence of coagulation abnormalities that could benefit from fibrinolytic therapy. Whole blood from potential DCDD donors suffering out-of-hospital cardiac arrest was sampled after declaration of death in the emergency department, and rotational thromboelastomeric analysis was performed. Between July 2012 and December 2013, samples from 33 potential DCDD donors were analyzed. All patients demonstrated hyperfibrinolysis (HF), as reflected by maximum clot lysis of 98-100% in all cases, indicating that there is no role for additional fibrinolytic therapy in this setting. As well, we observed correlations between thromboelastomeric lysis parameters and maximum hepatic transaminase levels measured in potential donors and renal artery flows measured during ex situ hypothermic oxygenated machine perfusion, indicating that further studies on the utility of thromboelastometry to evaluate organ injury and perhaps even viability in unexpected DCDD may be warranted.

A 25-year experience of kidney transplantation in Thailand: report from the Thai Transplant Registry

AIM

To report the kidney transplant activity and survival data during the past 25 years from the Thai Transplant Registry.

METHODS

By using the registry database that was collected and updated yearly by 26 transplant centres across the country, we have reported the donor, recipient, and transplant characteristics during the past 25 years from 1987 to 2012. The primary outcome was graft loss that was defined as return to dialysis, graft removal, retransplant, or patient death.

RESULTS

465 kidney transplants were performed in 2012, an 8.1% and 23.0% increase in living and deceased donor transplants compared to the previous year, respectively. Between 1987 and 2012 with the data of 3808 recipients, patient survival and graft survival improved significantly. Traffic accident was the most common cause of death in brain-dead donors. Additionally, the most common cause of end-stage kidney disease was glomerulonephritis. Infection has been among the most common causes of death in kidney transplant recipients.

CONCLUSION

We have reported the total number, the graft and the patient survival data of kidney transplant recipients in Thailand for the period from 1987 to 2012. Although the number of patients is much lower than that in the developed countries, the patients and the graft survival rates are comparable.

Urinary cell mRNA profiles predictive of human kidney allograft status

Kidney allograft status is currently characterized using the invasive percutaneous needle core biopsy procedure. The procedure has become safer over the years, but challenges and complications still exist including sampling error, interobserver variability, bleeding, arteriovenous fistula, graft loss, and even death. Because the most common type of acute rejection is distinguished by inflammatory cells exiting the intravascular compartment and gaining access to the renal tubular space, we reasoned that a kidney allograft may function as an in vivo flow cytometer and sort cells involved in rejection into urine. To test this idea, we developed quantitative polymerase chain reaction (PCR) assays for absolute quantification of mRNA and pre-amplification protocols to overcome the low RNA yield from urine. Here, we review our single center urinary cell mRNA profiling studies that led to the multicenter Clinical Trials in Organ Transplantation (CTOT-04) study and the discovery and validation of a 3-gene signature of 18S rRNA-normalized measures of CD3ε mRNA and IP-10 mRNA and 18S rRNA that is diagnostic and predictive of acute cellular rejection in the kidney allograft. We also review our development of a 4-gene signature of mRNAs for vimentin, NKCC2, E-cadherin, and 18S rRNA diagnostic of interstitial fibrosis/tubular atrophy (IF/TA).

Scaffolds from surgically removed kidneys as a potential source of organ transplantation

End stage renal disease (ESRD) is a common disease, which relates to nearly 600 million people in the total population. What is more, it seems to be a crucial problem from the epidemiological point of view. These facts lead to a further necessity of renal replacement therapy development connected with rising expenditures for the health care system. The aim of kidney tissue engineering is to develop and innovate methods of obtaining renal extracellular matrix (ECM) scaffolds derived from kidney decellularization. Recently, progress has been made towards developing a functional kidney graft in vitro on demand. In fact, decellularized tissues constitute ideal natural scaffolds, due to the preservation of native ECM architecture, as well as of cell-ECM binding domains critical in promoting cell attachment, migration, and proliferation. One of the potential sources of the natural scaffolds is the kidney, which cannot be transplanted immediately after excision.

Prospect for kidney bioengineering: shortcomings of the status quo

INTRODUCTION

Dialysis and renal transplantation are the only two therapeutic options offered to patients affected by end-stage kidney disease; however, neither treatment can be considered definitive. In fact, dialysis is able to replace only the filtration function of the kidney without substituting its endocrine and metabolic roles, and dramatically impacts on patient's quality of life. On the other hand, kidney transplantation is severely limited by the shortage of transplantable organs, the need for immunosuppressive therapies and a narrow half-life. Regenerative medicine approaches are promising tools aiming to improve this condition.

AREAS COVERED

Cell therapies, bioartificial kidney, organ bioengineering, 3D printer and kidney-on-chip represent the most appealing areas of research for the treatment of end-stage kidney failure. The scope of this review is to summarize the state of the art, limits and directions of each branch.

EXPERT OPINION

In the future, these emerging technologies could provide definitive, curative and theoretically infinite options for the treatment of end-stage kidney disease. Progress in stem cells-based therapies, decellularization techniques and the more recent scientific know-how for the use of the 3D printer and kidney-on-chip could lead to a perfect cellular-based therapy, the futuristic creation of a bioengineered kidney in the lab or to a valid bioartificial alternative.

