Abstract: The invention provides a perfusion stock composition, for preserving a donor organ for transplantation, comprising: a source of 60 to 100 mM Na+; a source of 10 to 20 mM K+; a source of 5 to 10 mM Mg2?; a source of 0.25 to 0.75 mM Ca2+; 10 to 40 mM Tris(hydroxymethyl)aminomethane hydrochloride (Tris or THAM), 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES), 3-(N-morpholino)propanesulfonic acid (MOPS), 2-(N-morpholino)ethanesulfonic acid (MES), N,/N-bis-(2-hydroxyethyl)-2-aminoethansulfonic acid (BES), or N/-tris(hydroxymethyl)methyl-2-aminoethanesulfonic acid (TES); a source of 10 to 30 mM HCO3?; 1 to 30 mM glucose; 1 to 20 U/L insulin; 1 to 10 mM fructose diphosphate or a salt thereof; 1 to 40 mM aspartate or glutamate; 1 to 10 mM adenosine, cAMP or cGMP; 1 to 10 mM reduced glutathione; and 30 to 100 mM lactobionate or mannitol; and optionally a diluent. The invention also provides a perfusion composition, a kit, a method, and a perfusion apparatus, each related to the perfusion stock composition.