Analysis of potential perv transmission to human endothelium in a pig-to-cynomolgus monkey kidney model
Introduction Neither PERV infection studies in small animal models nor retrospective studies on patients mirror clinical xenotransplantation very closely. Non-human primate models are excellently suited to mimic highly immunosuppressive clinical settings. The value of these models for risk assessment of potential PERV transmission, however, is currently questioned, since even those primate cells which can be infected in vitro are probably less permissive than certain human cell types. Therefore, we have developed a 'humanized pig-to-cynomolgus monkey' transplantation model. In this model, PERV particles, potentially released by the porcine graft will immediately get in close contact to primary human endothelial cells (hEC), which have been shown to be highly permissive for productive PERV infection.
Materials and methods Porcine kidneys are transplanted into cynomolgus monkeys. During the transplant operation the porcine kidney vein is replaced by a interposition graft constructed by human saphena vein. Recipients are immunosuppressed using a combination therapy of Cyclophosphamide induction, Cylcosporin, low-dose-steroids, mycophenolic acid as well as a short course of supplemental CI-Inhibitor. After rejection of the porcine kidneys or death of the recipient, the human interposition grafts are removed and analysed by a variety of assays for detection of potential PERV-infection. Moreover, blood, serum and tissue samples of the transplanted animals are screened for PERV specific immune response and indications for PERV transmission.
Results So far, five recipient monkeys died 2, 5, 13, 15 and 19 days after transplantation of unmodified and CD59 transgenic porcine grafts. Isolation of hEC was possible from all explanted human interposition grafts. Detailed results of the analysis of the explanted human vascular tissue, of isolated hEC and plasma and serum samples of the graft recipients will be presented at the congress.
Conclusions We analysed whether PERV-transmission from a porcine kidney to human endothelium may occur in a pig-to-humanized cynomolgus monkey transplantation model. In contrast to other PERV infection models, our model allows to investigate whether current xenotransplantation strategies impairing complement mediated virolysis and suppressing other humoral and cellular immune mechanisms may result in in vivo infection of human primary cells and tissue.