Incidence and impact of rejection following simultaneous liver-kidney transplantation

BACKGROUND & AIMS

Due to hepatic immunoregulation, simultaneous liver-kidney recipients are presumed to be reasonably protected from kidney rejection and typically receive less immunosuppression compared to kidney transplants alone. However, data to support these conclusions and practices are sparse.

METHODS

We characterized the incidence and types of rejection, graft function, and graft and patient survival in a large population of simultaneous liver-kidney recipients (n=140) with long-term follow-up at our centre (1998-2010).

RESULTS

Acute cellular, antibody-mediated, and chronic kidney rejection was diagnosed in 9 (6.4%), 2 (1.4%), and 1 (0.7%) patient, respectively. Borderline acute kidney rejection was diagnosed in another 16 patients (11.4%). Acute cellular liver rejection occurred in 16 (11.4%) and chronic liver rejection in 4 (2.9%). One-, three-, and five-year patient survival was 86.4%, 78.0%, and 74.0%, respectively, and did not significantly differ by presence or absence of kidney or liver rejection. However, kidney rejection was associated with decreased renal function by lower serum GFR over time (p=0.003).

CONCLUSIONS

Various forms of kidney rejection occurred in ∼20% of our simultaneous liver-kidney recipients and were associated with deterioration in graft function, indicating that the liver may not confer complete protective allo-immunity. More stringent graft monitoring and management strategies, perhaps more akin to kidney transplant alone, should be prospectively studied in simultaneous liver-kidney recipients.

Quantifying renal allograft loss following early antibody-mediated rejection

Unlike antibody-mediated rejection (AMR) with clinical features, it remains unclear whether subclinical AMR should be treated, as its effect on allograft loss is unknown. It is also uncertain if AMR's effect is homogeneous across donor (deceased/live) and (HLA/ABO) antibody types. We compared 219 patients with AMR (77 subclinical, 142 clinical) to controls matched on HLA/ABO-compatibility, donor type, prior transplant, panel reactive antibody (PRA), age and year. One and 5-year graft survival in subclinical AMR was 95.9% and 75.7%, compared to 96.8% and 88.4% in matched controls (p = 0.0097). Subclinical AMR was independently associated with a 2.15-fold increased risk of graft loss (95% CI: 1.19-3.91; p = 0.012) compared to matched controls, but not different from clinical AMR (p = 0.13). Fifty three point two percent of subclinical AMR patients were treated with plasmapheresis within 3 days of their AMR-defining biopsy. Treated subclinical AMR patients had no difference in graft loss compared to matched controls (HR 1.73; 95% CI: 0.73-4.05; p = 0.21), but untreated subclinical AMR patients did (HR 3.34; 95% CI: 1.37-8.11; p = 0.008). AMR's effect on graft loss was heterogeneous when stratified by compatible deceased donor (HR = 4.73; 95% CI: 1.57-14.26; p = 0.006), HLA-incompatible deceased donor (HR = 2.39; 95% CI: 1.10-5.19; p = 0.028), compatible live donor (no AMR patients experienced graft loss), ABO-incompatible live donor (HR = 6.13; 95% CI: 0.55-67.70; p = 0.14) and HLA-incompatible live donor (HR = 6.29; 95% CI: 3.81-10.39; p < 0.001) transplant. Subclinical AMR substantially increases graft loss, and treatment seems warranted.

Intra-patient variability in tacrolimus exposure: causes, consequences for clinical management

Tacrolimus (Tac) is widely used for the prevention of rejection after solid organ transplantation. Finding the optimal balance between effective Tac concentrations and toxicity is a challenge and requires therapeutic drug monitoring. In addition to the well-known inter-patient variability, the clinical use of Tac is also complicated by considerable intra-patient variability (IPV) in Tac exposure. Tac IPV is defined as the amount of fluctuation of whole-blood concentrations over a certain period of time during which the Tac dose remains unchanged. A high IPV in Tac exposure has recently been recognized as a strong risk factor for acute rejection and poor long-term kidney transplantation outcome. In addition to non-adherence, several other factors determine the magnitude of the IPV in Tac exposure. Quantification of IPV is easy and can be easily incorporated into everyday clinical practice as a tool for optimizing transplantation outcomes.

Prospective iterative trial of proteasome inhibitor-based desensitization

A prospective iterative trial of proteasome inhibitor (PI)-based therapy for reducing HLA antibody (Ab) levels was conducted in five phases differing in bortezomib dosing density and plasmapheresis timing. Phases included 1 or 2 bortezomib cycles (1.3 mg/m(2) × 6-8 doses), one rituximab dose and plasmapheresis. HLA Abs were measured by solid phase and flow cytometry (FCM) assays. Immunodominant Ab (iAb) was defined as highest HLA Ab level. Forty-four patients received 52 desensitization courses (7 patients enrolled in multiple phases): Phase 1 (n = 20), Phase 2 (n = 12), Phase 3 (n = 10), Phase 4 (n = 5), Phase 5 (n = 5). iAb reductions were observed in 38 of 44 (86%) patients and persisted up to 10 months. In Phase 1, a 51.5% iAb reduction was observed at 28 days with bortezomib alone. iAb reductions increased with higher bortezomib dosing densities and included class I, II, and public antigens (HLA DRβ3, HLA DRβ4 and HLA DRβ5). FCM median channel shifts decreased in 11/11 (100%) patients by a mean of 103 ± 54 mean channel shifts (log scale). Nineteen out of 44 patients (43.2%) were transplanted with low acute rejection rates (18.8%) and de novo DSA formation (12.5%). In conclusion, PI-based desensitization consistently and durably reduces HLA Ab levels providing an alternative to intravenous immune globulin-based desensitization.

