Artikel
Extracorporeal human blood perfusion of CD46 & HLA-E double transgenic pig limbs: A technique for the study of immunologic effects in composite tissue xenografts
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Veröffentlicht: | 10. September 2013 |
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Background: With increasing demand and limited availability of organ donors xenotransplantation of organs becomes a promising approach. Xenotransplantation of composite tissues would provide a large pool of available tissue for reconstructive surgery without donor site morbidity. Multiple transgene strategies are currently used to overcome rejection of pig-to-human xenografts. In a new founder line, overexpression of human CD46 and HLA-E was combined to prevent complement activation and NK cell reactivity.
Aim: To assess the feasibility of extracorporeal human blood perfusion of porcine composite tissue grafts and to study first immunologic reactions in a pig-to-human xenotransplantation setting.
Methods: 8 forelimbs (4 wildtype and 4 HLA-E/CD46 transgenic) were extracorporeally perfused with whole, heparin-anticoagulated human blood with a pediatric heart-lung machine for 12h and compared to the respective autologous perfusions (n=8). Blood gas analysis probes were collected and hemodynamic parameters monitored hourly. Muscular function was assessed by motor response on direct neural stimulation. Compartment pressure was measured before and after perfusion.
Results: No signs of hyperacute rejection were observed in this model and all limb perfusions could be performed continuously for 12h. Blood gas analysis showed constant physiologic potassium, lactate and pH values in both transgenic and wildtype animals. A statistical significant difference between human blood perfusion in wildtype (w) and transgenic (t) limbs could be detected assessing pH (w: 7.32±0.06; t: 7.35±0.025; p=0.043) and lactate (w: 10.78±0.63; t: 7.11±0.47; p=0.003) whereas no statistical significant differences were observed in potassium and hemoglobin values. In all autologous perfusions, no statistical difference was found in blood gas parameters. Stable and physiologic hemodynamic perfusion parameters (pressure, flow) could be maintained throughout all limb perfusions underlining the good perfusion quality without significant differences between human blood and autologous perfusions in both transgenic and wildtype animals. All limbs showed full muscular response on neural stimulation throughout the experiment in all perfusion groups. Compartment pressures were all within the normal range at the end of the perfusions.
Conclusion: The extracorporeal human blood perfusion of transgenic and wildtype pig limbs is feasible for at least 12 hours and does not cause hyperacute rejection and allows the detailed study of early immunologic effects in xenotransplantation.