Immunologic and patient selection strategies for successful utilization of less than 15 kg pediatric donor kidneys--long term experiences with 40 transplants

Complex Vascular Reconstruction of an En Bloc Pediatric Kidney Damaged during Organ Procurement

En bloc pediatric kidney (EBPK) allografts are a potential solution to expand the organ donor pool; however, EBPK transplantation has been traditionally considered suboptimal due to concerns of perioperative vascular and urologic complications. Accidental organ or vasculature injury during harvest is not uncommon; however, this does not necessarily mean that the organ should be discarded. Careful vascular reconstruction can be performed using donor vascular grafts, salvaging the organ without stenosis or thrombosis of the vessels. We report an extensive vascular reconstruction of the right renal artery, aorta, and inferior vena cava of a damaged EBPK allograft using a donor pediatric aorta vascular patch with the goal of avoiding postoperative vascular complications.

Successful Single-kidney Transplantation in Adult Recipients Using Pediatric Donors Aged 8 to 36 Months: Comparable Outcomes With Those Using Pediatric Donors Aged >3 Years

BACKGROUND

Using pediatric donors for single-kidney transplantation (SKT) can increase the number of possible recipients. However, it is unclear when SKT involving small pediatric donors and adult recipients can safely be performed without compromising graft outcome.

METHODS

From 2013 to 2017, a total of 102 SKTs in adult recipients were performed in our center using pediatric donors aged <12 years. We compared the outcomes from donors aged 8 to 36 months (the small-kidney group [SKG], n = 46) and from donors aged 3 to 12 years (the big-kidney group [BKG], n = 56). The median follow-up time was 30 months in the SKG and 28 months in the BKG.

RESULTS

All patients achieved satisfactory renal function after transplantation, despite the fact that some patients (SKG, 19.6%; BKG, 28.6%) developed delayed graft function. One-year graft survival and death-censored graft survival in the SKG were 89.1% and 100%, respectively, comparable to the results in the BKG (92.9% and 98.2%). One year later, the graft and patient survival rates in both groups remained unchanged. Pulmonary infection was the main cause of death in patients with a functioning graft (SKG, 4 patients; BKG, 2 patients). Proteinuria occurred early in some patients (SKG, 30.4%; BKG, 19.6%) and decreased gradually within the first year posttransplantation.

CONCLUSIONS

SKT from pediatric donors aged 8 to 36 months to selected adult recipients produced excellent intermediate-term outcomes, comparable with those when older pediatric donors were used. This study provides evidence to support a lower age limit for SKT from pediatric donors.

Utilisation of small paediatric donor kidneys for transplantation

With the increasing need for kidney transplantation in the paediatric population and changing donor demographics, children without a living donor option will potentially be offered an adult deceased donor transplant of marginal quality. Given the importance of long-term graft survival for paediatric recipients, consideration is now being given to kidneys from small paediatric donors (SPDs). There exist a lack of consensus and a reluctance amongst some centres in transplanting SPDs due to high surgical complication rates, graft loss and concerns regarding low nephron mass and long-term function. The aim of this review is to examine and present the evidence base regarding the transplantation of these organs. The literature in both the paediatric and adult renal transplant fields, as well as recent relevant conference proceedings, is reviewed. We discuss the surgical techniques, long-term graft function and rates of complications following transplantation of SPDs. We compare graft survival of SPDs to adult deceased donors and consider the use of small paediatric donors after circulatory death (DCD) organs. In conclusion, evidence is presented that may refute historically held paradigms regarding the transplantation of SPDs in paediatric recipients, thereby potentially allowing significant expansion of the donor pool.

Transplantation of pediatric renal allografts from donors less than 10 kg

Few transplant programs use kidneys from donors with body weight (BW) < 10 kg. We hypothesized that pediatric en bloc transplants from donors with BW < 10 kg would provide similar transplant outcomes to larger grafts. All pediatric en bloc renal transplants performed at our center between 2001 and 2017 were reviewed (N = 28). Data were stratified by smaller (donor BW < 10 kg; n = 11) or larger donors (BW > 10 kg; n = 17). Renal volume was assessed during follow-up with ultrasound. Demographic characteristics were similar between the 2 groups of recipients. After mean follow-up of 44 months (smaller donors) and 124 months (larger donors), graft and patient outcomes were similar between groups. Serum creatinine at 1, 3, and 5 years was no different between groups. At 1 day posttransplant, mean total renal volume in the smaller donors was 28 ± 9 mm³ vs 45 ± 12 mm³ (P < .01). By 3 weeks, it was 53 ± 19 mm³ (smaller donors) versus 73 ± 19 mm³ (larger donors) (P = NS). Complication rates were similar between both groups with 1 case of venous thrombosis in the smaller group. With experience, outcomes are equivalent to those from larger pediatric donors.

Influence of Cold Ischemia Time in Kidney Transplants From Small Pediatric Donors

Background

Clinicians may be reluctant to transplant small pediatric kidneys that have prolonged cold ischemia time (CIT) for fear of an additional deleterious effect because pediatric grafts are thought to be more sensitive to ischemia. We aimed to assess the risks associated with transplantation of small pediatric kidneys with prolonged CIT.

Methods

We performed a retrospective cohort study examining US registry data between 1998 and 2013 of adult first-time kidney-only recipients of small pediatric kidneys from donors weighing 10 to 20 kg, stratified by CIT levels of 0 to 18 (n = 1413), 19 to 30 (n = 1116), and longer than 30 (n = 338) hours.

Results

All-cause graft survival by CIT groups at 1-year was 92%, 88%, and 89%, respectively. 1-year risk-adjusted graft survival hazard ratios were significantly higher with CIT of 19 to 30 hours (adjusted hazard ratios, 1.37; 95% confidence interval, 1.04-1.81) and somewhat higher with CIT greater than 30 hours (adjusted hazard ratios, 1.24; 95% confidence interval, 0.82-1.88) relative to recipients with CIT 0 to 18 hours. There was little variation in the effect of CIT on graft survival when restricted to single kidney transplants only and no significant interaction of CIT category and single kidney transplantation (P = 0.93).

Conclusions

Although prolonged CIT is associated with lower early graft survival in small pediatric donor kidney transplants, absolute decreases in 1-year graft survival rates were 3% to 4%.

En bloc kidney transplantation from infant donors younger than 10 months into pediatric recipients

Early graft loss and poor graft function limit the use of kidneys from infant donors. Six en bloc kidney transplantations were performed from infant donors younger than 10 months into pediatric recipients between November 2012 and September 2015 at our center. We retrospectively analyzed recipient and donor demographics, surgery procedures, complications, graft function and size, and patient and graft survival with a follow-up of 6-39 months (median 15.5 months). Donor age ranged from 1 to 10 months with weight ranging from 3.5 to 10 kg. Recipient age ranged from 10 to 16 years with weight ranging from 30 to 39 kg. One kidney was removed due to arterial thrombosis during surgery, while the other kidney of this en bloc graft remained viable. Urine leak followed by bilateral ureteral obstruction occurred in one recipient. All of the recipients showed immediate graft function. The size of the en bloc kidney increased from 4.2±0.6 cm to 7.6±0.6 cm 6 months after surgery. Patient and graft survival were both 100% at the last follow-up. Our results show that en bloc kidney transplantation from infant donors younger than 10 months into pediatric recipients is effective under the condition of experienced surgical techniques and perioperative management.

Dual Kidney Transplantation From Pediatric Donors to Adult Recipients

BACKGROUND

The organ shortage is a global problem. A potential approach to expanding the deceased donor pool is to harvest organs from pediatric patients.

METHODS

Seven cases of dual kidney transplantation from pediatric donors to adult recipients were performed between 2012 and 2014 in our center. The proximal end of the donor aorta (AO) was anastomosed to the right common iliac artery or external artery. The proximal end of the donor inferior vena cava (IVC) was anastomosed to the right external iliac vein. Recipients received basiliximab or antithymocyte globulin as induction therapy, followed by tacrolimus, mycophenolate mofetil, and prednisone. Prophylactic anticoagulation was not universal in our study.

RESULTS

During the 21-month study period, both patient and graft survivals were 100%. No patient showed thrombotic complications. Complications included an acute rejection episode in 1 patient, urine leakage in 2, and anticoagulation related hemorrhage in 1. All recipients had excellent graft function with normal serum creatinine ranging from 0.49 to 1.45 mg/dL and estimated glomerular filtration rate ranging from 56.89 to 145.27 mL/min/1.73 m(2).

CONCLUSIONS

Dual kidney transplantation from pediatric donors to adult recipients is a promising way to expand the donor pool. Using the proximal end of the AO/IVC for anastomosis brings satisfactory results.

Does graft mass impact on pediatric kidney transplant outcomes?

BACKGROUND

The aim of this study is to assess the evolution of renal size and function in pediatric transplant patients according to the graft mass/recipient size ratio.

METHODS

Fifty pediatric renal transplant recipients were followed over 2 years. Grafts were weighed, and three different graft mass/m(2) ratios were determined: (1) low graft mass (58 g/m(2), range 31-57 g/m(2)), (2) median (142 g/m(2), range 59-141 g/m(2)) and high (267 g/m(2), range 143-353 g/m(2)). Patients underwent repeated ultrasound Doppler scans and repeated measurements of estimated glomerular filtration rate (eGFR; 1 week and 1, 6, 12 and 24 months), urinary retinol-binding protein (RBP) and proteinuria (1 week and 6, 12 and 24 months).

RESULTS

The volume of renal tissue increased by 12 ± 5.6 cm(3) at 24 months (p = 0.035) in the low graft mass and decreased by -14 ± 7 cm(3) (p = 0.046) in the high graft mass. The eGFR increased when either low (30 ± 5 ml/min/1.73 m(2), p < 0.001) or median (19 ± 4 ml/min/1.73 m(2), p < 0.001) graft mass was transplanted but remained stable when high graft mass was transplanted. The resistive index (RI) presented a significant decrease throughout early follow-up in the transplants involving low and median graft mass, whereas a slight rise was observed in those involving high graft mass. A significant difference was apparent 6 months post-transplant. Transplants of low and median graft mass were associated with an initial higher urinary RBP. No significant differences in proteinuria were detected.

CONCLUSIONS

Small kidneys undergo increases in volume and function without escalation of either proteinuria or urinary RBP, characterizing an adequate adaptation to the recipient. Children receiving larger kidneys present a reduction in volume, stable GFR and higher RI at 6 months.

Optimizing recovery, utilization and transplantation outcomes for kidneys from small, ≤20 kg, pediatric donors

The optimal balance between maximizing the number versus the outcome of transplantation utilizing kidneys from small (≤20 kg) pediatric donors remains unclear, complicated by the choice of single versus en bloc transplantation with their attendant technical risks. Using the Organ Procurement and Transplantation Network (OPTN) database, we examined kidney recovery and utilization patterns, and 1-year transplant outcomes by single kilogram weight strata. Between January 1, 2005 and June 30, 2010, 2352 kidneys from ≤20 kg donors were transplanted into 1531 recipients, 710 single kidney transplants (SKTs) and 821 en bloc kidney transplants (EBKTs). Increased donor weight was associated with higher rates of recovery, transplantation and SKT. Low donor weight (linear p < 0.001; quadratic p = 0.003), SKT versus EBKT (p = 0.008), increased cold ischemia time (p = 0.003), local versus nonlocal donor (p = 0.0044), low versus high volume center (p = 0.003) and the interaction term between center volume and donor weight (p = 0.0024) were associated with graft failure. Notably, lower donor weight exacerbated the negative impact of low center volume but did not worsen the negative impact of SKT on outcomes. Our data show that EBKT offers superior 1-year survival at the expense of accomplishing one rather than two transplants. However, SKTs yield excellent outcomes when performed at experienced centers.

