MITOCHONDRIAL METABOLISM IS PRESERVED FOLLOWING NORMOTHERMIC EX-VIVO KIDNEY PERFUSION OF GRAFTS PROCURED FOLLOWING CARDIAC DEATH

Abstract

Background: Normothermic ex-vivo kidney perfusion (NEVKP) preservation has demonstrated superior graft outcomes for kidneys procured following donation-after-cardiac death (DCD) over static cold storage (SCS). To determine the mechanisms for this advantage, we compared the transcriptome from both groups through an unbiased genome-wide microarray analysis. Methods: Kidneys from 30kg Yorkshire pigs were subjected to 30min of warm ischemia and then 8hrs of pressure-controlled NEVKP or SCS prior to heterotopic autotransplantation. Renal biopsies were collected on POD3 and RNA transcript expression was determined utilizing the Affymetrix GeneChip® Porcine Gene 1.0 ST Array platform examining over 23,000 transcripts. Gene set enrichment analysis (GSEA) was completed using the Hallmark gene sets and Gene Ontology (GO) pathways. Results: NEVKP-stored grafts demonstrated parameters associated with improved post-transplant graft function including lactate clearance (0hr:10.29+/-0.48mmol/L vs 8hr:1.67+/-0.67mmol/L,n=5,p<0.01), decreasing intra-renal resistance (0hr:1.63+/-0.20mmHg/mL/min vs 8hr:0.41+/-0.13 mmHg/mL/min,n=5,p<0.01), and continuous urine production. Graft function was significantly improved with NEVKP compared to SCS following transplantation with lower peak serum creatinine (POD1:4.0+/-1.15mg/dL vs POD3:12.0+/-0.78mg/dL,n=5,p<0.01) and higher creatinine clearance on POD3 (39.6+/-11.8mL/min vs 2.6+/-0.9ml/min,n=5,p<0.01). GSEA demonstrated 11 Hallmark Gene Sets enriched in NEVKP compared to SCS including sets associated with fatty-acid metabolism and oxidative phosphorylation, while 7 Gene Sets were enriched in SCS compared to NEVKP (FDR-value<0.25,p<0.05). GO analysis demonstrated pathways associated with lipid oxidation/metabolism, the Krebs cycle, and pyruvate metabolism enriched in NEVKP vs SCS (FDR-value<0.05) Conclusions: NEVKP maintained or enriched transcripts of key mitochondrial metabolic pathways compared to SCS in grafts procured following DCD, likely accounting for the improved post-transplant graft function.