Human iPSC-derived CD4+ Treg-like cells engineered with chimeric antigen receptors control GvHD in a xenograft model

CD4⁺ T cells induced from human iPSCs (iCD4⁺ T cells) offer a therapeutic opportunity for overcoming immune pathologies arising from hematopoietic stem cell transplantation. However, most iCD4⁺ T cells are conventional helper T cells, which secrete inflammatory cytokines. We induced high-level expression of FOXP3, a master transcription factor of regulatory T cells, in iCD4⁺ T cells. Human iPSC-derived, FOXP3-induced CD4⁺ T (iCD4⁺ Treg-like) cells did not secrete inflammatory cytokines upon activation. Moreover, they showed demethylation of the Treg-specific demethylation region, suggesting successful conversion to immunosuppressive iCD4⁺ Treg-like cells. We further assessed these iCD4⁺ Treg-like cells for CAR-mediated immunosuppressive ability. HLA-A2 CAR-transduced iCD4⁺ Treg-like cells inhibited CD8⁺ cytotoxic T cell (CTL) division in a mixed lymphocyte reaction assay with A2⁺ allogeneic CTLs and suppressed xenogeneic graft-versus-host disease (GVHD) in NSG mice treated with A2⁺ human PBMCs. In most cases, these cells suppressed the xenogeneic GvHD progression as much as natural CD25⁺CD127⁻ Tregs did.