Table 1.

Diverse preservation strategies of machine perfusion, depending on temperature and oxygen supply.

Perfusion Strategy	Temperature	Main Characteristics	Preservation Time (max)
HMP HOPE D-HOPE	4 °C	Reduced metabolism, ATP resynthesis, oxygen supplementation (HOPE, D-HOPE), perfusion via portal vein and hepatic artery (D-HOPE).	up to 24 h *
SNMP	20–25 °C	Sufficient metabolism for organ quality assessment, may combine advantages of HMP and NMP.	up to 24 h *
NMP	37 °C	Mimics in vivo conditions, organ quality assessment.	up to 7 d *
COR		Gradual rewarming → combination of the beneficial effects of different MP strategies.

HMP: hypothermic machine perfusion, HOPE: hypothermic oxygenated machine perfusion, D-HOPE: dual hypothermic oxygenated perfusion, SNMP: subnormothermic machine perfusion, NMP: normothermic machine perfusion, COR: controlled oxygenated rewarming, ATP: adenosine triphosphate, * data obtained in studies with discarded human livers without subsequent transplantation.