Bone Marrow Transplant

What is Bone Marrow?

Bone marrow is a fatty, spongy tissue present inside the bones. It produces some special cells called as stem cells. Stem cells are known for producing the important blood cells, which carry out some specialized functions. Red blood cells carry oxygen throughout the body. White blood cells are an important part of the immune system and they help fight infections. Platelets play a significant role in blood coagulation process and help stop bleeding outside the body. Without bone marrow and stem cells, blood cannot be produced.

What is Bone Marrow Transplant?

Bone marrow transplant (BMT) is also called as stem cell transplant. In this procedure, a damaged or diseased bone marrow is replaced with a healthy marrow. It was first successfully used in 1968. This procedure is generally performed when a patient doesn’t respond to high-dose chemotherapy or radiation treatment. BMT is relatively the latest technique, used to treat the diseases once thought incurable, including leukemia, multiple myeloma, aplastic anemia, immune deficiency disorders, lymphomas such as Hodgkin’s disease and some solid tumors such as ovarian cancer or breast cancer.

Types of Bone Marrow Transplant

Different types of bone marrow transplant are carried out such as allogeneic transplant, autologous transplant and syngeneic transplant. In autologous transplant, healthy bone marrow is taken from the patient’s body itself before undergoing radiotherapy or chemotherapy treatment and put back in the body when the treatment is over. This is also known as high-dose treatment and 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. In syngeneic transplant, stem cells are collected from the bone marrow or blood cells of an identical twin. Stem cells can also be collected from a newborn baby or an umbilical cord.

Why Bone Marrow Transplant is Required?

Bone marrow transplant is required when bone marrow is damaged or diseased and not functioning properly in certain medical conditions. In this situation, bone marrow 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 cells, decreased immunity and increased 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, chemotherapy), abnormal red cells production 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 syndrome.
• Certain forms of cancers such as lymphoma, leukemia and myeloma.

For undergoing the bone marrow transplant procedure, a recipient should be in relatively good health. If stem cells are received from the relatives with the same tissue types, then it minimizes a risk of transplant being rejected by the body. BMT is generally not recommended for the patients with kidney, liver, lungs and heart disorders and other diseases that can limit survival.

How Bone Marrow Transplant is Performed?

Undergoing bone marrow transplant can be a challenging and intensive experience. There are five stages in BMT procedure.

• The first stage involves a physical examination and general health checkup. The condition of your internal organs such as heart, liver and lungs is checked through scanning. If you have a cancer-related condition, then biopsy is needed to confirm the degree of cancer.
• The second stage includes obtaining stem cells for transplant. It is also known as stem cell harvesting. If you are undergoing an autologous transplant, then your own stem cells can be harvested. For this, bone marrow is removed using a special needle from the hipbone under general anesthesia. In an allogeneic transplant, the donor’s marrow is removed through a surgical procedure.
• Then the patient’s body is prepared for the procedure, which is also known as conditioning. For this, your body needs to receive several medicines. Therefore, a tube is inserted into a large vein near the heart, which is known as the central line. Because of this, you don’t have to undergo many painful injections. The conditioning process involves high doses of chemotherapy and possibly radiation. It is done to destroy any existing cancer cells, to destroy the existing bone marrow to make room for the transplanted tissue and to prevent functioning of immune system to avoid rejection of transplant. The conditioning process lasts for about 4-7 days.
• When the conditioning is finished, actual transplant procedure is performed after 1-2 days. The donated stem cells are passed 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 completes within an hour. This procedure is not much painful.
• During the first stage of recovery, stem cells start making new blood cells, which is called as engraftment. It occurs within 15-30 days after the transplant is conducted. Within this period, you have to receive regular blood transfusions because you will have a low red blood cell count. Due to decreased white blood cell count, your immunity is reduced. Hence, you need to remain in a sterile environment in the hospital. The visitors are advised to wear a gown, gloves and surgical mask to prevent the risk of infection. Once engraftment is completed, the body starts producing the blood cells.

Risk of Bone Marrow Transplant

Since BMT requires general anesthesia, the risk is associated with reaction to medications and breathing problems. Chemotherapy given 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 for 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.