Hyundai Cancer Institute :: Frequently Asked Questions About the Medical Basics of Bone or Marrow Transplant
The information below is provided by the CHOC Children's Blood and Marrow Transplant team. It is important to address specific questions and concerns about the transplant process with the patient's case coordinator or physician.
What is a blood or marrow transplant?
A blood or marrow transplant (BMT) is a special therapy for patients with certain cancers or other diseases. A transplant replaces unhealthy blood-forming cells with healthy ones. To prepare for the transplant, patients may be given strong chemotherapy and/or radiation therapy. These treatments kill the unhealthy cells. Healthy blood-forming cells (stem cells) are then given to the patient in a vein much like a blood transfusion. The transplanted stem cells begin to grow and make the red blood cells, white blood cells and platelets the body needs. This is called engraftment. Engraftment typically takes two to four weeks. Until the transplanted cells have engrafted, patients stay in the hospital.
What are stem cells?
Every type of blood cell in the bone marrow begins as a stem cell. Stem cells are immature cells that are able to produce other blood cells that mature and function as needed. Stem cells are the most important cells needed in a blood and bone marrow transplant. Stem cells, when transplanted, find their way to the recipient's marrow and begin to differentiate and produce all types of blood cells that are needed by the body.
Healthy stem cells come from three different sources:
- Bone marrow is sponge-like tissue that fills the hollow space inside bones. The bone marrow is responsible for the development and storage of most of the body's blood cells. This tissue contains the stem cells that produce red blood cells, white blood cells, and platelets. When a portion of a person’s bone marrow is collected for transplantation, it is called a “bone marrow harvest.”
- Peripheral blood is blood that circulates in the blood stream. Peripheral blood contains the same blood producing cells that are present in bone marrow. When a person’s peripheral stem cells are collected for transplantation, it is called a “peripheral blood stem cell collection” or “apheresis”.
- Umbilical cord blood is found in the umbilical cord of a newborn baby and is a rich source of stem cells that can be used in transplantation. Cord blood is collected from the umbilical cord of a newborn baby immediately after delivery. Once the cord blood has been collected, it is frozen and stored at a cord blood bank for future use. The stored cord blood is called a “cord blood unit (CBU).” Cord blood collection is a non-invasive procedure that is not harmful to either the mother or baby.
Why is a blood or marrow transplant needed?
The goal of a blood or marrow transplant is to cure many diseases and types of cancer. When a child's bone marrow has been damaged or destroyed due to a disease or intense treatments of radiation or chemotherapy for cancer, a transplant may be needed.
A blood or marrow transplant can be used to:
- replace diseased, non-functioning bone marrow with healthy functioning bone marrow for conditions such as leukemia, aplastic anemia and sickle cell anemia.
- replace the bone marrow and restore its normal function after high doses of chemotherapy or radiation are given to treat a malignancy. This process is often called "rescue" and used for diseases including lymphoma and neuroblastoma.
- replace bone marrow with genetically healthy functioning bone marrow to prevent further damage from a genetic disease process such as Hurler's syndrome and adrenoleukodystrophy disorder.
Blood and marrow transplants have risks involved, some of which are life threatening. The risks and benefits must be weighed in a thorough discussion with the transplant team prior to the procedure.
Each child experiences diseases differently and a transplant may not be appropriate for everyone who suffers from these diseases. Some of the diseases that have been treated with blood and marrow transplant include the following:
- some solid tumors (i.e., neuroblastoma, rhabdomyosarcoma, brain tumors)
- aplastic anemia
- immune deficiencies (severe combined immunodeficiency disorder, Wiskott-Aldrich syndrome)
- sickle cell disease
- Diamond-Blackfan anemia
- metabolic/storage diseases (i.e., Hurler's syndrome, adrenoleukodystrophy disorder)
- cancer of the kidneys
What are the different types of bone marrow transplants?
There are two different types of bone marrow transplants. An autologous BMT is an infusion of the patients' stem cells. An allogeneic BMT is an infusion of a donor's stem cells. This person may be either a family member (related donor) or an unrelated donor.
Related donors who are brothers or sisters and share the same parents have the highest chance of being a suitable donor since they may have inherited the same tissue type from their parents. Occasionally, a parent or an extended family member (half-siblings, cousins, etc.) is a donor match. Unfortunately, in many cases, parents may not be a good enough match to be their child’s donor. Immediate family members can take a blood test called “HLA Typing” to determine if there is an HLA matched donor in the family. This test is different than ABO blood typing. If no family donor match is found, the physician may request to search for an unrelated donor.
Unrelated donor searches are performed through The National Marrow Donor Program (NMDP). The NMDP has developed a registry of volunteer blood and marrow donors thar may be accessed to search for a donor on behalf of a patient in need of a BMT. Searching for an unrelated donor can take several months, sometimes even years.
What complications and side effects may occur following BMT?
Infections are common in children with severe bone marrow suppression. Blood tests are performed to prevent, detect and treat infections. Antibiotics, anti-fungal medications and anti-viral medications are often given to prevent serious infection. Bacterial infections are the most common and viral and fungal infections can be life threatening. Any infection can cause an extended hospital stay, prevent or delay engraftment, and/or cause permanent organ damage. Preventative measures for common sources of infection are also a part of transplant. This may include any or all of the following:
- special air filtered rooms
- diet restrictions
- isolation requirements
- restriction of visitors
- strict hygiene regimen
- frequent linen changes
Other complications can include:
- low platelets and low red blood cells
- fluid overload
- respiratory distress
- organ damage
- graft failure
- graft-versus-host disease
What is graft failure?
Failure of the graft (transplant) taking hold in the marrow is a potential complication. Graft failure may occur as a result of infection, recurrent disease or if the stem cell count of the donated marrow was insufficient to cause engraftment. Graft failure may be treated with an additional marrow transplant if a source is available.
What is graft-versus-host disease?
Graft-versus-host disease (GVHD) 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 cells do not recognize the tissues and organs of the recipient's body. The most common sites for GVHD are the gastrointestinal tract, liver, skin, and lungs. GVHD is graded from I to IV and can be acute (occurs suddenly or during the early period of transplant) or chronic (occurs over a period of time or during the later period of transplant). The child will be monitored closely for signs and symptoms of GVHD. Diarrhea, fever, rash, skin changes, abdominal pain, respiratory complications and decreased liver function may be present with GVHD. Medications are given prior to transplant to reduce the risk of this complication.
What is the long-term outlook for a BMT recipient?
As with any procedure, such as bone marrow transplant, prognosis and long-term survival can vary greatly from child to child. The amount of transplants occurring for an increased number of diseases, coupled with medical developments, has greatly improved the outcome for bone marrow transplant in children and adults. Continuous follow-up care is essential for the child following a transplant. New methods to improve treatment and to decrease complications and side effects of transplant are continually being discovered.
Can the recipient catch a disease from the donor?
Donors and cord blood units are carefully screened and tested. These tests are done to reduce the risk that a donor could pass a disease to a transplant patient. Before they are approved to donate, donors:
- are tested for infectious diseases such as AIDS and hepatitis.
- answer questions about their health history. This helps doctors find risks if the donors have an infectious or hereditary disease.
- are checked by doctors for signs of disease.
Marrow and cord blood donations are thoroughly screened, much the same as regular blood donations. Even so, donated whole blood cannot be guaranteed 100% free of infectious diseases. In the same way, the risk that donated blood or marrow cells carry a disease cannot be completely eliminated.