A Report of Four Depletional Induction Strategies in Non‐Human Primate Islet Xenotransplantation

BACKGROUND: Porcine islet xenotransplantation is limited by the availability of clinically applicable immunosuppressive regimens. We tested four depletional induction strategies and maintenance regimens in a non-human primate (NHP) islet xenotransplant model. METHODS: Genetically modified or wild-type neonatal porcine islets were transplanted via portal vein infusion in diabetic NHPs. Induction consisted of rhesus anti-thymocyte globulin (rhATG) (Group 1, n = 4), anti-CD4 monoclonal antibody (mAb, Group 2, n = 3), or human anti-thymocyte globulin (huATG) tocilizumab (Groups 3 and 4; n = 3 and n = 4, respectively). Maintenance consisted of B7 (Groups 1-3) or anti-CD154 (Group 4) costimulation blockade, tacrolimus transitioned to sirolimus (sirolimus only in Group 4), and mycophenolate mofetil. Xenografts were monitored for blood glucose and porcine c-peptide. RESULTS: infiltrates. CONCLUSIONS: Induction with huATG/tocilizumab and maintenance with 5c8 led to the best functional outcomes. CD4 T-cell depletion with anti-CD4 mAb induced compensatory CD8 T-cell proliferation and graft infiltration.