Liver transplantation is a life-saving treatment for several pediatric diseases. Compared to adults, in pediatric liver transplantation (PLT) the availability of grafts is more limited due to the need for adequate dimensional matching. Extended criteria donors (ECD) and long static cold storage (SCS) times are factors that negatively affect PLT outcomes. Hypothermic machine perfusion (HMP) is a valid tool to implement graft availability, allowing graft reconditioning and reducing cold ischemia time. However, evidence of HMP benefits is still lacking in PLT.

The study aim was to evaluate the impact of HMP on graft availability and on PLT outcome, retrospectively analyzing the case series of the two Italian centers with high volume of PLT.

Between 2018 and 2025, 386 PLT were performed at Ospedale Pediatrico Bambino Gesù (Rome) and Ospedale Papa Giovanni XXIII (Bergamo). Out of these, 27 grafts (7%) were transplanted after HMP, namely 8 left-lateral segments, 5 extended-right grafts, 6 whole graft and 8 non-standard splitted grafts. Ten ex situ SL under HMP generated 15 (56%) grafts transplanted in children and 5 transplanted into adult; these latter were excluded from the analysis. Indications to HMP split were: donor hemodynamic instability (40%), non-standard parenchymal division (30%) and expected long SCS (30%). Twelve (44%) grafts, either whole livers (n=6) or partial grafts after SL (n=6), underwent HMP due to ECD (33%), donors’ hemodynamic instability (25%) or expected long SCS (42%). Overall mean HMP was 233 min (IQR 101-480 min), mean total preservation time (TPT) was 625 min (IQR 362-852), and mean SCS was 388 min (IQR 182-550). No HMP procedures were aborted, and all grafts were transplanted. Recipients features were: mean age 117 months (IQR 1-208), mean weight 19,6 kg (IQR 3,78-55,5); mean PELD in chronic liver failure patients was 21 (IQR 6-38); 19% of recipients were status 1, and in 15% of the cases grafts were used for re-transplantation. Main indication to PLT was biliary atresia (22%). After a median follow up of 12 months (IQR 1–81 months), 1-year graft and patient survivals (GS, PS) were 89%. No primary non-function (PNF) occurred; incidence of delayed graft function (DGF) was 4%. Incidence of graft-related complications was 11%.

Graft outcome was compared to that of 81 grafts transplanted without HMP into severity-matched recipients (1:3 propensity score matching). Grafts were from standard risk donors (92%), either as a whole or SL with conventional parenchymal division only. Mean TPT was 452 min (IQR 240-682). One-year PS was 91% while 1-year GS was 90% (P= NS). No PNF occurred; DGF rate was 2% while graft-related complication incidence was 20%.

The results of this retrospective study, conducted in a recipient population with a significant proportion of acute liver failure and re-transplantation, document that the use of HMP is safe and allows for an expansion of the number of transplantable grafts