En bloc kidney transplant from an 18-month-old donor to an adult recipient: Case report and literature review

INTRODUCTION

There is an ever-increasing need for organ donations globally. Paediatric kidney transplantation into adult recipients is a well-recognised technique to expand the donor pool. The transplantation can be done either via en bloc kidney transplant (EBKT) or as single kidney transplantation (SKT).

PRESENTATION OF CASE

An EKBT from a 18-month-old (15 kg) male patient was transplanted in a 35-year old, 85 kg male with end stage renal failure (ESRF), secondary to Focal Segmental Glomerulosclerosis (FSGS) on haemodialysis. Post-operative recovery was uneventful. Immuno-suppressant drugs used were tacrolimus, basiliximab and prednisolone. Doppler ultrasound scans performed post-operatively showed normal renal resistive indices in both kidneys. Serum creatinine decreased from 1200 to 170 μmol/L 57 with eGFR improving from 4 to 38 mL/min/1.73 m² at four weeks post-transplant.

DISCUSSION

Given the low incidence of paediatric donors, EBKTs are relatively uncommon and subsequently published series tend to be centre specific with small numbers. The graft survival rates tell us that paediatric kidney donors should not be considered as marginal transplants. The difficulty is in determining when it is more appropriate to perform a paediatric EBKT as opposed to splitting and performing two SKT. Unfortunately there are no widely accepted guidelines to direct clinicians.

CONCLUSION

This case report highlights the first EKBT performed at our institution. The current literature demonstrates that paediatric donors are excellent resources that should be procured whenever available.

Single pediatric kidney transplantation in adult recipients: comparable outcomes with standard-criteria deceased-donor kidney transplantation

BACKGROUND

Single pediatric kidney transplantation (SKT) in adult recipients has traditionally been considered a high risk because of concerns of technical complications leading to poor graft outcomes. The primary goal of this single-center, retrospective analysis was to compare outcomes after SKT to standard-criteria deceased-donor kidney transplantation (SCDKT).

METHODS

We compared outcomes in adult recipients after SKT (n=31; mean donor weight, 27 kg); SCDKT (n=283); pediatric en bloc (n=21), living-donor (n=275), and extended criteria-donor (n=100) kidney transplantations.

RESULTS

The death-censored 5-year graft survival after SKT was significantly superior to SCDKT (81.4% vs. 74.5%, P=0.02). The serum creatinine level at 5 years after transplantation was significantly lower in SKT compared with that in SCDKT (1.2 vs. 1.6 mg/dL, P<0.0001). There was a significantly higher incidence of arterial anastomotic stenosis (6.8% vs. 0.4%, P=0.02) and hydronephrosis (12.9% vs. 5.3%, P=0.02) in the SKT cohort compared with SCDKT. Subgroup analysis of the SKT cohort by donor age less than 5 years vs. 6 to 10 years (mean weight, 16.4 vs. 32.7 kg) revealed no differences in patient or graft survival.

CONCLUSIONS

Despite a higher incidence of posttransplantation vascular and urological complications, long-term graft survival after SKT (in weight-matched pediatric donors and selected adult recipients) was comparable with that after SCDKT. SKT from very small donors (age, ≤5 years) yielded excellent long-term patient and graft survivals. The use of pediatric donor kidneys should be encouraged to address the problem of organ shortage.

Intermediate-term outcome of single kidney grafts from pediatric donors weighing 10-14 kg in adult recipients

BACKGROUND

Kidneys from pediatric donors weighing <10 kg are preferably transplanted en bloc, while kidneys from donors weighing >15 kg can be safely transplanted as single kidneys. However, single kidney transplantation from donors weighing 10-14 kg is controversial and has not been well investigated.

METHODS

We analyzed the outcome of 15 recipients of single kidneys from donors weighing 10-14 kg (study group) with 40 recipients receiving an allograft from ideal deceased donors (control group).

RESULTS

After a follow-up of three yr, death-censored graft survival was 100% in both groups. The calculated creatinine clearance was lower in the study group at six months (53 vs. 71 mL/min; p = 0.01) and similar at 12 months (68 vs. 68 mL/min; p = 0.48), 24 months (81 vs. 70 mL/min; p = 0.58), and 36 months (74 vs. 69 mL/min; p = 0.59). Urinary albumin/creatinine ratios were comparable between the two groups up to two yr. At three yr, urinary albumin/creatinine ratios were higher in the study group than the control group (10.5 vs. 0.9 mg/mmol; p = 0.007). Surveillance biopsies at three and six months post-transplant revealed no evidence for focal segmental glomerulosclerosis in the study group.

CONCLUSIONS

Transplantation of single pediatric kidneys from donors weighing 10-14 kg into adult recipients provides excellent intermediate-term outcomes. Low-grade albuminuria, three yr post-transplant, might indicate late-onset hyperfiltration injury.

En bloc kidney transplantation from pediatric donors: comparable outcomes with living donor kidney transplantation

BACKGROUND

En bloc kidneys from pediatric donors have been considered suboptimal for transplantation to adult recipients and their outcomes have rarely been compared with living donor kidney transplantation (LDKT). Traditionally, there has been hesitancy in transplanting en bloc kidneys from donors weighing less than 10 kg due to high risk of technical complications.

METHODS

Retrospective chart reviews were performed to compare outcomes after pediatric en bloc (n=20, mean donor weight 11.4 kg), standard criteria deceased (n=249), and living donor (n=215) kidney transplantation in adult recipients at our center. The outcomes after en bloc transplantation from young donors weighing less than or equal to 10 kg were compared with those from 11 to 15 kg donors.

RESULTS

The 5-year graft survival after en bloc, standard deceased, and LDKT were 92%, 70%, and 88%, respectively (P=ns). There were no vascular complications, and urine leak was seen in 1 of 20 en bloc transplants. The 1-year serum creatinine of 1.1±0.2 mg/dL in recipients from less than or equal to 10 kg donors was comparable with 0.9±0.5 mg/dL in 11 to 15 kg group (P=ns).

