Low-dose radiation plus rapamycin promotes long-term bone marrow chimerism.

Background: The ability to achieve significant donor engraftment without fully myeloablative conditioning has revolutionized allogeneic stem cell transplantation. These nonmyeloablative approaches may allow extension of this potentially curative modality to an increasing number of patients including those with non-malignant diseases. Although a number of regimens have been explored, the optimal means of conditioning has not been determined.