Umbilical cord blood (UCB) has recently been explored as an alternative haematopoietic stem cell (HSC) source for allogeneic immunotherapy in both adults and paediatric patients with haematological malignancies and marrow failure syndromes. The relative ease of procurement, tolerance of 1-2 antigen human-leukocyte antigen (HLA) mismatch and the lower than anticipated risk of severe graft-versus-host disease has made UCB an appealing alternative to marrow-derived HSC. Results from various registries and institutions observed graft cell dose to be the major factor determining engraftment and survival in unrelated UCB transplant recipients. Given that adults are larger than children, there was still limited enthusiasm for the use of UCB in adults. The use of reduced-intensity or nonmyeloablative preparative regimens to allow engraftment of UCB broadens the scope of patients who may benefit from allogeneic immunotherapy, particularly the elderly and medically infirm patients with no matched sibling donor. Further studies on improving graft cell dose such as the use of ex vivo expansion of UCB cells and multiple-unit transplant are currently being pursued, so as to make this potentially curative procedure available to more patients.
Allogeneic haematopoietic stem cell transplantation (HSCT) is an established form of treatment for many high-risk haematological malignancies and marrow failure syndromes. The use of HSCT is still limited by the availability of human leukocyte antigen (HLA) matched donors, even though unrelated donor registries have markedly improved the chances of finding a donor for many patients.
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