Advances in unrelated cord blood transplants in malignancies

Cord bloodis an unlimited source of hematopoietic stem cells (HSCs) for allogeneic HSC transplant. Since the first human cord blood transplantperformed 20 years ago, cord bloodbanks have been established worldwide for collection and cryopreservation of cord bloodfor allogeneic HSC transplant. More than 500 000 cord bloodunits are now available for international exchange of cord bloodunits. A global networkof cord bloodbanks and transplantcenters has been established for a common inventory and study of clinical outcomes. Results of unrelated allogeneic cord blood transplantsin malignant and nonmalignant diseases, in adults and children, show that, compared with HLA-matched unrelated bone marrow transplant, cord bloodhas several advantages including prompt availability of the transplant, decrease of graft versus host diseaseand better long-term immune recovery resulting in a similar long-term survival. Several studies have shown that the number of cells is the most important factor for engraftment while some degree of HLA mismatches is acceptable. Progresses in this field are expected to facilitate engraftment including ex vivo expansion of stem cells, intra-bone injection of cord bloodcells and double cord blood transplants.