Hematopoietic stem cell transplantation without irradiation

Long-term engraftment of hematopoietic stem cells into the bone marrow of a recipient depends on immunological compatibility between donor and host, or ablation of the host's immune system by irradiation. A 'universal recipient' mouse model now shows that mice that lack T, B and NK cells and bear mutations in the tyrosine kinase Kit accept any donor HSC without irradiation. Hematopoietic stem cell (HSC) transplantation is limited by histocompatibility barriers and by lack of space in bone marrow niches. These obstacles prevent in vivo analysis of histoincompatible mutant stem cells and of HSC functions in non-irradiated mice. By genetically combining immunodeficiency with impaired function of the growth factor receptor Kit in mice, we generated a 'universal' HSC recipient that efficiently accepts long-term histocompatible and histoincompatible HSCs without prior irradiation.