| Human umbilical cord blood cells have many | | | | with conventional therapies. Recently, it has been |
| advantages as grafts for cell transplantation mainly | | | | reported that umbilical cord blood contains |
| because of the immaturity of the newborn cells in | | | | mesenchymal progenitor cells capable of |
| comparison with adult cells. | | | | differentiating into marrow stroma, bone, cartilage, |
| In contrast to their hematopoietic and mesenchymal | | | | muscle, and connective tissues. |
| potential, it remains unclear whether umbilical cord | | | | Furthermore, umbilical cord blood provides no ethical |
| blood cells have endodermal competence. | | | | problems for basic suties and clinical applications. |
| Umbilical cord blood contains circulating stem | | | | Umbilical cord blood cells can be collected without any |
| progenitor cells, and the cellular contents of umbilical | | | | harm to the newborn infant, and umbilical cord blood |
| cord blood are known to be quite distinct from those | | | | hematopoietic stem cell grafts can be cryopreserved |
| of bone marrow and adult peripheral blood. Over the | | | | and transplanted to a host after thawing without |
| past two decades, the presence and characteristics | | | | losing their repopulating ability. For these reasons, |
| of hematopoietic stem cells in umbilical cord blood | | | | umbilical cord blood could be a prominent source of |
| have been clarified. The frequency of umbilical cord | | | | cells for transplantation in various diseases. It remains |
| blood hematopoietic stem/progenitor cells equals or | | | | obscure, however, whether umbilical cord blood |
| exceeds that of bone marrow and greatly surpasses | | | | contains stem/progenitor cells leading to endodermal |
| that of adult peripheral blood. Compared with adult | | | | cells, including hepatocytes. |
| cells, umbilical cord blood hematopoietic stem cells | | | | Human umbilical cord blood cells can proliferate |
| produce larger hematopoietic colonies in vitro, have | | | | hepatocyte lineage cells in the original primary culture |
| different growth factor requirements, are able to | | | | system in vitro, and differentiate into functionally |
| expand in long-term culture in vitro, and have longer | | | | mature hepatocytes in vivo. To our knowledge, this |
| telomeres. Umbilical cord blood transplantation for | | | | is the first evidence that human umbilical cord blood |
| various hematopoietic reconstitutions and a lower | | | | contains cells that produce endoderm-proliferating |
| incidence of graft-versus-host disease than expected | | | | cells. |