Clinical and experimental uses of umbilical cord blood.

Umbilical cord blood (UCB) has been used successfully as an alternative source of haemopoietic stem cells (HSC) in allogeneic stem-cell transplantation for the treatment of acquired and genetic diseases. Advantages of using UCB include: (i) no risk to the donor, (ii) no donor attrition, (iii) minimal risk of viral transmission and (iv) immediate availability. Early results have highlighted differences in engraftment rates and toxicity between UCB and other sources of HSC. These differences relate to the low cell dose in UCB and also to the intrinsic properties of UCB. In this article, the clinical outcome of UCB transplantation (UCBT) will be reviewed with a discussion of the biological characteristics of UCB that may account for some of the clinical outcomes. To overcome the limitations of low cell dose, novel approaches such as ex vivo expansion of HSC are being actively explored, and this will be summarized in the present study. Finally, the success of UCBT has led to the establishment of dedicated UCB banks worldwide and the regulatory issues surrounding this will be briefly discussed.