Dissecting the instant blood-mediated inflammatory reaction in islet xenotransplantation
(2008) Xenotransplantation — Vol. 15, n° 4, p. 225-234 (2008)
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- BACKGROUND: A massive destruction of transplanted tissue occurs immediately following transplantation of pancreatic islets from pig to non-human primates. The detrimental instant blood-mediated inflammatory reaction (IBMIR), triggered by the porcine islets, is a likely explanation for this tissue loss. This reaction may also be responsible for mediating an adaptive immune response in the recipient that requires a heavy immunosuppressive regimen. MATERIALS AND METHODS: Low molecular weight dextran sulfate (LMW-DS) and the complement inhibitor Compstatin were used in a combination of in vitro and in vivo studies designed to dissect the xenogeneic IBMIR in a non-human primate model of pancreatic islet transplantation. Adult porcine islets (10,000 IEQs/kg) were transplanted intraportally into three pairs of cynomolgus monkeys that had been treated with LMW-DS or heparin (control), and the effects on the IBMIR were characterized. Porcine islets were also incubated in human blood plasma in vitro to assess complement inhibition by LMW-DS and Compstatin. RESULTS: Morphological scoring and immunohistochemical staining revealed that the severe islet destruction and macrophage, neutrophilic granulocyte, and T-cell infiltration observed in the control (heparin-treated) animals were abrogated in the LMW-DS-treated monkeys. Both coagulation and complement activation were significantly reduced in monkeys treated with LMW-DS, but IgM and complement fragments were still found on the islet surface. This residual complement activation could be inhibited by Compstatin in vitro. CONCLUSIONS: The xenogeneic IBMIR in this non-human primate model is characterized by an immediate binding of antibodies that triggers deleterious complement activation and a subsequent clotting reaction that leads to further complement activation. The effectiveness of LMW-DS (in vivo and in vitro) and Compstatin (in vitro) in inhibiting this IBMIR provides the basis for a protocol that can be used to abrogate the IBMIR in pig-human clinical islet transplantation.
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Goto, M., Tjernberg, J., Dufrane, D., Elgue, G., Brandhorst, D., Ekdahl, K. N., Brandhorst, H., Wennberg, L., Kurokawa, Y., Satomi, S., Lambris, J. D., Gianello, P., Korsgren, O., & Nilsson, B. (2008). Dissecting the instant blood-mediated inflammatory reaction in islet xenotransplantation. Xenotransplantation, 15(4), 225-234. https://doi.org/10.1111/j.1399-3089.2008.00482.x (Original work published 2008)