History of cord blood transplantation.

Since the first human cord blood transplant, performed 20 years ago, cord blood banks have been established worldwide for the collection and cryopreservation of cord blood for allogeneic hematopoietic stem cell transplant. A global network of cord blood banks and transplant centers has been established for a common inventory and study of clinical outcomes. Results of unrelated allogeneic cord blood transplants in malignant and nonmalignant diseases, in adults and children, show that, compared with HLA-matched unrelated BM transplant, cord blood has several advantages, including prompt availability of the transplant, decrease of GVHD and 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, although some degree of HLA mismatches is acceptable. Developments are expected to facilitate engraftment, including ex vivo expansion of stem cells, intrabone injection of cord blood cells and double cord blood transplants. In addition to hematopoietic stem cells, cord blood and placenta contain a large number of nonhematopoietic stem cells. In the absence of ethical concern, the unlimited supply of cells explains the increasing interest of using cord blood for developing regenerative medicine.