Transplantation of single and paired pediatric kidneys into adult recipients

The effect of low donor-to-recipient body weight ratio on graft survival after dual kidney transplantation from pediatric deceased donors

BACKGROUND

Dual kidney transplantation (DKT) from small pediatric donors, either en-bloc or split dual kidney transplantation, contributes to mitigating organ scarcity. This study investigates the prognosis of DKT from pediatric deceased donors, and influencing factors.

METHOD

A retrospective study included recipients who underwent DKT from pediatric donors between 2012 and 2022. Recipients were categorized into low mismatch (BWLM, n = 30) and high mismatch (BWHM, n = 10) groups based on donor-recipient weight ratio of 1:10. Outcome encompassed recipient and graft survival, renal function, and adverse events.

RESULT

Forty recipients were included. The average follow-up period was 54.6 months. The 1, 3, and 5-year patient survival were 97.4%, with no significant differences between en-bloc and split dual kidney transplantation or between BWLM and BWHM groups. The graft survival at 1, 3, and 5 years were 89.9%, the graft survival of BWHM group was lower than BWLM group (70% vs 96.7%, p = 0.039). The average eGFR at 1, 3, and 5 years postoperatively were (78.93 ± 25.23), (83.82 ± 32.4), and (85.92 ± 37.08) mL/min/1.73 m2, respectively. The BWHM group also experienced higher rates of graft-related surgical complications (p = 0.006) and urinary tract surgical complications (p = 0.042).

CONCLUSION

DKT from pediatric donors yields favorable outcomes, with similar graft survival and complication rates across surgical subgroups. However, significant donor-recipient weight mismatch, particularly when the ratio is less than 1:10, may contribute to increased surgical complications and poorer graft survival. Efforts to minimize extreme weight mismatch are recommended to optimize outcomes.

Transplantation of En Bloc Pediatric Kidneys With a Bladder Segment Patch After a Complex Vascular Reconstruction: A Case Report

BACKGROUND

En bloc pediatric kidney (EBPK) allografts represent one potential solution to increase the number of organs available in the donor pool, thus facilitating transplantation of kidneys from young donors into adult recipients. However, EBPK transplantation has been traditionally considered suboptimal because of concerns for perioperative complications.

METHODS

An extensive reconstruction and successful transplantation of an EBPK allograft using same pediatric donor vascular grafts and a bladder patch aiming to avoid postoperative complications is presented in this report.

RESULTS

The warm ischemia time was 25 minutes. No surgical drainage or ureteral stent were used. Postoperative Doppler ultrasound showed laminar blood flow and normal parameters in both the external iliac and graft arteries, no collections, and no signs of obstructive uropathy. The patient had an uneventful recovery showing a creatinine level of 0.86 mg/dL and 0.85 mg/dL at 1 month and 3 months, respectively.

CONCLUSIONS

A refined back-table reconstruction of these allografts is crucial to avoid mishaps in the postoperative period.

Overcoming Mismatch Concerns for Adult Recipients of Small Pediatric Deceased Donor Kidneys

BACKGROUND

Kidneys from very young pediatric donors continue to be underutilized. To reduce discard, the Organ Procurement and Transplantation Network (OPTN) policy was recently updated to allow kidneys from donors weighing <18 kg to be recovered en bloc.

METHODS

We reviewed our center's experience with kidney transplantation in adult recipients of <18 kg pediatric donor kidneys to assess renal function outcomes specific to solitary vs en bloc usage.

RESULTS

The majority of <18 kg donors were used en bloc (n = 39, 72.2% vs n = 15, 27.8%). Donor weight (kg) was similar between the 2 groups (12.3 ± 3.2 vs 14.1 ± 2.5, P = .05). Recipient weight was lower in the solitary kidney group (P = .01). Both groups had a similar donor-to-recipient body weight ratio (0.24 ± 0.3 vs 0.18 ± 0.3, P = .51). The solitary kidney group had a lower estimated glomerular filtration rate at 1 (56.9 ± 24.3 vs 81.8 ± 24.8, P = .01) and 2 years (72 ± 18.6 vs 93.7 ± 21.6, P = .03). By 2 years, both groups had an average estimated glomerular filtration rate >60 mL/min. Kidney allograft growth occurred in both groups, with the largest increase occurring the first month posttransplant (11.9%, 18.6%, P < .0001).

