Peripheral blood stem cell transplantation as an alternative to bone marrow transplantation: an overview

Stem cells capable of restoring hematopoiesis following lethal bone marrow injury circulate in the blood of many animals, including humans. When collected through leukapheresis and reinfused following high-dose chemotherapy, stem cells offer a treatment option not currently open to some patients who are unable to undergo autologous bone marrow transplantation because of tumor involvement in the pelvis, prior pelvic radiation, or intolerance to general anesthesia. After stem cell infusion, hematologic and immunologic recovery are rapid in comparison to that after autologous bone marrow reinfusion; however, in some cases platelet engraftment is slower. There is some evidence that tumor contamination in the peripheral blood is much less than in the marrow. In any event, most relapses of malignant disease occur at the site of origin and represent treatment failure rather than growth of reinfused malignant cells. Prospective controlled trials are needed to evaluate stem cell in comparison to autologous bone marrow transplantation.