Once considered a waste product of birth, umbilical cord blood is now prized as a source of stem cells that can replace the diseased bone marrow of people with leukemia and other illnesses. Unfortunately, umbilical cords often don't contain enough blood for a viable transplant of stem cells that, like marrow cells, can produce new blood cells of various types.
Scientists now report that cord-blood stem cells proliferate rapidly when the blood is cultured with a protein called Delta-1 and a combination of growth enhancers.
When transplanted into mice, these treated cells grafted well into the animals' bone marrow, suggesting they had begun to rebuild the animals' store of red and white blood cells. Some stem cells even found their way to the thymus to begin transformation into immune system workhorses called T cells, the researchers report in the Oct. 15 Journal of Clinical Investigation.