Donors in chains: psychosocial outcomes of kidney donors in paired exchange

BACKGROUND

Kidney paired donation chains are initiated by nondirected donors and propagated by donors within the chain of transplants, or chain donors.

OBJECTIVE

To compare psychosocial and functional outcomes, and to test coercion, of chain donors in paired exchange versus traditional directed donors who have an established relationship with the recipient.

METHODS

Thirty chain donors from a transplant center who were part of the National Kidney Registry paired exchange program were compared with 34 traditional donors who donated around the same time. Participants completed online surveys: the postdonation section of the Living Donor Expectancies Questionnaire was used to assess psychosocial and functional outcomes 1 to 6 years after donation. A survey to assess coercion was used as well.

RESULTS

Chain donors and traditional donors were similar in terms of sex, race, age, and time after donation. The 2 groups had similar altruistic motives in donating their kidney, and both types of donors mentioned psychological benefits. No differences were found on questions regarding psychosocial outcomes save for the "quid pro quo scale" (P= .01), which suggested that the traditional donors felt more that the recipients are indebted to them. The 2 groups did not differ significantly in the coercion measure. Pressure to donate and stress of donation were not greater in chain donors than traditional donors (P= .60).

CONCLUSION

Kidney donors in kidney paired donation chains do as well as traditional donors psychosocially without any increased tendency toward experiencing coercion.

Vascular access for chronic hemodialysis in children: arteriovenous fistula or central venous catheter?

BACKGROUND

The choice of vascular access (VA) for hemodialysis (HD) in end-stage renal disease (ESRD) is arteriovenous fistula (AVF) or central venous catheter (CVC). Whereas clinical practice guidelines suggest AVF to preserve the vascular bed, pediatric nephrologists tend to favor CVC for shorter-term dialysis. Our objective was to determine whether pediatric priority allocation policies for deceased-donor kidneys affect VA planning.

METHODS

Pediatric priority for deceased-donor kidneys was instituted in Quebec in 2004. We retrospectively compared clinical practice on AVF, CVC, wait time on transplant list, HD duration in pre-policy (group A) and post-policy (group B) from 1997-2011.

RESULTS

We identified 78 patients with a median age of 14.7 years (range, 0.7-20.5 years) and weight of 46 kg (12.5-95 kg); AVF decreased from 76 % in group A to 41 % in group B (p = 0.002). Wait times on transplant list were significantly reduced: median 413.5 days (range, 2-1,910 days) in group A vs. 89 days (range, 18-692 days) in group B (p = 0.003). Time on HD for deceased-donor recipients was shorter: 705 (range, 51-1,965 days) group A vs. 349.5 days (range, 158-1,060 days) group B (p = 0.01).

CONCLUSIONS

This is the first study to document VA changes related to pediatric priority allocation policy. Our fistula-first center saw a shift toward CVC-first.

Histopathological diagnosis of acute and chronic rejection in pediatric kidney transplantation

ABO-compatible as well as ABO-incompatible kidney transplantation are well established in the pediatric population. There are particularities in the histopathological evaluation of pediatric kidney transplant biopsies as for example the recurrence of certain diseases different from the adult population. Furthermore, the challenging transition of pediatric renal transplant recipients to adulthood is associated with an increased rate of non-adherence triggered rejection episodes. With modern immunosuppressive drugs, T-cell-mediated rejection of renal allografts is well controlled. In contrast, antibody-mediated rejection (AMR) is increasingly recognized as one of the major reasons for allograft loss. However, the 2001 diagnostic Banff criteria for antibody-mediated rejection require further refinement, as the morphological spectrum of AMR expands while effective therapeutic strategies are lacking. For example, endarteritis, which traditionally has been attributed to T-cell-mediated rejection, has recently been shown to be part of the AMR spectrum in some cases. Many findings in transplant renal biopsies are not specific for a certain disease but need consideration of differential diagnoses. To use the term "chronic allograft nephropathy" as a diagnostic entity is no longer appropriate. Therefore, the precise identification of specific diseases is paramount in the assessment of transplant renal biopsies in order to enable tailored therapeutic management.

Circulating levels of 25-hydroxyvitamin D and acute cellular rejection in kidney allograft recipients

BACKGROUND

Vitamin D, in addition to its established role in bone metabolism, may regulate the immune system and affect the outcome of allografts.

METHODS

We identified 351 kidney allograft recipients who had serum levels of 25-hydroxyvitamin D (25[OH]D) measured within the first 30 days of transplantation. We evaluated the relationship between the circulating levels of 25(OH)D and acute cellular rejection (ACR), cytomegalovirus (CMV) disease, BK virus nephropathy, and kidney graft function.

