Oct. 16 (HealthDay News) -- U.S. researchers are testing a new approach in cord-blood transplants to treat genetic metabolic disorders in babies while they're still in the womb.

The new method uses a small, select number of therapeutic stem cells that have been treated to speed and improve engraftment (acceptance of the transplant by the body), explained Dr. Joanne Kurtzberg, a professor of pediatrics and pathology and director of the pediatric blood and marrow transplant program at Duke University Medical Center in Durham, N.C.

She and her team are studying the new procedure in a pilot trial open to pregnant women at risk for having children with fatal metabolic disorders, including Krabbe disease, metachromatic leukodystrophy, Pelizaeus-Maerzbacher disease, Tay-Sachs disease and Sandoff disease.

If untreated, these metabolic disorders can lead to bone, brain and central nervous system problems, and early death, the study authors noted in a Duke news release.

Donor cells used in the study will be made by the biopharmaceutical company Aldagen, Inc, which is a partner in the trial.

In many cases, cord-blood transplants after birth have proven successful in treating inherited metabolic disorders. Transplant timing is critical, Kurtzberg stressed.

"The idea is to give the baby cord-blood stem cells from a healthy donor that have the potential to provide healthy genes that can replace the ones that aren't working properly in the baby's own cells," Kurtzberg said in the news release.

In general, the earlier the transplant, the more likely it will work. That means that performing the transplant before the baby is born is ideal, she explained.

During the procedure, donor cells are injected directly into the fetus's abdomen at 12 to 14 weeks' pregnancy. At birth, the baby will be tested to see if the donor cells are present, and if they're fixing the malfunctioning genes. If not, the baby would be eligible for conventional cord-blood stem cell transplant within a few weeks.

SOURCE: Duke Medicine, news release, Oct. 13, 2009