Adult-size kidneys without acute tubular necrosis provide exceedingly superior long-term graft outcomes for infants and small children: a single center and UNOS analysis. United Network for Organ Sharing

Combined Organ Transplantation in Patients with Advanced Liver Disease

Transplantation of the liver in combination with other organs is an increasingly performed procedure. Over the years, continuous improvement in survival could be realized through careful patient selection and refined organ preservation techniques, in spite of the challenges posed by aging recipients and donors, as well as the increased use of steatotic liver grafts. Herein, we revisit the epidemiology, allocation policies in different transplant zones, indications, and outcomes with regard to simultaneous organ transplants involving the liver, that is combined heart-liver, liver-lung, liver-kidney, and multivisceral transplantation. We address challenges surrounding combined organ transplantation such as equity, utility, and logistics of dual organ implantation, but also advantages that come along with combined transplantation, thereby focusing on molecular mechanisms underlying immunoprotection provided by the liver to the other allografts. In addition, the current standing and knowledge of machine perfusion in combined organ transplantation, mostly based on center experience, will be reviewed. Notwithstanding all the technical advances, shortage of organs, and the lack of universal eligibility criteria for certain multi-organ combinations are hurdles that need to be tackled in the future.

Effect of donor-recipient size mismatch on long-term graft survival in pediatric kidney transplantation: a multicenter cohort study

BACKGROUND

Donor-recipient size mismatching is commonly occurs in pediatric kidney transplantation (KT). However, its effect on graft survival remains unknown. This study aimed to determine the effect of donor-recipient size mismatch on the long-term survival rate of transplant kidneys in pediatric KT.

METHODS

A total of 241 pediatric patients who received KT were enrolled. The medical records of all patients were retrospectively reviewed, and the correlation between donor-recipient size mismatch and graft function and long-term graft outcome was analyzed according to donor-recipient size mismatch.

RESULTS

Recipients and donors' mean body weight at the time of KT were 34.31 ± 16.85 and 56.53 ± 16.73 kg, respectively. The mean follow-up duration was 96.49 ± 52.98 months. A significant positive correlation was observed between donor-recipient body weight ratio (DRBWR) or donor-recipient body surface area ratio (DRBSR) and graft function until 1 year after KT. However, this correlation could not be confirmed at the last follow-up. The results of long-term survival analysis using Fine and Gray's subdistribution hazard model showed no significant difference of the survival rate of the transplant kidney according to DRBWR or DRBSR.

CONCLUSION

Donor-recipient size mismatch in pediatric KT is not an important factor in determining the long-term prognosis of transplant kidneys.

Postoperative surgical complications after pediatric kidney transplantation in low weight recipients (<15 kg): a systematic review

PURPOSE OF REVIEW

Kidney transplantation in low-weight recipients (<15 kg) is a challenging surgery with special characteristics. We proposed to perform a systematic review to determine the postoperative complication rate and the type of complications after kidney transplantation in low-weight recipients (<15 kg). The secondary objectives were to determine graft survival, functional outcomes, and patient survival after kidney transplantation in low-weight recipients.

METHODS

A systematic review was performed according to preferred reporting items for systematic reviews and meta-analyses. Medline and Embase databases were searched to identify all studies reporting outcomes on kidney transplantation in low-weight recipients (<15 kg).

RESULTS

A total of 1254 patients in 23 studies were included. The median postoperative complications rate was 20.0%, while 87.5% of those were major complications (Clavien ≥3). Further, urological and vascular complications rates were 6.3% (2.0-11.9) and 5.0% (3.0-10.0), whereas the rate of venous thrombosis ranged from 0 to 5.6%. Median 10-year graft and patient survival were 76 and 91.0%.

SUMMARY

Kidney transplantation in low-weight recipients is a challenging procedure complicated by a high rate of morbidity. Finally, pediatric kidney transplantation should be performed in centers with expertise and multidisciplinary pediatric teams.

Encouraging outcomes of using a small-donor single graft in pediatric kidney transplantation

BACKGROUND

The use of small pediatric kidneys as single grafts for transplantation is controversial, due to the potential risk for graft thrombosis and insufficient nephron mass.

METHODS

Aiming to test the benefits of transplanting these kidneys, 375 children who underwent kidney transplantation in a single center were evaluated: 49 (13.1%) received a single graft from a small pediatric donor (≤ 15 kg, SPD group), 244 (65.1%) from a bigger pediatric donor (> 15 kg, BPD group), and 82 (21.9%) from adult living donors (group ALD).

RESULTS

Groups had similar baseline main characteristics. After 5 years of follow-up, children from the SPD group were comparable to children from BPD and ALD in patient survival (94%, 96%, and 98%, respectively, p = 0.423); graft survival (89%, 88%, and 93%, respectively, p = 0.426); the frequency of acute rejection (p = 0.998); the incidence of post-transplant lymphoproliferative disease (p = 0.671); the odds ratio for severely increased proteinuria (p = 0.357); the rates of vascular thrombosis (p = 0.846); and the necessity for post-transplant surgical intervention prior to discharge (p = 0.905). The longitudinal evolution of eGFR was not uniform among groups. The three groups presented a decrease in eGFR, but the slope of the curve was steeper in ALD children. At 5 years, the eGFR of the ALD group was 10 ml/min/1.73m² inferior to the others. At that time, the eGFR from the SPD group was statistically similar to the BPD group (p = 0.952).

CONCLUSION

In a specialized transplant center, the use of a single small pediatric donor kidney for transplantation is as successful as bigger pediatric or adult living donors, after 5 years of follow-up. A higher resolution version of the Graphical abstract is available as Supplementary information.

Long-term outcomes of adult-size and size-matched kidney transplants in small pediatric recipients

INTRODUCTION

Adult-size kidneys are usually used for kidney transplantation in small pediatric recipients, but the influence of graft size in transplant outcome remains controversial. Our aim is to compare long-term transplant outcomes of using adult-size and size-matched kidneys in small pediatric recipients.

MATERIALS AND METHODS

Since 1999, 61 of 226 kidney transplants were achieved in recipients weighing <20 kg with 5 years of follow-up. Patients were analyzed according to the graft size received: (group-A) adult-size (n = 32), (group-B) size-matched (n = 29). Kidney size (KS), glomerular filtration rate (GFR) proteinuria and rejection were compared between groups at transplant time (T₀), at one (T₁), two (T₂), five years (T₅), and at the end of the follow-up (T_F) (median follow-up 8.47(0-17) years). Graft and patient survival were determined and compared between groups.