RESULTS

Vitamin D deficiency (circulating levels of 25[OH]D ≤20 ng/mL, defined using The Endocrine Society Clinical Practice 2011 Guideline) was observed in 216 (61.5%) of 351 kidney graft recipients. Vitamin D deficiency was more frequent in female recipients (P=0.007, Fisher exact test) and African American recipients (P<0.001) and was less frequent in preemptive kidney graft recipients (P=0.002). Biopsy-confirmed ACR was more frequent in the vitamin D-deficient group than in the sufficient group (10.2% vs. 3.7%, P=0.04). By multivariable Cox regression analysis, vitamin D deficiency was an independent risk factor for ACR (hazard ratio=3.3, P=0.02). Vitamin D deficiency was not associated with CMV disease, BK virus nephropathy, or kidney allograft function at 1 year. 1,25-Dihydroxyvitamin D3 supplementation initiated within the first 90 days of transplantation was associated with a lesser incidence of ACR compared to no treatment with 1,25-dihydroxyvitamin D3 (5.1% vs. 13.0%, P=0.099).

CONCLUSIONS

Vitamin D deficiency is an independent risk factor for development of ACR within the first year of kidney transplantation and 1,25-dihydroxyvitamin D3 supplementation may help reduce the occurrence of ACR in the vitamin D-deficient group.

Assessing the efficacy of kidney paired donation--performance of an integrated three-site program

BACKGROUND

Kidney paired donation (KPD) has emerged as a viable option for renal transplant candidates with incompatible living donors. The aim of this study was to assess the "performance" of a three-site KPD program that allowed screening of multiple donors per recipient.

METHODS

We reviewed retrospectively the activity of our KPD program involving three centers under the same institutional umbrella. The primary goal was to achieve a transplant that was both ABO compatible and had a negative or low-positive flow cytometric crossmatch (+XM).

RESULTS

During the 40-month study period, 114 kidney transplant candidates were enrolled-57% resulting from a +XM and 39% resulting from ABO incompatible (ABOi) donors. Important outcomes were as follows: (1) 81 (71%) candidates received a transplant and 33 (29%) were still waiting; (2) 368 donors were evaluated, including 10 nondirected donors; (3) 82% (37/45) of ABOi candidates underwent transplantation; (4) 56% (36/65) of +XM candidates underwent transplantation (however, all but four of these had a cPRA less than 95%); (5) at the end of the study period, 97% (28/29) of +XM candidates still waiting had a cPRA greater than 95%.

CONCLUSIONS

These data suggest evaluating large numbers of donors increases the chances of KPD. Patients with a cPRA greater than 95% are unlikely to receive a negative or low-positive +XM, suggesting the need for desensitization protocols in KPD.

A randomized cross-over comparison of short-term exposure of once-daily extended release tacrolimus and twice-daily tacrolimus on renal function in healthy volunteers

Calcineurin inhibitor nephrotoxicity remains an issue for transplant recipients. The pharmacokinetic profile (PK) of the once-daily tacrolimus extended release (Tac-ER) includes equivalent exposure [AUC(0-24 h) ] but lower Cmax versus twice-daily tacrolimus immediate release (Tac-IR). We hypothesized that the unique PK profiles would result in pharmacodynamic differences in renal function. Nineteen healthy male subjects were allocated to once-daily Tac-ER and twice-daily Tac-IR in a prospective, randomized, two period, cross-over study. Tacrolimus was titrated to achieve trough levels of 8-12 ng/ml. Twenty four hours ERPF and GFR estimated by para-aminohippurate and sinistrin clearance were performed at baseline and at the end of each 10-day dosing period. Mean Tac C0 was 11.0 ± 2.2 and 11.3 ± 1.8 ng/ml for Tac-ER and Tac-IR, respectively. The mean Effective 24 h renal plasma flow (ERPF) was significantly higher with Tac-ER compared with Tac-IR (658 ± 127 vs. 610 ± 93 ml/min/1.73 m(2) , P = 0.046). There was a trend to a greater mean GFR over 24 h for Tac-ER at 114.5 ± 13.6 ml/min/1.73 m(2) compared with 108.9 ± 9.7 ml/min/1.73 m(2) for Tac-IR, P = 0.116. Under controlled physiological conditions, ERPF was significantly improved with Tac-ER compared with Tac-IR, likely owing to the differing PKs of these tacrolimus preparations (ClinicalTrials.gov Identifier: NCT01681134).

Subnormothermic machine perfusion for preservation of porcine kidneys in a donation after circulatory death model

Machine perfusion for preservation led to compelling success for the outcome of renal transplantation. Further refinements of methods to decrease preservation injury remain an issue of high interest. This study investigates functional and morphological aspects of kidneys preserved by subnormothermic (20 °C) machine perfusion (SNTM) compared with oxygenated hypothermic machine perfusion (HMPox) and cold storage (CS) in a donation after circulatory death (DCD) model. After 30 min of warm ischaemia, porcine kidneys were randomly assigned to preservation for 7 h by CS, HMPox or SNTM. Afterwards, kidneys were reperfused for 2 h with autologous blood in vitro for assessment of function and integrity. Application of SNTM for preservation led to significantly higher blood flow and urine output compared with both other groups. SNTM led to a twofold increased creatinine clearance compared with HMPox and 10-fold increased creatinine clearance compared with CS. Structural integrity was best preserved by SNTM. In conclusion, this is the first study on SNTM for kidneys from DCD donors. SNTM seems to be a promising preservation method with the potential to improve functional parameters of kidneys during reperfusion.

