Medical Pros & Cons to Banking Umbilical Cord Blood (UCB)
Originally, bone marrow transplants obtained blood stem cells ("hematopoetic" stem cells) from the bone marrow of a matched donor. The National Marrow Donor Program (NMDP) maintains a public registry of adults who are willing to consider bone marrow donation, and similar registries exist in other countries. Despite these registries, about 50% of all patients needing a transplant cannot find a matching bone marrow donor.
Umbilical cord blood contains blood stem cells that are even more primitive than the blood stem cells found in bone marrow. They can also be transplanted to regenerate a patient's immune system. The web site of the National Marrow Donor Program is an excellent source of unbiased information about cord blood; just go to the NMDP home page and run a search on the key words "cord blood".
Do not confuse blood, or "hematopoetic", stem cells with "pluripotent" stem cells. Very recent medical research has found it is possible to use the fundamental, or pluripotent, stem cells from discarded human embryos to grow all manner of human tissues. Obviously, there are serious ethical issues in such research. The NIH website provides a primer on stem cell types . Pluripotent stem cells are not the topic of discussion here. We are only discussing blood stem cells, which can be removed from the umbilical cord without harm to mother or baby, and which can grow a complete immune system of blood cells.
RESEARCH UPDATE!
As of late 2000, medical researchers are finding that small numbers of pluripotent stem cells can be harvested from bone marrow, cord blood, and placentas. Even more amazing, under some circumstances, "blood" stem cells can be coaxed to grow into other types of tissue. See the page on News Reports .
The advantages of transplanting with cord blood instead of bone marrow:
Harvesting umbilical cord blood poses no risk to mother or child,
whereas a bone marrow donor must undergo anesthesia and is exposed to
the risk of infection.
Umbilical cord blood can be stored in cryogenic freezers,
ready for use as soon as it is needed, whereas the process of
contacting and testing bone marrow donors listed in the NMDP takes weeks.
Medical insurance providers prefer cord blood transplants over harvesting
marrow from adult donors, because the costs are much lower.
Because the stem cells in cord blood are more primitive than those in bone
marrow, they carry much lower incidence of graft versus host disease (GVHD).
This makes it possible to perform transplants with less than perfect
matches of type.
The disadvantages of transplanting with cord blood instead of bone marrow:
Because the stem cells in cord blood are more primitive than those in marrow,
the engraftment process takes longer with cord blood, leaving the patient
vulnerable to a fatal infection for a longer period of time.
A typical cord blood harvest only contains enough stem cells to transplant
a large child or small adult (weighing approx. 100 pounds).
Current research is exploring the methods and safety of
transplanting adults with cord blood (see the page on
On-Going Research ).
If cord blood is so great, why doesn't everybody bank it?
Because it costs money . Whereas a bone marrow registry is just a data base of potential donors, a cord blood registry consists of freezers full of frozen blood and staff to maintain them. In an ideal world, all babies would have their cord blood harvested at birth (with parental permission) and stored in public registries, much like public blood banks. In practice, only a limited number of institutions have the funding to maintain public banks which take donations for free. A separate web page explains the types of cord blood banks , and another tells you how to find a public bank to accept your donation.
For most parents, cord blood donation is not an option because the number of locations served by registries is very limited. You have to decide if you feel strongly enough about saving your child's stem cells to pay for private storage.
Transplant Photos
Shai receiving her bone marrow transplant
at Children's Hospital of Philadelphia 4/3/1997;
the arrow points to the bone marrow.
Story of Shai's bone marrow donor , a man in England.
Will banking my baby's umbilical cord blood provide this child with life-long "medical insurance"?
The odds that the average baby will ever use its banked cord blood have been estimated as 4 in 10,000 (.04%). This number comes from an article on cord blood banking by Dr. F. Leonard Johnson, which appeared in the Blood & Marrow Transplant Newsletter , specifically issue #43, Oct. 98, vol.9 no.3 . The American Academy of Pediatrics has also issued an opinion against private cord blood banking, because the expense is high and the odds of use are low. This was published in the July 1999 issue of PEDIATRICS, 104:116-118.
However, these official opinions were based on the already established uses of stem cell transplants in pediatric patients. There are several counter-arguments in favor of banking:
- One is that, as today's children grow up and some of them develop cancer as adults, autologous cord blood transplants will become more common. The reason is that pediatric cancers and adult cancers are completely different diseases at the cellular level (to learn more about cancer look up the National Cancer Institute ). While pediatric oncologists prefer not to transplant a sick child with her own blood, adult oncologists routinely perform autologous transplants using stem cells from the patient.