RESULTS

Mean KS was significantly different between groups at T₀ (A:11.3 ± 1.1 cm, B:8.8 ± 0.9 cm), (pT₀<0.01), group-B evidenced graft growth, reaching similar sizes to group-A at T₅ (A:11.7±1 cm, B:11.2±1 cm; pT₅ = 0.13) and T_F (A:12.2 ± 1.1 cm, B:12.4 ± 1.2 cm; pT_F = 0.63), and group-A had a slight graft growth at T_F (pT₀-T_F<0.01). Mean Schwartz-GFR at T₀ was greater in group-A (138 ± 33 ml/min/1.73 m²) than group-B (109 ± 34 mL/min/1.73 m²) (pT₀ = 0.01); during follow-up, it evidenced a reduction in group-A (T₅:90 ± 27, T_F:71 ± 24 mL/min/1.73 m²; pT₀-T₅<0.01; pT₀-T_F<0.01), meanwhile in group-B was stable until T₅ (104 ± 33 mL/min/1.73 m²; pT₀-T₅ = 0.54), declining at T_F (76 ± 31 mL/min/1.73 m²; pT₀-T_F<0.01); with no significant differences at T₁, T₂, T₅, and TF between groups. Similar results were observed in mean Filler-GFR of both groups (Figure). Proteinuria and episodes of rejection were no significantly different between groups during the follow-up (p > 0.01; p = 0.23). Graft and patient survival at 5 and 10 years did not show significant differences (p = 0.45; p = 0.10).

DISCUSSION

Despite the initial kidney size difference between groups, we have demonstrated that they tended to the same size during the follow-up. Adult-size kidneys presented a slight size increase in the long-term, suggesting that they have some growth potential in small recipients, in contrast to previous literature. Mean GFR between groups showed no significant differences in the long-term, suggesting that optimal graft perfusion and function can be achieved despite the size of the graft. We have demonstrated that there were no significant differences in long-term graft and patient survival; this results were similar to the most recent literature about this topic and different from the 90-2000s decades literature.

CONCLUSIONS

Adult-size kidneys may be transplanted to small recipients (<20 kg) with comparable outcomes to size-matched kidneys, with no significant differences in long-term KS, GFR, proteinuria, rejection, graft or patient survival.

Successful kidney transplantation in a small child with end-stage renal disease due to angiotensin receptor blocker fetopathy and atretic inferior vena cava

Kidney transplantation is the treatment of choice in pediatric patients with end-stage renal disease. This population presents technical challenges particularly in those less than 20 kg due to anomalous anatomy, vascular access issues prior to transplantation, and a generally small size for age. Standard allograft outflow is usually achieved utilizing the iliac veins or IVC. When use of the iliocaval system is not feasible, alternative anastomosis must be considered. Herein, we report a case of a pediatric kidney transplantation where successful allograft outflow was achieved using the SMV when he was found to have an atretic IVC intraoperatively. In this setting, use of the portal system was required to achieve adequate allograft outflow. We created a donor iliac graft for added length to anastomose the renal vein with the SMV. In the setting of IVC occlusion with poor drainage, we utilized a patent vessel with larger caliber for outflow to reduce the risk of high venous pressures, allograft failure, venous rotation, and thrombosis. We conclude that the SMV may serve as an alternative outflow tract in the small pediatric patient and provides the vessel caliber needed to reduce the risks of complications.

Surgical outcomes after pediatric kidney transplantation at the University of Heidelberg

BACKGROUND

Kidney transplantation (KTx) is the treatment of choice for children with end-stage renal disease (ESRD).

OBJECTIVE

An update of 48 years of surgical experience with pediatric KTx (PKTx) is presented, and the results between recipients of organs from deceased donors (DDs) and living donors (LDs) are compared.

STUDY DESIGN

All patients younger than 18 years who underwent KTx between 1967 and 2015 were evaluated. Data from 540 PKTx operations (409 DD and 131 LD) were obtained from the transplant center database. Peri-operative data and graft and patient survival were analyzed in the DD and LD groups.

RESULTS

Fewer recipients in the LD group underwent dialysis before PKTx than those in the DD group (50.8% in LD vs. 94.9% in DD, P < 0.001). The mean duration of dialysis (DD: 798 ± 525 days vs. LD: 625 ± 650 days, P = 0.03), time on the waiting list (DD: 472 ± 435 days vs. LD: 120 ± 243 days, P < 0.001), cold ischemia time (CIT) (DD: 1206 ± 368 min vs. LD: 140 ± 63 min, P < 0.001), operation time, and hospital stay were lower in the LD group. Except for arterial stenosis, the rates of postoperative vascular and urological complications were not different between the two groups. The cumulative 25-year graft and patient survival rates were 46.4% and 84.1% in the DD group and 76.5% and 96.1% in the LD group, respectively.

DISCUSSION

PKTx is the treatment of choice for children with ESRD. Graft quality has a direct impact on KTx outcome and rate of graft failure. Better HLA compatibility and shorter CIT reduce the impairment of graft function after LD PKTx. In addition, Establishment of an interdisciplinary approach using an individualized risk assessment and prevention model can improve PKTx outcomes.

CONCLUSION

Compared with DD PKTx, LD PKTx has better graft survival associated with a shorter duration of preceding dialysis, waiting time, and CIT and seems to be more beneficial for children.

