+ What is cord blood?
Why do we need to have cord blood donated to
public cord blood banks?
+ What are the advantages of cord blood?
+ Why is cord blood important for ethnic minorities?
+ Are there any unfavorable aspects of cord blood?
+ What is cord blood used for?
+ How long does cord blood remain viable?
Why do we need to have cord blood donated
to public cord blood banks?
1. Cord blood donated to a public bank provides another source of hope for patients who have no matching donor in their own family, no unrelated donor in bone marrow donor registries that is a suitable match or no time to find a donor. As with bone marrow, cord blood stem cells may be capable of generating all the cellular elements in the blood and immune system.
2. Donated bone marrow or peripheral blood containing mobilized stem cells have been the traditional sources of hematopoietic stem cells for transplantation. Their donors should be closely matched to the recipient; that is, matched at least for the HLA-A, -B, -C and -DRB1 alleles. Since there are usually two alleles for each, in a perfect match, the donor will have the same eight alleles as the patient, an 8/8 match. A perfect match is most likely to occur among family members. Among brothers or sisters of a patient, for example, each has a 25% chance of being a perfect match. Because the average number of children in U.S. families is slightly more than two, about 3 out of 10 patients will find such a match among their own siblings. Other blood relatives also may be well-matched but the chance is much lower.
When no relative is available, some other source of stem cells must be found. Bone marrow from unrelated donors has helped solve this problem for thousands of patients. Marrow donor registries around the world have recruited fourteen million volunteers willing to donate their bone marrow to a perfect stranger. The largest registry in the United States is the National Marrow Donor Program (NMDP) currently, the “Be the Match” Registry, which lists some 5.5 million volunteers.
3. Many patients who need a bone marrow transplant, however, cannot find a suitable donor - no relative that matches and no match among volunteer bone marrow donors. According to a report from the U.S. Government Accounting Office (GAO) released in October 2002, 10,000-15,000 people in the U.S. each year have a disease that could be treated with a transplant, but have no HLA-matched related donor. About one-third of these patients tried to find unrelated marrow donors through the NMDP but only 25% of them (9% of the total who might benefit) actually could get a transplant. The odds were even worse for African-American and other ethnic minority groups. This was one reason for the broad legislative support behind the Stem Cell Therapeutic and Research Act of 2005.
4. A cord blood transplant may not have to be a perfect match to the patient. Adult bone marrow contains immune cells (so-called T-lymphocytes or T-cells) that are “fully mature”. When transplanted, these T-cells may attack the patient's cells as “foreign”, causing a condition called graft vs. host disease (GvHD), which can be severe and even lethal. T-cells in cord blood do not appear to be as "immunologically mature" as those in bone marrow. As a result, cord blood transplants may be less likely than bone marrow to cause GvHD and, when it does occur, it appears to be less severe. [Click
here to read more about the advantages of cord blood].
Because cord blood transplants may cause less GvHD, it appears that the match to the patient does not need to be perfect. In fact, most cord blood transplants so far have been 5/6 or 4/6 matches for HLA-A, -B and -DRB1 antigens. This means that patients who cannot find a perfectly matched bone marrow donor may have a chance to find a suitable cord blood transplant. Patients with rare HLA types, African-Americans and members of other minority groups, therefore, could benefit especially from this stem cell resource. [Click here to read about cord blood's significance for ethnic minorities].