Cell‐free microRNAs as early predictors of graft viability during ex vivo normothermic machine perfusion of human donor livers

Abstract

Background Cell‐free microRNAs (miRs) have emerged as early and sensitive biomarkers for tissue injury and function. This study aimed to investigate whether the release of hepatocyte‐derived microRNAs (HDmiRs) and cholangiocyte‐derived miRs (CDmiRs) correlates with hepato‐cholangiocellular injury and function during oxygenated, normothermic machine perfusion (NMP) of human liver grafts. Methods Donor livers (n = 12), declined for transplantation, were subjected to oxygenated NMP (6 hours) after a period of static cold storage (median 544 minutes (IQR 421‐674)). Perfusate and bile samples were analyzed by qRT‐PCR for HDmiR‐122 and CDmiR‐222. Spearman correlations were performed between miR levels and currently available indicators and classic markers. Results Both HDmiR‐122 and CDmiR‐222 levels in perfusate at 30 minutes of NMP strongly correlated with hepatocyte injury (peak perfusate AST) and cholangiocyte injury (peak biliary LDH). In bile, only CDmiR‐222 correlated with these injury markers. For hepato‐cholangiocellular function, both miRs in perfusate correlated with total bilirubin, while HDmiR‐122 (in perfusate) and CDmiR‐222 (in bile) correlated with bicarbonate secretion. Both the relative ratio of HDmiR‐122/CDmiR‐222 and AST in perfusate at 30 minutes significantly correlated with cumulative bile production, but only the relative ratio was predictive of histopathological injury after 6 hours NMP. Conclusion Early levels of HDmiR‐122 and CDmiR‐222, in perfusate and/or bile, are predictive of excretory functions and hepato‐cholangiocellular injury after 6 hours NMP. These miRs may represent new biomarkers for graft viability and function during machine perfusion.

Viability Assessment in Liver Transplantation—What Is the Impact of Dynamic Organ Preservation?

“…Perfusates, bile and tissues can be obtained throughout the entire time an organ is exposed to dynamic perfusion modalities. A large body of tests, including the LIMAX test, the quantification of miRNA, mitochondrial DNA or Damps and cytokines, metabolomic/proteomic/genomic analyses, and ATP quantification, could be applied [ 25 , 61 , 62 , 63 ]. Clinical use of such modalities is limited by the prolonged time required to receive a result, or the need for tissue biopsies, where a systematic analysis to identify the best marker combination is still lacking today.…”

Machine Perfusion of the Liver: A Review of Clinical Trials

“…In 2020, Matton et al ( 44 ) investigated whether hepatocellular and cholangiocyte injury could be correlated with miRs in the perfusate and bile of NMP livers. Following a period of static cold storage, 12 livers underwent 6 h of NMP for viability assessment.…”

Restoring Mitochondrial Function While Avoiding Redox Stress: The Key to Preventing Ischemia/Reperfusion Injury in Machine Perfused Liver Grafts?

“…Another potential biomarker for the assessment of IRI may be cell-free microRNAs (miRNA). The release of hepatocyte-derived miRNAs (HDmiRNA) during NMP was shown to correlate with AST levels [58]. However, it must be taken into account that study protocols and donor criteria vary markedly between all the studies mentioned, and further clinical studies with subsequent transplantations and follow-up are urgently warranted to verify these findings.…”