Umbilical Cord Blood Banking
Umbilical Cord Blood Banking
Umbilical cord blood banking is the practice of preserving for future use fetal blood that remains in the umbilical cord at the time of birth.
During pregnancy, a developing fetus is attached to its mother's placenta by the umbilical cord. At birth, this cord is cut, and the placenta is expelled from the mother. Some fetal blood remains in the umbilical cord. Normally, this blood, along with the cord and the placenta, are simply disposed of. However, now there are ways to freeze the cord blood for future use.
Umbilical cord blood is special because it contains a lot of cells called hematopoietic stem cells. A stem cell is an unspecialized master cell that can develop into several different kinds of specialized cells. Hematopoietic stem cells normally develop into red blood cells that carry oxygen, white blood cells that fight infection, and platelets that help make blood clot. These hematopoietic stem cells are not the same as embryonic stem cells that are at the center political and ethical debate about their use in research. Their collection does not harm either the mother or the baby.
There are two other sources of hematopoietic stem cells—bone marrow and peripheral blood. Bone marrow is the spongy material inside bones that is the source for new blood cells produced throughout an individual's life. Peripheral blood is the blood that circulates through the body.
All cells have a protein profile that identifies them. When a foreign cell enters the body, immune system cells recognize the protein profile as foreign and attack the cell. The advantage of umbilical cord stem cells that they are more immature and have a less well developed protein profile than bone marrow or peripheral stem cells. As a result, they draw a weaker response from the body's immune system.
The protein profile of human cells is called the human leukocyte antigen (HLA) profile. Normally for transplanted cells such as bone marrow cells to be accepted, there must be a close to perfect match between the HLA profile of the donor and the recipient. Since there are over 10,000 HLA types, finding an exact match can be difficult. Because umbilical cord blood cells have a less well developed HLA profile, they do not have to match the recipient's HLA as closely to be accepted by the immune system of the transplant recipient.
Types of cord blood banks
There are two types of umbilical cord blood banks—private and public. Private blood cord banks can be for-profit or not-for-profit. They sell kits that can be used at any delivery to collect cord blood. They also charge a yearly fee to store the blood. The cord blood is available only to the child or members of the child's family from which it came. It is a perfect HLA match to child's blood. When a transplant is done using cells that came from the individual who needs the transplant, it is called an autologous transplant. Autologous transplants have a high rate of success.
Public cord banks do not charge a fee to collect or store cord blood. Parents of newborns donate the cord blood, and it is then available to anyone who needs it and is an appropriate match. This type of transplant where the recipient is not the same as the donor is called an allogeneic transplant. Much of the success of allogeneic transplants depends on finding a good HLA match. Because of funding considerations, there are a limited number of public cord blood banks. To donate to a public blood cord bank, the mother must give birth in a facility associated with a public blood cord bank.
How cord blood is used
The first successful umbilical cord stem cell transplantation occurred in 1988, when a newborn girl donated cord blood to cure her brother of Fanconi's anemia, a genetic defect. Many other blood diseases can now be treated successfully with cord stem cell transplants. These same diseases can be treated with bone marrow transplant if an appropriately matched donor can be found. In addition, research is ongoing in the hope that cord blood stem cells can be induced into differentiating into other types of cells, such as nerve cells that can be used to treat other diseases.
Some diseases treated with blood stem cell transplant include:
- acute lymphatic leukemia
- acute myelogenous leukemia
- chronic myelogenous leukemia
- Hodgkin disease
- Non-Hodgkin lymphoma
- severe combined immune deficiency
- anapalstic anemia
- sickle cell anemia
- Fanconi's anemia
In addition to being more readily accepted by the donor's body, cord blood offers other advantages over bone marrow transplantation. It is relatively quick and easy to thaw the cord blood and infuse it, while bone marrow harvesting is an invasive procedure with risks to the donor. In addition, cord blood is less likely to be contaminated with viruses that may create complications for the recipient.
Considerations in deciding to bank cord blood
Although the list of diseases treated with umbilical cord stem cells is impressive and growing, controversy exists about whether parents should pay private cord cell banks to preserve their newborn's blood. Private cord cell banks sell their services as a type of "insurance." In case the child develops a treatable disease, the child's own stem cells will be a perfect match. However, if the disease is caused by a genetic defect, (e.g., sickle cell and other anemias) the child's own stem cells will be useless, because they will contain the same genetic defect. In addition, the quantity of cord blood that can be collected is only enough to treat a child. Although research is being done to try to multiply cord cells in the laboratory in quantities great enough to treat an adult, results have not been successful. Therefore, if an adult develops a treatable disease, even if his own cord blood was banked, the quantity will be insufficient to produce a cure. Also, cord blood storage is a new enough technology, that it is not clear how long the blood can remain frozen and still be effective.
In the most recent statement on cord blood banking released by the American Academy of Pediatrics in 1999, they concluded:
- There are no good estimates of how often a child will need a transplant of his own cells. Estimates range from 1 in 1,000 to 1 in 200,000
- Certain genetic disorders are not cured by autologous transplants
- Parents should be encouraged to donate their child's cord blood to free public cord blood banks for the widest possible use rather than paying private companies to store cord blood
The American College of Obstetricians and Gynecologists supports the position that parents should not be sold private blood cord banking without a realistic assessment of their need, nor should parents feel guilty if they are not eager or able to meet the annual expense associated with private storage. Although cord blood collection is safe, unless there is a family history of diseases for which hematopoietic stem cells are helpful, most pediatricians and obstetricians feel private cord blood storage is an unnecessary expense.
Umbilical cord blood collection is usually not done in the case of multiple births.
Cord blood collection is a simple procedure that takes between three and seven minutes. It is done immediately after the baby is delivered. Cord blood is drained into a standard blood bag, and then processed and frozen at very low temperatures.
Parents who wish to bank their child's cord blood must plan ahead. Private storage requires ordering a kit in advance and coordinating with the health care providers doing the delivery to make sure the cord blood is collected properly. Mothers must test negative for infectious diseases such as HIV and hepatitis before delivery. Donation to a public cord blood bank is not always possible because of their limited number and location.
No special aftercare is required for mother or child, but the cord blood must remain frozen at low temperatures.
The main risk associated with umbilical cord blood collection is the possibility that it will become contaminated with bacteria during collection.
Allogeneic — A transplant where the donated material comes from different (although often related) individual than the recipient
Autologous — A transplant where the material for the transplant comes from the individual who is also the recipient; thus, the transplant material is genetically identical to the donor's body.
Hematopoietic stem cell — A cell that can develop into any type of specialized blood cell.
Parents who are interested in private cord blood storage should research the company with which they contract, just as they would in making any business decision. They need to know the costs, whether the annual fee can increase, and what will happen to the blood if the company goes out of business.
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