Bone marrow transplant (BMT) is a type of therapy for people with certain types of cancer or other diseases. A BMT is done by taking cells that are found in the bone marrow called stem cells. These cells are filtered. They're then given back to the donor (autologous transplant) or to another person (allogeneic transplant). The goal of BMT is to put healthy bone marrow cells into a person after their own unhealthy bone marrow has been treated to kill the abnormal cells.
BMT has been used since 1968 to treat diseases, such as:
Immune deficiency disorders
Some solid tumor cancers
Bone marrow is the soft, spongy tissue inside bones. It's where most of the body's blood cells develop and are stored. The cells that make other blood cells are called stem cells. It's the stem cells that are needed in BMT. The most basic of the stem cells is called the pluripotent stem cell. This is different than other blood cells in these ways:
Renewal. It's able to reproduce another cell identical to itself.
Differentiation. It's able to make one or more types of more mature cells.
Stem cells can either be collected from the circulating cells in the blood (the peripheral system) or from the bone marrow:
Peripheral blood stem cells. Peripheral blood stem cells (PBSCs) are collected by apheresis. This is a process in which the donor is connected to a special cell separation machine by needles inserted in to arm veins. Blood is taken from 1 vein and then circulated though the machine. This removes the stem cells and returns the remaining blood and plasma back to the donor through another needle inserted into the opposite arm. Several sessions may be needed to collect enough stem cells. This helps give a better chance that the transplanted cells will start to grow and make healthy blood cells (called engraftment) in the recipient. A medicine may be given to the donor for about 1 week before apheresis. This medicine will cause the bone marrow to make more new stem cells. These new stem cells will be released from the marrow and into the blood system. They can then be collected from the blood during apheresis.
Bone marrow harvest. This is done by collecting stem cells with a needle placed into the marrow. Most sites used for bone marrow harvesting are in the hip bones and the sternum. The procedure takes place in the operating room. The donor will be given medicine (general anesthesia) during the harvest. This puts them into a deep sleep so they won't feel the needle. In recovery, the donor may have some pain in the areas where the needle was inserted.
There are different BMT types based on who the donor is. The types of BMT include:
Autologous bone marrow transplant. The donor is also the recipient. Stem cells are taken from the person either by bone marrow harvest or by taking peripheral blood stem cells (apheresis). The cells are frozen. They're then thawed and given back to the person after they have treatment. This is often called rescue instead of a transplant.
Allogeneic bone marrow transplant. The donor shares the same genetic type as the recipient. The donor may be a brother or a sister. Stem cells are taken by bone marrow harvest. Or they may be taken with apheresis. Other donors for allogeneic bone marrow transplants may include:
A parent. A haploid-identical match is when the donor is a parent and the genetic match is at least half identical to the recipient. These transplants are rare.
Unrelated bone marrow transplants (UBMT). This is also called matched unrelated donor (MUD).The genetically-matched marrow or stem cells are from an unrelated donor. Unrelated donors are found through national bone marrow registries.
Umbilical cord blood transplant. Stem cells are taken from an umbilical cord right after the birth of a baby. These stem cells reproduce into mature, working blood cells quicker and better than stem cells taken from bone marrow. The stem cells are tested, typed, counted, and frozen until they're needed for a transplant.
Matching is done by typing human leukocyte antigen (HLA) tissue. Leukocytes are a type of white blood cell. The antigens on the surface of these white blood cells define the genetic makeup of a person's immune system. There are at least 100 HLA antigens. But there are a few major antigens that can show if a donor and recipient are a match.
Researchers are still learning the role all antigens play in the process of a bone marrow transplant. The more antigens that match, the better the donated marrow will work with the recipient. This is called engraftment. This is when the stem cells make their way to the marrow and begin making new blood cells.
Most of the genes that define the human immune system are on 1 chromosome. We only have 2 of each chromosome, 1 we received from each of our parents. Because of this, a full sibling of a person in need of a transplant has a 1 in 4 chance of having the same set of chromosomes. This means they're a full match for a transplant.
If an autologous transplant is planned, stem cells collected from either peripheral (apheresis) or harvest are counted, screened, and ready to infuse.
The goal of a bone marrow transplant is to cure many diseases and types of cancer. In some cases, the doses of chemotherapy (chemo) or radiation needed to cure a cancer are so high that a person's bone marrow stem cells will be permanently damaged or destroyed by the treatment. Then a bone marrow transplant may be needed. Bone marrow transplants may also be needed if the bone marrow has been destroyed by a disease.