Immunophenotyping and efficacy of low dose ATG in non-sensitized kidney recipients undergoing early steroid withdrawal: a randomized pilot study

Rabbit antithymocyte globulin (ATG) is commonly used as an induction therapy in renal transplant recipients, but the ideal dosage in tacrolimus-based early steroid withdrawal protocols has not been established. The purpose of this pilot study was to determine the immunophenotyping and efficacy of lower dose ATG in low immunological-risk kidney transplant recipients. In this prospective study, 45 patients were randomized (1∶1) to our standard dose ATG (total dose 3.75 mg/kg)(sATG) vs. lower dose 2.25 mg/kg (lowATG). All patients underwent early steroid withdrawal within 7 days. The primary end point was biopsy-proven acute rejection at 12 months. Prospective immunophenotyping of freshly isolated PBMCs was performed at baseline, 3, 6, 12 months post-transplant. The rate of acute rejection was 17% and 10% in the sATG and lowATG, respectively. Effector memory T cells, Tregs and recent thymic emigrants T cells had similar kinetics post-transplant in both groups. No statistically significant differences were found in graft survival, patient survival or infections between the two groups, though there was a non-significant increase in leukopenia (43%v s. 30%), CMV (8% vs. 0) and BK (4% vs. 0) infections in sATG group vs. lowATG. In sum, in low immunological risk kidney recipients undergoing steroid withdrawal, low dose ATG seems to be efficacious in preventing acute rejection and depleting T cells with potentially lower infectious complications. A larger study is warranted to confirm these findings.

Trial Registration

ClinicalTrials.gov NCT00548405

Mechanisms and consequences of injury and repair in older organ transplants

Donor organ scarcity remains a significant clinical challenge in transplantation. Older organs, increasingly utilized to meet the growing demand for donor organs, have been linked to inferior transplant outcomes. Susceptibility to organ injury, reduced repair capacity, and increased immunogenicity are interrelated and impacted by physiological and pathological aging processes. Insights into the underlying mechanisms are needed to develop age-specific interventional strategies with regards to organ preservation, immunosuppression, and allocation. In this overview, we summarize current knowledge of injury and repair mechanisms and the effects of aging relevant to transplantation.

Calcineurin inhibitors and hypertension: a role for pharmacogenetics?

Hypertension is a common side effect of calcineurin inhibitors (CNIs), which are drugs used to prevent rejection after transplantation. Hypertension after kidney transplantation has been associated with earlier graft failure and higher cardiovascular mortality in the recipient. Recent data indicate that enzymes and transporters involved in CNI pharmacokinetics and pharmacodynamics, including CYP3A5, ABCB1, WNK4 and SPAK, are also associated with salt-sensitive hypertension. These insights raise the question whether polymorphisms in the genes encoding these proteins increase the risk of CNI-induced hypertension. Predicting who is at risk for CNI-induced hypertension may be useful for when selecting specific interventions, including dietary salt restriction, thiazide diuretics or a CNI-free immunosuppressive regimen. This review aims to explore the pharmacogenetics of CNI-induced hypertension, highlighting the knowns and unknowns.

Long-term outcomes after organ transplantation in diabetic end-stage renal disease

Patients with type 1 diabetic end-stage renal disease (ESRD) may be offered single kidney transplantation from a live donor (LDK) or a deceased donor (DDK) to replace the lost kidney function. In the latter setting the patient may also receive a simultaneous pancreas together with a kidney from the same donor (SPK). Also in some cases a pancreas after kidney may be offered to those who have previously received a kidney alone (PAK). The obvious benefit of a successful SPK transplantation is that the patients not only recover from uremia but also obtain normal blood glucose control without use of insulin or other hypoglycemic agents. Accordingly, this combined procedure has become an established treatment for type 1 diabetic patients with ESRD. Adequate long-term blood glucose control may theoretically lead to reduced progression or even reversal of microvascular complications. Another potential beneficial effect may be improvement of patient and kidney graft survival. Development of diabetic complications usually takes a decade to develop and accordingly any potential benefits of a pancreas transplant will not easily be disclosed during the first decade after transplantation. The purpose of the review is to assess the present literature of outcomes after kidney transplantation in patients with diabetic ESRD, with our without a concomitant pancreas transplantation. The points of interest given in this review are microvascular complications, graft outcomes, cardiovascular outcomes and mortality.

Selecting suitable solid organ transplant donors: Reducing the risk of donor-transmitted infections

Selection of the appropriate donor is essential to a successful allograft recipient outcome for solid organ transplantation. Multiple infectious diseases have been transmitted from the donor to the recipient via transplantation. Donor-transmitted infections cause increased morbidity and mortality to the recipient. In recent years, a series of high-profile transmissions of infections have occurred in organ recipients prompting increased attention on the process of improving the selection of an appropriate donor that balances the shortage of needed allografts with an approach that mitigates the risk of donor-transmitted infection to the recipient. Important advances focused on improving donor screening diagnostics, using previously excluded high-risk donors, and individualizing the selection of allografts to recipients based on their prior infection history are serving to increase the donor pool and improve outcomes after transplant. This article serves to review the relevant literature surrounding this topic and to provide a suggested approach to the selection of an appropriate solid organ transplant donor.

