A blood and marrow stem cell transplant is a procedure that replaces a person's faulty stem cells with healthy ones.
Stem cells are found in bone marrow, a spongy tissue inside the bones. Stem cells develop into the three types of blood cells that the body needs:
Small numbers of stem cells also are found in the blood and in the umbilical cord (the cord that connects a fetus to its mother's placenta).
Another type of stem cell, called an embryonic (em-bre-ON-ik) stem cell, can develop into any type of cell in the body. These cells aren't found in bone marrow.
Doctors use stem cell transplants to treat people who have:
The two main types of stem cell transplants are autologous (aw-TOL-o-gus) and allogenic (a-LO-jen-ik).
For an autologous transplant, your own stem cells are collected and stored for use later on. This works best when you still have enough healthy stem cells, even though you're sick. If you have cancer, the cancer cells are removed or destroyed from the collected cells.
For an allogenic transplant, you get stem cells from a donor. The donor can be a relative (like a brother or sister) or an unrelated person. You also may get stem cells from umbilical cord blood donated by an unrelated person.
To prevent problems, the donor's stem cells should match yours as closely as possible. Donors and recipients are matched through a blood test called HLA tissue typing.
The stem cells used in transplants are collected from donors in several ways.
A procedure called apheresis (a-fer-E-sis) may be used. For this procedure, a needle is placed in the donor's arm to draw blood. Then, his or her blood is passed through a machine that removes the stem cells from the blood. The rest of the blood is returned to the donor.
Stem cells might be collected directly from a donor's pelvis. This procedure isn't used very much anymore because it must be done in a hospital using local or general anesthesia (AN-es-THE-ze-ah). For this procedure, a hollow needle is inserted repeatedly into the pelvis, and marrow is sucked out of the bone.
Blood containing stem cells may be collected from an umbilical cord and placenta after a baby is born. The blood is frozen and stored at a cord blood bank for future use.
Stem cell transplants have serious risks. Some complications are life threatening. For some people, however, stem cell transplants are the best hope for a cure or a longer life.
Your doctor may recommend a blood and marrow stem cell transplant if you have a disease or condition that prevents your body from making enough healthy blood cells. Examples of such diseases and conditions include:
Your primary care doctor and an oncologist or hematologist will determine whether you need a stem cell transplant. An oncologist specializes in diagnosing and treating cancer. A hematologist specializes in diagnosing and treating blood diseases and conditions.
When deciding whether you need a stem cell transplant, your doctors will consider:
You also will have tests to make sure you're healthy enough to have the procedure. Your doctors will want to find out whether you have any medical problems that could cause complications after the transplant. (For more information, go to "What To Expect Before a Blood and Marrow Stem Cell Transplant.")
If you're going to get stem cells from another person, your doctors will want to find a donor whose stem cells match yours as closely as possible.
A close match can reduce the risk that your immune system will attack the donor cells. A close match also reduces the risk that cells from the donor's marrow or blood will attack your body.
People having stem cell transplants are matched with donors through a test called HLA tissue typing. HLAs are proteins found on the surface of white blood cells. Your immune system uses HLAs to tell which cells belong to you and which don't.
Because HLA markers are inherited, an identical twin is the best donor match. Brothers or sisters also can be good matches. However, many people don't have a good match in their families.
If no matching donor is found in your family, the search widens to include people outside the family. Millions of volunteer donors are registered with the National Marrow Donor Program. Your doctors will look for:
People who provide their own stem cells for later use don't need to go through HLA matching.
You also will need other medical tests and exams before a stem cell transplant. Your doctors will want to make sure you're healthy enough to have a transplant.
They also will want to find out whether you have any medical problems that could cause complications after the transplant.
Before a stem cell transplant, you might have blood tests to check for HIV, herpes, pregnancy, and other conditions. These tests help your doctors learn about your overall health.
A chest x ray creates a picture of the structures in your chest, such as your heart and lungs. The test can show whether your heart is enlarged or whether your lungs have extra blood flow or extra fluid.
Lung function tests can show whether you have a lung infection or disease. They also show how well your blood is able to carry oxygen throughout your body.
These tests provide detailed images of your body. They're used to see whether you have any tumors in your bones that might complicate a transplant.
Your doctor may recommend a complete dental exam to check for problems that might cause an infection after your transplant.
An EKG detects and records your heart's electrical activity. Echo uses sound waves to create a moving picture of your heart. The picture shows how well your heart is working and its size and shape.
