Definition & Overview
A stem cell transplant, also called bone marrow transplant, is a medical procedure that infuses healthy stem cells back into the body following a successful cancer treatment.
Cancer patients undergo various treatment methods such as radiation therapy and chemotherapy, which are designed to destroy the cancer cells. Unfortunately, these treatments also destroy the bone marrow, a tissue that lies in the long bones and produces new blood cells. The goal of stem cell transplantation is to replenish the body's healthy cells and in some cases, to kill surviving cancer cells.
The procedure is recommended for patients with multiple myeloma, leukemia, neuroblastoma, some types of lymphoma, and blood-related genetic diseases. It is performed much like a blood transfusion in which the stem cells are injected into the body and travel through the blood until they reach the bone marrow. In the majority of cases, this procedure does not require surgery.
Two types of stem cell transplant
- Autologous – This type uses the patient's own stem cells, which are "harvested" before high-dose radiation or chemotherapy treatment is initiated. These cells are then infused back into the body following successful treatment. This type is highly advisable as it reduces the risk of serious complications (particularly graft-versus-host disease or GVHD) but patients who have weak or compromised bone marrow even before the cancer treatment has started do not qualify for it.
- Allogeneic – In this type, the stem cells are taken from a donor, which could be the patient's immediate family member or from various national bone marrow registries. Special tests are conducted to ensure that the donor's and patient's gene match to avoid complications. Under allogeneic transplant is umbilical cord blood transplant, in which stem cells are harvested from a newborn baby's umbilical cord.
Who should undergo and expected results
Stem cell transplant is recommended for patients whose bone marrow has been damaged or does not function properly due to the following:
- High-dose radiation or chemotherapy
- Congenital neutropenia
- Cancers that affect the marrow such as multiple myeloma, lymphoma, and leukemia, among others
- Sickle cell anemia
- Thalassemia (a condition that prevents the body from producing enough red blood cells)
- Germ cell tumors
- Some inherited and genetic diseases
- Aplastic anemia
- Hodgkin's and non-Hodgkin's lymphoma
- Myelodysplastic and myeloproliferative syndromes
The expected results are the recovery of blood counts to safe levels, treatment of the disease, and helping the patient restore his or her quality of life. However, realizing these goals is affected by several factors such as the patient's age and overall health condition, the type of bone marrow transplant, the type and dosage of chemotherapy or radiation therapy, if the donor's cells matches the recipient's cells, and if there are complications that developed throughout the procedure.
How the procedure works
Several tests and preparation are required before a stem cell transplant is initiated. Aside from a physical exam, various laboratory tests, and a thorough discussion of medical history, the patient is also encouraged to meet with a counselor to discuss the emotional stress that comes with the procedure. The patient's family and children are encouraged to join the counseling to help them understand the process, its risks and benefits, and expected results.
The procedure is completed in stages, which can take weeks or even months.
- Phase 1 involves the collection of blood stem cells. It begins by surgically placing a transplant catheter into a large vein. The white blood cell growth factor is then injected so the body will be strong enough to fight infection. The stem cell is then collected. This procedure is skipped if the patient will undergo allogeneic stem cell transplant where the needed stem cells are obtained from a donor or taken from a newly born baby's umbilical cord.
- Phase 2 involves administering cancer treatment such as high-dose chemotherapy and/or radiation therapy.
- Phase 3 involves the actual stem cell transplantation. As mentioned above, this is very much the same as a blood transfusion. The healthy cells are infused into the body using a central line. This procedure is performed while the patient is awake and is painless. The transplanted cells then make their way to the bone marrow and start to create new blood cells, a process that can take a few weeks to complete.
- Phase 4 focuses on ensuring that the patient recovers as expected. To make this happen, certain drugs will be given to suppress the immune system. Growth factors and antibiotics will also be provided. Blood transfusions will then be performed on a regular basis to manage symptoms and prevent possible complications.
Possible risks and complications
Some of the risks and symptoms that patients may develop after a stem cell transplant include:
- Chest pain
- Drop in blood pressure
- Shortness of breath
- Funny taste in the mouth
Meanwhile, complications include:
- Bleeding in different areas of the body such as brain, intestines, and lungs
- Blood clotting, particularly in small veins of the liver
- Organ damage, especially the kidneys, liver, heart, and lungs
- Early menopause
- Mild to extremely serious infections
- Stomach problems
One of the more serious complications is graft-versus-host disease (GVHD), wherein the newly transplanted donor cells attack the recipient's body. This can potentially damage the digestive tract, liver, lungs, and other vital organs. It also places the patient at a higher risk of developing severe infections. To counter the development of this complication, doctors typically provide medications to suppress the immune system following stem cell transplantation.
Bashir Q, Champlin R. Hematopoietic stem cell transplantation. In: Niederhuber JE, Armitage JO, Doroshow JH, et al., eds. Abeloff's Clinical Oncology. 5th ed. Philadelphia, PA: Elsevier Churchill Livingstone; 2013:chap 30.
Heslop HE. Overview of hematopoietic stem cell transplantation. In: Hoffman R, Benz EJ Jr, Silberstein LE, Heslop HE, Weitz JI, Anastasi JI, eds. Hematology: Basic Principles and Practice. 6th ed. Philadelphia, PA: Elsevier Saunders; 2012:chap 104.