Clinical implication of renal allograft volume to recipient body surface area ratio in pediatric renal transplant

Our study aims to assess the clinical implication of RAV/rBSA ratio in PRT as a predictor for attained renal function at 1 year post-transplantation and its association with surgical complications. A retrospective cohort was performed for PRT cases from January 2000 to December 2015 in our institution. Extracted clinical information includes the recipient's demographics, donor type, renal allograft characteristics, arterial, venous and ureteral anastomoses, vascular anastomosis time while kidney off ice, overall operative time, and estimated blood loss. The RAV/rBSA was extrapolated and assessed for its association with renal graft function attained in 1 year post-transplantation and surgical complications within 30-day post-transplantation. A total of 324 PRTs cases were analyzed. The cohort consisted of 187 (52.4%) male and 137 (42.3%) female recipients, with 152 (46.9%) living donor and 172 (53.1%) deceased donor renal transplants, and an overall median age of 155.26 months (IQR 76.70-186.98) at time of renal transplantation. The receiver operating characteristic identified that a RAV/rBSA ratio of 135 was the optimal cutoff in determining the renal graft function outcome. Univariate and multivariate analyses revealed the relative OR for RAV/rBSA ≥ 135 ratio in predicting an eGFR ≥ 90 attained within 1 year post-transplant was highest among younger pediatric recipients (<142.5 months) of deceased kidney donors (OR = 11.143, 95% CI = 3.156-39.34). Conversely, Kaplan-Meier analysis revealed that RAV/rBSA ratio ≥ 135 is associated with lower odds of having eGFR <60 (OR = 0.417, 95% CI = 0.203-0.856). The RAV/rBSA ratio was not associated nor predictive of transplant-related surgical complications. Our study determined that the RAV/rBSA ratio is predictive of renal graft function at 1-year PRT, but not associated with any increased surgical complications.

Intraoperative blood transfusion in pediatric patients undergoing renal transplant-Effect of renal graft size

In pediatric RT, donor allograft size often exceeds the expected recipient norms, especially in younger recipients. An "oversize" graft might not only present a technical- and space-related challenge, but may possibly lead to increased demands in perioperative volume requirements due to the disparity between donor and recipient in renal blood flow. We evaluated transfusion practices at a single tertiary institution with special consideration of kidney graft size, hypothesizing that oversize graft kidneys might lead to a quantifiable increased need of blood transfusion in smaller recipients. Retrospective analysis of all patients who underwent pediatric RT from January 2004 to June 2014 at a tertiary pediatric centre was performed. Variables analyzed included patient age, weight, pre- and postoperative Hb concentration, graft size, EBL, amount of intraoperative blood transfusion, and preoperative use of erythropoietin. Based on graft size in relation to patient's age, a SMR and an OvR were identified. A subcohort of age-matched pairs was used to allow for comparison between groups. We calculated the expected procedure- and transfusion-induced changes in Hb and compared these changes to the observed difference in pre- vs postoperative Hb to assess the influence of graft size on transfusion requirements. RT was performed in 188 pediatric recipients during the study period. In the matched cohort, percentage of transfused patients during transplantation in the OvR group was more than double compared with SMR (89% vs 39%, P < .001); similarly, the median number of transfused PRBC units in OvR was 1, while the median of SMR did not receive transfusion (P < .001). The difference between expected (calculated) and observed change in Hb was significantly higher in OvR with a median of 1.9 g/dL compared with SMR with a median of 1.0 g/dL (P = .026). Correspondingly, the calculated median volume taken up by a regular size kidney was significantly higher with 213 mL compared with 313 mL (P = .031) taken up by an oversize graft kidney. Median estimated intraoperative blood loss was significantly higher in OvR than in SMR (6.9 mL/kg, vs 5.3 mL/kg, respectively; P = .04). Median postoperative Hb was similar among groups (10.4 g/dL vs 10.6 g/dL for SMR vs OvR, respectively). Transplantation of an oversized kidney in pediatric RT recipients is associated with a quantifiable higher need for blood transfusion. This may be caused by a higher intraoperative EBL and/or greater blood volume sequestered by the larger renal allograft and requires further evaluation.

Intraoperative hemodynamic factors predicting early postoperative renal function in pediatric kidney transplantation

BACKGROUND

The anesthetic management of kidney transplantation in children remains somewhat empirical. The goal of the present study was to investigate intraoperative hemodynamic factors affecting posttransplantation kidney function.

METHODS

We performed a retrospective analysis of data from patients undergoing kidney transplantation in our pediatric teaching hospital from 2000 to 2014. Data collected included: donor and recipient demographic data, recipient comorbidities, fluids administered intraoperatively, and intraoperative blood pressure and central venous pressure. The main outcome of the study was the creatinine clearance at day 1 corrected to a body surface area of 1.73 m². Analysis was performed using Classification Tree Analysis with 10-fold cross-validation.

RESULTS

One hundred and two patients were included. The following predictors of increased postoperative creatinine clearance at day 1 were identified: decreasing recipient weight, mean blood pressure-to-weight ratio 10 minutes after reperfusion, reduced cold ischemia duration, and increased intraoperative albumin infusion. Increased creatinine clearance was observed when mean blood pressure-to-weight ratio 10 minutes after reperfusion was ≥4.3 in patients weighing 13-21 kg and ≥2.5 in those ≥22 kg. Overall, the model explained 64% (and at cross-validation 60%) of creatinine clearance variability at day 1.

CONCLUSION

Intraoperative hemodynamics during kidney transplantation should be optimized in order to increase mean blood pressure according to values indicated by our analyses. Cold ischemia duration should be shortened as far as possible.

Successful Renal Transplantation in Small Children With a Completely Thrombosed Inferior Vena Cava

In small children with end-stage renal disease, an adult-sized kidney transplant is the best option. However, in the face of a completely thrombosed inferior vena cava (IVC), such transplants can be challenging, given the difficulty of achieving adequate renal venous outflow and the risk of graft thrombosis. Using a new technique to anastomose the renal vein to the right hepatic vein/IVC junction, we successfully implanted an adult-sized graft in two small children (9.8 and 14 kg) who had end-stage renal disease and a completely thrombosed IVC. After mobilizing the right lobe of the liver and obtaining total vascular occlusion of the liver, we used a Fogarty catheter to dilate the retrohepatic IVC. In the right hepatic vein, we made a venotomy and extended it inferiorly onto the retrohepatic IVC. To that venotomy, we anastomosed the donor left renal vein, using continuous 7-0 Prolene sutures. Both patients attained excellent renal allograft function: One had a serum creatinine level of 0.30 mg/dL at 6 mo after transplant, and the other had a level of 0.29 mg/dL at 1 year. In these two small children with completely thrombosed IVC, our technique for transplanting an adult-sized kidney provided adequate venous outflow.

