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Cord Blood Stem Cells Save Children With Hurler’s Syndrome

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Duke Health News 919-660-1306

DURHAM, N.C. -- Stem cells from a newborn baby's umbilical cord
blood can save the lives of children with Hurler's syndrome and can
repair much of the progressive brain and organ damage that would
otherwise be fatal to children, according to physicians at the Duke
Comprehensive Cancer Center's Pediatric Blood and Marrow Transplant
Program.

Children with this rare metabolic disease die by the age
of 6 because they are missing an important enzyme, alpha-L-iduronidase,
which leads to progressive damage in the brain, heart, bones,
cartilage, liver and corneas. Stem cells from cord blood provide the
needed enzyme in the brain and the rest of the body, thus halting the
disease and aiding repair in these organs and tissues, the Duke study
showed.

In fact, survival was higher and complications lower
among the Duke children who received cord blood than among children
previously described in the medical literature who had received adult
bone marrow, said Duke's Susan Staba, M.D., lead author of the study.
Results of the study in 20 children with Hurler's Syndrome are
published in the May 6, 2004, issue of the New England Journal of
Medicine. The research was partially funded by the National Heart,
Lung, and Blood Institute.

Bone marrow from adult donors can save
some Hurler's patients, but an exact match cannot be found in time for
more than 50 percent of children, and time is critical in treating
these children, said the researchers. Moreover, adult bone marrow fails
to engraft in 28 to 37 percent of Hurler's patients, meaning the donor
bone marrow does not take hold and begin to grow in the patient.

As
an alternative treatment, Duke physician Joanne Kurtzberg, M.D.,
director of the Pediatric Blood and Marrow Transplant Program at Duke
and senior author of the paper, tested the ability of cord blood stem
cells to provide the missing enzyme and thereby halt the progressive
organ deterioration in these children. Stem cells in cord blood are
less mature than adult bone marrow cells and thus do not need to
perfectly match the patient's immune-related blood proteins called
antigens, said Kurtzberg. Moreover, cord blood stem cells appear to
repair more of the damage caused by Hurler's syndrome than does adult
bone marrow.

In the Duke study, 85 percent of children who
received cord blood survived for two to seven years -- the longest
period of time they have been followed. Survival among Hurler's
children who receive bone marrow is between 63 and 72 percent.

"Cord
blood stem cells appear to correct the organ damage better than adult
bone marrow does," said Kurtzberg. "The children's cognitive skills
continued to improve after transplant to such a degree that they
actually gain mental skills faster than age-matched control children
and cross over into the normal range at three to four years post
transplant."

Such cognitive gains might be related, in part, to
transplanting the children at a slightly younger age, before their
disease has progressed beyond repair, said Kurtzberg. Yet stem cells in
cord blood have many traits that create a more favorable environment
for recovery, she added. Because they are immature, they can more
readily turn into other cell types and thus have a better chance of
repairing existing damage, she said.

Moreover, said Kurtzberg,
stem cells' immaturity significantly reduces their ability to recognize
the patient as foreign and attack his or her tissues, a
life-threatening condition called graft-versus-host disease.
Graft-versus-host disease occurred in 30 to 50 percent of Hurler's
syndrome patients receiving adult bone marrow. This condition
contributes to up to half of the deaths among children who receive
adult bone marrow transplants.

Kurtzberg's team has also utilized
the benefits of cord blood to avoid giving children radiation prior to
transplant, a neurologically toxic regimen that is often necessary to
make bone marrow transplants -- but not cord blood transplants --
successful.

"We have created a chemotherapy regimen that
facilitates engraftment without giving the child radiation," said
Kurtzberg. "We're able avoid radiation in large part because the
properties of cord blood enable us to achieve engraftment more readily
and with less manipulation of cells than is possible with adult bone
marrow."

The findings are yet another example of the promising
capabilities of stem cells derived from umbilical cord blood, she said.
Kurtzberg pioneered the use of unrelated umbilical cord blood
transplants to cure children with resistant cancers and rare metabolic
diseases. She and her colleagues have transplanted more children using
cord blood than any other group in the world -- 460 to date -- and
proved just this year that stem cells from cord blood actually
infiltrate the brain and damaged heart muscle to repair the damage.

Kurtzberg's
team has also treated more children with Hurler's syndrome than any
center in the world. The current study reported the first 20 children
who were treated with cord blood transplants between December 1995 and
October 2002. After transplantation, children were followed and
evaluated by Maria Escolar, M.D., at the University of North Carolina
Center for Child Development to chart their physical growth and
cognitive skills. All children had either stable or improved brain
function after transplantation, the study showed. Growth velocity also
returned to normal in the majority of children within one year of
transplant. Kurtzberg also assessed their organ function and found
improvements in each deficit area following transplant.

"Cord
blood presents an excellent source of stem cells, and it is readily
available to nearly every child who needs it," said Kurtzberg. "It
provides an important therapeutic option for young patients with severe
Hurler's syndrome who lack a perfectly matched and related adult bone
marrow donor."

Patients with a milder form of the disease, with
no brain involvement, can receive enzyme therapy alone. However,
because enzymes do not cross the blood-brain barrier, they cannot
repair the brain damage that occurs in more severe forms of the
disease, said Kurtzberg. For these children, transplantation is
essential.

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