Bone marrow or stem cell transplantation
A bone marrow or stem cell
transplant is where abnormal stem cells from a person's bone marrow are
destroyed and replaced with healthy stem cells, either from that person or from
a donor.
About bone marrow transplants
The bone marrow is a spongy substance in the centre of most bones. Your bone
marrow contains stem cells, which are the most basic kind of cell. These stem
cells in your bone marrow mature and into three types of cells:
- White blood cells - protect your body from infection
- Red blood cells - carry oxygen around your body
- Platelets - involved in normal blood clotting
They are then
released into your bloodstream.
Although it's often called a bone marrow
transplant, the procedure is really a transplant of the stem cells in the bone
marrow - a bit like a blood transfusion.
A bone marrow transplant involves
having your own stem cells in your bone marrow killed off by a high dose of
chemotherapy and replaced with healthy stem cells. The healthy stem cells are
fed into your blood through a drip and they find their way to your bone marrow
to make new cells. The stem cells can either come from:
- Another person (a donor) - this is called an allogeneic transplant
- Your own bone marrow (if the stem cells were extracted at an earlier time
when they were still healthy) - this is called an autologous treatment and is
rarer
The stem cells are either taken directly from the donor's bone
marrow, or taken from his or her blood using a machine called a cell separator
(this is called a peripheral stem cell harvest).
Why
would I need to have one?
Bone marrow transplantation is used in the
treatment of cancers - such as leukaemia, lymphomas and myelomas - that affect
the bone marrow. You may have a bone marrow transplant if:
- Your cancer is in remission (the symptoms go away and the disease is under
control but not necessarily cured)
- Your cancer relapses (returns) after initial treatment
- Your cancer has not responded to other treatment
A bone marrow
transplant is a very intensive treatment, and your age and general health will
be taken into consideration when deciding whether this is a suitable treatment
for you. Generally you need to be below 65 to have this
treatment.
Preparing for the procedure
A
donor will usually be a close relative because their cells need to match yours.
There is a one in four chance that a brother or sister's cells will match yours
(ie that they will be a "match"). To find out if a potential
donor is a match, you will both need to have a blood test. The doctor will look
at both of your blood cells under a microscope to see if they have the same
proteins on the surface. This is called tissue typing or HLA matching (HLA
stands for human leukocyte antigen).
It's sometimes possible to find a
matching donor who isn't related to you. This may be done by your doctor trying
to find a matched unrelated donor (MUD) for you from the Anthony Nolan Bone
Marrow Register.
It can sometimes take several months for different
people to be screened to find you a donor.
Chemotherapy
Before you can have the bone marrow
transplantation, your leukemia or other cancer needs to be at the lowest
possible level. Ideally you should be in remission.
Harvesting the stem
cells
The first step is to collect, or "harvest",
the stem cells. The exact process depends on whether the stem cells are coming
from a donor or from you.
Peripheral stem cell
harvest
If the stem cells are coming from your own bone marrow (an
autologous transplant), you will have a dose of chemotherapy first, and then a
course of injections of growth factors. These injections encourage the stem
cells to move from your bone marrow into your bloodstream. You will have regular
blood tests, and when there are enough of your stem cells in your blood, these
can be harvested.
Harvesting the stem cells from your blood takes about
three to four hours. During this time you will be lying down on a bed or a
couch, and will normally have a drip connected to both of your arms. Blood will
be taken from one arm, and this will go through a machine called a cell
separator. This machine separates out the stem cells from the other blood cells.
It will keep the stem cells and return any other blood cells to your bloodstream
through the drip in your other arm. The stem cells are then frozen until you
have had your high dose of chemotherapy.
Sometimes the drip will be connected
to veins in your legs instead of your arms, or through a central line in your
chest.Harvesting a donor's stem cells follows the same process, except they are
not given chemotherapy.
Harvesting stem cells from the
bone marrow
Stem cells can also be harvested by extracting bone
marrow through a needle inserted into either your or your donor's pelvic bones.
This is done under general anesthesia, so you or your donor will be asleep
during the procedure and feel no pain.
High dose of
chemotherapy
The next step of the treatment is for you to have a
very high dose of chemotherapy, to completely destroy your own bone marrow and
any remaining cancer cells in your body. This treatment takes several days and
it can make you feel very sick. You may be given medicines to help relieve the
sickness.
About the procedure
The actual
transfer of the stem cells is a relatively simple procedure. A needle is
inserted into a vein and the cells are injected. They find their own way to the
bone marrow and settle there.
It will take some time (usually between two
and four weeks) for the new stem cells reach your bone marrow and start making
new blood cells.
Side-effects
Side-effects are the unwanted, but mostly
temporary effects of a successful treatment. Straight after a bone marrow
transplant the levels of blood cells in your body will be very low. This will
cause a number of side-effects, including:
- Infections - due to a lack of white blood cells
- Anemia - a condition when you have too few red blood cells or not enough
hemoglobin in your blood
- Bleeding - due to a lack of platelets
- Eating problems - due feeling sick, not feeling hungry or having a sore
mouth after treatment
While your levels of blood cells are low, you
will need blood and platelet transfusions and antibiotics to protect you from
infection. You may also need to have fluids You may need to stay in hospital
until your blood cells have gone back up to a safe level.
Autologous
treatment normally causes fewer side-effects than an allogenic transplant,
because your body is less likely to reject stem cells that have come from your
own body.
Complications
Complications are
when problems occur during or after the procedure.
Graft-versus-host disease
One possible complication of
receiving bone marrow cells from a donor is called graft-versus-host disease.
This happens when the white blood cells of the donor attack the tissues of your
body. You will be given medicines to prevent this, so normally the symptoms are
mild. But sometimes it can cause severe skin rashes, sickness, vomiting,
diarrhea, muscle weakness and yellowing of the skin (jaundice).
Having graft-versus-host disease doesn't mean that the transplant has not
worked. In fact, it may actually help by attacking any cancer cells in your body
that have survived the high-dose chemotherapy treatment.
Graft failure
Rarely, the new stem cells that have been
fed into your blood may not produce enough blood cells. You will need another
stem cell transplant if this happens.
What to expect
afterwards
Once the levels of your blood cells have returned to a
safe level, you will be able to leave the hospital. The specialist team who
looks after you will monitor you closely during regular outpatient appointments.
You will be told specifically what problems to look out for, such as
fever.
The success of bone marrow transplantation depends very much on
the reason that it was done, the exact method used and how old you are. Many of
the methods used are still very new and advances are being made all the time, so
this type of treatment looks ever more promising. With some types of leukemia,
bone marrow transplant offers the best chance of a cure.
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