Renal transplantation in infants

Renal transplantation (RTx) has become an accepted mode of therapy in infants with severe renal failure. The major indications are structural abnormalities of the urinary tract, congenital nephrotic syndrome, polycystic diseases, and neonatal kidney injury. Assessment of these infants needs expertise and time as well as active treatment before RTx to ensure optimal growth and development, and to avoid complications that could lead to permanent neurological defects. RTx can be performed already in infants weighing around 5 kg, but most operations occur in infants with a weight of 10 kg or more. Perioperative management focuses on adequate perfusion of the allograft and avoidance of thrombotic and other surgical complications. Important long-term issues include rejections, infections, graft function, growth, bone health, metabolic problems, neurocognitive development, adherence to medication, pubertal maturation, and quality of life. The overall outcome of infant RTx has dramatically improved, with long-term patient and graft survivals of over 90 and 80 %, respectively.

Liver transplant tolerance and its application to the clinic: can we exploit the high dose effect?

The tolerogenic properties of the liver have long been recognised, especially in regard to transplantation. Spontaneous acceptance of liver grafts occurs in a number of experimental models and also in a proportion of clinical transplant recipients. Liver graft acceptance results from donor antigen-specific tolerance, demonstrated by the extension of tolerance to other grafts of donor origin. A number of factors have been proposed to be involved in liver transplant tolerance induction, including the release of soluble major histocompatibility (MHC) molecules from the liver, its complement of immunosuppressive donor leucocytes, and the ability of hepatocytes to directly interact with and destroy antigen-specific T cells. The large tissue mass of the liver has also been suggested to act as a cytokine sink, with the potential to exhaust the immune response. In this review, we outline the growing body of evidence, from experimental models and clinical transplantation, which supports a role for large tissue mass and high antigen dose in the induction of tolerance. We also discuss a novel gene therapy approach to exploit this dose effect and induce antigen-specific tolerance robust enough to overcome a primed T cell memory response.

Subclinical inflammation and chronic renal allograft injury in a randomized trial on steroid avoidance in pediatric kidney transplantation

Steroid avoidance is safe and effective in children receiving kidney transplants in terms of graft function and survival, but the effects on allograft histology are unknown. In this multicenter trial, 130 pediatric renal transplant recipients were randomized to steroid-free (SF; n = 60) or steroid-based (SB; n = 70) immunosuppression, and underwent renal allograft biopsies at the time of graft dysfunction and per protocol at implantation and 6, 12 and 24 months after transplantation. Clinical follow-up was 3 years posttransplant. Subclinical acute rejection was present in 10.6% SF versus 11.3% SB biopsies at 6 months (p = 0.91), 0% SF versus 4.3% SB biopsies at 1 year (p = 0.21) and 0% versus 4.8% at 2 years (p = 0.20). Clinical acute rejection was present in 13.3% SF and 11.4% SB patients by 1 year (p = 0.74) and in 16.7% SF and 17.1% SB patients by 3 years (p = 0.94) after transplantation. The cumulative incidence of antibody-mediated rejection was 6.7% in SF and 2.9% in SB by 3 years after transplantation (p = 0.30). There was a significant increase in chronic histological damage over time (p < 0.001), without difference between SF and SB patients. Smaller recipient size and higher donor age were the main risk factors for chronic histological injury in posttransplant biopsies.

Primer on renal transplantation

Renal transplantation transforms chronically ill children with end stage renal disease (ESRD) into near normal resulting in improvement in nutrition, growth, neurodevelopment and quality of life, and is the goal of therapy. However, the benefits of transplantation come at a price of life-long treatment with immunosuppressive medications, increased risk of infections and malignancy. Children younger than 10 y of age have the best, and adolescents have the worst 5-y graft survival likely due to non-adherence with medications in the adolescents. Long-term complications include ongoing issues related to chronic kidney disease (CKD) and cardiovascular morbidity and mortality contributing to graft loss and shortened life expectancy, thus limiting the success of organ transplantation. Therefore, appropriate management of CKD and cardiovascular issues should be integral to the care of pediatric transplant patients. The other ongoing challenges include organ shortage, prevention and treatment of late acute rejections and chronic graft dysfunction, discovering reliable noninvasive immune monitoring tools, improving adherence, psychosocial rehabilitation, and the elusive goal of tolerance.

Appropriate donor size for porcine liver xenotransplant

OBJECTIVES

Owing to an imbalance between demand and supply, which is more prominent in pediatric transplant, every year more patients lose their lives on waiting lists. In addition to the use of deceased-donor split and living-donor organs, xenotransplant could provide a solution if associated problems, such as immunologic and physiologic ones, are solved. This study sought to analyze the surgical aspects for liver xenotransplant in a porcine model.

MATERIALS AND METHODS

Landrace pigs (n=22, 23 to 37 kg) underwent a laparotomy under general anesthesia. The hepatic hilum was prepared and the common bile ducts, common hepatic artery, portal vein, supra- and infrahepatic inferior vena cava were identified. The length and diameter of each vessel and bile duct and the weight of the liver were measured.

RESULTS

Pearson tests showed a clear correlation between the increase of the pigs' weight and the livers' weight, and the length of the vessels and the bile ducts. We did not find a clear correlation between the increase of the pigs' liver weight and the diameters of the vessels and the bile duct.

CONCLUSIONS

As the first reporting, this study on xenotransplants from the surgical point of view, we postulate that it could be possible to estimate the size of the liver and the proper length of its vessels and bile duct by weighing only the pigs. It was not feasible to match the diameter of mentioned structures by the livers' weight. However, the weight of pig's liver as well as vascular anatomy of pigs appeared to be suitable alternative for the human liver.

The coin toss of B cells in rejection and tolerance: danger versus defense

Transplantation is the preferred therapy for the end stage organ disease. Since the introduction of organ transplantation into medical practice in 1953 [1], significant progress has been achieved in patient and graft survival rates due to improvements in surgical techniques and more targeted immunosuppressive medications [2]. Nevertheless, current gaps in the management of the transplant patient stem from an incomplete understanding about the heterogeneity of the injury response in organ transplantation, at different rates and different time points after transplantation, as well as our inability to monitor the immunologic threshold of risk versus safety in each individual patient. Recent advances in immunology/transplantation biology with the advent of high throughput "omic" assays such as gene microarrays, proteomics, metabolomics, antibiomics, chemical genomics and functional imaging with nanoparticles, offers us unique methods to interrogate and decipher the variability and unpredictability of the immune response in organ transplantation (Fig. 1) [3]. Recent studies using these applications [3-8] have uncovered a critical and pivotal role for specific B cell lineages in organ injury [9] and organ acceptance [10,11] (Fig. 2). The availability of specific therapies against some of these defined B cell populations provides for an exciting new field of B cell targeted manipulation that can both abrogate the allospecific injury response, as well as promote allospecific graft accommodation and health.

