[Cord blood transplantation].

Unrelated cord blood transplantation (CBT) has now become more common. In the last decade, CBT has increasingly been utilized not only for children, but also for adults. As a source of hematopoietic stem cells (HSCs), umbilical cord blood has the advantages of speed of availability, tolerance of 1-2 antigen HLA mismatch, and a low incidence of severe graft-versus-host disease (GVHD). Thus, UCB represents a highly convenient HSC source that may significantly extend the HSC donor pool. As graft cell dose is the major factor determining hematopoietic recovery and survival in CBT, methods to increase cell dose such as multiple-unit transplant and ex vivo expansion, or to increase stem cell homing such as intra-bone transplantation are being pursued. We could also speculate the existence of unique pathophysiology of acute GVHD after CBT compared with after bone marrow transplantation due to our clinical analysis. It might be very important to establish new standard management including immunosuppressive procedure after CBT to consistently keep better clinical results. Umbilical cord blood is promising alternative to bone marrow-derived stem cells. More prospective studies are needed to establish the role of CBT during various allogeneic HSC transplantations.