Allograft rejection and tubulointerstitial fibrosis in human kidney allografts: interrogation by urinary cell mRNA profiling

Because the kidney allograft has the potential to function as an in-vivo flow cytometer and facilitate the access of immune cells and kidney parenchymal cells in to the urinary space, we hypothesized that mRNA profiling of urinary cells offers a noninvasive means of assessing the kidney allograft status. We overcame the inherent challenges of urinary cell mRNA profiling by developing pre-amplification protocols to compensate for low RNA yield from urinary cells and by developing robust protocols for absolute quantification mRNAs using RT-PCR assays. Armed with these tools, we undertook first single-center studies urinary cell mRNA profiling and then embarked on the multicenter Clinical Trials in Organ Transplantation-04 study of kidney transplant recipients. We report here our discovery and validation of diagnostic and prognostic biomarkers of acute cellular rejection and of interstitial fibrosis and tubular atrophy (IF/TA). Our urinary cell mRNA profiling studies, in addition to demonstrating the feasibility of accurate diagnosis of acute cellular rejection and IF/TA in the kidney allograft, advance mechanistic and potentially targetable biomarkers. Interventional trials, guided by urinary cell mRNA profiles, may lead to personalized immunosuppression in recipients of kidney allografts.

Foundations and principles of the Canadian living donor paired exchange program

Purpose of review

Kidney paired donation (KPD) remains an important strategy to facilitate transplantation in patients who have a healthy and willing donor, but are unable to proceed with directed donation due to either ABO incompatibility or a positive cross-match against their intended donor.

Sources of information

Personal knowledge, The Canadian Blood Services Database for Living Donor Exchange, published reports and personal communications.

Findings

The national Living Donor Paired Exchange Programme (LDPE) in Canada was established in 2009. 235 transplants were completed of which 190 were registered recipients and 45 were from the deceased donor (DD) wait list. At 1 year, patient survival was 100%, graft survival 98%, with a biopsy proven acute rejection rate of 8%. The mean serum creatinine (Cr) at the end of one year was 109 mmol/l. Donor survival is 100%. Key to success are national standards for antibody testing and cross-matching, and for evaluating donors and recipients, as well infrastructure (software and personnel) to run the program. The structure of the Canadian program is compared with that of other programs in the United Kingdom, Australia, the Netherlands, and the United States.

Limitations

This review does not include information on travel distances and difficulties, or patient satisfaction.

Implications

National collaboration and acceptance of common standards is possible and leads to substantial benefits, especially for those patients who are hardest to match.

What was known before: Kidney paired donation is considered ethically acceptable. National and regional programs have been created in a number of countries.

What this paper adds: Key to the success of the Canadian national program are acceptance of standardized procedures and national and provincial support and oversight.

Renal bioengineering with scaffolds generated from human kidneys

BACKGROUND

In 2012, about 16,487 people received kidney transplants in the USA whereas 95,022 candidates were on the waiting list at the end of the year. Moreover, more than 2,600 kidneys procured annually for transplantation are discarded for a variety of reasons. We hypothesize that this pool of discarded kidneys could in part meet the growing, urgent need for transplantable kidneys using current methods for organ bioengineering and regeneration and surgical transplantation. The recellularization of extracellular matrix (ECM) scaffolds has the potential to meet the uniquely ambitious engineering challenges posed by complex solid organs such as the kidney.

SUMMARY

Attempts to manufacture and implant simpler, hollow structures such as bladders, vessels, urethras, and segments of the upper airways have been successful in the short and mid terms. However, the bioengineering of complex solid organs such as the kidney is a more challenging task that requires a different approach. In previous studies, we showed that decellularized porcine kidneys yield renal ECM scaffolds that preserve their basic architecture and structural components, support cell growth in vivo and in vitro, and maintain a patent vasculature capable of sustaining physiological blood pressure. In a subsequent report, using the same methods, we found that detergent-based decellularization of discarded human renal kidneys preserved their innate ECM framework, biochemical properties, and angiogenic capacity and - importantly - a patent vascular network. Furthermore, the process resulted in the clearance of immunogenic antigens, which has monumental implications for clinical outcomes in the long term in terms of graft rejection. Consequently, these kidneys show promise in bioengineering and transplantation. We refer to this avenue of research and development as 'cell-scaffold technology'.

KEY MESSAGES

In 2011, more than 4,700 patients died while on the waiting list for a kidney transplant. In this context, we believe that cell-scaffold technology has the potential to form a bridge between regenerative medicine and transplantation surgery. These methods, in theory, could provide a potentially inexhaustible source of transplantable organs. Unfortunately, current investigations are still in their very early stages and clinical translation is not immediately available in the short term. Thus, identifying the most important obstacles confronting cell-scaffold technology and focusing research efforts in this direction will be important for advancing the state of the art and meeting the clinical needs. We believe that cell-scaffold technology research and development would benefit greatly from a deeper understanding of the physiological mechanisms underlying the natural organogenesis, regeneration, and repair that characterize embryonic humans and simpler organisms. Furthermore, the importance of vascularization - the fundamental caveat of modern surgery - cannot be overstated, especially when discussing the implantation of de novo organs.