CONCLUSION

For pediatric donors weighing <18 kg, improvements in renal function continue beyond the first posttransplant year. Risk for hyperfiltration injury appears low and renal mass-recipient mass matching is useful in guiding decision-making for solitary vs en bloc utilization.

Kidney transplantation with allografts from infant donors-Small organs, big value

BACKGROUND

Although infant organ donors remain a rare source of organs for transplantation, technical challenges have resulted in increased rates of complications and inferior graft function. The aim of the present study was to investigate the outcomes of kidneys procured from juvenile and infant donors.

PATIENTS AND METHODS

We evaluated all kidney transplants from deceased donors < 16 years of age performed at our center between 01/2008 and 08/2019. We defined three groups based on quartiles of donor body weight: <13 kg (infant donors), 13-40 kg (juvenile donors), and > 40 kg (standard criteria donors). Clinical characteristics and outcomes were compared between groups.

RESULTS

Ninety-two transplants were included in this study. Out of 92 recipients, there were 32 (34.8%) adult and 60 (65.2%) pediatric patients. All groups demonstrated excellent graft function and survival on both short and long-term follow-up. 1-year, 3-year, and 5-year graft survival rates for the standard criteria donor group were 100%, 95.2%, and 88.4%, respectively, compared with 95.8% for infant and 95% for juvenile donors at all times (P = .79). eGFR at 5 years was 98.9 ± 5.5, 74.1 ± 6.2, and 81.6 ± 6.9 mL/min/1.73 m² for infant, juvenile, and standard criteria donors, respectively (P < .01).

CONCLUSION

Infant donor allografts can be transplanted with excellent long-term outcomes in both pediatric and adult recipients. Implanting them as single allografts onto pediatric candidates allows for the transplantation of two patients. As such, pediatric recipients should be prioritized for these donor organs.

Successful Pediatric Kidney Transplantation Into an Adult Recipient: A Case Report

BACKGROUND

The constant shortage of kidney donors prompts exploration into new strategies of transplantation. One of these strategies is the use of pediatric donors aged up to 5 years whose kidneys can be transplanted into adult recipients, mainly en bloc. This involves retrieving kidneys en bloc with aorta and inferior vena cava and anastomosing them to the recipient's external iliac vessels.

CASE PRESENTATION

In our hospital, kidneys from a 3-year-old child were transplanted to a 30-year-old man. The recipient with end-stage renal failure, due to glomerular nephritis, was dialyzed for 12 years and had 1 failed transplantation with consequent graftectomy. In 2009, kidneys were transplanted to the external iliac artery and vein with reconstruction of the renal vessels. Shortly after transplantation the patient had normal renal measures. Three months later a critical stenosis of 1 renal artery was detected. Angioplasty was performed but technical reasons did not allow for effective dilatation of the vessel. Further, 6 months after kidney transplantation (KTx) nephrotic proteinuria appeared and features of membranous nephropathy were detected in a renal biopsy. The proteinuria subsided after administration of ramipril and losartan. Doppler ultrasound revealed that 1 artery remained 90% stenotic with a peak systolic velocity of 377 cm/sec. Despite reported complications, renal function appeared normal over 7 years of observation.

CONCLUSIONS

A transplantation of 2 pediatric kidneys into an adult recipient has very high efficacy. The survival of both graft and recipient is similar to the results obtained after living donor kidney transplantation.

