You’d think doctors and patients would be clamoring for cells so versatile they could help reboot a body suffering from everything from leukemia to diabetes. But a new report shows that an important source of these stem cells—discarded umbilical cords—is rarely used because of high costs and the risk of failure.

Stem cells drawn from newborns’ umbilical cord blood are sometimes used to treat medical conditions, especially bone and blood cancers like multiple myeloma or lymphoma by replacing dysfunctional blood-producing cells in bone marrow. Generally the diseased cells are destroyed with chemotherapy and irradiation. Then new stem cells are transplanted into the patient to restore function. Cord blood stem cells are an alternative to bone marrow transplants and peripheral blood transplants, in which stem cells are gathered from the blood stream. Cord blood tends to integrate better with the body and it is easier to find a suitable donor than the alternatives.

Yet less than 3 percent of cord blood collected in the U.S. is ever used whereas the rest sits uselessly in blood banks, according to a recent report in Genetic Engineering & Biotechnology News. Immunologist Enal Razvi is author of the report and managing director of Select Biosciences, a biotechnology consulting agency. Razvi found that public cord blood banks, which store donated frozen units for transplants as needed, have only a 1 to 3 percent turnover annually. Most of their inventory sits unused year after year. For example, at Community Blood Services in New Jersey, patients have only used 278 of its 13,000 cords since it opened in 1996, according to business development director Misty Marchioni. Usage is even lower at private cord blood banks, which charge clients thousands of dollars to store a cord in the event a family member one day needs it.

Unlike bone marrow, the main alternative stem cell source, cells transplanted from cord blood carry little risk of graft-versus-host disease, a deadly condition in which the body rejects a transplant. Scientists believe this is because a baby’s immune system is closer to a blank slate, so their stem cells can integrate with the patient’s body more easily. But cord blood transplants also take longer to start working, requiring longer hospital stays and upping the bill. Due to storage and testing costs, the cords themselves also get pricy. “The cost of the cord is prohibitively high,” Razvi explains. Each unit of cord blood costs between $35,000 and $40,000 and most adults require two units for a successful transplant. Insurance companies will generally pay a set amount for a stem cell transplant regardless of where the cells come from. The price tag on a cord blood transplant can run up to $300,000, which may not be fully covered.

Cord blood stem cell transplants also have a higher failure rate than other transplant methods. If the transplant fails, it leaves patients with a compromised immune system in addition to their original disease and medical bills. Because the preparation for transplant includes wiping out the patient’s original bone marrow, the entire body has to be repopulated with stem cells able to replace it. There are not many stem cells in each cord. Compared with bone marrow or peripheral blood there is a greater chance that there will not be enough stem cells that actually implant and begin producing blood and bone marrow. “It’s like spreading a small amount of seeds in a big garden,” says Mitchell Horwitz, who teaches cell therapy at Duke University Medical Center. “Sometimes it just doesn’t take.”

Martin Smithmyer, chief executive of the private bank Americord, claims that more clients will eventually use their cords, especially as more applications are found for cord blood stem cells. But some scientists disagree. Steven Joffe, a professor of medical ethics at the University of Pennsylvania Perelman School of Medicine, says that many treatments cannot be done with a patient’s own stem cells because genetic diseases would already be present in the cord blood and that bone marrow might be a better option for relatives. “The likelihood they are ever going to use that product is vanishingly small,” he says.

Despite the low usage, advocates say cord blood programs have been crucial in improving transplant options for racial minorities, because it can be hard to find a bone marrow match for some groups. Cord blood does not need to match the patient as perfectly as bone marrow. “This has transformed the treatment of minority patients,” says Andromachi Scaradavou, medical director of the National Cord Blood Program, a public bank based in New York City. “In the past we didn’t have good donors to offer them.” Community Blood Services’s Marchioni also maintains that cord blood is a good emergency option, because finding a compatible bone marrow or peripheral blood donor can take months or years. “If you need a transplant quickly,” she says, “it’s easy to get cord blood off of a shelf.”

Still, experts are working on more efficient ways of ensuring widespread availability of cord blood without having so much of it sit forever unused. Researchers are also continuing to look for ways to improve transplant success and to increase the number of stem cells obtained from each cord, potentially bringing down costs and making cord blood transplants feasible for more patients. “If the cost could be lowered,” Scaradavou says, “it would help a lot of patients get the treatment they need.”

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