- Secondly, recent news reports constantly announce new medical advances using stem cells. Future applications will probably include tissue repair to various organs of the body.
- Another factor families should consider is whether the odds given for the "average baby" apply to you. Some families do have a higher predisposition to cancer and immune disorders.
- Finally, if your family, especially your children, are of mixed ethnic background, it may be impossible to find an adult bone marrow donor who is a perfect match. In that event, cord blood from even a partially matched sibling would be invaluable.
|
This table displays the mean probability that patients of the indicated race will find a 6/6 HLA-A,B,DR match from amongst a registry of 500,000 donors composed entirely of the indicated race. | |||||||||||||||||||||||||||||||||||||||||||
|
|
Parents should be aware of the following limitations to the use of banked cord blood as a source of life-long "medical insurance":
-
Diseases which require transplantation of blood stem cells are still rare,
although the list of diseases amenable to such treatment is steadily growing.
-
The banked cord blood only provides insurance for so long as the
frozen cells are still viable. So far, research has confirmed the
long-term viability of cord blood
for up to 15 years, but the existing literature on cryogenic storage
of living cells indicates that storage for decades is feasible.
-
The banked cord blood only provides insurance providing there are
enough stem cells in the sample for a successful transplant,
even after your new baby grows up to become a much larger adult.
Again, on-going research
is exploring several methods to transplant large adults with
banked cord blood.
-
In some medical situations it would not be advisable to transplant
a person with her own stem cells ("autologous" treatment).
The autologous use of stem cells is very unlikely for a child with cancer
or an immune disorder, because these diseases are believed to have a
genetic basis.
Autologous stem cell transplants are very common for adults with cancer,
but the cells are usually harvested from the patient's blood.
Autologous stem cells would be preferable for any future treatments
where stem cells are used to repair traumatic injury (stroke, heart attack)
or degenerative disease (Parkinson's, etc.)
When parents bank the cord blood from a new baby, in the near term they are most likely providing medical insurance for that child's siblings, and only in the long term when the donor grows up will they have value for self-use.
The crucial thing is not the volume of the blood sample, but the number of
stem cells it contains. These are measured with a test "CD34+" that picks out
all mononuclear cells.
In a study of 542 families collecting cord blood at several hundred
different hospitals, the mean cord blood volume and nucleated cell
count were 103.1 mL (including anticoagulant) and 890 million,
respectively.
YES! YES! YES!
Since the year 2000 there have been dramatic medical advances in the arena of
stem cell research, and more are announced every month.
See the latest press releases under
"News Reports" .
Highlights:
YES!
First, you don't know if the tissue type of the next child will
match the previous child. Your children's HLA types come in pairs;
in each pair, one is from the mother and one is from the father.
The odds of siblings being a perfect match are 1 in 4.
A cord blood transplant
with a 5/6 or 4/6 mis-match of key HLA types carries less graft-vs-host disease
than a perfect 6/6 bone marrow transplant
Second, you can't predict which child may someday need a transplant.
Last modified:
Copyright 2000, 2001, 2002, 2003, 2004, Frances Verter
How much cord blood is needed for a transplant?
The "optimal (transplant) dose is about 20 million nucleated cells per
kilogram of body weight"
(one kilogram equals 2.2 pounds).
The number of stem cells becomes crucial if cord blood is used for adult
patients: "patients who received no more than 10 million nucleated cells
per kilogram had a 75 percent probability of death, whereas recipients
of at least 30 million nucleated cells per kilogram had a 30 percent
probability of death."
Reference: Editorial by Gluckman, E. NEJM 2001;344:1860
Reference: W Reed, et al, Blood 2003; 101(1):351
Thus, on average, a cord blood sample contains 8.6 million
nucleated cells per millileter, and a successful transplant requires
harvesting 1 millileter of cord blood per pound of patient weight
(1 ml and 1 cc are the same amount).
Are the potential uses of cord blood likely to increase?
As a result of these advances, it is not unreasonable to hope that
cord blood may eventually be used to treat a wider variety
of auto-immune and degenerative diseases than is currently feasible.
If I banked cord blood from one child, should I bank the next?
Reference: V Rocha, et al, 2000; NEJM 342:1846
Home Page