A novel technique for en bloc kidney transplantation from infant donors with extremely low body weight by using the distal abdominal aorta as an outflow tract

Pediatric kidney donors remain underutilized due to the high risk of postoperative thrombosis. To address this problem, we developed a novel en bloc kidney transplantation technique using donor thoracic aorta and the distal abdominal aorta as inflow and outflow tracts, respectively. Briefly, eight kidneys from deceased infant donors under five months old and with low body weight (1.9-4.9 kg) were transplanted en bloc into four pediatric and four adult patients. The donor's common iliac artery or external iliac artery was anastomosed to the recipient's distal external iliac artery or inferior epigastric artery, respectively, as an outflow tract. Recipients received basiliximab or antithymocyte globulin as induction therapy followed by tacrolimus, mycophenolate mofetil, and prednisone but without prophylactic anticoagulation. Delayed graft function was observed in one patient but was reversed at 90 days posttransplant. Two patients had urine leakage, which was cured by conservative treatment. Two recipients developed lung infections that eventually cleared. No patients experienced posttransplant vascular thrombosis. After 1-1.5 years of follow-up, all patients are well and have normal serum creatinine levels. In conclusion, this novel en bloc kidney transplantation technique using a modified arterial inflow and outflow tract can prevent vascular thrombosis and provide adequate graft function.

Advances in Regenerative Medicine and Tissue Engineering: Innovation and Transformation of Medicine

Humans and animals lose tissues and organs due to congenital defects, trauma, and diseases. The human body has a low regenerative potential as opposed to the urodele amphibians commonly referred to as salamanders. Globally, millions of people would benefit immensely if tissues and organs can be replaced on demand. Traditionally, transplantation of intact tissues and organs has been the bedrock to replace damaged and diseased parts of the body. The sole reliance on transplantation has created a waiting list of people requiring donated tissues and organs, and generally, supply cannot meet the demand. The total cost to society in terms of caring for patients with failing organs and debilitating diseases is enormous. Scientists and clinicians, motivated by the need to develop safe and reliable sources of tissues and organs, have been improving therapies and technologies that can regenerate tissues and in some cases create new tissues altogether. Tissue engineering and/or regenerative medicine are fields of life science employing both engineering and biological principles to create new tissues and organs and to promote the regeneration of damaged or diseased tissues and organs. Major advances and innovations are being made in the fields of tissue engineering and regenerative medicine and have a huge impact on three-dimensional bioprinting (3D bioprinting) of tissues and organs. 3D bioprinting holds great promise for artificial tissue and organ bioprinting, thereby revolutionizing the field of regenerative medicine. This review discusses how recent advances in the field of regenerative medicine and tissue engineering can improve 3D bioprinting and vice versa. Several challenges must be overcome in the application of 3D bioprinting before this disruptive technology is widely used to create organotypic constructs for regenerative medicine.

Single vs dual (en bloc) kidney transplants from donors ≤ 5 years of age: A single center experience

AIM: To compare outcomes between single and dual en bloc (EB) kidney transplants (KT) from small pediatric donors.

METHODS: Monocentric nonprospective review of KTs from pediatric donors ≤ 5 years of age. Dual EB KT was defined as keeping both donor kidneys attached to the inferior vena cava and aorta, which were then used as venous and arterial conduits for the subsequent transplant into a single recipient. Donor age was less useful than either donor weight or kidney size in decision-making for kidney utilization as kidneys from donors < 8 kg or kidneys < 6 cm in length were not transplanted. Post-transplant management strategies were standardized in all patients.

RESULTS: From 2002-2015, 59 KTs were performed including 34 dual EB and 25 single KTs. Mean age of donors (17 mo vs 38 mo, P < 0.001), mean weight (11.0 kg vs 17.4 kg, P = 0.046) and male donors (50% vs 84%, P = 0.01) were lower in the dual EB compared to the single KT group, respectively. Mean cold ischemia time (21 h), kidney donor profile index (KDPI; 73% vs 62%) and levels of serum creatinine (SCr, 0.37 mg/dL vs 0.49 mg/dL, all P = NS) were comparable in the dual EB and single KT groups, respectively. Actuarial graft and patient survival rates at 5-years follow-up were comparable. There was one case of thrombosis resulting in graft loss in each group. Delayed graft function incidence (12% dual EB vs 20% single KT, P = NS) was slightly lower in dual EB KT recipients. Initial duration of hospital stay (mean 5.4 d vs 5.6 d) and the one-year incidences of acute rejection (6% vs 16%), operative complications (3% vs 4%), and major infection were comparable in the dual EB and single KT groups, respectively (all P = NS). Mean 12 mo SCr and abbreviated MDRD levels were 1.17 mg/dL vs 1.35 mg/dL and 72.5 mL/min per 1.73 m²vs 60.5 mL/min per 1.73 m² (both P = NS) in the dual EB and single KT groups, respectively.

