Improving cord blood transplantation in children.

Umbilical cord blood transplantation (UCBT) is widely used to treat children affected by many disorders. In comparison to bone marrow transplantation, the advantages of UCBT are represented by lower incidence and severity of graft-versus-host disease, easier procurement and prompter availability of cord blood cells, and by the possibility of using donors showing human leucocyte antigen disparities with the recipient. Despite these advantages, the large experience gained over the last decade has clearly demonstrated that UCBT patients may be exposed to an increased risk of early fatal complications, due to the lower engraftment rate of donor haematopoiesis, delayed kinetics of neutrophil recovery and lack of adoptive transfer of pathogen-specific memory T-cells. An inverse correlation between the number of nucleated cord blood cells infused per kilogramme recipient body weight and the risk of dying from transplantation-related causes exists. Thus, it is not surprising that strategies aimed at increasing the number of cord blood progenitors, favouring stem cell homing, and transferring pathogen-specific lymphocytes, have been recently investigated. In particular, selection of the richest cord blood units, infusion of 2 units in the same recipient, intrabone injection of cord blood cells, and transplantation of ex-vivo expanded progenitors can contribute to improve the results of UCBT.