A bone marrow transplant can be used to:
Replace diseased bone marrow with healthy bone marrow for conditions, such as leukemia, aplastic anemia, and sickle cell anemia.
Help build a new immune system that will fight leukemia or other cancers not killed by chemo or radiation.
Replace the bone marrow and restore its normal function after high doses of chemo or radiation are given to treat cancer. This is often called rescue .
Replace bone marrow with healthy bone marrow to prevent more damage from a genetic disease, such as Hurler's syndrome or adrenoleukodystrophy.
Talk with your healthcare provider and specialists in bone marrow transplants about risks and benefits before the procedure.
Risks may vary, depending on:
The type of marrow transplant
The type of disease that leads to transplant
The way prep is done for the transplant
Age and overall health of the recipient
How well tissues match between donor and recipient
Any severe complications
Possible complications that may happen with a bone marrow transplant include:
Infections. Infections are likely in a recipient with severe bone marrow suppression. Bacterial infections are the most common. Viral and fungal infections can be life-threatening. Any infection can cause an extended hospital stay. They can prevent or delay engraftment. They can also cause permanent organ damage. Antibiotics, antifungal medicines, and antiviral medicines are often given to try to prevent serious infection.
Low platelets and low red blood cells. Thrombocytopenia (low platelets) and anemia (low red blood cells) can be dangerous and even life-threatening. These can happen when bone marrow isn't making new cells yet. Low platelets can cause dangerous bleeding in the lungs, gastrointestinal (GI) tract, and brain.
Pain. Pain related to mouth sores and GI irritation is common. High doses of chemo and radiation can cause severe mucositis. This is inflammation of the mouth and GI tract.
Fluid overload. This is a complication that can lead to pneumonia, liver damage, and high blood pressure. The main reason for fluid overload is because the kidneys can't keep up with the large amount of fluid being given. The fluid is given in the form of IV (intravenous) medicines, nutrition, and blood products. The kidneys may also be damaged. This can happen from disease, infection, chemo, radiation, or antibiotics.
Graft-versus-host disease (GVHD). This can be a serious and life-threatening complication of a bone marrow transplant. GVHD occurs when the donor's immune system reacts against the recipient's tissue. The new or transplanted immune system can attack the recipient’s whole body and all of their organs. This is because the new cells don't see the tissues and organs of the recipient's body as native cells. Over time and with the help of medicines to suppress the new immune system, it will begin to accept its new body and stop attacking it. The most common sites for GVHD are GI tract, liver, skin, and lungs.
Respiratory distress. The respiratory system may suffer during transplant. This may be due to infection, inflammation of the airway, fluid overload, graft-versus-host disease, or bleeding. These are all possibly life-threatening problems that may happen in the lungs and pulmonary system.
Organ damage. The liver and heart may be damaged during the transplant process. This may be temporary or permanent damage. It may be caused by infection, graft-versus-host disease, high doses of chemo and radiation, or fluid overload.
Graft failure. In some cases, the graft (transplant) may not take hold in the marrow. Graft failure may happen as a result of infection or recurrent disease. It may happen if the stem cell count of the donated marrow wasn't enough to cause engraftment.
For the person getting the transplant, here is what happens before the procedure:
Before the transplant, a full evaluation is done by the bone marrow transplant team. All other treatment choices are discussed and evaluated for risks and benefits.
A complete medical history and physical exam are done. This includes tests to check the recipient’s blood and organ functions. For example, tests may assess the heart, kidney, liver, and lungs.
A recipient will often come into the transplant center up to 10 days before transplant. They'll have hydration, evaluation, and other preparations. A flexible tube (catheter) is surgically placed in a vein in the chest area. This is called a central venous line. Blood products and medicines will be given through this line during treatment.
For an allogeneic transplant, a suitable donor must be available. This means a donor who is tissue typed and matched. Finding a matching donor can be a difficult and lengthy process if a sibling match isn't available. Bone marrow donors are listed in several registries. A bone marrow search is done by searching these registries. The search checks for donors whose blood most closely matches the person needing the transplant.
The group of specialists involved in the care of people going through transplant is often called the transplant team. All team members work together to give the best chance for a successful transplant. The team consists of:
Healthcare providers. These include doctors who specialize in oncology, hematology, immunology, and bone marrow transplants.
Bone marrow transplant nurse coordinator . This is a nurse who organizes all aspects of care before and after the transplant. They'll give information and manage the testing and follow-up care.
Social workers. These are providers who will help your family deal with many issues that may arise. Issues may include lodging and transportation, finances, and legal issues.