Effect of donor and recipient variables on the long-term live-donor renal allograft survival in children

Objective

We aimed to analyse donor and recipient predictors of graft survival in children who received live-donor renal grafts.

Patients and methods

The study comprised 273 children who received live-donor renal transplants at our center between March 1976 and October 2010. The follow-up ranged from 6 months to 25 years. Donor variables included donor age, gender, donor/recipient body weight ratio (DR BWR), ABO blood groups, human leukocyte antigen, and DR mismatching. Donor-specific problems, e.g., ischemia time during surgery and number of renal arteries, were included. Recipient variables included recipient age, sex, original kidney disease, ischemia time, acute tubular necrosis (ATN) after transplantation, immunosuppression, number of acute rejection episodes, re-transplantation, and development of hypertension.

Results

Independent variables with a sustained effect on the 5- and 10-year graft survival on multivariate analysis were: ATN after transplant, number of acute rejections, hypertension, and DR BWR. At the last follow-up, 185 patients (67.8%) had a functioning graft, while 82 (30.0%) had graft failure. Only six patients (0.02%) were lost to follow-up.

Conclusion

Donor and recipient variables that affect short- and long-term graft survival in children with a live-donor renal allograft are DR BWR, number of acute rejections, ATN and hypertension after transplant. Considering these variables provides a better outcome.

Transplantation of adult-sized kidneys in low-weight pediatric recipients achieves short-term outcomes comparable to size-matched grafts

Low-weight pediatric recipients are disadvantaged by scarcity of size-matched donors. ASK have been successfully used for pediatric recipients. We report the results of renal transplantation using ASK in low-weight pediatric recipients and compare outcomes in weight-matched and unmatched donor-recipient pairs. The outcomes of renal transplants using ASK grafts in low-weight (<20 kg) recipients from a single center over a 10-yr period were reviewed. Two groups, comprising recipients of grafts from weight-matched and mismatched donors, were compared. Primary outcome was one-yr graft survival. Secondary outcomes were one- and two-yr calculated eGFR, changes in recipient body weight, perioperative cardiovascular stability, rates of AR and DGF. Twenty-three low-weight recipients were transplanted. Eleven received ASK grafts from high-weight donors and 12 grafts from low-weight donors. One patient in each group had early graft loss. No significant difference was observed in rates of DGF, AR, one-yr graft or patient survival and perioperative cardiovascular parameters. ASK with considerable donor:recipient weight discrepancies can be safely transplanted into small pediatric recipients with comparable outcomes to grafts with less weight discrepancy.

Successful adult-to-child renal transplantation utilizing the ovarian vein in children with inferior vena cava/iliac vein thrombosis

IVC/iliac vein thrombosis has previously been considered to be a contraindication to renal transplantation because of the technical difficulties and the increased risk of graft thrombosis. We report two successful cases of adult-to-child kidney transplantation in which we anastomosed the graft renal vein to the recipient ovarian vein in the presence of IVC and/or iliac vein thrombosis, with no short or long term vascular complications. Our experience, which adds to the successful reports from several other centers, suggests that the inability to use the iliocaval axis should no longer be considered a contraindication to pediatric renal transplantation.

Pediatric kidney transplantation

Kidney transplantation in pediatric patients has become a routinely successful procedure, with 1- and 5-year patient survival rates of 98% and 94%, and 1- and 5-year graft survival rates of 93% to 95% and 77% to 85% (the range takes into account differences between living and deceased donors). These good outcomes represent the cumulative effect of improvements in pre- and posttransplant patient care, operative techniques, immunosuppression, and infection prophylaxis, diagnosis, and treatment. This article provides a brief historical overview, discusses the indications for transplantation, describes the evaluation process for the recipient and the potential donor, outlines the operative details, reviews the various causes of and risk factors for graft dysfunction, and analyzes outcomes.

Pediatric renal transplantation: an overview and update

PURPOSE OF REVIEW

Transplantation is the preferred method of treatment for end-stage renal disease in children. The rate of pediatric kidney transplantation has been steadily rising over the past decade. The use of increasingly potent immunosuppressive drugs has lessened the risk for acute rejection substantially and improved short-term outcomes; however, the long-term outcomes have remained inadequate.

RECENT FINDINGS

The follow-up of pediatric cohorts and the encouraging results from data registries prompt us to revisit our practices in transplantation so as to devise additional strategies to improve long-term outcomes.

SUMMARY

This review presents a comprehensive discussion of the major issues in pediatric renal transplantation, the newer immunosuppression approaches to limit toxicities of therapies in children and some critical issues that remain to be addressed, specific to the care of the transplanted child. The ultimate goal of designing optimum conditions for equating graft survival to patient survival still remains a major goal for pediatric organ transplantation.

Patterns of chronic injury in pediatric renal allografts

BACKGROUND

In pediatric recipients, the pathophysiology of chronic renal allograft injury is poorly understood.

METHODS

We studied the evolution and determinants of tubulointerstitial, vascular, and glomerular injury in 240 pediatric protocol renal allograft biopsies during the first 5 years posttransplant.

RESULTS

Chronic tubulointerstitial injury (ci, ct) developed predominantly during the first 12 months posttransplant, whereas chronic vascular damage (cv, and arteriolar hyalinosis [ah]) and global glomerulosclerosis (gs) became increasingly prevalent at 25 to 36 months and beyond. Chronic interstitial lesions were associated with acute rejection and borderline histology (odds ratio [OR] 2.3, P<0.04), recipient body surface area less than 1.0 m2 (OR 3.6, P<0.05), and obesity (OR 2.0, P<0.03). Determinants of ct were acute rejection (OR 2.6, P=0.02) and acute tubular necrosis (OR 2.8, P<0.04). Vascular fibrous intimal thickening and ah were associated with donor hypertension (OR 3.6, P=0.001) and recipient body surface area less than 1.0 m (OR 2.6, P=0.02), respectively. The severity of ah correlated with the incidence of gs (r=0.32, P<0.0001), with 7.8% gs for ah0, 14.3% gs for ah1, 60.0% gs for ah2, and 95.5% gs for ah3 (median values). Antibody induction conferred protection from ci (OR 0.31, P=0.008), ct (OR 0.33, P=0.002), and ah (OR 0.12, P<0.001) progression.

