Do tissue damage biomarkers used to assess machine-perfused NHBD kidneys predict long-term renal function post-transplant?

Background: Renal transplantation in many units is limited by the availability of donor organs. Kidneys obtained from non-heart-beating donors (NHBD) represent an important resource, with the potential to substantially increase the available donor organ pool. Such kidneys are associated with increased warm ischaemic tissue injury which may be assessed by hypothermic machine perfusion. Within our transplant centre, a key component of such damage assessment and viability screening involves the quantification of the tissue damage biomarkers glutathione S-transferase in kidney perfusates. Methods: Since 1998, 126 NHBD kidneys were machine-perfused prior to implantation, resulting in 74 transplants. Kidney perfusate samples were assayed for glutathione S-transferase in “real time”, and alanine aminopeptidase and fatty acid binding protein in “retrospect”. Results: The pre-transplant concentration of these tissue injury biomarkers determined pre-transplant did not correlate with subsequent longer-term renal function, as assessed by measurement of serum creatinine (tGST: Spearman correlation r=−0.02; Ala-AP: r=0.02; H-FABP: r=−0.05) and creatinine clearance (tGST: r=0.08; Ala-AP: r=−0.02; H-FABP: r=0.14) for those kidneys that had passed their viability tests. Conclusions: Thus whilst these biomarkers may represent reliable pre-transplant indicators of immediate kidney viability and short-term kidney function, they do not predict the efficacy of renal function in the longer term.