En Bloc Cadaver Kidney Transplantation From a 9-Month-Old Donor to an Adult Recipient: Maturation of Glomerular Size and Podocyte in the Recipient

Abstract

BackgroundFavorable outcomes of en bloc pediatric donor kidney transplantation to adult recipients are attributed primarily to grafting of twice the nephron mass of a single kidney.MethodsThe kidneys of a 9-month-old male infant were transplanted en bloc in a 56-year-old man. Biopsies were performed 1 hour postreperfusion, 6 months and 3.5 years posttransplant.ResultsWarm and cold ischemia times were 21 and 426 minutes, respectively. The recipient was released from hemodialysis 10 days posttransplant and discharged 91 days posttransplant when serum creatinine was 0.9 mg/dL. At 4 years and 9 months posttransplant, serum creatinine was 1.0 mg/dL, and estimated glomerular filtration rate was 58.0 mL/min per 1.73 m2. The grafts increased in size until they reached adult size by 3 months posttransplant. The glomerular area and volume, respectively, increased from 5.9 × 103 μm2 and 0.34 × 106 μm3 at 1 hour postreperfusion to 14.9 × 103 μm2 and 1.27 × 106 μm3 at 3.5 years posttransplant, both of which were less than half of adult size. At 1 hour postreperfusion, podocytes were structurally immature. At 6 months posttransplant, podocyte immaturity was still evident. At 3.5 years posttransplant, podocytes were mature.ConclusionsThese findings suggest that podocytes and glomerular size of pediatric donor kidneys can continue to mature in adult recipients at rates appropriate for donor age when transplanted en bloc. The maturational levels of podocytes and glomeruli may also be a factor involved in favorable outcomes of en bloc pediatric donor kidney transplantation.

Transplantation of pediatric renal allografts from donors less than 10 kg

“…Interestingly, the grafts provide adequate renal function almost immediately after transplant, despite their small size. In the first days posttransplant, grafts in the small group had a mean volume of 28 ± 9 mm 3 , whereas adult kidneys have been measured by magnetic resonance imaging and ex vivo water displacement to be closer to 200 mm 3 Hirukawa et al recently reported that glomerular volume continued to increase for at least 3.5 years posttransplant, while podocytes took approximately 3 years to mature in 1 case. Our data suggest continued growth in all grafts, in agreement with Hirukawa et al, and that grafts from smaller donors undergo a rapid “catch‐up” period during the first posttransplant year; the final growth capacity over years is unknown.…”

Structural and Histopathologic Changes in Renal Allografts from an Infant Donor

“…Transplantation of the kidney results in denervation and insufficiency of the hemodynamic autoregulation system, leading to GBM stretching due to acute increased blood flow from a larger recipient into the pediatric kidney. However, the basement membrane soon returns to baseline due to the myogenic response and the effects of angiotensin II [6,7]. Hyperperfusion leading to increased filtration may also explain why pediatric grafts grow to adult size only months after transplant.…”

Novel Histopathologic and Ultrastructural Findings in Renal Allografts From Patients With Size and Age Mismatches: A Case Series

“…Interestingly, though the early days post-transplantation exhibited worse allograft function when compared to the others in this series, the patient's renal function continued to improve and ended up becoming a well-functioning allograft. Though there was no follow-up biopsy for this patient, it is likely based on cases and in vivo studies that the glomerular immaturity resolved in the months following transplantation [13][14][15].…”