Treatment Overview
What is a stem cell transplant?
Most stem cells
are in your
bone marrow. You also have some that circulate from
your marrow into your blood. Bone marrow stem cells turn into
red blood cells,
white blood cells, or
platelets to help your body stay healthy. If your bone
marrow is damaged or destroyed, it can no longer make normal blood cells. In a
stem cell transplant, healthy stem cells are placed in your body through an
IV to help your bone marrow start to work
right.
When the stem cells come from another person, it is called
an allogeneic transplant. The donor may be a relative or a complete stranger.
The important thing is that the donor's immune system markers are closely
matched to yours. This is more likely when the donor is your brother or
sister.
When the stem cells come from your own blood or bone
marrow, it is called an
autologous transplant.
Stem cells can
also be found in your bloodstream and in the blood inside a newborn's
umbilical cord.
When is a stem cell transplant needed?
Doctors use
stem cell transplants to:
- Treat diseases that damage or destroy the
bone marrow, such as
non-Hodgkin's lymphoma and
Hodgkin's lymphoma,
leukemia,
multiple myeloma, and
aplastic anemia.
- Restore bone marrow that
has been damaged by total body radiation and high doses of chemotherapy used
for cancer treatment.
Other uses for stem cells are being studied, such as the
treatment of immune system defects,
diabetes,
sickle cell disease, and
thalassemia.
How do I know if I am a good candidate for a stem cell transplant?
Your doctor will consider your health and your age.
People who are good candidates usually are younger than 70, do not have other
diseases such as heart disease or diabetes, and have a normal kidney and liver.
Your doctor will also consider how much your disease has grown and how
aggressive your cancer is. People with aggressive cancer that has spread to
many areas of the body are not usually good candidates. Your doctor may also
consider if you have cancer that has come back, such as relapsed
non-Hodgkin's lymphoma or
leukemia.
How are stem cells collected?
It depends on where
the stem cells come from. If they are taken from the bone marrow, a small
amount of the liquid portion of the bone marrow is removed through a needle
inserted into the bone. This is done many times to collect enough stem cells
for the person receiving the donated bone marrow. This is called a
bone marrow aspiration. The bone marrow cells are put
into a blood bag. They are often frozen for future use.
If the
stem cells are taken from blood, the growth factor G-CSF may be used to
stimulate the growth of new stem cells so they spill over into the blood. G-CSF
is a protein that is produced naturally in the body. The blood is removed from
the vein and passed through a machine that takes out the stem cells. The
machine then returns the remaining blood through a needle in the person's arm
or through a
central venous catheter. This way of collecting stem
cells is called
apheresis.
Why are chemotherapy and radiation therapy used before a transplant?
Doctors use chemotherapy and radiation to destroy
your bone marrow. This also gets rid of the cancer cells—along with the normal
cells—in your bone marrow and the rest of your body. Later, when you get
healthy stem cells from a donor, those new cells will go to the marrow and be
able to take over the job of making new blood cells.
How are stem cells transplanted?
A central venous
catheter is inserted into your chest. The stem cells travel through the
catheter into your blood, and to your bone marrow, where they will begin to
produce new cells in 1 to 3 weeks. During this time:
- You may be in isolation and given antibiotics
to prevent or treat infection. Because the chemotherapy destroys your white
blood cells, your body will not be able to fight infection until it starts
making new white blood cells.
- Your blood will be tested often to
check the levels of red blood cells, white blood cells, and platelets in your
body.
- You may need to receive several
transfusions of blood cells and platelets until your
body begins to produce its own.
- You may need more antibiotics or other medicines if you get an
infection.
What new techniques are being developed?
Researchers are studying a new technique called a mini-transplant or
nonmyeloablative transplant. This involves giving lower, less harmful doses of
chemotherapy and radiation than are normally used in transplants. Lower doses
destroy some, but not all, of your bone marrow and weaken your immune system to
keep your body from rejecting the transplanted cells. And because lower doses
of chemotherapy and radiation therapy are used, the transplant is less
dangerous. This may be a good treatment option for people who would otherwise
not be considered for an allogeneic stem cell transplant.1