Transplants, bone marrow stem-cell transfusions

Although research into stem cells is new, the use of stem cells for therapy has been with us for some time. Most of us are familiar with bone marrow transplant for patients with leukemia. This procedure involves finding a matching donor to harvest bone marrow stem cells and transfuse them into the patient with leukemia (see Exhibit 4.16 for details). 

G-CSF is widely used to mobilise bone marrow stem cells into the peripheral blood to support both autologous and allogeneic peripheral blood progenitor transplantation. The use of peripheral blood progenitors as opposed to bone marrow progenitors is associated with earlier neutrophil and platelet recovery, fewer red cell transfusions and earlier discharge from hospital. 

Hematopoietic stem cells are used to treat people whose own blood-forming cells fail because of a rare condition called aplastic anemia, or to help people who have been accidentally exposed to very high doses of irradiation. Hematopoietic stem cells are most often used as part of the treatment for certain forms of cancer. Sometimes cancer patients are given very high doses of irradiation and/or chemotherapy drugs that destroy the blood-forming stem cells in the bone marrow. Transplants with the patient s own blood stem cells that were removed before the treatment, or stem cells from a healthy donor, allow the patient to recover. The transplant process is very simple The cells in a salt solution are slowly injected into a vein just like a blood transfusion. If the blood stem cells come from a donor, then the donor and the patient must share certain inherited proteins to make sure that the donor s immune system cells will not attack the treated patient. 

Stem cell-derived blood cells could provide potentially unlimited and on-demand source of therapeutic cells for a variety of clinical applications, including bone marrow transplantation, adoptive T cell and dendritic cell therapies, as well as for blood transfusions, for example, platelet or red blood cell therapy. Some of these applications, for example, bone marrow transplantation, has been used for decades and have revolutionized modern medicine. Yet, current paradigms of isolating donor or patient cells for acute or future transplantation, with or without in vitro modification, are unsustainable in the face of high demand and immediate needs. The true impact of these therapies could only be realized if blood lineage cells (hematopoietic stem and progenitor cells, dendritic cells, T cells, red blood cells, platelets, etc.) are available on-demand and as ready-to-use therapeutics. 

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