Forest plots comparing HA and animal survival for all studies comparing different MP to CS in animal studies. (a) HA. NMP (SMD: -3.97, 95% CI:-5.46 to -2.47), HMP (SMD: -0.80, 95% CI:-1.68 to 0.09), and SNMP (SMD: -2.48, 95% CI:-4.21 to -0.74) reduced the release of HA; (b) animal survival. NMP (RR: 1.29, 95% CI: 0.79 to 2.09), HMP (SMD: 1.16, 95% CI: 0.13 to 10.37), and SNMP (SMD: 1.44, 95% CI: 0.95 to 2.20) improved the survival. HA: hyaluronic acid; MP: machine perfusion; HMP: hypothermic machine perfusion; NMP: normothermic machine perfusion; SNMP: subnormothermic machine perfusion; CS: cold static storage; SMD: standardized mean differences; CI: confidence interval; RR: relative risk.