Renal function changes over time in adult recipients of small pediatric kidneys. Evidence against hyperperfusion injury

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.

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.

Assessment of Factors Determining Graft Size in Transplant of Cadaver Kidneys from Child Donors

BACKGROUND

Kidneys from child donors are very efficient at adapting to the recipient organism. This research aims to verify the size of kidney grafts from pediatric donors after transplant and to identify factors responsible for the size attained by these kidneys. Moreover, it aims to seek relationships between size and function of the transplanted pediatric kidney.

METHODS

Seventy-seven renal transplants performed at least 6 months earlier, with cadaver donor 15 years old or younger, had ultrasound measurements of the graft and renal function assessment. Potential factors for graft volume were analyzed using bivariate analysis, followed by multiple linear regression.

RESULTS

After a follow up of 4.2+/-3.3 years posttransplant, the grafts presented the following range of measures: length 10.61+/-1.13 cm, width 4.67+/-0.84 cm, and depth 4.76+/-0.99 cm. Graft volumes were 126.62+/-47.76 cm. Bivariate analysis showed that (1) age of both donor and recipient at transplantation; (2) sex of recipient; (3) occurrence of acute rejection episodes were statistically significant. After multivariate analysis, age and sex of recipients were the only significant factors influencing graft volume; child kidneys reached greater volumes when transplanted into adult and male individuals. Larger volume kidneys presented significantly more proteinuria. No difference was evident with regard to creatinine clearance values or urinary retinol binding protein among kidneys of differing sizes.

CONCLUSIONS

The size of the recipient (age and sex) is the main factor responsible for volumes achieved by kidneys from pediatric donors. The volume attained by these kidneys demonstrated no relationship with glomerular or tubular function of the organ.

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.

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.

Early proteinuria in renal transplant recipients treated with cyclosporin

PURPOSE

To establish the risk profile for the development of proteinuria in the first months after renal transplantation and to disclose the prognostic significance of this finding.

DESIGN

We conducted an observational historic cohort study.

SETTING

We conducted the study in a tertiary care hospital renal transplantation unit covering a potential population of approximately 2 million. We made extensive use of suboptimal donors.

POPULATION

In our unit, 560 cadaveric renal transplants were performed between January 1988 and June 1997, under Cyclosporine immunosuppression, with a minimum follow up of 1 year.

METHOD

The risk profile analysis explored early clinical factors reported to be related to the late course of renal transplantation. The study of the prognostic significance of proteinuria included survival analysis and correlation with late markers of graft dysfunction, taking into consideration the intensity and persistence of early proteinuria. A multivariate approach was used in all cases.

RESULTS

Early proteinuria was strongly associated with delayed graft function (odds ratio [OR] 1.03/day of dialysis), acute rejection (OR 1.7 for steroid-sensitive and 6.2 for steroid-resistant rejection), renal transplant to a hypersensitized recipient (OR 2.5), and pediatric (<5 years)(OR 4.1) or older (>60 years)(OR 3.0) donors. The predictive model for persistency of proteinuria was very similar, whereas transient proteinuria could not be adequately modeled. Increasing intensity of proteinuria was strongly associated with poor patient and graft survival. Persistent, but not transient, proteinuria supported this relationship.

CONCLUSIONS

Proteinuria appearing early after renal transplantation is strongly associated with delayed graft function, acute rejection, and the use of pediatric or older donors. Whatever its background, proteinuria is a strong predictor of poor patient and graft survival. This effect is directly related to the intensity and persistence of the disorder.

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.