CONCLUSIONS

Excellent long-term outcome after pediatric en bloc kidney transplantation from donors weighing less than or equal to 15 kg are comparable with those after LDKT. By using meticulous surgical technique and judicious recipient selection criteria, technical graft losses can be minimized when using en bloc pediatric kidneys from donors weighing less than or equal to 10 kg. Use of pediatric en bloc kidneys should be encouraged continuously to address the problem of organ shortage.

En-bloc pediatric kidney transplantation together with a partial bladder segment: a case report

There is a continuing debate about the techniques of kidney transplantation from small donors because of the high vascular thromboses and ureteric leak rates. Transplantation of en-bloc pediatric kidneys with a partial bladder segment has potential benefits over established techniques. We transplanted cadaveric en-bloc kidneys together with a partial bladder segment from a 1.5-year-old donor to a 12-year-old boy with end-stage renal disease due to vesicoureteral reflux (VUR) of a solitary kidney. En-bloc kidneys were transplanted together with both ureters and a partial bladder segment. Using donor bladder segment augmented the recipient bladder. Thereby, potential complications of bilateral ureteroneocystostomies of small ureters were avoided. During the following 12 months, the clinical course was normal and there was no evidence of VUR. In conclusion, the technique of using en-bloc pediatric kidneys together with a partial bladder segment is feasible and safe as well as an efficient procedure to preserve the natural anti-reflux mechanism in childhood.

A one year prospective comparison of kidney growth and function in children recipients of grafts from children and adults

BACKGROUND

Renal grafts have demonstrated capacity to adapt to the recipient. The aim of this study was to assess the growth of renal grafts transplanted to children, during the first year posttransplant.

METHODS

We conducted a 1 year prospective study comparing the growth of renal grafts from children and adults donors transplanted in children, and correlated this growth with graft function. Two groups were studied: (a) group 1-32 children transplanted with pediatric deceased kidneys from donors younger than 16 years and (b) group 2-31 children transplanted with organs from adult living donors. Anthropometric assessment, sonographic measurement of the graft, and serum creatinine at 1 week, 1, 6, and 12 months posttransplantation were performed.

RESULTS

Children from group 1 presented an 18% increase in graft volume after the sixth month of transplant, whereas in group 2 grafts presented a 14% reduction in volume, mainly during the first month; the variation in renal diameters was not uniform. Children from group 1 presented a glomerular filtration rate (GFR) increase during the follow-up (46-102 mL/min/1.73 m). After 1 year, GFR and graft volume were similar. Growth of individuals from both groups was comparable.

CONCLUSIONS

In the short term, pediatric kidneys raise volume and GFR, whereas adult kidneys slightly lower volume and GFR when transplanted in children. Taking our and other studies results into consideration, we can hypothesize that in addition to compensatory hypertrophy, pediatric grafts are likely capable of continued somatic growth.

Pediatric en bloc kidney transplantation to adult recipients: more than suboptimal?

BACKGROUND

To optimize available organs, kidneys from young donors traditionally believed to be suboptimal are transplanted to adults. The purpose of this study is to compare graft survival (GS) of en bloc kidney (EBK) from young pediatric donors to other deceased donor transplants in adult recipients.

METHODS

We analyzed United Network of Organ Sharing/STAR data on primary deceased donor kidney transplants to adult recipients (1988-2006). EBK (age younger than 5 years, n=1696) was compared with solitary pediatric (SP; age younger than 5 years) kidneys (n=1502), and matched standard adult donors (age 18-59 years, n=9594) and expanded criteria donor (ECD; n=6396). The adjusted GS was obtained using Cox proportional hazard model and hazard ratios were calculated.

RESULTS

EBK had lowest acute rejection rates (6.0%) but similar to standard adult transplants (6.3%), and lower than SP and ECD (9.0% and 8.2%; P<0.0001). Delayed graft function rates were lowest in EBK (17.9%), highest in ECD (34.8%; P<0.0001), and similar among SP and standard adult transplants (24.4% and 24.2%). The estimated glomerular filtration rate (eGFR) was best in EBK and worst in ECD (P<0.0001). The eGFR of EBK and SP transplants continuously improved but the eGFR of standard adult and ECD declined. Graft loss was higher in EBK and SP transplants than adult donor transplants during the first 6 months. Despite the highest thrombosis rates in EBK (5.0%) (SP, 3.3%; standard adult, 1.8%; ECD, 2.0%, P<0.0001), GS of EBK became similar to standard adult donor transplants by 5 years and best at 10 years posttransplant (64.0%) and worst in ECD (39.6%; P<0.0001).

CONCLUSION

EBK had the best long-term outcomes among deceased donor transplants and offer unique options for adult kidney transplant recipients.

Twenty-year graft survival and graft function analysis by a matched pair study between pediatric en bloc kidney and deceased adult donors grafts

BACKGROUND

Pediatric en bloc kidney grafts, especially those from donors aged younger than 12 months, are still regarded controversially with respect to long-term graft survival and function as well as the postoperative development of serious hypertension and proteinuria.

PATIENTS AND METHODS

This retrospective single-center study analyzed 78 pediatric en bloc kidney grafts transplanted between October 1989 and December 2008. Mean donor age was 15 months in the pediatric en bloc kidney donor group and 37.8 years in the matched pair group. The mean follow-up period was 9.3 years (range, 1-19 years). Statistical analysis was performed using the Kaplan-Meier test for patient and graft survival. Continuous variables were compared using independent sample t test.

RESULTS

Graft survival for the pediatric donors after 1, 5, and 10 years were 83.1%, 76.0%, 73.9% and for the matched pair control group 89.6%, 78.7%, and 57.8%, respectively. Serum creatinine levels after 1, 5, and 10 years were 1.0, 0.8, 1.1 mg/dL and for the matched pair control group 1.5, 1.7, and 1.6 mg/dL, respectively. No significant long-term differences were detected between the study cohort groups with respect to the postoperative development of hypertension and proteinuria.

CONCLUSION

Overall, pediatric en bloc kidney grafts are well suited to extend the scarce kidney donor pool in experienced centers because of a superior long-term outcome for graft survival and function in comparison with deceased adult kidney grafts. Special attention has to be paid to the substantial higher initial graft loss rate during the first postoperative year.

