Modification of Hyperacute Xenograft Rejection of a Porcine Kidney by Serial Organ Perfusion of Canine Blood Through the Pig's Liver and Kidney

Abstract

BACKGROUND: The major problem in transplants between widely disparate species is hyperacute rejection, a rapid and violent rejection that damages the graft within minutes or hours. Hyperacute rejection is mediated by the components of natural immunity, most notably natural antibodies and complements. The absorption of natural antibodies on endothelial cells by passing the recipient's blood through a donor kidney or liver is very effective in removing xenoreactive natural antibodies from a recipient's blood. To modify hyperacute rejection in a pig-to-dog renal transplant, we transplanted a porcine kidney, which had been perfused after organ perfusion of canine blood through a pig's liver and kidney, was transplanted en-bloc with the kidney. METHODS: The en-bloc organ procurement from male pigs weighing 15-20 kg, including the liver and two kidneys, was performed after perfusion with a cold Euro-Collins solution through the aorta and portal vein. The harvested organs were vascularized to male dogs weighing 25-30 kg by anastomosis of the graft aorta to the recipient's infrarenal aorta, the graft inferior vena cava to the recipient's infrarenal inferior vena cava, and the graft portal vein to the recipient's portal vein with a end-to-side fashion. The recipient's blood was perfused into the liver and one kidney, and then into the other kidney 60 minutes later. During the procedure, the recipient's blood was sampled and assayed for natural xenoreactive antibodies. Natural anti-porcine endothelial antibodies were measured by ELISA with porcine aortic endothelial cells in the culture as targets. Each grafted organ was biopsied serially at 2, 4, 6, 8, 10, 20, 40, and 60 minutes after reperfusion for light microscopic and immunofluorescent examinations. RESULTS: Natural anti-porcine endothelial antibody levels(both IgM and IgG) of canine serum decreased at 60 minutes after organ perfusion of canine blood through a porcine liver and one kidney. Hyperacute rejection (capillary congestion, interstitial hemorrhage, thrombosis, etc.) of the kidneys appeared within20 minutes after blood perfusion regardless of organ absorption of natural antibodies through the porcine liver and one kidney. The appearance of interstitial hemorrhage and thrombosis of the kidney was delayed about 4-10 minutes by organ absorption of natural antibodies. However, acute tubular necrosis appeared early and more obviously in the second kidneys. Immunofluorescence showed granular deposits of canine IgM and IgG in the glomerular mesangium and on the microvessels. Canine IgM, but not IgG, deposition on the second kidney decreased after organ absorption of natural antibodies. Complement deposition was not altered by organ absoption. CONCLUSIONS: The organ perfusion of canine blood through a porcine liver and kidney was effective for only a short time in decreasing the natural anti-porcine endothelial IgM and IgG antibodies of canine serum, and histologic changes appeared in the second kidney of a slightly later time than in the kidney used in antibody absorption. Further efforts should be made toward modifying the technique for removal of specific natural antibodies and complements.