Effects of Oxygen on Renal Function and Oxidative Stress During Hypothermic Machine Perfusion in an Experimental Porcine Model of Kidney Donation after Cardiac Death

Abstract

The efficacy and safety of using high concentrations of oxygen during hypothermic machine perfusion (HMP) have not been fully elucidated to date. This study investigated the impact of administering high concentrations of oxygen on renal function during HMP in a porcine donation after circulatory death (DCD), as well as the metabolic and biochemical effects of this method. A randomized nonblinded cohort study was established in a porcine transplant (KT) model mimicking Maastricht type III DCD under oxygen-supplemented HMP (Ox-HMP) compared to non-supplemented (nOx-HMP) (LifePort® kidney transporter) conditions. The primary endpoint was evolution of renal function post-KT, whereas secondary endpoints included changes in perfusion dynamics, miRNA expression and cellular lesion measured by LDH and lactate levels in perfusate, lipid peroxidation in kidney biopsies, ATP generation, epithelial mesenchymal transition (EMT) and oxidative gene expression in cell cultures and histology evaluation. ATP generation and oxidative stress, as measured by lipid peroxidation, increased simultaneously after warm ischemia in the Ox-HMP group. Ox-HMP did not exhibit a significant effect on kidney function or animal survival. A significant increase in lipid peroxidation was observed in the Ox-HMP group. This resulted in a greater expression of the genes responsible for producing superoxide dismutase 1 (SOD-1) and catalase oxygenation enzymes, although only SOD-1 showed statistical significance. Respiratory chain dysfunction was maintained in the Ox-HMP group with a non-significant decrease in ATP production, increased proton leakage, and a decrease in respiratory reserve. Regarding epithelial-mesenchymal transition, an upward trend in the expression of vimentin, fibronectin, and collagen genes was observed only in the Ox-HMP group. Finally, the expression levels of miR-101 and miR-126, related to characteristic functions of the tubular epithelium, were significantly modified (miRNA levels expressed as DCT. A brief bubble Ox-HMP treatment did not show a clear positive effect on renal function and oxidative stress markers. The role and safety of adding oxygen during HMP still need to be elucidated. Currently, this Ox-HMP method cannot be considered standard practice.