Single kidney transplantation from young pediatric donors in the United States

Kidney transplantation (KTX) from small pediatric donors is performed as single or en bloc. Criteria to determine when to split pediatric donor kidneys and transplant as singles are not well established. Data reported to the Scientific Registry of Transplant Recipient for donors <10 yrs from 1995 to 2007 were reviewed (n = 5079). Donors were categorized by weight group by 5 kg increments and solitary (n = 3503) versus en bloc (n = 1576). The primary outcome was overall graft survival. Results were compared as adjusted hazard ratios (aHR) relative to ideal standard criteria donors (SCDs) (defined as age 18-39 without other risk factors), non-ideal SCDs (all other SCDs) and expanded criteria donors (age 50-59 with other risk factors or age >or=60). Single KTX from donors >or= 35 kg conferred a similar risk of graft survival as ideal SCDs. Of donors 10-34 kg, risks of en bloc KTX were similar to ideal and risks of single KTX to non-ideal SCDs; single and en bloc KTXs had 7.9 and 5.2 graft losses per 100 follow-up years, respectively. Single KTX from donors >35 kg are similar to ideal SCDs. Single KTX from donors 10-35 kg are similar to non-ideal SCDs. From a resource perspective, pediatric donors 10-35 kg used as singles offer more cumulative graft years than when used en bloc.

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.

Recovery factors affecting utilization of small pediatric donor kidneys

Kidneys from small pediatric donors are underutilized. Using data from the Scientific Registry of Transplant Recipients for donors <21 kg in which at least one organ was recovered from 1997 to 2007 (n = 3341), donor and recovery factors were evaluated by multivariate analysis for associations with (a) kidney nonrecovery and (b) transplantation of recovered kidneys.

RESULTS

The proportion of kidney recoveries were 55% during liver procurements and 40% during intestine procurements amongst donors <10 kg (p < 0.01) compared to 93% and 88%, respectively, for donors weighing 10-20 kg (p = 0.003). Intestine procurement was independently associated with an 81% greater likelihood of kidney nonrecovery (p < 0.0001) and a 48% lower likelihood of transplantation (p = 0.0004). A multivariate Cox model indicated that single kidney recipients had a 63% higher risk of graft failure compared with en bloc kidney recipients (p < 0.0001); however, concurrent intestine recovery was not a significant risk factor for graft loss. Intestine recovery from donors <21 kg of age is strongly associated with higher kidney nonrecovery and lower transplantation rates. Graft survival is worse with single kidney transplantation, but is not significantly affected by intestine recovery. Small pediatric donors procurement teams should strive to increase kidney recoveries overall and en bloc recoveries in particular.

Single versus en bloc kidney transplantation from pediatric donors less than or equal to 15 kg

BACKGROUND

Kidney transplantation from small pediatric donors is being performed with increased frequency as single (SK) or en bloc (EBK) kidneys.

METHODS

Between 2002 and 2006, 19 EBK and 14 SK transplants from pediatric donors less than or equal to 15 kg were performed. SK arterial anastomoses were performed to the aortic patch (n=8), aortic conduit (n=1), or renal artery orifice (n=5).

RESULTS

En bloc kidney donors were on average younger (12+/-10 vs. 24+/-8 months, respectively; P=0.0102) and weighed less (10+/-3 vs. 13+/-3, respectively; P=0.0184). There were no differences between the two groups in recipient age, race, body mass index, degree of sensitization, retransplantation, and cold ischemia time; however, EBK recipients were somewhat better matched at the human leukocyte antigen DR locus (P=0.0515). Delayed graft function was more frequent in the SK group (25% vs. 0%; P=0.0542). Acute rejection occurred in 21% of recipients in both groups. Glomerular filtration rates were significantly higher with EBK than SK at 12-months posttransplantation. At 1 year, graft survival for SK and EBK was 86% and 79%, respectively (P=1.000). Graft thrombosis occurred in 0% (0/9) of SK recipients in which an aortic cuff or conduit was used, 40% (2/5) of SK recipients without an aortic cuff, and 5% (1/19) of EBK recipients (P=0.03).

CONCLUSION

Short-term outcomes of kidneys from small pediatric donors are satisfactory when transplanted as SKs or en bloc; however, the absence of an aortic patch in SK transplantation is a risk factor for early thrombosis.

Superiority of pediatric en bloc renal allografts over living donor kidneys: a long-term functional study

BACKGROUND

Growing waiting list for kidney transplantation in the United States makes it imperative to expand donor pool to use of pediatric kidneys. Because en bloc pediatric kidneys double nephron numbers, it would be interesting to learn how they fare compared to living donor kidneys long term.

METHODS

Retrospective chart review was performed on all 72 pediatric en bloc and 75 live adult donor kidney recipients transplanted between January 1990 and December 2001. Long term graft function was assessed with glomerular filtration rate (GFR) using the abbreviated modification of diet in renal disease (MDRD) formula.

RESULTS

Pediatric donor was 16.9 +/- 11.2 months old and weighed 10.7 +/- 3.8 kg. Nine en bloc kidneys thrombosed at a mean of 4.2 days posttransplantation. Proteinuria was detected later posttransplantation in en bloc group (45.6 +/- 33.6 months vs. 23.4 +/- 16.3 months, P = 0.002). Pediatric en bloc recipients had significantly higher GFR up to 8 years posttransplantation. One-year graft survival was significantly better in live donor group (93.3% vs. 81.9%, P = 0.041) but five-year graft survival rates were similar (86.7% vs. 76.3%, P = 0.125). One-year and five-year patient survival rates were similar between en bloc and live donor groups (97.3% vs. 98.6%, P = 0.585 and 94.6% vs. 93.0%, P = 0.688, respectively).

CONCLUSION

Early postoperative graft thrombosis remain a challenge with pediatric en bloc renal transplants, but once the allografts survive early postoperative course, they provide better long-term function than living donor kidney transplants. In order to alleviate burden on waiting list, pediatric en bloc kidneys should be transplanted more often when available.

