UNLABELLED - In aggregate, livers donated after circulatory death (DCD) provide lower rates of graft and patient survival compared to brain dead donors (DBD). A method to identify DCD livers likely to perform well would lead to better decision-making regarding which livers to use and which to discard and is an important unmet clinical need. We hypothesized that the ischemic time between extubation and cold perfusion in the donor leads to immediate and unique biochemical and molecular changes that could be used to predict subsequent function.
METHODS - Biopsies from normal perfused liver, immediately after cold perfusion during DCD or DBD liver procurement, and during subsequent cold storage were analyzed and compared. Biochemical analysis included adenosine triphosphate (ATP), adenosine diphosphate, adenosine monophosphate, hypoxanthine, xanthine, inosine, nicotinamide adenine dinucleotide, and flavin adenine dinucleotide. Levels of these metabolites were compared to peak posttransplant aspartate aminotransferase as a marker of ischemic injury. Molecular analysis was performed by transcriptional profiling using high throughput sequencing.
RESULTS - Immediately after cold perfusion in the donor, biochemical analysis revealed lower levels of ATP and adenosine diphosphate in DCD versus DBD liver samples (P < 0.01 in both cases). The ATP levels showed high negative correlation with peak aspartate aminotransferase levels in recipients (P = 0.029). Four hundred seventy genes showed differential expression in DCD but not DBD samples immediately after cold perfusion compared with normal liver samples. Upregulated genes function in inflammation and immunity, whereas downregulated genes function in translation. During cold storage, samples were transcriptionally inactive with no consistent changes in messenger RNA expression.
CONCLUSION - The ATP content of liver samples taken immediately postperfusion correlates with ischemic injury. Transcriptional profiling identifies biological process that may be relevant for enhancing function in DCD liver transplantation. Transcriptional inactivity of cold stored samples suggests messenger RNA levels over time are unlikely to provide prognostic data.