Mismatched Cord Blood Can Save Kids
Cord Blood Transplant as Good as Bone Marrow Transplant for Leukemia
Cord Blood and Child Leukemia
Wagner and colleagues studied children treated for leukemia before their 16th birthday. Treatment means using chemotherapy to kill off their white blood cells. To replenish these crucial immune system cells, 282 of the kids got bone marrow transplants and 503 got cord blood transplants.
Both bone marrow and cord blood contain blood stem cells capable of replacing the cells lost to chemotherapy. But the transplants only take if the donor's tissues carry nearly all the same "self" markers -- called HLA -- as the patient's tissues.
The worse the HLA match, the greater the chance the transplanted cells will see the patient's body as "foreign" and attack it.
But earlier studies suggested that cord blood cells didn't have to be a perfect match. Of the six crucial HLA markers, cord blood seemed to work if one or even two HLA markers were mismatched.
Wagner and colleagues looked at how many kids remained leukemia-free after five years -- a milepost that usually means the patient is cured of cancer.
Sure enough, kids who got cord blood transplants mismatched for one or two HLA markers did as well as kids who got matched bone-marrow transplants. And kids who got perfectly matched cord blood transplants seemed to do even better than those who got matched bone marrow transplants.
Kids with leukemia aren't the only patients who badly need bone marrow transplants. The treatment can also save the lives of children born with dysfunctional immune systems. Many such children, Kleiner says, can't survive a long search for a matched marrow donor.
"No longer do we have to keep searching for that matched marrow donor," Wagner says. "Fifteen thousand patients -- right now -- cannot find a donor. This now gives them another option. Matching is no longer the barrier it is with marrow donors."
Wagner says that doctors are now much better at cord blood transplants than they were when the study began. Patients today can expect much better results than those seen in the study, he says.
The Wagner study appears in The Lancet. In an editorial accompanying the study, Vanderson Rocha and Eliane Gluckman of Saint Louis Hospital in Paris, advise doctors to start their search for cord blood banks and bone marrow registries at the same time -- and to use the one they find first.
Wagner says that his group is studying whether cord blood works as well for older adults as it does for children.