Bone marrow transplant is a procedure in which a healthy bone marrow is transplanted into a patient who has an unhealthy bone marrow. This procedure is performed to treat a number of medical conditions such as hereditary metabolic diseases, hereditary blood diseases, different types of cancers, and hereditary immune deficiencies. This article provides some useful information about this procedure and its types.
Bone marrow (BM) is a fatty, spongy tissue present inside some bones. It produces some special cells called stem cells. Stem cells are known for producing the important blood cells, which carry out specialized functions. Red blood cells carry oxygen throughout the body, while the white blood cells help fight infections. Platelets play a significant role in blood coagulation process and help stop bleeding. Without bone marrow and stem cells, blood cannot be produced.
Bone marrow transplant (BMT) is also called stem cell transplant. It was used successfully for the first time in 1968. This procedure is generally performed when a patient doesn’t respond to high-dose chemotherapy or radiation treatment. BMT is the latest technique used to treat the diseases which were once thought incurable, including leukemia, multiple myeloma, aplastic anemia, and immune deficiency disorders. It is also used to treat lymphomas such as Hodgkin’s disease, and some solid tumors such as ovarian cancer or breast cancer.
There are different types of bone marrow transplant such as allogeneic transplant, autologous transplant, and syngeneic transplant. In the autologous transplant, healthy BM is taken from the patient’s body before undergoing radiotherapy or chemotherapy treatment. Then, it is put back in the body once the treatment is over. This is also known as high-dose treatment or stem cell support. Sometimes, the marrow is purged of cancer cells, before it is put back.
In allogeneic transplant, stem cells are harvested from a related (sister or brother) or unrelated donor and transferred in the person. In the syngeneic transplant, stem cells are collected from the BM or blood cells of an identical twin. Stem cells can also be collected from a newborn or the umbilical cord.
BMT is required when the bone marrow is either damaged or diseased and not functioning properly in certain medical conditions. In this situation, the BM is no longer able to produce normal blood cells. It can give rise to some serious health problems such as reduced oxygen supply due to decreased number of red blood cell and decreased immunity. It can also increase the risk of developing serious infections due to less number of white blood cells, and bleeding disorders because of reduced platelets.
There are a number of conditions that affect bone marrow such as:
- Bone marrow deficiency disease caused by aggressive cancer treatments for lymphoma or leukemia (radiation therapy and chemotherapy), abnormal production of red blood cells in sickle cell disease or thalassemia, and lack of normal blood cell production in aplastic anemia.
- Immunodeficiencies (immune system disorders) such as congenital neutropenia and severe combined immunodeficiency (SCID) syndrome.
- Certain forms of cancers such as lymphoma, leukemia, and myeloma.
To undergoing the bone marrow transplant procedure, a recipient should be in a relatively good health. If stem cells are received from the relatives with the same tissue types, then it minimizes a risk of transplant rejection. BMT is generally not recommended for the patients with kidney, liver, lung, and heart disorders, or any other disease that can limit survival.
Undergoing BMT can be an intensive experience. There are five stages in a BMT procedure.
- The first stage involves a physical examination and general health checkup. The condition of the internal organs such as heart, liver, and lungs is checked through scanning. If a cancer-related condition is diagnosed, then a biopsy is needed to confirm the stage of the cancer.
- The second stage includes obtaining stem cells for the transplant. It is also known as stem cell harvesting. For this, the BM is removed from the hipbone using a special needle. This is done under general anesthesia. In an allogeneic transplant, the donor’s marrow is removed by a surgical procedure.
- After this, the patient’s body is prepared for the procedure, which is also known as conditioning. For this, a tube is inserted into a large vein near the heart, which is known as the central line. After this, high doses of immunosuppressant drugs are administered or radiation therapy is given. This kills all the cancer cells and the cells of the immune system. The decreased immunity ensures that there is no rejection of transplanted BM. The conditioning process lasts for about 4-7 days.
- When the conditioning is over, the actual transplant procedure is performed. The donated stem cells are supplied through the central line into the body. The marrow is inserted through a thin plastic tube known as Hickman line, usually in the groin or neck. This process is not painful and is completed within an hour.
- During the first stage of recovery, stem cells start making new blood cells, which is called engraftment. It occurs within 15-30 days after the transplant is conducted. Within this period, the person has to receive regular blood transfusions because the body is not producing blood, and he/she may have a low red blood cell count. Due to the decreased white blood cell count, the immunity is reduced; hence, one needs to stay in a sterile environment in the hospital. Once engraftment is completed, the body starts producing the blood cells.
Since BMT requires general anesthesia, the risks are associated with the reaction to medications and breathing problems. Chemotherapy before BMT procedure can cause significant toxicity, giving rise to diarrhea, mouth sores, lung damage, or liver damage. During the period of growth of bone marrow, patient is at high risk of infections. Another major problem is developing graft-versus-host disease (GVHD). In this case, the transplanted healthy marrow cells attack the patient’s cells. To prevent this, some immunosuppressant drugs can be given. However, it decreases body’s immunity to fight infections.
The transplant can completely or partially cure the condition. People can go home as soon as they start feeling better. However, it may take 1 year to completely recover.