ANNOUNCER: Stem cell transplants are part of a therapy that can sometimes be used to save the lives of people who are seriously ill with certain diseases, especially leukemia and lymphoma.
First radiation, chemotherapy, or both, are used to kill diseased cells in a patient's bone marrow. Then stem cells are transplanted, or transfused, to rebuild the patient's capability to produce new blood cells.
There are different types of stem cells. Those that can turn into blood cells are called hematopoietic stem cells.
NELSON CHAO, MD: Stem cells are mother cells, if you will. They are the seeds that give rise to all our blood elements. So when we look at the blood we have, we have red blood cells, white blood cells and platelets, and they are derived from stem cells, when we talk about hematopoietic stem cells.
ANNOUNCER: Doctors have different ways to harvest stem cells.
NELSON CHAO, MD: There are many sources of stem cells. Most commonly, when we talk about stem cells, in hematology we're really talking about bone marrow stem cells.
ANNOUNCER: Stem cells can also be collected from the bloodstream. Some researchers think a third source of blood should be utilized more often, and that this could save many lives when bone marrow donors cannot be found.
NELSON CHAO, MD: It's the blood that is in the umbilical cord, and basically the way it's collected now is that after the child's delivered, the umbilical cord is clamped and cut, and then the placenta's delivered. And the blood that is in the umbilical cord on the placenta side is collected. So that is blood within the placenta.
Cord blood's unique for various reasons. It's very rich in stem cells. The T-cells or the immune cells in cord blood tend to be more immature, and it's a ready, available source of stem cells that currently is just discarded.
ANNOUNCER: When bone marrow is used for stem cell transplants, it is important that there be a perfect or close-to-perfect match with regard to certain proteins on the surface of the cells. Without a good match, it is more likely that a patient experiences graft-versus-host disease. That's when the transplanted cells attack the patient's tissue. But researchers have found that the match does not have to be quite so good when cord stem cells are used.
NELSON CHAO, MD: They all require matching. The better the match, the better the results. In cord blood, the degree of matching can be -- there's a little more wiggle room in cord blood than there is with bone marrow, for example.
ANNOUNCER: The use of cord blood for stem cell transplants in cases where the cells are not perfectly matched is still experimental. And there are some problems to overcome. Placentas and umbilical cords don't yield much blood volume, so transplants of cord blood have traditionally been used only for treating children. Another problem is that stem cells taken from cord blood tend to take longer to mature than adult stem cells taken from marrow or blood. That leaves patients who received radiation or chemotherapy for a longer period of time without healthy replacement white blood cells.
NELSON CHAO, MD: The major downside is that there's higher risks of complications. So every day you spend without white blood cells, you have higher risk of infection, higher risk of bleeding, and then there's the huge cost associated with that as well.
ANNOUNCER: If these problems are solved, and if research findings about cord blood are verified, experts say many thousands of lives might be saved. That would happen if cord blood becomes a widely-used, alternative source to bone marrow, for stem cell transplants.