New national allocation policy for deceased donor kidneys in the United States and possible effect on patient outcomes

In 2013, the Organ Procurement and Transplantation Network in the United States approved a new national deceased donor kidney allocation policy that introduces the kidney donor profile index (KDPI), which gives scores of 0%-100% based on 10 donor factors. Kidneys with lower KDPI scores are associated with better post-transplant survival. Important features of the new policy include first allocating kidneys from donors with a KDPI≤20% to candidates in the top 20th percentile of estimated post-transplant survival, adding waiting time from dialysis initiation, conferring priority points for a calculated panel-reactive antibody (CPRA)>19%, broader sharing of kidneys for candidates with a CPRA≥99%, broader sharing of kidneys from donors with a KDPI>85%, eliminating the payback system, and allocating blood type A2 and A2B kidneys to blood type B candidates. We simulated the distribution of kidneys under the new policy compared with the current allocation policy. The simulation showed increases in projected median allograft years of life with the new policy (9.07 years) compared with the current policy (8.82 years). With the new policy, candidates with a CPRA>20%, with blood type B, and aged 18-49 years were more likely to undergo transplant, but transplants declined in candidates aged 50-64 years (4.1% decline) and ≥65 years (2.7% decline). These simulations demonstrate that the new deceased donor kidney allocation policy may improve overall post-transplant survival and access for highly sensitized candidates, with minimal effects on access to transplant by race/ethnicity and declines in kidney allocation for candidates aged ≥50 years.

Organ protection in allograft recipients: anesthetic strategies to reduce postoperative morbidity and mortality

PURPOSE OF REVIEW

Organ protection remains a primary objective in the anesthetic management of patients undergoing transplantation. An ongoing effort has been made to develop strategies to improve graft outcome and reduce postoperative morbidity and mortality, but trials have reported conflicting results. The aim of this review was to provide a comprehensive summary of the anesthetic management in transplant recipients and to identify current strategies for organ protection.

RECENT FINDINGS

Decreasing blood products requirements, intraoperative blood glucose control and adequate postoperative pain therapy may improve patient outcome. Vasopressors have been reported to reduce perioperative bleeding but might be associated with postoperative acute renal failure in liver transplantation. Early extubation may increase survival rates in recipients. These perioperative challenges, along with other protective strategies, have been addressed in 20 recently published studies: 10 randomized controlled trials, nine retrospective studies and one prospective study.

SUMMARY

This review identified several promising strategies ensuring organ protection and improving patient outcome after solid organ transplantation. However, as outcomes were difficult to compare, further evidence will be needed before drawing firm conclusions.

Conversion from twice daily tacrolimus capsules to once daily extended-release tacrolimus (LCP-Tacro): phase 2 trial of stable liver transplant recipients

LCP-Tacro is an extended-release formulation of tacrolimus designed for once-daily dosing. Studies in renal transplantation demonstrate greater bioavailability with similar safety and efficacy vs. twice-daily tacrolimus capsules. In this phase 2 study, adult stable liver transplant patients on tacrolimus capsules (Prograf) twice-daily were converted to tacrolimus tablets (LCP-Tacro) once-daily; patients continued on LCP-Tacro once-daily for days 8-21; target trough levels were 5-15 ng/mL; 24-hour pharmacokinetic (PK) assessments were done on days 7 (baseline pre-switch), 14, and 21. A 6 month extension study phase evaluated PK and safety following a total of 52 weeks of LCP-Tacro. Fifty-seven patients completed LCP-Tacro dosing in the core study; 43 completed the extension phase. The mean conversion ratio was 0.71 (Prograf:LCP-Tacro). PK data demonstrated consistent exposure (AUC) at the lower conversion dose. Cmax , Cmax /Cmin ratio, percent fluctuation and swing were significantly (P<0.001) lower and Tmax significantly (P<0.001) longer for LCP-Tacro vs. Prograf. AUC24 and Cmin correlation coefficients after 7 and 14 days of therapy were ≥0.93. There were no significant differences in PK parameters at week 26 vs. 14. One patient experienced an unrelated serious adverse event (SAE) during the core study and discontinued. There were six unrelated SAEs in the extension and 1 possibly related (rejection) that resolved; there were 3 discontinuations due to AEs during the extension. In this study, patients were safely converted from Prograf twice-daily to LCP-Tacro. The greater bioavailability of LCP-Tacro allowed for once-daily dosing and similar (AUC) exposure at a dose approximately 30% less than the total daily dose of Prograf. LCP-Tacro displayed significantly lower peak and peak-trough fluctuations. LCP-Tacro administered over one year was well tolerated with no new safety concerns.

Antibody-mediated rejection in kidney transplantation: a review of pathophysiology, diagnosis, and treatment options

Antibody-mediated rejection (AMR), also known as B-cell-mediated or humoral rejection, is a significant complication after kidney transplantation that carries a poor prognosis. Although fewer than 10% of kidney transplant patients experience AMR, as many as 30% of these patients experience graft loss as a consequence. Although AMR is mediated by antibodies against an allograft and results in histologic changes in allograft vasculature that differ from cellular rejection, it has not been recognized as a separate disease process until recently. With an improved understanding about the importance of the development of antibodies against allografts as well as complement activation, significant advances have occurred in the treatment of AMR. The standard of care for AMR includes plasmapheresis and intravenous immunoglobulin that remove and neutralize antibodies, respectively. Agents targeting B cells (rituximab and alemtuzumab), plasma cells (bortezomib), and the complement system (eculizumab) have also been used successfully to treat AMR in kidney transplant recipients. However, the high cost of these medications, their use for unlabeled indications, and a lack of prospective studies evaluating their efficacy and safety limit the routine use of these agents in the treatment of AMR in kidney transplant recipients.

