Following the birth of a baby, the umbilical cord usually is discarded along with the placenta. However, it is now known that blood retrieved from the umbilical cord is a rich source of stem cells. Stem cells are unspecialized blood cells that produce all other blood cells, including blood-clotting platelets and red and white blood cells. Like donated bone marrow, umbilical cord blood can be used to treat various genetic disorders that affect the blood and immune system, leukemia and certain cancers, and some inherited disorders of body chemistry. To date, more than 45 disorders can be treated with stem cells from umbilical cord blood.Currently, commercial companies provide services to parents to store their newborn baby’s cord blood. Prospective parents who are considering this option should have as much information as possible to make an informed decision.
What are stem cells and why are they valuable?
Blood stem cells, most often found deep in bone marrow, are the factory of the blood system. They continually make new copies of themselves and produce cells that make every other type of blood cell. Stem cells are the key to successful bone marrow transplantations (BMTs) because they continue to manufacture blood cells indefinitely.
Bone marrow transplants can be lifesaving for people with leukemia (cancer of the white blood cells) and other cancers, or for those with serious blood disorders, such as aplastic anemia, in which the body does not produce enough blood cells. Stem cells can help enhance a person’s blood producing capability and immune system that are impaired through an inherited (genetic) defect or that have been severely damaged or deliberately destroyed by cancer treatments. At present, donated bone marrow is the most common source of stem cells.
What are the advantages of stem cells from cord blood?
Studies suggest that stem cells from cord blood offer some important advantages over those retrieved from bone marrow. For one thing, stem cells from cord blood are much easier to get because they are readily obtained from the placenta at the time of delivery. Harvesting stem cells from bone marrow requires a surgical procedure, usually under general anesthesia, that can cause post-operative pain and poses a small risk to the donor.
A broader range of recipients may benefit from cord blood stem cells. These can be stored and transplanted back into the donor, to a family member or to an unrelated recipient. For a bone marrow transplant to succeed, there must be a nearly perfect match of certain tissue proteins between the donor and the recipient. When stem cells from cord blood are used, the donor cells appear more likely to “take” or engraft, even when there are partial tissue mismatches.
A potentially fatal complication called graft versus host disease (GVHD), in which donor cells can attack the recipient’s tissues, appears to occur less frequently with cord blood than with bone marrow. This may be because cord blood has a muted immune system and certain cells, usually active in an immune reaction, are not yet educated to attack the recipient. A 2000 study found that children who received a cord blood transplant from a closely matched sibling were 59 percent less likely to develop GVHD than children who received a bone marrow transplant from a closely matched sibling.
The use of cord blood may make blood stem cell transplants available more quickly for people who need them. About 30,000 individuals each year are diagnosed with conditions that could be treated with a bone marrow transplant. Approximately 25 percent of these individuals have a relative who is an appropriate tissue match. While suitable donors can be located for many through national bone marrow registries, the process can take months. Donors can be located within 4 months for about 50 percent of patients. It often is more difficult to find a bone marrow match for members of non-white ethnic and racial groups; transplants from cord blood may make timely treatment available for more of these individuals. Banked stem cells from cord blood can be more readily available, and this can be especially crucial for patients with severe cases of leukemia, anemia or immune deficiency who would, otherwise, die before a match can be found.
Cord blood also is less likely to contain certain infectious agents, like some viruses, that can pose a risk to transplant recipients.
In addition, some studies suggest that cord blood may have a greater ability to generate new blood cells than bone marrow. Ounce for ounce, there are nearly 10 times as many blood-producing cells in cord blood. This fact suggests that a smaller number of cord blood cells are needed for a successful transplantation.
In addition, cord blood stem cells offer some exciting possibilities for gene therapy for certain genetic diseases, especially those involving the immune system. Donald Kohn, MD, and colleagues at the Children’s Hospital of the University of Southern California in Los Angeles and the University of California in San Francisco, made the first attempt at gene therapy with cord blood in 1993 in three children suffering from adenosine deaminase (ADA) deficiency, a potentially fatal defect that cripples the immune system. The children, who also receive additional drug treatment, appear healthy to date, even though their blood now carries only a small amount of the gene introduced into their stem cells.
Where and when is cord blood collected and stored?
Expectant parents can make arrangements before the birth of their child to have their baby’s cord blood collected immediately after birth (within 15 minutes of delivery) and stored by a commercial blood bank for their own use. Or they can donate it to a public bank to be available to any appropriately matched individual needing a transplant. If parents use a commercial bank, the initial cost ranges from $250 to $1,500, plus an annual storage fee of $50 to $100. Some health insurance companies are beginning to cover these costs.
