Dual kidney transplantation

Organ availability still represents a major problem for renal transplantation programs. The number of patients awaiting transplantation greatly exceeds the available donor organs, and this discrepancy continues to grow. The attempt to reduce this gap inevitably led to consideration for kidney transplantation of organs from older donors or from donors with hypertension, diabetes or other renal diseases. This review focuses on the different strategies adopted to increase transplant activities by expanding the criteria for donor and recipient selection without exposing the recipient to the drawbacks of inadequate nephron mass supply. To this purpose some centers restricted the transplantation of suboptimal organs to recipients with reduced metabolic requirements. Others made the opposite and increased nephron mass supply by simultaneously transplanting two suboptimal kidneys to the same recipient. In both cases, a critical aspect is to assess whether the filtration power provided with the grafts was fit with the metabolic requirement of the recipients. To this purpose, morphological parameters assessed on kidney biopsies at the time of donor evaluation may serve to quantify the preserved tissue and to predict the post-transplant performance of the graft. The histological evaluation may also help to discriminate chronic irreversible lesions from acute changes that may account for a transiently impaired renal function in the donor, that may recover post-transplant. Preliminary reports of dual transplants from expanded criteria donors have shown a remarkably good short-term renal function compared to that of single transplants from ideal donors, and also very low incidence of acute rejections and delayed graft function. Longer follow-up is needed to assess the long-term performance of these grafts.