CONCLUSION: By transplanting kidneys from young pediatric donors into adult recipients, one can effectively expand the limited donor pool and achieve excellent medium-term outcomes.

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.

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.

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.

Recovery and utilization of deceased donor kidneys from small pediatric donors

The optimal use of kidneys from small pediatric deceased donors remains undetermined. Using data from the Scientific Registry of Transplant Recipients, 2886 small (< 21 kg) pediatric donors between 1993 and 2002 were identified. Donor factors predictive of kidney recovery and transplantation (1343 en bloc; 1600 single) were identified by logistic regression. Multivariable Cox regression was used to assess the risk of graft loss. The rate of kidney recovery from small pediatric donors was significantly higher with increasing age, weight and height. The odds of transplant of recovered small donor kidneys were significantly higher with increasing age, weight, height and en bloc recovery (adjusted odds ratio = 65.8 vs. single; p < 0.0001), and significantly lower with increasing creatinine. Compared to en bloc, solitary transplants had a 78% higher risk of graft loss (p < 0.0001). En bloc transplants had a similar graft survival to ideal donors (p = 0.45) while solitary transplants had an increased risk of graft loss (p < 0.0001). En bloc recovery of kidneys from small pediatric donors may result in the highest probability of transplantation. Although limited by the retrospective nature of the study, kidneys transplanted en bloc had a similar graft survival to ideal donors but may not maximize the number of successfully transplanted recipients.

Transplantation of adult recipients by single cadaveric kidneys from pediatric donors weighing < or = 25 kg can be a reliable option

The evidence in favor of transplanting single allografts from cadaveric pediatric donors into adult recipients is equivocal. This study was performed to assess the outcome of transplantation of single kidneys from pediatric donors weighing < 25 kg. Thirty-five adults transplanted by renal allografts from pediatric donors weighing < 25 kg were compared with 30 matched recipients of kidneys from adult donors. Donors in study group were aged 4.2 +/- 2.1 years weighing 16.0 +/- 5.3 kg. In the study group, surgical complications occurred in five of 35 patients, in the control group four of 30. Serum creatinine reached nadir in 47.5 days in study group versus 30 days in controls (P < 0.01). Serum creatinine at 1 and 3 years were comparable in both groups. A 38.9% had proteinuria at 1 year in the study group compared with 22.7% in controls (P = 0.36). One-year graft survival was 91.7% in the study group versus 92.8% for controls. The surgical complications and graft survival in the study group was comparable with that of controls. The incidence of proteinuria may be more frequent, but does not appear to impact graft function. The use of single, as compared with paired, pediatric donor kidneys would allow more patients to be transplanted with equivalent results.

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.

Superior long-term results of simultaneous pancreas-kidney transplantation from pediatric donors

The shortage of cadaveric donors for simultaneous pancreas-kidney transplantation has prompted the use of cadaveric organs from pediatric donors. The long-term outcome and its impact on overall long-term survival are unknown. A total of 680 recipients receiving cadaver Simultaneous pancreas-kidney (SPK) transplantation from pediatric and adult donors between July 1986 and September 2001 were analyzed and compared. Ten-year kidney and pancreas graft survival for SPK transplantation from donors aged <18 years (n = 142) were 80% and 72%, respectively, compared to 61% pancreas and kidney graft survival from donors > or =18 years of age (n = 538; p = 0.03 and 0.05, respectively). Five years post-transplant, blood glucose, HbA1c and creatinine clearance were significantly better in recipients from pediatric donors (85.3 +/- 13 mg/dL, 5.5 +/- 3.5% and 65.6 +/- 16 mL/min, respectively), compared to recipients from adult donors (95.1 +/- 29 mg/dL, 5.9 +/- 3.5% and 58.3 +/- 17 mL/min; p = 0.001, 0.01 and 0.002, respectively). Causes of graft failure for kidney and pancreas transplants were similar between the two groups. No statistically significant difference was observed in patient survival between recipients from pediatric donors compared to adult donors (85% vs. 76%, p = 0.29). When recipients of SPK from pediatric donors were stratified according to age (3-11 years and 12-17 years) and compared, no difference in kidney or pancreas graft survival was observed (kidney 76.4% vs. 81.3%, p = 0.15; pancreas 75% vs. 76%, p = 0.10, respectively). Pediatric donors represent a valuable source of organs, providing excellent short- and long-term outcomes. Wide utilization of pediatric organs will substantially increase 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.

