Transient Maternal Cell Growth in Cord Blood Recipients can be Treated
MIAMI, FL -- Mothers' cells may begin to grow and form bone marrow in children receiving umbilical cord blood transplants, but any resulting rejection problems can be dealt with, researchers from Duke University Medical Center said.
In a presentation prepared for Monday at the annual conference of the American Society of Hematology, Dr. Joanne Kurtzberg said engraftment of stray maternal cells may not be a threat to transplant patients' survival.
"We found that, indeed, there can be times when a few of the cells from the mother can be mixed in the placental, or umbilical cord, blood. Those cells can actually engraft in the patient receiving the transplant and cause graft-versus-host disease symptoms," explained Kurtzberg, who directs Duke's pediatric bone marrow and cord blood transplant program.
Between August 1993 and August 1998, Duke physicians treated 160 pediatric patients with umbilical cord blood transplants to rescue their bone marrow. Two patients showed graft-versus-host disease (GVH), a condition in which the new marrow begins to fight against the rest of the body. Tests showed the presence of cells from the mothers of the infants whose cord blood was collected from the afterbirth for later use in transplant.
Umbilical cord blood can substitute for marrow in a transplant because the blood is rich in immature cells, called stem cells, that generate developing and mature blood cells. The tissue-type match between the donor and recipient doesn't need to be as close as in bone marrow transplant, probably due to that same immaturity of cells in the cord blood that would normally trigger rejection of tissue, researchers think.
Doctors treat GVH by suppressing the developing immune system until the new marrow's cells have spread throughout the body and it recognizes all cells as related rather than as foreign intruders. But in the cases where maternal cells were causing GVH symptoms, the Duke doctors reversed typical treatment, withdrawing the anti-GVH medications and thus letting the developing immune system reject the transient maternal cells.
Once doctors stopped suppressing the immune system, Kurtzberg said, the symptoms of graft versus host gradually subsided. In one of the patients, the presence of maternal cells had markedly decreased at nine months post transplant and by 12 months post transplant, no maternal cells were detected.