Abstract 16582: Costimulation Blockade With Anti Cd80 and Cd86 Monoclonal Antibodies Prolonged Graft Survival in Allogeneic Ips Cell-Derived Cardiomyocyte Patch Transplantation

Abstract

Introduction: How to avoid immune rejection after transplantation should be elucidated for confirmed efficacy in clinical application of allogenic induced pluripotent stem cell derived cardiomyocyte patch. The blockade of CD28-CD80/86 costimulation is known to induce T cell anergy and immune tolerance by the recruitment of regulatory T cells (T reg) and prolong graft survival in organ transplantation. Hypothesis: We hypothesized that the blockade of CD28-CD80/CD86 costimulatory pathway by anti-CD80/CD86 monoclonal antibodies (mAbs) induces T cell anergy in vivo and suppresses immune rejection in allogeneic iPSC-CMs subcutaneous transplantation mice model. Methods: T cell anergy was induced in vitro by co-culture of Balb/c and 25Gy irradiated C57BL/6 splenocytes with anti-CD80/86 mAbs for 5 days. The inhibitory effect of anergic cells was evaluated by mixed lymphocyte reaction (MLR) in C57BL/6 and Balb/c splenocytes with anergic cells. IFN-g in MLR supernatants was measured by ELISAs to assess immune response. C57BL/6 iPSC-CMs expressing luciferase were subcutaneously transplanted into Balb/c. Anti-CD80/CD86 mAbs were injected intraperitoneally 250μg/dose on day 0, 1, and 2 (treated mice, n=6). In control mice (n=6), equivalent volume of saline was injected. To evaluate iPSC-CMs graft survival, photon counts of iPSC-CMs were measured by bioluminescence imaging system (BLI). Cells of harvested grafts were analyzed by immunofluorescence staining (IF). Results: On ELISAs, IFN-g in MLR supernatants co-cultured with anergic cells was significantly lower as compared with those without anergic cells (12.3±14.4 vs. 251±80.2 pg/ml, p=0.007). The ability to suppress the alloresponses was dose-dependent. BLI showed that photon counts on day 14 in treated mice were significantly higher than in control mice (7397±2651 vs. 2703±1271, p=0.003). IF showed a siginificantly higher ratio of CD4 and Foxp3 double positive cells to CD4-postive cells in the grafts on day 7 in treated mice as compared with in control mice (23±3% vs. 9±3%, p=0.009) Conclusions: The blockade of CD28-CD80/CD86 costimulatory pathway might suppress immune rejection in allogeneic iPSC-CMs transplantation mice model and T reg might involve this immune tolerance.