CONCLUSIONS

By 5 years posttransplant, pediatric renal allografts manifest a substantial burden of tubulointerstitial and microvascular injury. These lesions are associated with donor hypertension, acute inflammation, renal hypoperfusion, obesity, and calcineurin inhibitor toxicity. The pervasiveness and rapid progression of microvascular lesions at 25 to 36 months suggest that attempts at reducing calcineurin inhibitor exposure should be made before two years posttransplant.

Variables affecting estimated glomerular filtration rate after renal transplantation in children: a NAPRTCS data analysis

Short-term graft survival has improved in renal transplants without significant effect on long-term graft survival. As GFR decline precedes graft loss, an understanding of variables affecting eGFR after TX may help improve graft survival. NAPRTCS data were analyzed to assess effects of donor, recipient, and other variables on Schwartz eGFR after transplantation. For 8438 children with a functioning graft at day 30, data were censored for children dying with a functioning graft, and those with <3 yr follow-up. Multivariate linear regression and repeated measures analyses identified factors related to eGFR at day 30 after TX and during follow-up. Young, female, non-black, children without ATN and acute rejection in the first 30 days, TX after 1995, those with better eGFR at day 30, and receiving tacrolimus had better long-term eGFR. Transplant from ideal (6-35 yr) donors had best short-term eGFR, young donors (<5 yr) had lower eGFR and poor graft survival. After one yr, eGFR improved in surviving grafts of young donors and matched ideal donors. Acute rejection, BP medications, and hospitalizations in prior six months had negative association with subsequent eGFR. Regardless of variables, eGFR deteriorated with time. Slope of eGFR decline has not changed in the recent era indicating the need for innovative therapies.

The relationship of donor source and age on short- and long-term allograft survival in pediatric renal transplantation

Limited pediatric data on allograft survival from advanced aged kidney donors exist. To determine the influence of donor source and age on allograft survival in pediatric renal transplant recipients, we analyzed the OPTN database. Allograft survival for 7291 pediatric renal transplants was evaluated. Up to five yr post-transplantation, graft survival was higher for LD vs. DD recipients. At seven yr, allograft survival was 71% in 18-54 yr-old LD recipients, 59.1% in >or=55 yr-old LD, and 45.1% in >or=50 yr-old DD recipients. An approximate 35% improvement in allograft survival in 18-54 yr-old LD recipients was observed. Multivariate results showed that recipients of LD 35-49 (aRR 0.66, 95% CI 0.55-0.80) and LD 50-54 (aRR 0.65, 95% CI 0.45-0.94) have a graft survival advantage over the ideal DD. In LD >or=55 yr, no improvement in graft survival was observed when compared with the 18-34 yr-old DD. In summary, we observed in a pediatric population, <55 yr-old LD kidneys afford improved long-term allograft survival when compared with DD kidney recipients. Increasing awareness of the long-term graft survival advantage for children receiving an LD kidney, even from older donors, should be a priority.

Successful urgent transplantation of an adult kidney into a child with inferior vena cava thrombosis

Poor venous drainage options following inferior vena cava (IVC) thrombosis have been considered to complicate or preclude renal transplantation of adult kidneys into pediatric patients. We describe urgent renal transplantation in a 5-year-old (15.3 kg) male with IVC thrombosis using an adult living donor. Preoperative magnetic resonance venography revealed a patent infrahepatic/suprarenal vena cava and portal system. In surgery, the right liver lobe was mobilized sufficiently to anastomose the graft renal vein to the native IVC at the confluence of the native left renal vein and proximal vena cava. Graft function has remained excellent with serum creatinine of 0.5 mg/dL at 36 months. IVC thrombosis need not preclude successful transplantation of adult-sized kidneys into children.

Kidney transplantation and donation in children

It has been shown that kidney transplantation results in superior life expectancy and quality of life compared with dialysis treatment for patients with end-stage renal disease. However, kidney transplantation in children differs in many aspects from adult kidney transplantation. This review focuses on specific issues of surgical care associated with kidney transplantation in children, including timing of transplantation, technical considerations, patient and graft survival, growth retardation and post-transplant malignancy. At the same time, there is a large discrepancy between the number of available donor kidneys and the number of patients on the waiting list for kidney transplantation. There is a general reluctance to use paediatric donor kidneys, because of relatively frequent complications such as graft thrombosis and early graft failure. We review the specific aspects of kidney transplantation from paediatric donors such as the incidence of graft thrombosis, hyperfiltration injury and 'en bloc' transplantation of two kidneys from one donor with an excellent long-term outcome, which is comparable with adult donor kidney transplantation. We also discuss the potential use of paediatric non-heart-beating donor kidneys, from donors whose heart stopped beating with the preservation techniques used.

The effect of donor/recipient body surface area ratio on outcomes in pediatric kidney transplantation

In pediatric kidney transplantation, the effect of inadequate nephron dosing on graft survival remains undetermined. The aim of this study was to assess the use of D/R BSA, as a reliable indicator of adequate nephron dosing, and eventually a tool to optimize pediatric graft allocation. Following Institutional Review Board approval, we reviewed deceased donor pediatric kidney transplantation (N = 156). We divided patients into three groups, based on D/R BSA: A < or =0.8; B 0.81-1.19; C > or =1.2. Five-yr graft survival rates in the groups were: A 82.0%; B 94.9%; C 97.1% (p = 0.01). Group C had the lowest rate of acute rejection, suggesting a protective effect of increased D/R BSA (group A = 35.7%, group B = 38.9%, group C = 18.8%; p = 0.029). The logistic regression analysis showed that decreased D/R BSA ratio is a risk factor for loss of graft function, at one and five yr [i.e., group A OR 6 (95% CI 1.14-39.30, p = 0.015) and OR 4.49 (95% CI 1.46-13.79, p = 0.009), respectively]. We conclude that for pediatric recipients, D/R BSA is a valuable adjunct when determining long-term graft survival. Its utility may avoid an alloimmune-independent risk factor, increasing the long-term protective value of a good matching policy.

