Letter to the editor: Is there a place for machine perfusion strategies in pediatric liver transplantation?

Liver transplantation of partial grafts after ex situ splitting during hypothermic oxygenated perfusion-The HOPE-Split pilot study

Partial liver grafts from ex situ splitting are considered marginal due to prolonged static cold storage. The use of ex situ hypothermic oxygenated perfusion (HOPE) may offer a strategy to improve preservation of ex situ split grafts. In this single-center pilot study, we prospectively performed ex situ liver splitting during HOPE (HOPE-Split) for adult and pediatric partial grafts over a 1-year period (November 1, 2020 to December 1, 2021). The primary safety endpoint was based on the number of liver graft-related adverse events (LGRAEs) per recipient, including primary nonfunction, biliary complications, hepatic vascular complications, and early relaparotomies and was compared with consecutive single-center standard ex situ split transplantations (Static-Split) performed from 2018 to 2020. Secondary endpoints included preservation characteristics and early outcomes. Sixteen consecutive HOPE-Split liver transplantations (8 HOPE-Split procedures) were included and compared with 24 Static-Splits. All HOPE-Split grafts were successfully transplanted, and no graft loss nor recipient death was encountered during the median follow-up of 7.5 months (interquartile range, 5.5-12.5). Mean LGRAE per recipient was similar in both groups (0.31 ± 0.60 vs. 0.46 ± 0.83; p = 0.78) and split duration was not significantly increased for HOPE-Split (216 vs. 180 min; p = 0.45). HOPE-Split grafts underwent perfusion for a median of 125 min, which significantly shortened static cold storage (472 vs. 544 min; p = 0.001), whereas it prolonged total ex vivo preservation (595 vs. 544 min; p = 0.007) and reduced neutrophil infiltration on reperfusion biopsies (p = 0.04) compared with Static-Split. This clinical pilot study presents first feasibility and safety data for transplantation of partial liver grafts undergoing ex situ split during HOPE and suggests improved preservation compared with static ex situ splitting. These preliminary results will allow to set up large-scale trials on the use of machine perfusion in pediatric and split-liver transplantation.

Full left/full right liver graft ex situ split during hypothermic oxygenated perfusion

BACKGROUND

Ex vivo split liver transplantation in pediatric recipients has shown inferior results compared with whole grafts. One factor among others contributing to split grafts being considered as marginal is the prolonged static cold storage time related to ex vivo liver splitting. End ischemic hypothermic oxygenated perfusion is a validated strategy to improve outcomes of marginal whole grafts and may thus also benefit split liver grafts.

METHOD

We present the first case of full left/full right split procedure performed during hypothermic oxygenated perfusion.

RESULTS

We present a standardized surgical two-step approach where parenchymal transection was performed during end ischemic hypothermic oxygenated perfusion via the portal vein to shorten static cold storage duration. Both split grafts were successfully transplanted in a 4-year-old pediatric and a 38-year-old adult recipient. Despite high-risk procedure (retransplantation), extended donor criteria including a prolonged cardiac arrest and high donor risk index (2,25), both grafts showed early recovery of hepatic function and low serum transaminase release. At 6 months, both recipients were alive with a normal liver biology and a functioning graft.

CONCLUSION

Although challenging, full left/full right liver split procedure during end ischemic hypothermic oxygenated perfusion can be successfully performed and is a promising strategy to improve post-transplant outcomes.