Donation after circulatory death: current practices, ongoing challenges, and potential improvements

Organ donation after circulatory death (DCD) has been endorsed by the World Health Organization and is practiced worldwide. This overview examines current DCD practices, identifies problems and challenges, and suggests clinical strategies for possible improvement. Although there is uniform agreement on DCD donor candidacy (ventilator-dependent individuals with nonrecoverable or irreversible neurologic injury not meeting brain death criteria), there are variations in all aspects of DCD practice. Utilization of DCD organs is limited by hypoxia, hypotension, reduced--then absent--organ perfusion, and ischemia/reperfusion syndrome. Nevertheless, DCD kidneys exhibit comparable function and survival to donors with brain death kidneys, although they have higher rates of primary graft nonfunction, delayed graft function, discard, and retrieval associated injury. Concern over ischemic organ injury underscores the reluctance to recover extrarenal DCD organs since lack of medical therapy to support inadequate allograft function limits their acceptability. Nevertheless, limited results with DCD pancreas, liver, and lung allografts (but not heart) are now approaching that of donors with brain death organs. Pretransplant machine perfusion of DCD kidneys (vs. static storage) may reduce delayed graft function but has no effect on long-term organ function and survival. Normothermic regional perfusion used during DCD abdominal organ retrieval may reduce ischemic organ injury and increase the number of usable organs, although critical confirmative studies have yet to be done. Minor increases in usable DCD kidneys could accrue from increased use of pediatric DCD kidneys and from selective use of DCD/ECD kidneys, whereas a modest increase could result through utilization of donors declared dead beyond 1 hr from withdrawal of life support therapy. A significant increase in transplantable kidneys could be achieved by extension of the concept of living kidney donation in relation to imminent death of potential DCD donors. Progress in research to identify, prevent, and repair DCD-associated organ retrieval injury should improve utilization of DCD organs. Recent results using ex situ pretransplant organ perfusion of DCD organs has been encouraging in this regard.

Temporal trends in the incidence, treatment and outcomes of hip fracture after first kidney transplantation in the United States

It is currently unknown whether any secular trends exist in the incidence and outcomes of hip fracture in kidney transplant recipients (KTR). We identified first-time KTR (1997-2010) who had >1 year of Medicare coverage and no recorded history of hip fracture. New hip fractures were identified from corresponding diagnosis and surgical procedure codes. Outcomes studied included time to hip fracture, type of surgery received and 30-day mortality. Of 69,740 KTR transplanted in 1997-2010, 597 experienced a hip fracture event during 155,341 person-years of follow-up for an incidence rate of 3.8 per 1000 person-years. While unadjusted hip fracture incidence did not change, strong confounding by case mix was present. Using year of transplantation as a continuous variable, the hazard ratio (HR) for hip fracture in 2010 compared with 1997, adjusted for demographic, dialysis, comorbid and most transplant-related factors, was 0.56 (95% confidence interval [CI]: 0.41-0.77). Adjusting for baseline immunosuppression modestly attenuated the HR (0.68; 95% CI: 0.47-0.99). The 30-day mortality was 2.2 (95% CI: 1.3-3.7) per 100 events. In summary, hip fractures remain an important complication after kidney transplantation. Since 1997, case-mix adjusted posttransplant hip fracture rates have declined substantially. Changes in immunosuppressive therapy appear to be partly responsible for these favorable findings.

Assessment of chimerism in epithelial cancers in transplanted patients

Cancer is now the most severe complication in the long term in transplant recipients. As most solid-organ or hematopoietic stem-cell transplantations are allogeneic, chimerism studies can be performed on cancers occurring in recipients. We summarize here the different methods used to study chimerism in cancers developing in allogeneic-transplant recipients, analyze their respective advantages and report the main results obtained from these studies. Chimerism analyses of cancers in transplant recipients require methods suited to tissue samples. In the case of gender-mismatched transplantation, the XY chromosomes can be explored using fluorescent in situ hybridization on whole-tissue sections or Y-sequence-specific PCR after the laser microdissection of tumor cells. For cancers occurring after gender-matched transplantation, laser microdissection of tumor cells enables studies of microsatellite markers and high-resolution melting analysis of mitochondrial DNA on genes with marked polymorphism, provided these are different in the donor and the recipient. The results of different studies address the cancers that develop in both recipients and in transplants. The presence of chimeric cells in these two types of cancer implies an exchange of progenitor/stem-cells between transplant and recipient, and the plasticity of these progenitor/stem-cells contributes to epithelial cancers. The presence of chimeric cells in concomitant cancers and preneoplastic lesions implies that the oncogenesis of these cancers progresses through a multistep process.

What are the harms of refusing to allow living kidney donation? An expanded view of risks and benefits

Recent Organ Procurement and Transplantation Network policies relating to living kidney donation (LKD)warrant renewed attention to the ethics of transplantation from living donors. These policies focus on risks related to potential donor evaluation, informed consent and follow-up. The ethical basis of living donation is a favorable risk/benefit ratio for the donor, but regulations and research have given less attention to the benefits of donation. Relatedly, the transplant field has also failed to consider potential harms from denying patients the opportunity to donate. These harms may be substantial in the setting of directed kidney donation to a spouse/partner, sibling or child.We argue that complete assessment of donor risks and benefits demands consideration of not only the risks and benefits of donation, but also those of refusing a donor. In contrast to the ever-expanding literature on risks of donation, there are no data describing outcomes for individuals who were turned down as kidney donors. We consider factors contributing to this omission in the transplant literature, argue that current regulations may perpetuate a narrow understanding of relevant risks and benefits in LKD, and identify areas for improvement in research and clinical practice.