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Stem Cells From Cord Blood Could Become the Standard

Posted on: Tuesday, 11 September 2007, 06:00 CDT

By Fred Tasker, The Miami Herald

Today, stem cells from bone marrow are considered the "gold standard" for treating leukemia, many immunologists say. But that may be changing.

"I think it's likely that cord blood will become the standard in the future," says Deborah Banker, vice president of the Leukemia & Lymphoma Society.

In 2006, 17.5 percent of the transplants coordinated by the National Marrow Donor Program were from cord blood, said spokeswoman Shauna Sheffer. "That is up 4.2 percent from last year and that number continues growing," she said.

Because demand is expanding so rapidly, with a need for 150,000 units in storage to serve all who need it, Congress in 2005 allocated $79 million to increase the supply.

"It's not enough to achieve 150,000 units, but it's a good start," says Dr. Edward Guindi, president of CORD:USE, an Orlando company that takes part in the collection process.

The National Marrow Donor Program has up to 5 million registered bone marrow donor volunteers. But blood marrow has several drawbacks. The biggest is that only about 30 percent of patients who need stem cell transplants can find a properly matched donor with bone marrow -- while a match from umbilical cord blood is much easier.

Also, it takes about three months to obtain bone marrow for a transplant, because the donor must be located and brought to the recipient. Cord blood stem cells are stored in a national bank, ready for quick matching and immediate delivery.

Evidence of the value of umbilical cord blood stem cells for fighting leukemia came in a June article in the medical journal The Lancet, by Dr. John Wagner of the University of Minnesota. In the study, the five-year probability of leukemia-free survival for patients was:

--38 percent after transplantation of perfectly matched bone marrow stem cells.

--36 percent after slightly mismatched cord-blood stem cells.

--60 percent after perfectly matched cord-blood stem cells.

A current limitation with cord blood stem cell transplants is that a single umbilical cord has enough cells for only about a 120-pound recipient. So Wagner has been changing tactics to transplant the blood from two umbilical cords into a single patient.

"Two cords have enough cells for 93 percent of adults," says Wagner. "Our largest patient was 270 pounds."

Another drawback of using umbilical cord blood stem cells is that once they're used, they're gone, says Dr. Morton Cowan, director of pediatric bone marrow transplantation at University of California in San Francisco. A doctor can't go back to transplant more if needed -- as with bone marrow.

In the meantime, cord blood supporters continue trying to increase donations.

"The major limitation is the number of units available," says Banker, of the Leukemia Society. "In a perfect world, if we could recover a cord from every live birth, there would be a unit available for every human."

Source: The Miami Herald

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