Double umbilical cord blood transplantation.

Unrelated umbilical cord blood (UCB) is an alternative donor source for allogeneic haematopoietic cell transplantation and, compared with unrelated donor bone marrow, has the advantages of rapid availability, greater tolerance of HLA disparity and lower incidence of severe graft-versus-host disease. Graft cell dose is an important determinant of haematopoietic recovery and overall outcome following UCB transplantation, and the limited cell dose of single UCB units has been a major barrier to its more widespread use. Transplantation with two unrelated UCB units is feasible, safe and effective and can overcome the limitation of cell dose of single UCB units.