Peripheral blood stem cell versus bone marrow allotransplantation: does the source of hematopoietic stem cells matter?

Hematopoietic stem cells from 4 different sources have been or are being used for the reconstitution of lymphohematopoietic function after myeloablative, near-myeloablative, or nonmyeloablative treatment. Bone marrow (BM)-derived stem cells, introduced by E. D. Thomas in 1963, are considered the classical stem cell source. Fetal liver stem cell transplantation has been performed on a limited number of patients with aplastic anemia or acute leukemia, but only transient engraftment has been demonstrated. Peripheral blood as a stem cell source was introduced in 1981, and cord blood was introduced as a source in 1988. The various stem cell sources differ in their reconstitutive and immunogenic characteristics, which are based on the proportion of early pluripotent and self-renewing stem cells to lineage-committed late progenitor cells and on the number and characteristics of accompanying "accessory cells" contained in stem cell allografts.