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 CD25CD127 Tregs did.