Perfusion storage methods can mechanically injury the vascular endothelium of the kidney, which leads to arterial thrombosis or fibrin deposition after reimplantation. Hill noted that, in human kidneys, fibrin deposition in the glomerulus after reimplantation and postoperative function, correlated with the length of perfusion storage. He had taken biopsies at revascularisation from human kidneys preserved by perfusion or ice storage, and showed by electron microscopy that endothelial disruption only occurred in those kidneys that had been perfused. Biopsies taken one hour after revascularisation showed platelets and fibrin adherent to any areas of denuded vascular basement membrane. A different type of vascular damage was described by Sheil who showed how a jet lesion could be produced distal to the cannula tied into the renal artery, leading to arterial thrombosis approximately 1 cm distal to the cannula site. Post reimplantation injury There is evidence that immunological mechanisms may injure hypothermically perfused kidneys after reimplantation if the perfusate contained specific antibody. Cross described two pairs of human cadaver kidneys that were perfused simultaneously with cryoprecipitated plasma containing type specific HLA antibody to one of the pairs. Both these kidneys suffered early arterial thrombosis. Light described similar hyperacute rejection following perfusion storage and showed that the cryoprecipitated plasma used contained cytotoxic IgM antibody. This potential danger of using cryoprecipitated plasma was demonstrated experimentally by Filo who perfused dog kidneys for 24 hours with specifically sensitised cryoprecipitated dog plasma and found that he could induce glomerular and vascular lesions with capillary engorgement, endothelial swelling, infiltration by polymorphonuclear leucocytes and arterial thrombosis. Immunofluorescent microscopy demonstrated specific binding of IgG along endothelial surfaces, in glomeruli, and also in vessels. After reimplantation, complement fixation and tissue damage occurred in a similar pattern. There was some correlation between the severity of the histological damage and subsequent function of the kidneys. Many workers have attempted to prevent kidneys rewarming during reimplantation but only Cohen has described using a system of active cooling. Measurements of lysosomal enzyme release from kidneys subjected to sham anastomoses, when either in or out of the cooling system, demonstrated how sensitive kidneys were to rewarming after a period of cold storage, and confirmed the effectiveness of the cooling system in preventing enzyme release. A further factor in minimising injury at the reimplantation operations may have been that the kidneys were kept at 7 °C within the cooling coil, which was within a degree of the temperature