A bone marrow biopsy helps show whether your bone marrow is making enough healthy blood cells. If you're being treated for a blood cancer, this test shows whether your cancer is inactive.
A blood and marrow stem cell transplant has three parts: preparation, transplant, and recovery in the hospital.
You'll check into the hospital a few days before the transplant. Using a simple surgical procedure, doctors will place a tube in a large vein in your chest. This tube is called a central venous catheter or a central line. It allows easy access to your bloodstream.
Doctors will use the central line to give you fluids, medicines, and blood products and to collect blood samples. The tube will stay in place for at least 6 months after your transplant.
To prepare your body for the transplant, your doctors will give you high doses of chemotherapy and possibly radiation.
This treatment destroys the stem cells in your bone marrow that aren't working correctly. It also suppresses your body's immune system so that it won't attack the new stem cells after the transplant. Some people may get more than one cycle of chemotherapy before the transplant.
The high doses of chemotherapy and radiation can cause side effects, including nausea (feeling sick to your stomach), vomiting, diarrhea, and tiredness. Medicines can help relieve these symptoms.
In older patients or those who aren't very strong, doctors may choose "reduced-intensity" treatment. This treatment involves lower doses of chemotherapy or radiation.
Your immune system will be very weak after this treatment, and you can easily get an infection. As a result, you'll stay in a hospital room that has special features, such as filtered air, to keep the room as clean as possible.
Doctors, nurses, and visitors will have to carefully wash their hands and follow other procedures to make sure you don't get an infection. For example, they may wear face masks while in contact with you.
Preparation before a stem cell transplant may take up to 10 days. The time depends on your medical situation, general health, and whether you need chemotherapy or chemotherapy and radiation.
A stem cell transplant is like a blood transfusion. During the procedure, you'll get donated stem cells through your central line. Once the stem cells are in your body, they will travel to your bone marrow and begin making new red blood cells, white blood cells, and platelets.
You'll be awake during the transplant. You may get medicine to help you stay calm and relaxed. Doctors and nurses will check your blood pressure, breathing, and pulse, and they'll watch for signs of fever or chills. Side effects of the transplant can include headache or nausea, but you may not have side effects.
The transplant will take an hour or more. This includes the time to set up the procedure, do the transplant, and check you afterward.
You'll stay in the hospital for weeks or even months after your stem cell transplant. In the first few days after the procedure, your blood cell levels will continue to go down. This is because of the chemotherapy and/or radiation you got before the transplant.
Your doctors will test your blood 7 to 10 days after the transplant to see whether new blood cells have begun to grow. They'll check your blood counts every day to track your progress.
You'll stay in the hospital until your immune system recovers and your doctors are sure that your transplant was successful. During your time in the hospital, your doctors and nurses will carefully watch you for side effects from chemotherapy and radiation, infections, graft-versus-host disease, and graft failure.
Having support from family and friends, especially having someone who can be with you most days in the hospital, can help you recover.
The chemotherapy and possible radiation you get before the stem cell transplant have side effects. These side effects may begin to occur a few days after the transplant. Some of these side effects are painful or uncomfortable; others are very serious.
Side effects include:
Doctors use mouth rinses, medicines, and other methods to treat these side effects. Some go away on their own once your blood cells begin to grow and your immune system recovers.
You can easily get infections after the transplant because your immune system is weak. Infections can be serious and may be caused by:
To prevent infections, you'll stay in a private room. The air will be filtered to keep germs out. Doctors, nurses, and others who visit you will wear face masks and carefully wash their hands. Your doctor may have you take medicine to fight infections, even if you don't already have an infection.
You also can take other steps to prevent infections, such as:
Donated stem cells can attack your body. This is called graft-versus-host disease (GVHD). Your immune system also can attack the donated stem cells. This is called graft failure.
GVHD and graft failure can be minor or life threatening. They can happen soon after transplant, or they might develop slowly over months.
For more information about these complications, go to "What Are the Risks of a Blood and Marrow Stem Cell Transplant?"
You'll stay in the hospital for weeks or even months after your blood and marrow stem cell transplant. Your doctors will want to make sure that you're healthy and strong enough to go home.
They'll also want to make sure:
During the first weeks and months after you leave the hospital, you'll make frequent trips to an outpatient clinic. This allows your doctors to track your progress. These visits will happen less often over time.
Staff at the clinic will teach you and your caregiver how to care for your central line (which will stay in place for at least 6 months after your transplant), how to watch for and prevent infections, and other ways to care for you. They also will tell you who to call and what to do in case of an emergency.
