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