Milestones in umbilical cord blood transplantation.

Much has been learned about umbilical cord blood (UCB) since the first human cord blood transplant was performed back in 1988. Cord blood banks have been established worldwide for the collection, cryopreservation and distribution of UCB for allogeneic haematopoietic stem cell transplantation. UCB has now become one of the most commonly used sources of haematopoietic stem cells for allogeneic transplantation. Today, a global network of cord blood banks and transplant centres has been established with a large common inventory, allowing for more than 20000 transplants worldwide in children and adults with severe haematological diseases. Several studies have been published on UCB transplant, assessing risk factors such as cell dose and human leucocyte antigen mismatch. New strategies are ongoing to facilitate engraftment and reduce transplant-related mortality and include the use of reduced-intensity conditioning regimen, intra-bone injection of cord blood cells, double cord blood transplants or ex vivo expansion of cord blood cells. The absence of ethical concern and the unlimited supply of cells explain the increasing interest of using UCB for developing regenerative medicine.