Human hematopoietic stem cells: potential use as tumor-free autografts after high-dose myeloablative cancer therapy

Human hematopoietic stem cells are rare cells residing within the marrow and peripheral blood of humans. These cells are capable of producing each of the myeloid and lymphoid cell types and have the ability to produce additional stem cells. The infusion of stem cells in a graft is responsible for hematopoietic reconstitution after the delivery of lethal irradiation and/or high dose chemotherapy. Stem cells have been extensively characterized, and their phenotype has been defined. Technologies have now been developed that permit the isolation of sufficient numbers of stem cells for their use as grafts during hematopoietic cell transplantation. Mobilized peripheral blood grafts obtained from patients with cancer are frequently contaminated with tumor cells. The isolation of stem cells from mobilized peripheral blood permits the creation of a potentially free tumor-free graft. Such tumor free autografts might prevent the infusion of tumor cells receiving curative myeloablative therapies and thereby improve the efficacy of autotransplantation strategies for patients with selected cancers.