Potential influence of tacrolimus and steroid avoidance on early graft function in pediatric renal transplantation

With the increasing adoption of steroid-sparing immunosuppression protocols in renal transplantation, it is important to evaluate any adverse effects of steroid avoidance on graft function. Early graft function, measured by CrCl was retrospectively studied in 158 consecutive pediatric renal transplant recipients from 1996 to 2005, receiving either steroid-free or steroid-based immunosuppression. Patients receiving steroid-free immunosuppression vs. steroid-based immunosuppression had no difference change in CrCl (DeltaCrCl) in the first week post-transplantation (p = 0.12). When stratified by corticosteroid usage, patients with higher tacrolimus trough levels (> or =14 ng/mL) had slower graft function recovery in the first week post-transplantation than those with lower tacrolimus trough levels (p = 0.008) in the steroid-free group only. Despite initial slower graft function recovery in this subgroup, there was no negative impact on graft function in the steroid-free group; in fact steroid-free patients trended towards better CrCl at six months (p = 0.047) and 12 months (p < 0.001) post-transplant than the steroid-based group. With the improved immunological outcomes with steroid avoidance, close surveillance should be performed of tacrolimus levels to avoid levels >14 ng/mL. In patients with slow recovery of early graft function, short-term perioperative steroids may be considered.

The evolution of nonimmune histological injury and its clinical relevance in adult-sized kidney grafts in pediatric recipients

To describe the evolution, risk factors and impact of nonimmune histological injury after pediatric kidney transplantation, we analyzed 245 renal allograft protocol biopsies taken regularly from the time of transplantation to 2 years thereafter in 81 consecutive rejection-free pediatric recipients of an adult-sized kidney. Isometric tubular vacuolization was present early after transplantation was not progressive, and was associated with higher tacrolimus pre-dose trough levels. Chronic tubulo-interstitial damage and tubular microcalcifications were already noted at 3 months, were progressive and had a greater association with small recipient size, male donor gender, higher donor age and female recipient gender, but not with tacrolimus exposure. Renal function assessment showed that older recipients had a significant increase in absolute glomerular filtration rate with time after transplantation, which differed from small recipients who showed no increase. It is concluded that progressive, functionally relevant, nonimmune injury is detected early after adult-sized kidney transplantation in pediatric recipients. Renal graft ischemia associated with the donor-recipient size discrepancy appears to be a greater risk factor for this chronic histological injury, suggesting that the exploration of additional therapeutic approaches to increase allograft perfusion could further extend the graft survival benefit of adult-sized kidneys transplanted into small children.

Immunosuppression minimization in pediatric transplantation

The greatest benefit of immunosuppression minimization for children may lie in improving patient morbidity, by the elimination of the inherent side effects of steroid and calcineurin inhibitors (CNI). The newer generation of powerful induction and maintenance immunosuppressants offers an option for selected immunosuppression minimization strategies, some of which have been shown to also reduce graft morbidity. Steroid minimization and avoidance in single-center uncontrolled trials have shown early promise and the availability of data from an ongoing randomized, prospective, controlled trial of steroid avoidance in children will provide necessary data to support a practice change for steroid elimination in children. Calcineurin inhibitor minimization and addition of mycophenolate mofetil (MMF) or sirolimus have shown variable improvements in renal function, though suboptimal efficacy and safety with the currently proposed regimes have limited their application. Randomized, prospective studies of steroid and calcineurin inhibitor minimization and/or avoidance are warranted to clearly confirm the short and long-term safety and efficacy of alternative immunosuppression combinations. Linked pharmacokinetic and mechanistic studies within these trials will allow for optimizing drug dosing and monitoring. This article reviews published experience to date with steroid and calcineurin minimization in pediatric renal transplantation and discusses the risks and benefits of these approaches.

Young for young! Mandatory age-matched exchange of paediatric kidneys

Some allocation systems include a mandatory donation of paediatric kidneys to children, others do not. Both approaches have medical and organisational advantages and disadvantages for adults and children. This article discusses why "young for young" is the best allocation system for children. Primary age-matched kidney allocation to children is one important factor leading to: (1) higher long-term glomerular filtration rates (GFRs) and graft survival and, thereby, to lesser need for dialysis; (2) better psychosocial rehabilitation, growth and development of children and, last but not least, (3) likely increase of the donor pool. As a consequence, health care costs will be reduced for children with end-stage renal failure. The chance of adults receiving an adequate kidney would be only minimally reduced by this policy. Therefore, we recommend an age-matched allocation programme giving children with end- stage kidney diseases a better prognosis.

Pediatric renal transplantation with mycophenolate mofetil immunosuppression in a single center from Mexico

An MMF-based immunosuppression has reduced the acute rejection rate in adults and in children in the early post-transplantation period. In the present study, pediatric renal transplantation patients on a CyA, MMF, and steroids regimen were prospectively evaluated. Patients with CyA, MMF, and steroid therapy without antibody induction were evaluated for surgical aspects, renal function, rejection, and survival, growth after transplantation, adverse events and medication discontinuation. Between February 2003 and May 2005, 21 kidney transplantation patients under 18 yr old were followed for at least 12 months. Within one year after transplantation, three patients developed four episodes of acute rejection (19%). Graft loss because of rejection occurred in one patient. One-year mean serum creatinine was 1.19 +/- 0.3 mg/dL. Mean calculated CrCl by Schwartz formula was 82.3 +/- 19.7 mL/min*1.73 m(2). Major adverse events included infections of the urinary tract and diarrhea, abdominal pain, and GI symptoms. No patients have discontinued the use of MMF. Good results in pediatric kidney transplantation can be achieved by using CyA/MMF/steroids. MMF is effective and relatively safe in reducing the incidence of acute rejection even without induction therapy 12 months after transplantation.

Health insurance considerations for adolescent transplant recipients as they transition to adulthood

The advent of improved immunosuppression and enhanced allograft outcomes has resulted in a growing number of patients taking expensive immunosuppression medications for the rest of their lives. Healthcare costs for the majority of transplantation procedures in the USA currently are covered by Medicare, but coverage ends for outpatient immunosuppression medications 36-44 months after transplantation. Two or three immunosuppressive agents typically are included in post-transplant regimens with a total annual cost that can exceed 13,000 dollars. This represents a significant financial burden for families no matter if they have adequate health insurance coverage because of co-payment obligations. Evidence suggests that some patients have reduced immunosuppression doses because of an inability to afford their medication, increasing the risk of graft failure. The purpose of this article was to review these and other issues pertaining to medical insurance coverage and transplantation, particularly for adolescent recipients as they transition to adulthood.

