![]() Table 2 illustrates the currently known advantages to the use of UCB over adult stem/progenitor cell sources such as BM and adult peripheral blood (APB). Its use as an alternative to BM transplantation continues to grow as research better defines its composition, mechanisms of action, and broad therapeutic capacity. UCB’s relative cellular immaturity compared to adult sources suggests a potentially unrivaled degree of plasticity. Like BM, UCB use has thus far been limited to hematopoietic malignancies, marrow failure, and immunodeficiency disorders ( Table 1), but current research suggests it may be a much more powerful clinical weapon. Subsequently, more than 6,000 UCB transplants have been performed worldwide, many of them with unrelated donors ( 4, 41, 69, 76). UCB cell transplantation made its clinical debut in 1988 when it was used to successfully treat a 5-year-old child afflicted with Fanconi anemia ( 27). Umbilical cord blood (UCB), a once discarded material, has shown both in the lab and clinically to circumvent a number of these BM transplantation complexities. ![]() The most notable BM transplantation disadvantages include: 1) The average length of time from commencement of the donor search to procurement of BM cells and treatment is 135 days ( 38), 2) the cost of locating a donor and harvesting the cells is considerable, ranging from $25,000 to $50,000 ( 38), 3) there is a low availability of human leukocyte antigen (HLA)-matched donors with BM, which is crucial for histocompatibility and avoidance of graft-versus-host disease (GvHD) in this type of allograft, 4) the National Donor Marrow Program has a strong European bias, making it difficult to find sufficient matches for people of other descents ( 17), 5) BM recipients have a high incidence of viral infection (90%) ( 5), and 6) patients with malignancies are often unable to use BM autografts because of the risk of reinfection with tumorgenic cells. However, only 30% of eligible patients have a matched donor enabling them to receive its life-saving capability ( 2). Allogenic and autogenic marrow can reconstitute erythrocytes, platelets, granulocytes, T- and B-lymphocytes, macrophages, osteocytes, Langerhans’ cells, Kupffer’s cells, and microglia ( 1). Bone marrow transplantation was first performed in the 1960s and is currently the treatment of choice for more than 15,000 patients worldwide each year ( 1). Of these, bone marrow (BM) is the current gold standard source of hematopoietic progenitor cells (HPC) used to reconstitute blood lineages after myeloablative therapy in a number of malignant and nonmalignant blood diseases ( 21). New sources of stem/progenitor cells that can replace lost or diseased cells of the body are being sought due to tight government restrictions, availability, and ethical considerations regarding the use of embryonic and fetal tissues.
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