Long-term ex situ normothermic machine perfusion allows regeneration of human livers with severe bile duct injury.

Bile duct regeneration is hypothesized to prevent biliary strictures, a leading cause of morbidity after liver transplantation. Assessing the capacity for biliary regeneration may identify grafts as suitable for transplantation that are currently declined, but this has been unfeasible until now. This study used long-term ex situ normothermic machine perfusion (LT-NMP) to assess biliary regeneration. Human livers that were declined for transplantation were perfused at 36 °C for up to 13.5 days. Bile duct biopsies, bile, and perfusate were collected throughout perfusion, which were examined for features of injury and regeneration. Biliary regeneration was defined as new Ki-67-positive biliary epithelium following severe injury. Ten livers were perfused for a median duration of 7.5 days. Severe bile duct injury occurred in all grafts, and biliary regeneration occurred in 70% of grafts. Traditional biomarkers of biliary viability such as bile glucose improved during perfusion but this was not associated with biliary regeneration (P > .05). In contrast, the maintenance of interleukin-6 and vascular endothelial growth factor-A levels in bile was associated with biliary regeneration (P = .017 for both cytokines). This is the first study to demonstrate biliary regeneration during LT-NMP and identify a cytokine signature in bile as a novel biomarker for biliary regeneration during LT-NMP.