Subclinical cytomegalovirus and Epstein-Barr virus viremia are associated with adverse outcomes in pediatric renal transplantation

Post-transplant clinical disease with cytomegalovirus (CMV) and Epstein-Barr virus (EBV) is a known risk factor for graft dysfunction and lymphoproliferation. We postulate that subclinical, asymptomatic viremia also adversely impacts outcomes, and may warrant re-assessment of current monitoring and antiviral prophylaxis protocols. A single-center study was conducted on 102 pediatric (51 steroid-free and 51 matched steroid-based historical controls). Quantitative viral loads were serially monitored and correlated with outcome measures. Overall, the incidence of CMV and EBV clinical disease was 5% (1% CMV and 4% EBV); however, the incidence of subclinical viremia was 44% (12.7% CMV, 38.2% EBV, 6.9% CMV + EBV). Risk factors for subclinical viremia were EBV naivety (p = 0.07), age less than five yr (p = 0.04), lack of prophylaxis (p = 0.01), and steroid usage (p = 0.0007). Subclinical viremia was associated with lower three-yr graft function (p = 0.03), increased risk of acute rejection (odds ratio 2.07; p = 0.025), hypertension (p = 0.04), and graft loss (p = 0.03). Subclinical asymptomatic CMV and EBV viremia is a risk factor for graft injury and loss. These findings support the need for aggressive, serial viral monitoring to better determine the appropriate length of post-transplant antiviral prophylaxis, and to determine the effect of immunosuppression protocols on the development of viremia.

Chronic allograft nephropathy in paediatric renal transplantation

Chronic allograft nephropathy (CAN) is now the leading cause of renal transplant loss in paediatric transplant recipients. Despite improvements in immunosuppression, which have significantly reduced the incidence of acute rejection, the rates of chronic kidney loss have remained unchanged in paediatric transplant patients over the last 20 years. Chronic allograft nephropathy is a pathological diagnosis of which the key features are tubular atrophy and interstitial fibrosis. More consistent definitions and grading of these through the Banff classification have allowed more rigorous study of the development of chronic allograft nephropathy along with further identification of specific lesions associated with the underlying aetiologies. While initially thought to be primarily due to immune injury, it is now evident that CAN is the end result of a variety of immune and non-immune injuries including ischaemia reperfusion injury, calcineurin inhibitor (CNI) toxicity and infections. Protocol biopsy studies have demonstrated rates of CAN development in children similar to those in adults with comparable underlying pathological processes. This review outlines the current knowledge of CAN within the context of paediatric renal transplantation.

The anesthetic management of a child with chronic hypotension for renal transplantation

The anesthetic management of renal transplant recipients requires the maintenance of an adequate perfusion pressure to ensure viability of the donated kidney. A common finding among patients with end-stage renal disease is chronic hypertension. We report a case involving a 2-year-old child with an age-adjusted blood pressure below normal, undergoing transplantation of an adult cadaveric kidney, during which high-dose vasopressor medications were used to sustain the child's blood pressure at above-normal levels to help ensure perfusion of the adult allograft.

Successful Renal Transplantation in High-Risk Small Children with a Completely Thrombosed Inferior Vena Cava

BACKGROUND

Inferior vena cava (IVC) thrombosis is generally a contraindication to renal transplantation in small children because of the technical difficulty and limitations in allograft venous outflow drainage that risk graft thrombosis.

METHODS

The records of six consecutive children (9.9-27.4 kg) with end-stage renal disease and thrombosed IVCs were reviewed. Small deceased donor renal allografts were utilized in all cases where immediate posttransplant venous renal outflow would theoretically not exceed the drainage capacity of the iliac or adjacent pelvic collateral veins.

RESULTS

There is 100% patient survival with two patients returning to dialysis at seven and three years posttransplantation. There were no surgical complications or delayed graft function. Postoperatively, progressive renal vein and simultaneous iliac venous enlargement was observed in five of six recipients concomitant with renal allograft enlargement. In these patients, maximum renal volume achieved was between 152 and 275 ml and last recorded Schwartz glomerular filtration rates ranged from 67 to 118 ml/min. The sixth allograft had an early, severe rejection episode that limited renal growth and attainment of good renal function. All patients demonstrated resumption of growth rates commensurate with age but without significant catch-up growth.

CONCLUSION

A small deceased donor kidney can provide freedom from dialysis and better quality of life for small children with IVC thrombosis during an age when dialysis treatment is difficult and the complications of the thrombosed IVC may compromise life. Good renal function was attained in patients without rejection episodes. In those with rejection, our approach allowed for patient growth during allograft function, providing a bridge for a repeat transplant.

Pediatric renal transplantation with considerations for successful outcomes

Renal transplantation in the pediatric population, although conceptually similar to that in adults, differs in many aspects. This review will focus on the issues unique to the pediatric recipient. In particular, we will focus on the incidence and etiology of end stage renal disease in children, and the results as measured by patient and graft survival. Pretransplant surgical considerations of timing of the transplant, management of congenital urologic abnormalities and the abnormal bladder will be addressed. Etiologies of renal failure unique to the pediatric population will be discussed, including autosomal recessive polycystic kidney disease, congenital nephrotic syndrome, inferior vena cava thrombosis, and primary hyperoxaluria Type 1. Lastly, special transplant surgical considerations including transplantation of an adult-size kidney (ASK) into an infant or small child and ureteral implantation, management of the urinary bladder, and fluid management in infants and small children will be discussed.

Management of infants and young children with combined heart and kidney failure

Most infants and children referred for cardiac transplantation have low cardiac output with concurrent renal hypoperfusion leading to renal insufficiency and failure. This article is a review of the literature of and a single center's experience with combined heart and kidney failure in infants and children less than 10 yr of age. While 39 infants less than 10 yr of age were dialyzed pre- or peri-operatively, none required dialysis support at the time of discharge or in 5-10 yr follow-up. Based on our experience we recommend heart transplant alone in infants and young children with primary heart disease even though they have renal dysfunction.