Subnormothermic Regulated Hepatic Reperfusion Preserves Mitochondrial Function in Swine Liver Procured after Cardiac Death

Livers procured after cardiac death can have an extreme degree of ischemia‐reperfusion injury (IRI) and are at increased risk of graft failure after liver transplantation. Reductions in respiratory control index (RCI) and Ca 2+ retention capacity (CRC) are markers of mitochondrial dysfunction and cell apoptosis. Regulated hepatic reperfusion (RHR) is a novel organ resuscitation therapy that may facilitate hepatic mitochondrial recovery from IRI using an energy substrate‐enriched, leukocyte‐depleted, oxygen‐saturated perfusate delivered in a pressure, and temperature‐controlled milieu. We used a swine donation after cardiac death (DCD) model, in which all livers were subjected to 60 min of in situ warm ischemia and 120 min of cold static (CS) preservation. All livers were subsequently reperfused and monitored for 2 h in the ex vivo perfusion machine. Four methods of reperfusion were compared with 5 animals in each treatment group. Group I: Sanguineous‐Subnormothermic (SS); Group II: RHR‐Subnormothermic (s‐RHR); Group III: Sanguineous‐Normothermic (NS); Group IV: RHR‐Normothermic (n‐RHR). Liver biopsies were collected at baseline (pre‐ischemia), at 2 h of CS following 1 h of in situ warm ischemia, and after 30 min of ex vivo reperfusion. We isolated mitochondria via differential centrifugation and measured mitochondrial bioenergetics, i.e. the ability to utilize nutrients and O 2 (respiration) to generate energy (state 3 (added ADP)/state 4 (depleted ADP) respiration = RCI) and CRC, i.e. the capability of mitochondria to tolerate a challenge of 20 μM CaCl 2 boluses every 90 s until mitochondrial bioenergetic failure. We found that with substrate glutamate/malate (GM), RCI with s‐RHR was 60% higher than its baseline and 2.3‐fold higher than after NS reperfusion. With substrate succinate (SC), RCI with s‐RHR reperfusion was 99% of its baseline and 2‐fold higher than NS. These changes were due mostly to the lower state 4 respiration rate in the s‐RHR group, indicating less proton leaking compared to other groups. Reperfusion lowered CRC by about 33% across all groups; however, with substrate GM, CRC after s‐RHR was 2‐fold larger than in the SS group; with substrate SC, CRC after s‐RHR was 3‐fold larger compared to other groups. Mitochondria likely play a critical role in control of hepatocyte function and viability during liver transplantation; thus preservation of mitochondrial function is critically important. Ex vivo subnormothermic‐regulated hepatic reperfusion best preserved mitochondrial function and viability. This novel strategy has potential applicability to human liver transplantation. Support or Funding Information MCW Institutional Funding This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .