Diagnostics
Bone Marrow Transplant
What is a bone marrow transplant?
A bone marrow transplant, also called a hematopoietic stem cell transplant, is a procedure that replaces damaged or diseased bone marrow with healthy stem cells.
The bone marrow is a soft tissue inside the bones responsible for producing important blood components, such as red blood cells, white blood cells, and platelets. Blood stem cells are transplanted into the body during a bone marrow transplant. These stem cells travel to the bone marrow and help create new blood cells, allowing the bone marrow to function properly. Bone marrow contains special cells called hematopoietic stem cells (HSCs) that can develop into different types of blood cells. These stem cells can multiply and produce more stem cells or differentiate into specific blood cell types. They are crucial in maintaining a healthy blood supply throughout a person’s life.
A bone marrow transplant may be necessary when the bone marrow fails to function properly and does not produce enough healthy blood cells. This may be due to chronic illness, infection, or cancer treatment.
Who performs bone marrow transplant?
Hematologists, oncologists, and transplant physicians carry out bone marrow transplants. These doctors have expertise in conducting and managing bone marrow transplant procedures.
Bone marrow transplant procedures are typically carried out in specialized transplant centers or hospitals with dedicated transplant units.
Types of bone marrow transplant
The two primary types of bone marrow transplants are autologous (using the patient’s own stem cells) and allogeneic (using stem cells from a donor).
Autologous Bone Marrow Transplant: The patient serves as their own donor in this type. Stem cells are collected from the patient either through bone marrow harvest (extracting stem cells from the soft center of the bone marrow using a needle) or apheresis (a process of collecting stem cells that float in the blood, i.e., peripheral blood stem cells).
Allogeneic Bone Marrow Transplant: In this case, the donor has the same genetic type as the patient. Stem cells are obtained from a genetically matched donor, often a sibling, through bone marrow harvest or apheresis. Other potential donors for allogeneic transplants include parents in rare cases or unrelated donors found through national bone marrow registries.
What are some reasons why a bone marrow transplant may be necessary?
Some reasons for a bone marrow transplant are:
- Aplastic anemia is a disease in which the bone marrow stops producing new blood cells.
- Cancers that affect the bones, such as leukemia, lymphoma, and multiple myeloma
- Drugs that cause bone damage
- Congenital neutropenia is an inherited disorder that causes recurrent infections.
- Sickle cell anemia is a congenital blood disorder that causes red blood cell abnormalities.
- Thalassemia is a congenital blood disorder in which the body produces an abnormal form of hemoglobin, an integral part of red blood cells.
How is a bone marrow transplant performed?
Preparing for a bone marrow transplant
- The medical team will assess the patient’s overall health, conduct tests, and evaluate eligibility for a transplant.
- If an allogeneic transplant is planned, the medical team will search for a suitable donor through bone marrow registries or family members.
- Before the transplant, the patient may undergo chemotherapy, radiation therapy, or a combination of both to eliminate diseased cells and prepare the body for transplant.
- The medical team will provide information on managing side effects, nutrition, and emotional support during the transplant process.
- A written consent is typically signed by the patient or family member after they have been provided with information about the surgery.
- A long, thin central line tube will be inserted into a large vein in the chest or neck. This tube will stay in place throughout the treatment and allows the delivery of transplanted stem cells, medications, and blood products into the body.
Transplant procedure
Collecting stem cells begins once a suitable match is found for a patient requiring a bone marrow transplant. This can be done through either a bone marrow harvest, which involves extracting stem cells from the soft center of the bone marrow using a needle, or a peripheral blood stem cell collection method.
The collected stem cells are infused into the patient’s bloodstream, similar to a blood transfusion. Over time, the transplanted stem cells find their way to the bone marrow, producing new, healthy blood cells.
Following the transplant, the patient will require close monitoring in a specialized unit to manage potential complications, such as infections and graft-versus-host disease (GVHD).
Once the new stem cells are introduced into the body, they circulate through the bloodstream and reach the bone marrow. Over time, these cells multiply and begin the process of producing fresh and healthy blood cells. This crucial phase is known as engraftment. Typically, it takes several weeks for the blood cell count to start returning to the normal range. However, in certain individuals, this process may take longer. Engraftment occurs when the transplanted stem cells establish and produce new blood cells in the patient’s bone marrow.
Post-transplant care and follow-up
- The patient will need to stay in the hospital for at least a few weeks until the transplant starts to take effect.
- The patient will need to take medications to prevent infection, manage GVHD (if applicable), and support the function of the transplanted cells.
- Following a bone marrow transplant, it may be necessary to make dietary adjustments to maintain overall health and prevent excessive weight gain.
- Regular follow-up visits with the doctor will be necessary to monitor progress, address any complications, and provide supportive care.
The risk associated with bone marrow transplant
Stem cell transplants are complex procedures that carry significant risks. It is crucial to have a clear understanding of both the risks and potential benefits before undergoing treatment.
Potential complications that can arise during or after the transplant process include:
- In allogeneic transplants, where donor cells are used, there is a risk of Graft-versus-host disease (GvHD). This occurs when the transplanted cells recognize the recipient’s body as foreign and attack healthy cells.
- Following the transplant, there may be a decrease in the number of blood cells, leading to conditions such as iron deficiency anemia, increased susceptibility to infections, excessive bleeding, or bruising.
- Patients with severe bone marrow suppression are at high risk of developing infections, primarily bacterial infections. However, viral and fungal infections can be life-threatening. Infections can lead to prolonged hospital stays, hinder engraftment, and potentially cause permanent organ damage. To prevent serious infections in immunosuppressed patients, doctors often administer antibiotics, antifungal medications, and antiviral drugs.
- A potential complication of a bone marrow transplant is the graft (transplanted cells) failing to take hold in the recipient’s marrow. Graft failure can occur due to infection, recurring disease, or if the donated marrow’s stem cell count is not enough to establish successful engraftment.
- During a transplant, the respiratory status, or breathing function, is a critical aspect that may be affected.
- Chemotherapy can cause side effects such as nausea, fatigue, hair loss, and infertility.
Discussing these potential risks with doctors and being aware of the steps they will take to monitor and manage any complications that may arise during the transplant process is important.
References
- Mayo Clinic. Bone marrow transplant. Available from: https://www.mayoclinic.org/tests-procedures/bone-marrow-transplant/about/pac-20384854
- Bone Marrow Transplantation. Available from: https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/bone-marrow-transplantation
- Bone marrow transplant. Available from: https://www.healthline.com/health/bone-marrow-transplant
- Overview of stem cell and bone marrow transplants. Available from: https://www.nhs.uk/conditions/stem-cell-transplant/
