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Cord Blood Stem Cells: Your Questions Answered

來源:www.webmd.com 作者:R. MorganGriffin 2006-6-27
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摘要: What are cord blood stem cells。 Stem cells are immature cells that can transform into other kinds of cells and reproduce themselves。 Cord blood stem cells are in the placenta and umbilical cord。 After birth, the blood can be removed and stored。...


What are cord blood stem cells?

Stem cells are immature cells that can transform into other kinds of cells and reproduce themselves. Cord blood stem cells are in the placenta and umbilical cord. After birth, the blood can be removed and stored.

Cord blood stem cells can be used to treat certain diseases, such as leukemia, lymphoma, sickle cell anemia, and others. They can also treat people whose bone marrow has been damaged by chemotherapy or radiation. During treatment, these cells are injected into the bloodstream. Once there, doctors hope that they will make new, healthy blood cells.

Experts hope that stem cells will become treatment for all sorts of diseases in the future, such as Alzheimer's, diabetes, and other conditions. But right now, these applications are only theoretical.

How are these cord blood stem cells collected?

The procedure is simple. It's safe and painless for both mother and child. Right after birth, the umbilical cord is clamped and cut, and the baby is passed off to a pediatrician. Meanwhile, a doctor or nurse uses a sterile solution to wash a small area of the umbilical cord that is still attached to the placenta. Then he or she will stick a needle into the cord's umbilical vein. The blood will flow by gravity through the needle, through a tube, and into a collection bag. The whole process takes a few minutes.

Collecting cord blood is not always possible. For instance, if there are any problems with the delivery -- either for the mother or child -- the doctors will want to focus on resolving them instead of taking the cord blood.

Also, since collecting cord blood isn't routine, you'll need to set up the procedure with the hospital in advance. Experts recommend that you contact the cord blood bank by your 34th week of pregnancy.

How long does cord blood last?

Once collected, the blood is shipped to a storage facility and frozen. The National Marrow Donor Program suggests that cord blood will last for up to 10 years. After that, it's unclear how long the cells will still be viable as treatment.

Is cord blood the only source of stem cells?

No. Similar stem cells are also in bone marrow, the spongy substance inside larger bones that makes your body's blood cells. Both types of stem cells are called hematopoietic progenitor cells (HPCs.) They can be injected into a sick person to replenish the supply of platelets and red and white blood cells.

Embryonic stem cells are a completely different type. They are derived directly from aborted fetuses or unused embryos that were frozen for in vitro fertilization. They are potentially the most malleable of the stem cells, since they are the building blocks of every cell of the body. But since the process destroys the embryos, the ethics of embryonic stem cell research is hotly debated.

What's the difference between stem cells from cord blood vs. bone marrow?

Both umbilical cord blood and bone marrow contain the same sort of stem cells: hematopoietic progenitor cells (HPCs). The potential advantage of cord blood over bone marrow is that the immune cells in cord blood are less mature. They are less likely to cause a dangerous condition called graft-versus-host disease, in which the body rejects and attacks the transplanted cells.

Another advantage of cord blood is that it's simple and safe to donate. Donating bone marrow is a much more involved process. Donors have to go under anesthesia and are at risk of infection. Since bone marrow is taken from donors as needed, collecting it can take much longer than retrieving frozen cord blood.

One disadvantage of cord blood is that, after the transplant, it takes longer to have an effect than stem cells from bone marrow. Cord blood can't be used in most adults. Since only a few ounces are available in the umbilical cord, there is usually only enough to treat children.

What's the difference between private and public cord blood banks?

Private banks charge a fee for the storage of your child's cord blood. In return, the cord blood is saved specifically for your family's use. Public cord blood banks are like public blood or bone marrow banks. You donate the cord blood and it's made available to anyone who needs it.

While private banking does ensure that you have access to the blood, the odds are very low that you will ever need it. The diseases that cord blood can be used to treat are rare. And even if your child ever develops one of these conditions, cord blood may not be the best treatment anyway.

Private cord blood banking is pricey. There's an initial charge of up to $1,800 and an annual fee of about $100 a year. Major medical organizations -- like the American Academy of Pediatrics and the American College of Obstetricians and Gynecologists -- do not support private cord blood banking. They argue that the costs are too high to justify the low odds of ever using banked cord blood. However, these organizations do support the donation of cord blood to public banks.

Congress is looking into establishing a national network for cord blood donation. But right now, there isn't a system in place. Even if you want to give away your child's cord blood, public donation isn't possible in many parts of the country. Experts hope that this will change in coming years.

How do I bank my baby's cord blood for private use?

According to the Institute of Medicine, there are more than 20 companies in the U.S. that privately bank cord blood and about 22 public banks. Settling on a private bank can be difficult. No federal standards exist for how these banks collect or store blood. As a result, it's possible that a bank's practices might not meet the standards of safety at some hospitals. This could mean that your hospital may refuse to use the blood that you banked if your child ever needs it.

Do some research. First, make sure you choose a bank well before you're expecting to give birth. Your health care provider and the hospital staff will also need to know about your decision in advance. They have to be prepared to take the blood right after delivery.

Shop around. Make sure to compare the prices both for the initial fee as well as the annual storage. Obviously, you also want to choose a company that seems financially stable. If the bank goes out of business in the next few years and unplugs its freezers, you're out of luck, says bioethicist Arthur Caplan, director of the Center for Bioethics at the University of Pennsylvania.

You should certainly talk to your health care provider about privately banking your cord blood. If he or she doesn't know much about it, ask for the name of a colleague who does. You might also try looking at the Parents' Guide to Cord Blood Banks, available on the Internet at www.parentsguidecordblood.com/.

Published July 2005.


SOURCES: Arthur Caplan, PhD, chairman, department of medical ethics; director, Center for Bioethics, University of Pennsylvania. Jeffrey Ecker, MD, high-risk obstetrician, Massachusetts General Hospital; assistant professor of obstetrics, gynecology, and reproductive biology, Harvard Medical School. Stephen Feig, MD, professor of pediatrics, UCLA. Ecker, J. and M. Greene. Obstetrics and Gynecology, June, 2005; vol 105: pp 1-3. Rottman, G. Pediatrics, 1997; vol 99: pp 475-476. Rogers I. and R. Casher, Human Reproduction Update, 2003; vol 9: pp 25-33. Institute of Medicine (E. A. Meyer, K. Hanna, and K. Gebbie, eds.): Cord Blood: Establishing a National Hematopoietic Stem Cell Bank Program, The National Academies Press, 2005. National Marrow Donor Program web site. American College of Obstetricians and Gynecologists web site. National Academy of Sciences web site. A Parent's Guide to Cord Blood Banks web site. WebMD Medical Reference from Healthwise: "Umbilical Cord Blood Stem Cells."


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