Transplantation of infant en bloc kidneys into paediatric recipients

En bloc renal transplantation (EBT) from infant donors is an option for children with end-stage renal failure. Owing to potential complications, EBT is not performed in all paediatric nephrology centres. We evaluated the perioperative and long-term course of five children undergoing EBT. Primary diagnosis was atypical (diarrhoea-negative) haemolytic uraemic syndrome (n=2), interstitial nephropathy (two siblings) and branchio-oto-renal syndrome (n=1). Recipient and donor ages ranged between 5.9 and 11.1 years and 0.3 and 2.5 years, respectively. Follow-up time after EBT was 2.1-13.2 years. Perioperative complications included (1) a renal artery thrombosis, with immediate intraoperative reconstruction and primary non-functioning of the graft, with recovery after 10 days, and (2) a vesico-ureteric obstruction, successfully managed with temporary insertion of a JJ-catheter. All grafts had good long-term function. Absolute glomerular filtration rate (GFR; millilitres/minute) increased in all patients, whereas relative GFR (millilitres/minute per 1.73 m(2) body surface area) remained stable during the follow-up period in all but one. Kidney size increased significantly, with maximal growth during the first year after EBT; magnetic resonance imaging (MRI) showed normal structure and vasculature. EBT is a safe and effective option for young children with end-stage renal failure. Absolute GFR and graft size increase and adapt to the children's growing body mass.

Outcome of renal transplants from pediatric donors <5 yr of age

AIM

Outcomes of single renal transplants from donors <5 yr old have traditionally been inferior to those from older donors. We retrospectively studied our experience with patients who received renal transplants, either individually or en bloc, from young donors (<5 yr of age) to determine the utility of these organs. We also compared the outcomes of these transplant patients maintained on either cyclosporine- (CyA) or tacrolimus-based (TRL) immunosuppression regimens.

PATIENTS

Ninety-eight patients received transplants at our center from donors <5 yr of age between August 1993 and August 2003. They were followed-up from 12 months to 11 yr. Patients were divided into four groups based on whether they received single or en bloc transplants, and whether CyA or TRL was the base immunosuppressive agent. Patients in group I (n = 13) received single pediatric kidneys and were treated with CyA regimens; group II patients (n = 26) also received single pediatric kidneys, but were treated with TRL regimens; group III patients (n = 31) were transplanted en bloc and were treated with CyA; and group IV patients (n = 28) received en bloc transplants and were treated with TRL.

RESULTS

One-year patient and death-censored graft survival was not significantly different between recipients of en bloc vs. single grafts (i.e. 88 and 85% vs. 90 and 87%, respectively), or between the four treatment groups (group I: 85 and 85%, group II: 92 and 88%, group III: 87 and 84%, and group IV: 89 and 86%, respectively). The overall 1-yr rejection rate was 30% (29 of 98), which was significantly higher in the CyA-treated patients 19 of 44; i.e. 43%, than in TRL-treated patients 10 of 54, i.e. 19%, p = 0.03). In the en bloc recipients, seven grafts (12%) were lost as a result of vascular thrombosis. Notably, none of the single kidneys were lost because of vascular thrombosis. At the end of follow-up the creatinine levels of both groups were comparable.

CONCLUSIONS

Pediatric donor kidneys transplanted individually provide for equal patient and graft survival when compared with en bloc transplants. TRL can be used reduce the detrimental effect of acute rejection on graft growth and function when compared with CyA. Single use of such kidneys can safely and efficaciously be transplanted into adult recipients, greatly expanding the donor pool.

Solitary renal allografts from pediatric cadaver donors less than 2 years of age transplanted into adult recipients

BACKGROUND

Transplantation of solitary pediatric renal allografts from donors 2 years of age or younger into adult recipients is controversial.

METHODS

Between 1998 and 2001, 15 solitary renal allografts from pediatric donors 2 years of age or younger were transplanted into adult recipients. Thirty-three en bloc renal allografts transplanted between 1994 and 2001 were used for comparison. En bloc kidneys were considered for separation if they measured greater than or equal to 6 cm in length. Renal function (creatinine clearance [CrCl]) was estimated using the Cockroft-Gault formula.

RESULTS

Two-year graft survival for the solitary and en bloc groups were 93% and 77%, respectively (P =0.405). Five grafts were lost because of arterial thrombosis (four en bloc and one solitary). Ureteral complications occurred in three grafts in the en bloc group. One-year postoperative CrCl of the surviving solitary (n=14) and en bloc (n=26) grafts were 51.4+/-26.2 mL/min and 55.1+/-27.5 mL/min (P >0.05), respectively. Donor weight and kidney length were greater in the solitary group (14.3+/-3.5 kg and 6.3+/-0.4 cm, respectively) compared with the en bloc group (10.8+/-2.6 kg and 5.9+/-0.3 cm, respectively) (P =0.001 and P <0.001).

CONCLUSIONS

Separation of en bloc pairs into solitary allografts can be considered when the graft measures greater than or equal to 6 cm in length and donor weight is greater than or equal to 14 kg. The transplantation of solitary pediatric kidneys into adult recipients is successful, and the majority of pediatric en bloc allografts can be separated before transplantation.

Transplantation of Pediatric En Bloc Cadaver Kidneys into Adult Recipients: A Single-Center Experience

Faced with an extreme shortage of organs transplant professionals continue to explore various strategies to expand the donor pool. Transplantation of kidneys from older and very young donors are two such options. Although kidneys from young donors (less than 5 years of age) have been associated with a high rate of technical complications and suboptimal results, use of these kidneys en bloc has been advocated to improve the outcomes. We reviewed our experience with en bloc kidney transplantation at the University of Kentucky over the past 10 years. Between 1991 and 2000 ten patients underwent kidney transplantation using kidneys en bloc from donors <5 years age. The mean age of the donors was 2.8 years with a mean weight of 16 kg (range 13–21). Mean age of the recipients was 42 years. One patient lost the graft on day one from venous thrombosis. One patient lost the graft 7 years post-transplant from chronic rejection. All of the remaining patients are doing well with functioning grafts (mean follow-up 4.5 years; range 6 months to 10 years). Both one-year and five-year graft survival rates are 89 per cent. The present study confirms that excellent results can be achieved with kidney transplantation using kidney transplantation using kidneys en bloc from donors younger than 5 years of age.

