Abstract: A method for achieving hemolymphopoietic chimerism is disclosed. The method involves the steps of administering to a recipient a bone seeking radiopharmaceutical; transplanting bone marrow-derived cells into the recipient; and transiently suppressing lymphocyte response so as to induce hemolymphopoietic chimerism. The method is useful for decreasing rejection of transplanted organs, tissues or cells and for treating autoimmune diseases. The present invention has the advantage of inducing hemolymphopoietic chimerism without the need for external radiation or harsh cytotoxic drugs. The present invention has the additional advantage of significantly prolonging tolerance to an organ, cell, or tissue transplant.

Abstract: Non-lethal methods of conditioning a recipient prior to bone marrow transplantation to achieve highly enhanced, stable, long-term hematopoietic chimerism in presence of transient immunosuppression are described. In particular, the administration of non-lethal doses of bone-seeking radiopharmaceuticals such as 153Samarium Lexidronam, a radioactive compound linked to a tetraphosphonate group, to target bone marrow cells, are disclosed herein.