RESUMO
Allogeneic hematopoietic stem cell (HSC) transplantation has been used to treat thousands of patients, both adults and children, who have life-threatening hematological diseases. The principal limitations of allogeneic bone marrow transplantation (BMT) are, for the majority of patients, the lack of suitable HLA-matched donors and the complications of graft-versus-host disease (GVHD) associated with HLA mismatches. The lack of an HLA-identical sibling donor in 70% of the cases has been overcome through the establishment of registries of potential marrow donors. These registries, however, often are restricted in terms of HLA polymorphism and ethnic diversity. Despite a bone marrow donor registry which contains >3.7 million donors worldwide, some patients cannot be transplanted because of the lack of a suitable HLA-identical donor. New approaches have been investigated, including the use of HLA partially mismatched, T cell-depleted, mobilized peripheral blood HSC or umbilical cord HSC.