ScienceWeek

SCIENCE POLICY: ON CORD-BLOOD CONTROVERSIES

Notes by ScienceWeek:

Stem cells are undifferentiated cells that give rise to all the varieties of cells. Bone marrow stem cells are undifferentiated cells in bone marrow that give rise to all the varieties of blood cells, including the various leukocytes (white blood cells) of the immune system: B-cells, T-cells, and macrophages. Umbilical cord stem cells can produce red and white blood cells and platelets, and their transplantation is more effective and cheaper than conventional methods involving stem cells from bone marrow donors. Umbilical cord stem cells, for example, have lower immunogenicity, which reduces the risk of rejection by the patient.

The following points are made by Robert Steinbrook (New Engl. J. Med. 2004 351:2255):

1) Umbilical-cord blood is increasingly used as a source of stem cells to repopulate the bone marrow in the treatment of life-threatening diseases in children and adults. This scientific progress, however, has triggered a continuing debate about how to organize cord-blood banks and the role of public and private facilities.

2) The blood that remains in the placenta after birth is readily available, can be collected at no risk to the mother or newborn, and may be stored frozen for years. Cord blood has less restrictive HLA-compatibility requirements than bone marrow and can be provided quickly. An important caveat is that a unit of cord blood -- the blood collected from one donor -- may vary in volume from 40 ml to 100 ml or more, and even the largest units contain substantially fewer hematopoietic progenitor cells than a typical bone marrow donation. Some units thus contain insufficient cells to treat an adult.

3) The first cord-blood transplantation was performed in France in 1988.[1] A six-year-old boy from North Carolina with severe Fanconi's anemia received cryopreserved umbilical-cord blood from an HLA-identical younger sister who was unaffected by the disorder. Sixteen years later, he is healthy, his graft is durable, and he has had no further manifestations of the disease, according to his physician.

4) Although exact statistics are not available, 5000 to 6000 cord-blood transplantations have now been performed worldwide, primarily in the US, Western Europe, Japan, and Australia. The number of transplantations performed annually is increasing, and adults now account for about one third of all recipients. About two thirds of transplants are used in patients with leukemia, and about a quarter in patients with genetic diseases. In 2004, there are expected to be about 2000 cord-blood transplantations, including 600 in the US and 800 in Japan, which has developed an effective transplantation system in the past five years.

5) There are currently both private and public cord-blood banks in the US. Private banks market their services to couples who are expecting a child. They store cord blood for the future use of the donor or members of the donor's family. There are about 20 private cord-blood banks in this country; their collection fees are typically $1,000 to $1,500, and storage costs about $100 a year.[2] Blood from private banks has been used in only a small minority of transplants. One company, Cord Blood Registry (headquartered in San Bruno, Calif.), stated in September that it has "approximately 250,000 cryopreserved units at its Tucson facility" and "has provided stem cells for 34 client treatments" -- more, it claims, than all other private cord-blood banks combined. Most of the samples have been used for the treatment of a sibling of the donor. Overall statistics for private cord-blood banks are not available.

6) Public storage banks are similar to blood banks in that they are a source of cord blood from unrelated donors. Umbilical-cord blood and blood from the mother are typed for HLA antigens and blood group and screened for infectious diseases, and information is collected about the medical history of the mother and the family. Policies vary with regard to the follow-up of donors for the development of diseases that could be transmitted through a transplant. Unlike private banks, public banks do not charge for collection or storage. They charge $15,000 to $25,000 when a unit is provided for transplantation -- a fee that is usually covered by health insurance. Worldwide, there are between 175,000 and 200,000 units of cord blood in storage in public banks. Some of these units, however, would not meet current collection standards, most commonly because they contain an insufficient number of nucleated cells, which are used as a surrogate for stem cells.

7) Advocates of public cord-blood banks argue that private banks exploit the emotional vulnerabilities of expectant parents for financial gain and that their practices make little sense, except in unusual circumstances.[2] A person's own cord blood is very unlikely to be needed for personal or family use, so patients and society are better served when matches from unrelated persons can be found in a public bank. As medicine is currently practiced, a child's own cord blood cannot be used if the child is born with a genetic disease or develops leukemia. The primary exception is the very small number of families -- fewer than 1000 in the US each year -- with a child whose illness might be treated with cord blood from a sibling. There may be more uses for cord blood, such as transplantation in patients with sickle cell anemia or another hemoglobinopathy, which is currently performed infrequently. The production of organs and tissues that are unrelated to the hematopoietic system, another potential use, is still theoretical.

8) Private cord-blood banks are currently mired in yet another controversy -- a patent dispute. PharmaStem Therapeutics (Wayne, Pa.) claims that its patents covering the collection, cryopreservation, storage, and therapeutic use of cord blood entitle it to receive licensing fees. PharmaStem was founded in 1985 as Biocyte Corporation, which partially supported the first cord-blood transplantation.[1] The company says it has licensing agreements with 16 private cord-blood banks. It has brought suit against the others and has sought to force obstetricians to collect cord blood only for the banks it has licensed. According to a letter sent in August 2004 by Cord Blood Registry, which has not signed a licensing agreement, PharmaStem's position is "analogous to demanding a licensing fee for all bone marrow or peripheral blood that is cryopreserved or used in transplant." In September 2004, the US Patent and Trademark Office agreed to reexamine two of the patents, and litigation is ongoing in the federal courts.[3]

References:

1. Gluckman E, Broxmeyer HA, Auerbach AD, et al. Hematopoietic reconstitution in a patient with Fanconi's anemia by means of umbilical-cord blood from an HLA-identical sibling. N Engl J Med 1989;321:1174-1178

2. Private cord blood banks. Med Lett Drugs Ther 2004;46:21-22

3. Abelson R. Therapy impasse -- a cancer hope deferred; blood treatment's promise mired in bureaucracy. New York Times. May 29, 2004:A1

New Engl. J. Med. http://www.nejm.org

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