CD8+ T cell-mediated rejection of allogenic human induced pluripotent stem cell-derived cardiomyocyte sheets in human PBMC-transferred NOG MHC double knockout mice

Abstract

Background

Transplantation of human induced pluripotent stem cell-derived cardiomyocytes (hiPS-CMs) has emerged as a promising therapy to treat end-stage heart failure. However, immunogenicity of hiPS-CMs in transplanted patients has not been fully elucidated. Thus, in vivo models are required to estimate immune responses against hiPS-CMs in transplant recipients.

Methods

We transferred human peripheral blood mononuclear cells (hPBMCs) into NOD/Shi-scid IL2rg^null (NOG) MHC class I/II double knockout (NOG-ΔMHC) mice, which were reported to accept hPBMCs without xenogeneic-graft-versus-host disease (xeno-GVHD). Then, hiPS-CM sheets generated from the hiPS cell line 201B7 harboring a luciferase transgene were transplanted into the subcutaneous space of NOG-ΔMHC mice. Graft survival was monitored by bioluminescent images using a Xenogen In Vivo Imaging System.

Results

The human immune cells were engrafted for more than three months in NOG-ΔMHC mice without lethal xeno-GVHD. The hiPS-CMs expressed a moderate level of human leukocyte antigen (HLA)-class I, but not HLA-class II, molecules even after interferon-gamma (IFN-γ) stimulation. Consistently, the allogenic IFN-γ-treated hiPS-CMs induced weak CD8⁺ but not CD4⁺, T cell responses in vitro. hiPS-CM sheets disappeared approximately 17–24 days after transplantation in hPBMC-transferred NOG-ΔMHC mice, and CD8⁺ T cell depletion significantly prolonged graft survival, similar to what was observed following tacrolimus treatment.

Conclusion

hiPS-CMs are less immunogenic in vitro but induce sufficient CD8⁺ T cell-mediated immune responses for graft rejection in vivo.