Background The mixed chimerism approach induces donor-specific tolerance in both pre-
clinical models and clinical pilot trials. However, chronic rejection of heart allografts and
acute rejection of skin allografts were observed in some chimeric animals despite persistent
hematopoietic chimerism and tolerance toward donor antigens in vitro. We tested whether
additional cell therapy with regulatory T cells (Tregs) is able to induce full immunologic
tolerance and prevent chronic rejection. Methods We recently developed a murine “Treg …