BackgroundApproaches to increase organ availability for orthotopic liver transplantation (OLT) often result in the procurement of marginal livers that are more susceptible to ischaemia, preservation and reperfusion injury (IPRI). MethodsThe effects of post-OLT hyperbaric oxygen (HBO) therapy on IPRI in a syngeneic rat OLT model were examined at various time-points. The effects of IPRI and HBO on hepatocyte necrosis, apoptosis, proliferation, and sinusoidal morphology and ultrastructure were assessed. ResultsPost-OLT HBO therapy significantly reduced the severity of IPRI; both apoptosis [at 12h: 6.4±0.4% in controls vs. 1.6±0.7% in the HBO treatment group (p < 0.001); at 48h: 2.4±0.2% in controls vs. 0.4±0.1% in the HBO treatment group (p < 0.001)] and necrosis [at 12h: 18.7±1.8% in controls vs. 2.4±0.4% in the HBO treatment group (p < 0.001); at 48h: 8.5±1.3% in controls vs. 3.4±0.9% in the HBO treatment group (P= 0.019)] were decreased. Serum alanine transaminase was reduced [at 12h: 1068±920IU/l in controls vs. 370±63IU/l in the HBO treatment group (P= 0.030); at 48h: 573±261IU/l in controls vs. 160±10IU/l in the HBO treatment group (P= 0.029)]. Treatment with HBO also promoted liver regeneration [proliferation at 12h: 4.5±0.1% in controls vs. 1.0±0.3% in the HBO treatment group (p < 0.001); at 48h: 8.6±0.7% in controls vs. 2.9±0.2% in the HBO treatment group (p < 0.01)] and improved sinusoidal diameter and microvascular density index. ConclusionsHyperbaric oxygen therapy has persistent positive effects post-OLT that may potentially transfer into clinical practice.