Ex vivo and extracorporeal perfusion with hDAF pig kidneys.

The present study was undertaken to determine whether human decay accelerating factor (hDAF) transgene would prevent hyperacute rejection (HAR) while perfused with human blood or extracorporeally in baboons. Four hDAF pig kidneys and three non-hDAF pig kidneys were perfused ex vivo with fresh human blood for 6 h. Additionally four hDAF pig kidneys and four non-hDAF pig kidneys were extracorporeally perfused in baboons and pigs, respectively, for 3 h. In ex vivo perfusion, the color of hDAF pig kidneys remained pink at the end of 6-h perfusion and they had normal histology, while non-hDAF kidneys developed HAR. HDAF pig kidneys had superior function over non-transgenic pig kidneys. Urine output was 17.31 +/- 3.70 ml/h for hDAF pig kidneys, and only 5.81 +/- 0.26 ml/h for non-hDAF kidneys (P < 0.05). Creatinine clearance was 1.16 +/- 1.24 ml/min for hDAF kidneys and 0.22 +/- 0.15 ml/min for non-hDAF kidneys (P < 0.05). Other functional data including potassium, urine specific density, and osmolality were normal in the hDAF kidneys, while in non-hDAF kidneys, serum potassium was elevated to over 9 mmol/l by the end of perfusion (P < 0.01). Non-hDAF kidneys also lost more sodium through urine than hDAF kidneys (173.67 +/- 14.05 mmol/l vs. 109 +/- 31 mmol/l, P < 0.05). In the extracorporeal perfusion, all the baboons tolerated the procedure well with normal hemodynamic and hemotologic profiles. These baboons were well until killed 42 to 56 days after perfusion, although their antiporcine antibodies were greatly elevated. We conclude that hDAF transgene protects against HAR, allowing the pig kidney to function normally while perfused with human blood, and that extracorporeal perfusion using hDAF pig kidneys is a safe procedure in baboons.

HDAF transgenic pig livers are protected from hyperacute rejection during ex vivo perfusion with human blood.

The aim of this study was to determine if human decay-accelerating factor (hDAF) protects against hyperacute rejection in an ex vivo liver perfusion system using human blood. Pig livers were perfused ex vivo via the portal vein for an average of 5-6 h using a membrane oxygenator. Three groups were studied. Group I: Wild-type pig livers were alloperfused with fresh pig blood (n = 5). Group II: Wild-type pig livers were xenoperfused with fresh human blood (n = 5). Group III: hDAF transgenic pig livers were xenoperfused with fresh human blood (n = 5). The graft ischemic time, ratio of perfusate volume to liver weight, flow rate, and perfusate hematocrit were similar in each group. The hDAF livers perfused with human blood (Group III) had a lower ALT level, less protein and albumin losses, lower bilirubin levels in the perfusate, less weight gain, and greater bile production than the wild-type livers perfused with human blood. Histology showed classic features of hyperacute rejection in Group II, including massive hemorrhage, severe vasculitits, fibrin and C5b-9 deposition, and endothelial damage within 1 h of perfusion, whereas liver histology studies in Groups I and III were near normal. IgG and IgM deposits were seen in the xenoperfused livers. Electron microscopy (EM) and immuno-EM showed loss of endothelial cells, trapping of white blood cells and platelets, and diffuse fibrin deposits in Group II only. hDAF pig livers perfused with human blood showed superior function and histology when compared with wild-type pig livers. These data suggest that (1) hyperacute rejection may contribute to the inconsistent results using wild-type pig livers for extracorporeal liver support and (2) genetically modified pigs that express hDAF may provide a better donor source than wild-type pigs for extracorporeal liver support.