Successful long-term outcomes using pediatric en bloc kidneys for transplantation

GOAL

The objective of our study was to determine whether acceptable long-term graft survival and function can be achieved using pediatric en bloc renal transplants by employing specific immunologic and selection strategies.

MATERIALS AND METHODS

A retrospective analysis of pediatric en bloc kidney transplants at a single institution was performed. A Kaplan-Meier analysis was used to evaluate graft survival.

FINDINGS

Fifty-seven adult recipients with at least a 1-year follow-up period were successfully transplanted using pediatric en bloc kidneys between 1993 and 1998. Complete data regarding immunosuppression were available for 53 patients. All patients had a cyclosporine (CsA)- or tacrolimus (TAC)-based regimen with either azathioprine (Aza) or mycophenolate mofetil (MMF) and corticosteroids. All but two received induction with OKT3. One-, 3-, 4-, 5- and 7-year graft survival was calculated to be 88%, 86%, 83%, 68% and 68%, respectively. The mean serum creatinine value at 3 years was 1.0+/-0.4 mg/dL. Thirteen patients (23%) had biopsy-proven rejection. Ten of 19 (53%) patients treated with CsA/Aza had rejection, whereas 2/15 (13%) on CsA/MMF and 1/19 (5%) of patients on TAC/MMF had rejection. Nine patients (16%) had surgical complications.

CONCLUSION

Excellent long-term results can be achieved in pediatric en bloc kidney transplantation using OKT3, TAC and MMF in carefully selected adult recipients.

Long-term results of en bloc transplantation of pediatric kidneys into adults using a vicryl mesh envelope technique

En bloc transplantation of pediatric kidneys into adults is a suitable measure to help correct the shortage of available kidneys. This practice, however, is not widespread because of the high incidence of vascular complications. Our institution has previously described a vicryl mesh technique for en bloc kidneys, with an attempt to reduce the incidence of vascular complications. The purpose of this study was to evaluate the long-term results of recipients with en bloc kidneys stabilized with this technique. The charts of 644 adult renal transplants performed between July 1987 and July 1999 were reviewed. During this period, 14 adult patients have received 14 pairs of en bloc pediatric kidneys using the vicryl mesh technique. All patients received OKT3 as an induction immunosuppression with cyclosporine started 10-14 d after the transplant. The median donor age was 24 months (range 14-84 months), and the median recipient age was 49 yr (range 23-68 yr). The mean recipient weight was 79 kg (range 60-114 kg). The mean cold ischemia time was 14.2 hr. None of the patients developed vascular or urological complications. Delayed graft function and moderate acute rejection occurred in one patient each. At a mean follow-up of 51 months (range 7-96 months), all 14 patients maintained excellent renal function with a mean creatinine of 1.01 mg/dL. Renal measurements pre-operatively and at follow-up ultrasound examinations were available in 9 patients, and the mean length of the kidneys had grown approximately 5.0 cm. These data demonstrate that minimal vascular and immunological complication rates can be achieved with pediatric en bloc kidneys using the vicryl mesh envelope technique.

Does renal mass exert an independent effect on the determinants of antigen-dependent injury?

The aim of this retrospective study was to determine whether nephron mass may exert a direct, independent effect on immunological tolerance. To this end, data corresponding to patients transplanted with en block pediatric kidneys (EBPK) (n=48) were compared with those of renal transplants with a low risk of hyperfiltration (LRH) comprised of recipients of a kidney from young donors (age 5-40 years) (n=173), and transplants with a high risk of hyperfiltration (HRH) comprised of patients who had received a graft from an elderly donor (older than 55 years) (n=91). All the patients had been subjected to the same immunosuppressive treatment. The median follow-up period was 54 months (6-127 months). The EBPK group showed lowest serum creatinine and highest creatinine clearance levels at each follow-up time. The rate of proteinuria >500 mg/day was 5.7% in EBPK, 7.4% in LRH, and 27.3% in HRH (P=0.000). The incidence of acute corticoresistant rejection was minor in EBPK (7.0% in EBPK, 21.3% in LRH, and 23.3% in HRH; P=0.04). Logistic regression analysis showed that the type of transplant was predictive of acute corticoresistant rejection [RR 5.33 (95% confidence interval (CI) 1.15-24.62) for HRH and RR 4.75 (95%CI 1.06-21.27) for LRH, P=0.03]. Multivariate analyses for graft failure due to chronic rejection and for graft failure due to acute rejection according to Cox's regression analysis demonstrated that HRH transplant was a significant predictive variable of both types of failure [4.08 (95%CI 1.27-13.04) for graft loss due to chronic rejection and 8.69 (95%CI 1.69-44.67) for graft loss due to acute rejection]. The present stratification of data according to nephronal mass would appear to indicate that the greater the mass, the lower the incidence of both acute and chronic rejection. This finding lends support to the hypothesis that a large mass of transplanted tissue relative to recipient mass may dampen the immune response.

