Estudio experimental aleatorizado sobre la eficacia de la preservación renal hipotérmica en máquina con suplementación de oxígeno

Zusammenfassung

The efficacy and safety of employing high concentrations of oxygen during hypothermic machine perfusion (HMP) has not been fully elucidated to date. This study investigates the impact on renal function of administering high concentrations of oxygen during HMP in a porcine model of donation after circulatory death, as well as its metabolic and biochemical effects. Methods: A randomized non-blinded prospective cohort study was established in a porcine transplant model mimicking Maastricht type III DCD under oxygensupplemented HMP (Ox-HMP) compared with non-supplemented (nOx-HMP) (LifePort® kidney transporter) conditions. Primary endpoint was post-KT renal function, meanwhile secondary endpoints included changes in perfusion dynamics, cellular lesion measured by LDH and lactate levels in perfusate, lipid peroxidation in kidney biopsies, epithelial mesenchymal transition (EMT) and oxidative gene expression in cell cultures, ATP generation measured by SeaHorse assays in cell cultures, miRNA expression in preservation solution and finally histology assessment. Results: ATP generation and oxidative stress, as measured by lipid peroxidation, both increased simultaneously after warm ischemia in the Ox-HMP group. OxHMP did not exhibit a significant effect on kidney function or animal survival. It was observed a clear increase of lipid peroxidation in the Ox-HMP group which also resulted in a greater expression of the genes responsible for superoxide dismutase 1 (SOD-1) and catalase antioxidant enzymes. Respiratory chain dysfunction was maintained in the Ox-HMP group with a decrease in ATP production, increased proton leakage and a decrease in respiratory reserve. Regarding EMT, an increase in the expression of vimentin, fibronectin and collagen genes was also observed 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. Conclusions: Although a trend towards better renal function and survival was observed in the Ox-HMP group, its metabolic assessment revealed lower respiratory chain efficiency and increased oxidative stress that resulted into increased expression of EMT genes, which could lead to renal fibrosis. The different miRNA profile associated with Ox-HMP could be an expression of a different underlying cellular metabolism. Therefore, Ox-HMP cannot be considered a standard practice at present and its role in renal preservation needs to be clarified.