Leukemia: cord blood for allogeneic stem cell transplantation

Cord blood is considered an acceptable alternative to hematopoietic stem cells. This review focuses on clinical results of cord blood transplantation including factors associated with transplantation outcomes for aiding graft selection. Immunological analysis of T cell recovery processes and approaches to cellular therapy using cord blood-derived immune cells are also discussed.

To resolve problems with cord blood transplantation, including high toxicity especially in the early phase after transplant and delayed engraftment, a reduced intensity regimen and double cord blood units from different donors are applied. For adequate graft selection, cell dose and human leukocyte antigen compatibility are important to reduce transplant-related toxicity, although the importance of human leukocyte antigen compatibility seems to disappear in leukemia patients because of a possible graft-versus-leukemia effect in a human leukocyte antigen-mismatched setting. Immune reconstitution after cord blood transplantation is also important to reduce the risk of infectious complication. Recent technologies make it possible to generate antigen-specific T cells from naïve T cells from cord blood in vitro.

Stem cell sources are now available for almost all leukemia patients. The efficacy of cord blood transplantation warrants further clarification by larger clinical experience and well designed studies. Efforts to reduce toxicity and improve engraftment are still in progress.