Enhanced myocardial protection in cardiac donation after circulatory death using Intralipid^® postconditioning in a...

Intralipid^® (ILE), a clinically used lipid emulsion, reduces ischemia-reperfusion (IR) injury in healthy and infarct-remodelled rat hearts. We tested whether ILE is also cardioprotective in large porcine hearts in the context of the donation after circulatory death (DCD) model, where human hearts are procured for transplantation after cardiac arrest and thus are exposed to significant IR injury.

After induction of anesthesia, surgical preparation, termination of ventilator support, and cardiac arrest, hearts of female pigs were procured following a 15 min standoff period, with an optimized normokalemic crystalloid adenosine-lidocaine cardioplegia. Hearts were then randomly allocated to ex vivo reperfusion (38°C) in the absence (control) or presence of 1% ILE. All hearts were perfused with blood and Krebs-Henseleit solution (1:1) for 30 min in Langendorff mode and for an additional 30 min in working mode to assess mechanical function. Left ventricular (LV) biopsies were obtained after five minutes of reperfusion and LV tissue was preserved at the end of reperfusion for biochemical analyses and immunohistochemistry.

Intralipid^® postconditioning reduced cell membrane damage as assessed by the mean (standard deviation) leakage of myocardial glutathione disulfide (39 (9) nmol·mg^-1 protein vs 19 (7) nmol·mg^-1 protein; P = 0.006), protected LV tissue from protein carbonylation (3.4 [0.6] nmol·mg^-1 protein vs 5.3 [0.9] nmol·mg^-1 protein; P = 0.006), decreased myeloperoxidase activity (35 [8] nmol·min^-1·mg^-1 protein vs 75 [11] nmol·min^-1·mg^-1 protein; P < 0.001), and increased inotropy (maximum rate of rise of LV pressure 2001 [345] mmHg·sec^-1vs 1584 [192] mmHg·sec^-1; P = 0.044). Intralipid^® postconditioning triggered reactive oxygen species signalling at early reperfusion and activated protection signalling (Akt, signal transducer and activator of transcription 3, and glycogen synthase kinase 3β) in LV tissue, recapitulating all features of ILE-mediated protection reported in small rodent hearts.

Our data show that ILE postconditioning elicits protection signalling in large mammalian hearts while mimicking clinical conditions, and is capable of enhancing protection of DCD hearts.