Increasing the donor pool using en bloc pediatric kidneys for transplant

OBJECTIVES

En bloc pediatric kidney transplants (EBPKT) are still a subject of controversy. The aim of this study was to determine whether acceptable long-term graft survival and function can be achieved in EBPKT compared with the transplant of single, cadaveric, adult donor kidneys.

METHODS

A retrospective review was conducted of 66 recipients of en bloc kidneys from cadaveric pediatric donors and 434 patients who underwent transplantation with a single kidney from an adult donor between January 1990 and May 2002 at the authors' hospital. The recipients were well-matched demographically. Both transplant groups were analyzed for short- and long-term performance in terms of transplant outcome and quality of graft function.

RESULTS

Overall death-censored actuarial graft survival rates at 1 and 5 years were 89.2% and 84.6% in the adult kidney transplants (AKT) and 83.3% and 81.1% in EBPKT, respectively (P=0.56). In the EBPKT group, graft function was improved over that observed in AKT. Vascular thrombosis was the most common cause of graft loss in EBPKT. Acute rejection occurred more frequently in AKT and Cox's regression analysis indicated that undergoing an AKT was a predictive factor for acute vascular rejection (adjusted risk ratio, 3.8; 95% confidence interval, 1.4-10.2; P=0.001).

CONCLUSIONS

Overall graft survival was similar in both groups, vascular complications were the main cause of graft loss in EBPKT, and the EBPKT showed excellent long-term graft function and a low incidence of acute rejection.

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.

Graft survival and graft function of pediatric en bloc kidneys in paraaortal position

BACKGROUND

En bloc kidneys from pediatric donors are regarded as questionable with respect to the safety and quality of the transplant outcome. Therefore, we retrospectively studied graft outcome and graft function of our 56 en bloc kidneys transplanted in paraaortal position between 1992 and 1999.

METHODS

Graft outcome of en bloc kidneys (group A) was compared with graft outcome of single cadaveric adult donor kidneys (group B). Matched pairs were generated regarding HLA-missmatch, cold ischemic time, recipient age, body mass index, and systolic arterial blood pressure.

RESULTS

Allograft survival rates of pediatric en bloc kidneys at 1, 3, and 5 years were significantly lower (group A: 78, 70, 70% vs. group B: 92, 92, 81%, P<0.05). Lower survival rate was caused by a higher number of graft losses in the early postoperative period (group A: 21% vs. group B: 4%, P<0.01) due to vascular complications. Main risk factor for graft loss was donor age of less than 12 months. Five years after transplantation serum creatinine of pediatric en bloc kidneys was significantly better than of adult kidneys (0.9+/-0.06 vs. 1.8+/-0.2 mg/dl, P<0.001).

CONCLUSION

En bloc kidneys show a high percentage of graft survival with excellent long-term graft function. However, the early postoperative period carries a higher risk of graft loss in very young donors due to vascular complications. In the face of donor shortage en bloc kidneys from pediatric donors can successfully be transplanted in a paraaortal position.

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.

Fibrous intimal thickening at implantation as a risk factor for the outcome of cadaveric renal allografts

BACKGROUND

During the past decade, the donor age of cadaveric renal allografts steadily increased. Because cerebrovascular injury is the main cause of death in this donor population, an increased prevalence of atherosclerotic lesions in the retrieved grafts could be anticipated. In a prospective study, we investigated the predictive value of morphologic lesions at implantation for the functional and morphologic outcome of cadaveric renal allografts at 1 1/2 years.

METHODS

In 50 consecutive adult recipients of a cadaveric renal allograft, under cyclosporine-based regimen, implantation biopsies and subsequent protocol biopsies at 18 months were performed, and morphometrically analyzed for the extent of glomerulosclerosis, interstitial fibrosis, and atherosclerosis. Risk factors were assessed at implantation and during the subsequent observation period of 18 months. Endpoints for this study were: the 24-hr creatinine clearance (normalized for body surface area) and the fractional interstitial volume at 1 1/2 years.

RESULTS

In multivariate analysis, fibrous intimal thickening at implantation (FIT) was the main determinant of the functional and morphologic outcome at 1 1/2 years. FIT represented a relative risk of 4.55 for interstitial fibrosis (95% CI=1.855-11.138), and 1.89 for impaired renal function (95% CI=1.185-3.007) at 1 1/2 years. FIT adversely affected fractional interstitial volume at 1 1/2 years (34.3 vs. 27.7%, P=0.004), as well as renal function (54 vs. 68 ml/min/1.73 m2, P=0.028).

CONCLUSIONS

Fibrous intimal thickening at implantation is a determinant risk factor for the functional and morphologic outcome of cadaveric renal allografts at 1 1/2 years.

Expanded criteria donors: attempts to increase the renal transplant donor pool

There is a growing disparity between the demand for and the supply of kidneys for transplantation. The demographics of the donor pool are also changing. The average potential cadaveric organ donor is now more likely to be older, at greater risk for co-morbid conditions such as hypertension or viral infections, and more likely to die from cerebrovascular disease. These factors have led to an expansion of the criteria that defines the suitable organ donor. Expanded criteria donors are defined as the following: (1) at the upper and lower extremes in age; (2) having a history of hypertension or diabetes; (3) hemodynamically unstable; (4) non-heartbeating (cardiopulmonary death rather than brain death); (5) seropositive for hepatitis B or C; (6) having systemic infections; (7) having displayed high-risk social behavior for HIV infection; (8) having a history of malignancy; (9) having abnormal organ function; or (10) with renal anatomic anomalies or injuries. Use of kidneys from these "expanded criteria donors" is a two-edged sword. While they provide more organs for transplantation, the risk of suboptimal recipient outcome is increased. A rational approach to the use of each of these types of kidneys and proper selection of recipients is essential to obtain acceptable results. The article reviews the factors that have contributed to the successful transplantation of kidneys procured from expanded criteria organ donors and how these organs can be allocated most efficaciously to the appropriate recipients.

Diffuse glomerular basement membrane lamellation in renal allografts from pediatric donors to adult recipients

The transplantation of kidneys from pediatric cadaveric donors into adult recipients is performed in many centers. However, some studies indicate that the outcome of such renal transplants may be inferior compared with that of adult donors, particularly if the donor is an infant. Morphologic studies of failed pediatric donor kidneys in adult recipients describe various degrees of segmental or global glomerular sclerosis. The authors have performed ultrastructural examinations on such transplants and have identified six cases with diffuse irregular lamellation of the glomerular basement membrane (GBM), a change that may develop as early as 10 weeks after transplantation. The age of all donors was < or =6 years; three were infants. The incidence of the lesion was 9% at our institution in renal transplant patients who received a graft from donors <10 years old. Diffuse GBM lamellation has not been found in renal transplants from adult donors. Light microscopy showed various degrees of diffuse mesangial expansion, usually with segmental glomerular sclerosis. The patients had severe proteinuria. While recurrent focal segmental glomerular sclerosis (FSGS) has to be excluded, such diffuse GBM lamellation is generally not seen in recurrent FSGS cases. The pathogenesis of the lesion is most likely related to hyperperfusion injury of small pediatric donor kidneys grafted into adult recipients.

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.