Bone marrow transplants are complicated but can save a child
By Joanne Kurtzberg, MD and Dennis Clements , MD. PhD, MPH
normal levels of treatment for a child with cancer arent enough,
more extreme measures may be necessary. Higher levels of radiation,
used to kill cancerous cells, can also threaten important bone marrow
and necessitate a bone marrow transplant -- a complicated but lifesaving
a bone marrow transplant, the sick childs bone marrow is permanently
replaced with new bone marrow.
transplant itself is simple; the marrow is infused into the blood
like a blood transfusion.
before the transplant, the child has typically been treated with
up to two weeks of high doses of potentially lethal chemotherapy
or radiation therapy (or both) that cause side effects for one to
three months afterwards.
this time, the child experiences many complications, is at high
risk for developing a serious or fatal infection, and must be hospitalized
in an isolation unit.
from the transplant begin to grow after about one month, but full
recovery takes one to two years. Children undergoing the procedure
cannot go to school, church, malls, movies, or other group activities
for approximately one year.
Is Bone Marrow?
Bone marrow is the bodys blood factory, manufacturing millions
of blood cells every day. It produces red blood cells that carry
oxygen, white blood cells that fight infection, and platelets --
small particles that help with blood clotting.
marrow is one of the only organs in the body that produces new cells
on a continuous basis. This makes bone marrow susceptible to serious
side effects from chemotherapy used to treat patients with cancer.
kills dividing cells regardless of whether they are normal or cancer
cells. The only dividing cells in our bodies are our hair cells,
the cells that line the mouth, stomach and intestines, and the bone
marrow cells. Thats why chemotherapy commonly causes side
effects like hair loss, mouth sores, vomiting and diarrhea (called
mucositis), and low blood counts.
blood counts can lead to serious infections or bleeding and can
some patients with cancer, the standard doses of chemotherapy or
radiation therapy fail to cure their disease. If too much chemotherapy
is given, the bone marrow will be permanently damaged and the patient
wont be able to make blood cells, a complication that would
treat the cancer but avoid permanent loss of bone marrow function,
a transplant is given to rescue the bone marrow from the toxic effects
of the therapy necessary to cure resistant cancer.
Most of the time, another persons blood stem cells must serve
as the donor cells. Donors must be matched through a system called
human leukocyte antigens (HLA).
system identifies proteins on the surface of our cells which code
for our unique identity. Each of us has six important proteins --
three inherited from our mother and three from our father.
a typical family, each parent will match halfway and each sibling
will have a 25 percent chance of matching the patient. Since a full
match is best, many patients dont have a close enough match
in their family.
National Marrow Donor Program (NMDP) was established 20 years ago
to allow adults to donate their blood stem cells to a patient in
need of a bone marrow donor. Currently there are over seven million
adults who have volunteered to participate in the NMDP registry.
The NMDP has facilitated over 20,000 transplants in the past 17
with the NMDP, roughly half of the patients in need of a bone marrow
transplant cannot find a fully matched donor. Umbilical cord blood,
a relatively new source of blood stem cells, which doesnt
have to match completely, can be used for some patients transplants.
cord blood is the babys blood left over in the afterbirth
(placenta) after the baby is born. It can be collected without any
risk to the mother or baby. In fact, it is frequently discarded
as waste, but is now known to contain lifesaving stem cells similar
to those found in bone marrow.
blood can be collected from the afterbirth within minutes of the
babys birth and then stored at ultra-cold temperatures until
needed for a transplant. With support of the National Institutes
of Health, the NMDP, and private philanthropy, approximately 15
public cord blood banks have been established in the U.S. to provide
cord blood donors for patients in need of transplantation therapy.
While bone marrow transplantation has traditionally been used to
treat patients with cancer, it also can be used to correct genetic
which cause defective blood formation like sickle cell anemia, thalassemia,
or immune deficiency (bubble boy disease) can be cured with a bone
learned that the bone marrow can also be a factory to
produce an enzyme or protein that might be missing in a child with
a metabolic disease. While these diseases are very rare, they cause
severe damage to the brain, heart, liver, lungs, eyes, and other
organs during childhood.
a transplant is performed early in the course of the disease, before
too much damage has occurred, the disease is corrected and organ
damage is prevented.
exceptional successes have been seen in young children with Hurler
syndrome, Krabbe disease, adrenoleukodystrophy (Lorenzos oil
disease), and other diseases.
Today bone marrow transplantation is performed only in children
with very serious and life-threatening conditions. The majority
of children going through the procedure have a life expectancy of
less than one year without treatment.
half of the children who have a transplant are cured of their underlying
disease. The others die from relapses of their disease or complications
from the procedure.
children and infants with genetic diseases and children who have
only had one relapse of their cancer have the best prognosis. In
these cases 70 to 90 percent of children do well.
marrow transplantation is also teaching us about what cells can
do to repair damaged tissues.
to 10 years from now, what we are learning from bone marrow transplantation
today could lead to the development of less risky cellular therapies
that will repair and regenerate tissues and organs damaged by disease,
accidents, or treatment.
Kurtzberg, MD, is a pediatric hematologist oncologist who directs
the Childrens Blood and Marrow Transplant Program at Duke.
She is also the founder and director of the Carolinas Cord Blood
Bank at Duke, a public cord blood banking facility. Dennis Clements
, MD. PhD, MPH, is the chief medical officer of Duke Children's
Hospital. For more information, visit www.dukehealth.org
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