New Approaches in TransplantationExperimental transplantationHypothermic Machine Perfusion's Protection on Porcine Kidney Graft Uncovers Greater Akt-Erk Phosphorylation

•This is the first study to identify the Akt and Erk signaling pathway specifically affected by HMP using a clinically relevant model.•This in vitro large-animal study proved HMP reduced kidney preservation injuries with less accumulation of toxic metabolites, improved electrolytes homoeostasis, and reduced oxidative damage, inflammation, and apoptosis, which involved Akt and Erk signaling in vitro.•Our study provides new information about HMP before transplantation and clear clues for promising results in the future studies.

BackgroundTo investigate the potential mechanisms of hypothermic machine perfusion (HMP)'s beneficial effects on kidney graft over static cold storage (SCS) in vitro.MethodsTen kidneys of 5 Bama miniature male pigs were paired into 2 groups: SCS group and HMP group. Preservation solutions were taken at 0, 1, 3, and 6 hours for the measurement of K+, Na+, Cl−, blood urea nitrogen (BUN), creatinine (Cr), and lactate dehydrogenase (LDH) using the standard laboratory methods. Renal cortex were harvested at 6 hours for the following measurement: lactic acid (LD), adenosine triphosphate (ATP), malondialdehyde (MDA), neutrophil accumulation (MPO), interleukin-10 (IL-10), and transforming growth factor-β (TGF-β). Ischemia-induced apoptosis and the protein expression levels of total Akt, phospho-Akt, total Erk, and phospho-Erk were analyzed by Western blotting.ResultsAlmost all of the tested metabolites in preservation solutions were reduced with time in the HMP group. Levels of Na+, Cl−, BUN, Cr, K+, and LDH were lower in the HMP group compared with the SCS group, with differences in the first 4 reaching statistical significance. HMP alleviated ATP degradation and LD accumulation, diminished the MDA (P < .05) and MPO (P = .227) levels, and greatly raised IL-10 and TGF-β (P < .05) expression. A marked decrease of proapoptotic and a large increase of antiapoptotic markers (P < .05) along with greatly raised Akt (P < .05) and Erk (P < .01) phosphorylation was observed in the kidney of the HMP group compared with the SCS group.ConclusionHMP's kidney graft protection involves inhibition of accumulation of toxic metabolites, oxidative damage, and apoptosis along with upregulation of the Akt and Erk signaling pathway.