Circulating cell-free DNA in liver transplantation: A pre- and post-transplant biomarker of graft dysfunction

Liver transplantation (LT) is still limited by organ shortage and post-transplant monitoring issues. While machine perfusion techniques allow for improving organ preservation, biomarkers like donor-derived cell-free DNA (dd-cfDNA) and mitochondrial cfDNA (mt-cfDNA) may provide insights into graft injury and viability pre- and post-LT. Methods. A prospective observational cohort study was conducted on LT recipients (n = 45) to evaluate dd-cfDNA as a biomarker of graft dysfunction during the first 6 months after LT. Dd-cfDNA was quantified on blood samples collected pre-LT and post-LT using droplet digital PCR. In livers undergoing dual hypothermic oxygenated machine perfusion (D-HOPE), total cfDNA and mt-cfDNA levels were measured on perfusate samples collected at 30-min intervals. Correlations with graft function and clinical outcomes were assessed. Results Dd-cfDNA levels peaked post-LT and correlated with transaminase levels and histological injury severity. The longitudinal assessment showed that postoperative complications and rejection were associated with an increase in dd-cfDNA levels. Mt-cfDNA levels in D-HOPE perfusate correlated with graft function parameters post-LT and were higher in patients with early allograft dysfunction and severe complications. Conclusions This study confirms dd-cfDNA as a marker of graft injury after LT and suggests that perfusate mt-cfDNA levels during D-HOPE correlate with graft function and post-transplant clinical outcome. Integration of these tests into clinical practice may improve transplant management and viability assessment during hypothermic perfusion.