Not all blood cells are created equal. Some are born, carry out their appointed tasks-red blood cells oxygenating the blood, white blood cells fighting infection-and die. But an elusive subset have special properties: they are the progenitors of all the many types of peripheral (circulatory) blood cells, and as such, they have the potential to reconstitute an entire blood supply. Known as hematopoietic stem cells, these blood cells reproduce indefinitely. For patients with leukemia or other blood diseases, the transplantation of hematopoietic stem cells from another person's bone marrow can provide the gift of life.
Blood As a Biological "Drug": Scientific, Legal, and Policy Issues in the Regulation of Placental and Umbilical Cord Stem Cell Transplantation,
U. Rich. L. Rev.
Available at: http://scholarship.richmond.edu/lawreview/vol32/iss2/3