Dietitians. These are providers who will help you meet your nutritional needs before and after the transplant. They'll work closely with you and your family.
Physical therapists. These are providers who will help you recover and become strong after the transplant.
Pastoral care. Chaplains can give spiritual care and support.
Other team members. Several other team members will assess you before the transplant. And they'll give follow-up care as needed. These include:
Infectious disease specialists
A detailed assessment is done by the bone marrow transplant team. The decision for you to have a bone marrow transplant will be based on many factors. These include:
Your age, overall health, and medical history
Extent of the disease
Availability of a donor
Your tolerance for specific medicines, procedures, or therapies
Expectations for the course of the disease
Expectations for the course of the transplant
Your opinion or preference
The preparations for a bone marrow transplant vary depending on the type of transplant, the disease that caused the need for a transplant, and your tolerance for certain medicines. Most often, high doses of chemo or radiation are included in the preparations. This intense therapy is required to treat the cancer and make room in the bone marrow for the new cells to grow. This therapy is often called ablative, or myeloablative, because of the effect on the bone marrow. The bone marrow produces most of the blood cells in our body. Ablative therapy prevents this process of cell production and the marrow becomes empty. An empty marrow is needed to make room for the new stem cells to grow and establish a new blood cell production system.
After the chemo or radiation is administered, the marrow transplant is given through the central venous catheter into the bloodstream. It isn't a surgical procedure to place the marrow into the bone. It's more like receiving a blood transfusion. The stem cells find their way into the bone marrow and begin reproducing and growing new, healthy blood cells.
The days before transplant are counted as minus days. The day of transplant is considered day zero. Engraftment and recovery after the transplant are counted as plus days. For example, a recipient may enter the hospital on day -8 for preparative regimen. The day of transplant is numbered zero. Days +1, +2, etc., will follow. There are specific events, complications, and risks associated with each day before, during, and after transplant. The days are numbered to help the recipient and family understand where they are in terms of risks and discharge planning.
During infusion of bone marrow, the recipient may have:
After the transplant, supportive care is given to prevent and treat infections, side effects of treatments, and complications. The recipient may:
Spend several weeks in the hospital
Be very at risk of infection
Have a lot of bleeding
Need blood transfusions
Be confined to a clean environment
Take multiple antibiotics and other medicines
Be given medicine to prevent GVHD—if the transplant was allogeneic. The transplanted new cells (the graft) tend to attack the recipient’s tissues (the host), even if the donor is a relative.
Have continual lab tests
Have nausea, vomiting, diarrhea, mouth sores, and extreme weakness
Have short-term mental confusion and emotional distress
After leaving the hospital, the recovery process continues for several months or longer. During this time the recipient can’t return to work or many activities. The recipient must also make frequent follow-up visits to the hospital or healthcare provider's office.
Engraftment of the stem cells happens when the donated cells make their way to the marrow and begin making new blood cells. Engraftment usually happens around day +15 or +30. The timing depends on the type of transplant and the disease being treated. Blood counts will be checked often during the days after transplant. This is done to assess the progress of engraftment. Platelets are often the last blood cell to recover.
Engraftment can be delayed in the body. This may happen because of infection, medicines, low donated stem cell count, or graft failure. The new bone marrow may begin making cells in the first 30 days following transplant. But it may take months or years for the whole immune system to fully recover.
The long-term outlook for a bone marrow transplant varies. It depends on the:
Type of transplant
Type and extent of the disease being treated
Disease response to treatment
Your age and overall health
Your tolerance of specific medicines, procedures, or therapies
Severity of complications
As with any procedure, in bone marrow transplant the prognosis and long-term survival can vary greatly from person to person. The number of transplants being done for an increasing number of diseases, as well as ongoing medical developments, have greatly improved the outcome for bone marrow transplant in children and adults. Ongoing follow-up care is essential for the recipient after a bone marrow transplant. New methods to improve treatment and to decrease complications and side effects of a bone marrow transplant are continually being discovered.
Before you agree to the test or the procedure make sure you know:
The name of the test or procedure
The reason you're having the test or procedure
What results to expect and what they mean
The risks and benefits of the test or procedure
What the possible side effects or complications are
When and where you're to have the test or procedure
Who will do the test or procedure and what that person’s qualifications are
What would happen if you didn't have the test or procedure
Any alternative tests or procedures to think about
When and how you'll get the results
Who to call after the test or procedure if you have questions or problems
How much you'll have to pay for the test or procedure