Recovery from a stem cell transplant is slow. It takes 6–12 months to recover normal blood cell levels and immune function. During this time, take steps to reduce the risk of infections. Also, get plenty of rest and follow your doctors' instructions about medicines and checkups.
The main risks of a blood and marrow stem cell transplant are infections, graft-versus-host disease (GVHD), and graft failure.
You can easily get infections after the transplant because your immune system is weak. The risk of infections decreases as your immune system recovers.
You can take steps to prevent infections, such as:
Transplant recipients sometimes are given vaccines to prevent viruses and infections, such as the flu and pneumonia. If you develop an infection, your doctor will prescribe medicine to treat it.
GVHD is a common complication for people who get stem cells from a donor. In GVHD, the new stem cells attack your body.
Acute GVHD occurs within 90 to 100 days of the transplant. Chronic GVHD begins more than 90 to 100 days after the transplant or goes beyond 90 days after the transplant.
GVHD can be minor or life threatening. Signs and symptoms include:
Doctors prescribe medicines to treat GVHD. Acute GVHD is treated with glucocorticoids, such as methyl prednisone, prednisone in combination with cyclosporine, antithymocyte globulin, or monoclonal antibodies.
Chronic GVHD is treated with steroids—usually cyclosporine and prednisone on alternating days.
Older people, people who have had acute GVHD before, and people who receive stem cells from mismatched or unrelated donors are at increased risk for GVHD.
Doctors can reduce your chances of getting GVHD by:
Graft failure occurs if your immune system rejects the new stem cells. It also can occur if not enough stem cells are used, the new stem cells are damaged during storage, or your bone marrow is damaged after the transplant.
Graft failure is more likely to occur in people who receive less preparation for their transplants. People who get stem cells from poorly matched donors also are more likely to have graft failure.
The chemotherapy and/or radiation you receive during transplant preparation can cause complications. Sometimes these complications occur long after the transplant.
Complications can include infertility, cataracts, new cancers, and damage to the liver, kidneys, lungs, or heart.
In some people who get stem cell transplants to treat cancer (such as leukemia), the cancer eventually comes back. This happens more often in people who use their own stem cells for the transplant (an autologous transplant) than in people who get stem cells from a donor (an allogenic transplant).
This difference occurs because stem cells received from another person recognize new cancer cells as foreign and destroy them. This is called the graft-versus-tumor effect. A person's own stem cells don't recognize the new cancer cells as foreign. This allows the cancer cells to grow and multiply.
Doctors use immunotherapy to help prevent or treat the recurrence of cancer in people who have had stem cell transplants. This treatment stimulates the immune system to attack cancer cells.
The National Heart, Lung, and Blood Institute (NHLBI) is strongly committed to supporting research aimed at preventing and treating heart, lung, and blood diseases and conditions and sleep disorders.
NHLBI-supported research has led to many advances in medical knowledge and care. For example, this research has helped evaluate treatments and therapies for many diseases and conditions.
The NHLBI continues to support research on various treatments, including blood and marrow stem cell transplants. For example, NHLBI-sponsored research includes studies that:
Much of this research depends on the willingness of volunteers to take part in clinical trials. Clinical trials test new ways to prevent, diagnose, or treat various diseases and conditions.
For example, new treatments for a disease or condition (such as medicines, medical devices, surgeries, or procedures) are tested in volunteers who have the illness. Testing shows whether a treatment is safe and effective in humans before it is made available for widespread use.
By taking part in a clinical trial, you can gain access to new treatments before they're widely available. You also will have the support of a team of health care providers, who will likely monitor your health closely. Even if you don't directly benefit from the results of a clinical trial, the information gathered can help others and add to scientific knowledge.
If you volunteer for a clinical trial, the research will be explained to you in detail. You'll learn about treatments and tests you may receive, and the benefits and risks they may pose. You'll also be given a chance to ask questions about the research. This process is called informed consent.
If you agree to take part in the trial, you'll be asked to sign an informed consent form. This form is not a contract. You have the right to withdraw from a study at any time, for any reason. Also, you have the right to learn about new risks or findings that emerge during the trial.
For more information about clinical trials related to stem cell transplants, talk with your doctor. You also can visit the following Web sites to learn more about clinical research and to search for clinical trials:
For more information about clinical trials for children, visit the NHLBI's Children and Clinical Studies Web page.
The NHLBI updates Health Topics articles on a biennial cycle based on a thorough review of research findings and new literature. The articles also are updated as needed if important new research is published. The date on each Health Topics article reflects when the content was originally posted or last revised.