Although public banks pay for processing the cord blood sample, they require completion of a lengthy parental health/disease questionnaire. Required testing for diseases such as hepatitis and HIV can be costly for parents. In addition, expectant parents must make arrangements with these banks at least 90 days before the expected delivery date.
Who should consider storing cord blood?
Expectant parents who have a family history of certain genetic diseases, such as severe anemias, immune disorders or some cancers, may want to consider the family benefit of storing cord blood. Most families have no such risk factors, and only about a 1-in-20,000 chance of needing a stem cell transplantation. Families can get complete information and counseling from health care providers, including genetic counselors.
Families who want to donate their baby’s cord blood to a public bank for use by others should be fully informed of their responsibilities and other implications of such donations.
What are some concerns?
Universal guidelines for collection and storage of cord blood have not been established but are necessary for samples to be interchanged among banks. Currently, some banks store whole blood samples, while others separate the red cells, white cells and other blood components before freezing. There are also safety issues about the method of cord blood collection to prevent contamination. The Food and Drug Administration (FDA) is studying these concerns.
There are many ethical issues in connection with umbilical cord blood banking that have yet to be resolved. Some questions are: Who owns the cord blood sample? How is informed consent obtained from parents before harvesting cord blood? How is the counseling process for informed consent provided? How should the obligation to notify parents and donor-children of the results of medical testing for infectious diseases and genetic information to be handled? How are privacy and confidentiality to be maintained? How will services for the harvesting of and access to umbilical cord blood be provided fairly?
Is cord blood transplantation still experimental?
The use of umbilical cord blood stem cells for transplantation treatment holds exciting promise, but this area of medical science is still largely investigational. It was only in 1988 that French researchers performed the first successful stem cell transplantation using umbilical cord blood. The transplant was taken from a newborn and given to a 5-year-old sibling with a severe anemia syndrome that included skeletal defects (Fanconi anemia). Since then, cord blood cells from related and unrelated donors have been successfully transplanted in about 2,000 individuals worldwide. Doctors at Mattel Children’s Hospital at the University of California, Los Angeles, recently reported that three boys treated for life-threatening immune deficiencies (X-linked lymphoproliferative syndrome and hyper-IgM immunodeficiency) had normal immune systems two years after receiving cord blood cells from unrelated donors.
In 1998, the largest study of unrelated cord blood transplants to date suggested that cord blood transplantation is a feasible procedure for patients (adults and children) who do not have a related matching donor. Survival rates were similar for patients who received cord blood or bone marrow from unrelated donors.
However, until the results of additional large studies are available, insurance companies and Medicaid still are hesitant to cover the cost of storage. Therefore, the service is most often available to families who can afford it.
It is highly unlikely that a child will require a stem cell transplant or, if he does, that the child’s own cord blood would be the desired source of stem cells. There is no proof that a transplant using the child’s own stem cells is effective or even safe, especially in cases of childhood cancers. For these reasons, the American Academy of Pediatrics (AAP) considers unwise the private storage of cord blood as biological insurance by families who do not have a history of the disorders previously mentioned. However, the AAP and some other scientists favor the collection and storage of cord blood in public banks to be used for unrelated recipients who urgently need blood cell transplants. This could prove especially helpful for ethnic and racial groups who are poorly represented in national bone marrow volunteer registries.
The March of Dimes is optimistic about the treatment possibilities using umbilical cord blood, and is assessing research results that, thus far, seem promising. However, expectant parents should be well informed so that any choice is based upon sound advice and medical evidence.
References
American Academy of Pediatrics Work Group on Cord Blood Banking. Cord blood banking for potential future transplantation: subject review. Pediatrics, volume 104, number 11, July 1999, pages 116-118.
Rocha, V., et al. Graft-versus-host disease in children who have received a cord-blood or bone marrow transplant from an HLA-identical sibling. New England Journal of Medicine, volume 342, number 26, June 22, 2000, pages 1846- 1854.
Rubenstein, P., et al. Outcomes among 562 recipients of placental-blood transplants from unrelated donors. New England Journal of Medicine, 1998, volume 339, pages 1565-1576. Ziegner, U., et al. Unrelated umbilical cord stem transplantation for X-linked immunodeficiencies. Journal of Pediatrics, volume 134, number 4, April 2001, pages 570-573.
Zeigner, U., et al. Unrelated umbilical cord sterm transplantation for X-linked immunodeficiencies. Journal of Pediatrics, volume 134, number 4, April 2001, pages 570-573
Source: http://www.marchofdimes.com/professionals/681_1160.asp