Pediatric renal transplantation in the Netherlands

In the Netherlands, pediatric kidney transplantation programs are available in four centers. We retrospectively analyzed the results obtained over the past decade. Between 1985 and 1995, 231 patients (139 boys) received 269 transplants, including 61 repeat. The recipients were aged 1.9-21.8 yrs (mean 10.9), the donors 0.3-63.3 yrs (median 11.4, mean 19.7). Immunosuppression consisted of corticosteroids, cyclosporin A and azathioprine, in various combinations and dosages. The patient survival during follow-up was 97%. The overall graft survival was 73% at 1 yr and 60% at 5 yrs after transplantation. Major causes of graft loss were acute rejection (21%), thrombosis (12%) and chronic rejection (28%). Acute rejection episodes were noted in 74% of all grafts. First acute rejection episodes had a moderate predictive value for graft loss (relative risk (RR), compared to rejection-free grafts, 5.9). First rejection episodes occurring later than 3 months after transplantation were considerably more predictive (RR 18.3) than early ones. Grafts from living related donors (n = 35) yielded a superior 5-yr graft survival (77%) and remained free of rejection more often than grafts from adult cadaveric donors(43% vs. 25%). The results of pre-emptive transplants were excellent (n = 13, 5-yr survival 100%). Repeat transplants had the same results as primary transplants. Recipients younger than 4 yrs showed a poor 5-yr graft survival of 38% (n = 13). Single kidney grafts from donors younger than 4 yrs (n = 35) had a 5-yr graft survival of 44%. In contrast, kidneys from these young donors did well if transplanted en bloc (n = 10, 5-yr graft survival 89%). These overall results are in line with those of others. The results may be improved by expansion of immunosuppressive therapy in the first year and by thrombosis prophylaxis in high-risk patient-donor combinations. Better results may be expected from more extensive use of living related donations, pre-emptive transplantation and en bloc transplantation instead of single kidneys of young donors.

Transplantation of pediatric en bloc cadaver kidneys into adult recipients

BACKGROUND

To maximize the renal donor pool, cadaveric pediatric en bloc kidneys have been transplanted as a dual unit by some transplant centers. We compared the short- and long-term outcomes of adult recipients of cadaveric pediatric en bloc renal transplants versus those of matched recipients of cadaveric adult kidneys.

METHODS

Thirty-three adults who received pediatric en bloc kidney transplants between April 1990 and September 1997 were retrospectively identified and were compared with 33 matched adults who received adult cadaveric kidney transplants. The groups were identical for transplantation era, immunosuppression, recipient sex, race, cause of renal failure, mean weight, and follow-up duration (37.8 vs. 37.5 months). The mean recipient age study versus control was lower (36.3 vs. 48.9 years, P=0.0003). Results. There was no difference between the en bloc and adult donor groups in the 3-year patient survival rates (95% vs. 87%, P=0.16) or the 3-year graft survival rates (87.3% vs. 84.2%, P=0.35). Further, there was no difference in en bloc patient or en bloc graft survival time stratified by recipient age (14-44 vs. >45 years, P=0.11), en bloc donor age (<24 vs. >24 months, P=0.39), or recipient weight (<60, 61-75, >75 kg; P=0.60). Differences in serum creatinine (mg/dl) for the en bloc versus the control group at the time of discharge (3.0 vs. 7.8 mg/dl, P=0.06), at 1 year (1.4 vs. 2.0 mg/dl, P=0.06), and at 2 years (1.1 vs. 1.6 mg/dl, P=0.14) had dissipated by the time of the 5-year follow-up examination (1.1 vs. 1.6 mg/dl, P=0.14). Vascular complications were more prevalent in the en bloc group: renal vein thrombosis (one case), thrombosis of donor aorta (two cases), arterial thrombosis of one renal moiety (two cases), and renal artery stenosis (two cases). There were no differences between groups in delayed graft function, acute or chronic rejection, posttransplant hypertension, posttransplant protein-uria, or long-term graft function.

CONCLUSIONS

Collectively, these data indicate that transplanting pediatric en bloc kidneys into adult recipients results in equivalent patient and graft survival compared with adult cadaveric kidneys. Further, the data also suggest that pediatric en bloc kidneys need not be strictly allocated based on recipient weight or age criteria.

Pediatric solid organ transplantation

Solid organ transplantation offers hope for long-term survival and more normal lifestyles for children. Many of the procedures used are scaled-down versions of those used in adults and are associated with distinct challenges in children. Recent studies have provided insights into how transplantation can best serve these patients.

En bloc transplantation of infant kidneys: ten-year experience

BACKGROUND

Recent data have shown that en bloc infant kidneys transplanted to adult recipients functioned well. Longterm graft survival and function are not available, however. This study analyzes the 10-year experience with transplantation of en bloc infant kidneys from 1987-1997.

STUDY DESIGN

This is a chart review of adult recipients of en bloc infant kidneys with respect to donors' and recipients' age, weight, creatinine, HLA antigen matching, panel reactive antibodies, cold ischemia time, surgical complications, original disease, and longterm graft function and survival.

RESULTS

Five en bloc kidneys thrombosed (6.4%). Two ureteral fistulas were repaired successfully. Five patients underwent dialysis (6.4%). Two patients died of infection, six of heart attack and stroke, and one of cancer. All had excellent graft function at patients' death. Renal artery stenosis was dilated in seven patients. Six grafts were lost to rejection (one from noncompliance at 20 months). The original disease recurred in three patients with massive proteinuria despite excellent function. Graft survival at 43 months (range, 6-123 months) was 79%, with serum creatinine levels at 1, 3, 9 and 10 years of 1.2, 1.0, 0.8 and 0.8 mg/dl, respectively. Creatinine clearance averaged 88 mL/min (range, 34-188 mL) and 24-hour proteinuria was 146 mg (normal range, 10-150).

CONCLUSIONS

In conclusion, en bloc infant kidneys can be transplanted successfully with excellent longterm function, hyperfiltration injury was not observed, and infant kidneys should be used more frequently.

Renal transplantation: surgical aspects, complications and results

Despite the fact that kidney transplants have routinely been successfully performed for over 30 years there continues to be challenges for the transplant surgeon. These include a static donor pool, growing recipient list, declining number of ideal donors and greater reliance on marginal donors. Innovative methods to deal with these problems continue to be sought.

Clinical outcome of renal transplantation. Factors influencing patient and graft survival

The 1-year graft survival rate for primary cadaver kidney transplants performed in the US during the past 9 years was 82%, and it was 94% when living donor kidneys were transplanted. After the first year, however, half of the surviving cadaveric grafts will fail within 8 years. This late rate has not changed substantially in the past 20 years. This article describes some of the factors that affect long-term graft and patient survival rates.