Bone Marrow Transplant
Bone marrow is the spongy soft tissue found within the interior of the bones. Bone marrow contains necessary blood-forming cells, (stem cells), connective tissues and fat cells. Within the bone marrow, stem cells develop into white or red blood cells (platelets), that help the blood to clot properly and keep the body healthy. These stem cells act as a repair system for the body, replenishing damaged tissues. A bone marrow transplant may be performed to replace bone marrow that is not functioning properly or has been destroyed. Bone marrow transplants, also referred to as stem cell transplants, provide the body with healthy cells so bone marrow function can be restored. Bone marrow transplants involve injecting healthy stem cells into the body to replace damaged or diseased stem cells.
Reasons for a Bone Marrow Transplant
A bone marrow transplant is performed to treat various diseases that damage or destroy the bone marrow. Most commonly, it is used in addition to chemotherapy, to treat cancers such as leukemia and lymphoma. A bone marrow transplant may also be performed on individuals with multiple myeloma, sickle cell anemia, or immunodeficiency syndromes. It is also used to restore bone marrow damaged by radiation or chemotherapy.
Types of Bone Marrow Transplants
A series of diagnostic tests are performed prior to the bone marrow transplant, to assess the health of the patient and determine whether they are a good candidate for this procedure. There are several types of bone marrow transplants that may be performed. Each procedure varies based on where the cells are harvested from.
Autologous Transplant
During an autologous transplant, stem cells are removed from the patient's own body prior to chemotherapy or radiation treatments, and stored in a freezer, or cryopreserved. After these treatments, the stems cells are put back into the patient's body to regenerate normal blood cells. This is also referred to as a rescue transplant.
Allogenic Transplant
For an allogenic transplant, stem cells are removed from another person, or a donor. Blood tests are performed prior to the transplant to ensure that the donor's genes are a match for the recipient. A family member is often a good match, but in some cases a donor may be found through a national bone marrow registry.
Syngeneic Transplant
A syngeneic transplant is performed with stem cells that are harvested from an identical twin or triplet. This is an ideal situation for a stem cell transplant, as the donor is someone who will have the same tissue type as the recipient.
The transplantation procedure involves infusing, or injecting, these stem cells through a vein into the recipient's body.
The Bone Marrow Removal Process
The bones of the hip contain the most marrow and contain a large numbers of stem cells. During the bone marrow removal procedure, the donor is sedated under general anesthesia. A needle is used to extract bone marrow from the back of the hip bone. The thick liquid marrow is pulled out through the needle. Once the stem cells have been harvested either from the patient or donor, they are processed and preserved.
Preparing for the Bone Marrow Transplant
Following pre-transplant tests, the patient will undergo a process known as conditioning. The portion of the treatment may require chemotherapy and/or radiation therapy. The conditioning process will usually last a few days and is customized for a patient based on their particular disease, overall health and the specific bone marrow transplant procedure that will be performed. Conditioning is necessary to destroy any malignant cells that are present as well as to suppress the immune system to ensure that the patient's body does not reject the transplanted stem cells.
The Bone Marrow Transplant Procedure
A few days after the conditioning process has been completed, the actual transplant takes place. The new stem cells are delivered into the bloodstream through a central venous catheter. This technique helps transport the stem cells through the blood into the bone marrow, initiating the formation of new blood cells. No sedation is necessary and the patient is awake during this process. The infusion usually takes several hours to complete. Within several weeks, the patient's blood count should start to recover and new blood cells will form.
Recovery from a Bone Marrow Transplant
Following a bone marrow transplant, patients are closely monitored through blood tests and other monitoring tests to assess their recovery and health. Medication may be necessary to manage side effects such as nausea and diarrhea. Some patients may have headaches or develop a fever after a transplant. In some cases, a transfusion of platelets and red blood cells may be needed, depending on how quickly the body begins producing adequate amounts of these cells.
Risks of a Bone Marrow Transplant
While some people experience little or no side effects from a bone marrow transplant, others may develop complications that may require additional treatment or hospitalization. There are risks associated with a bone marrow transplant, which may include:
- Infection
- Bleeding
- Blood clots
- Inflammation
- Damage to organs
- Graft failure
- Fever
- Hives
- Anemia
- Drop in blood pressure
After a bone marrow transplant, there is a risk of developing a condition called graft-versus-host disease. This condition occurs when the donor's transplanted stem cells attack some of the recipient's organs, which may include the skin, gastrointestinal tract, lungs, eyes and liver. This can affect the function of the organs and increase the chances of infection. These types of reactions are not uncommon and can range from mild to severe. Therefore, medical monitoring is extremely important after a bone marrow transplant. Complications and recovery vary greatly for each individual based on their age, illness, type of transplant and overall health.