Most bone marrow transplants are used to help individuals with cancer fight the disease. A stem cell transplant lets a physician treat cancer very aggressively, with high doses of chemotherapy. Stem cell transplants are also used in non-cancerous conditions such as Aplastic Anemia and others.
How Stem Cell Transplants Work
Normal bone marrow produces three main types of blood cells and come from a "parent" cell - the stem cell:
- Red cells which carry oxygen
- Platelets which help prevent bleeding
- White cells which are part of the body's immune system and help fight infections
In a stem cell transplant, stem cells are collected from the blood or bone marrow and stored, the patient is given high doses of chemotherapy, and the stem cells are given back following chemotherapy. The choice between an autologous or allogeneic transplant is made according to the stage of disease, the recommendations of the physician and the patient's wishes.
Bone marrow: Bone marrow is the soft, sponge-like material found inside our bones. It contains stem cells that are capable of producing all the blood cells in our body. The bone marrow has the greatest number of stem cells; however, a small number of stem cells can also be found in the bloodstream. Stem cells divide to form more stem cells, or mature into white blood cells, red blood cells, or platelets.
Chemotherapy: Treatment with anticancer drugs.
Stem cells: Cells that develop into one of the three types of mature blood cells, red blood cells, white blood cells, or platelets. Stem cells can also divide to become new stem cells. Without stem cells one would not be able to live.
Red blood cells (RBC): RBC’s contain hemoglobin (Hgb), a protein that carries oxygen from the lungs to the rest of the cells in the body. When RBC’s decrease in number, one is said to have anemia. Anemia makes one pale and feel short of breath.
White blood cells (WBC): WBC’s are the body’s defense against infection. There are many different types of WBC’s. Each of the different types of white blood cells plays a specific role in destroying organisms that are foreign to the body. Low WBC’s can leave one at increased risk of infection.
Platelets (PLT ): PLT’s are sticky, disc-shaped cells that enable the blood to clot properly, which prevents excess bleeding. When platelets are low, risk of bleeding increases. Low platelets can cause bruising, nose bleeds or bleeding gums.
Stem Cell Sources
Bone marrow or stem cell transplant is a procedure that is used to “rescue” the bone marrow that has been destroyed by high doses of chemotherapy and/or radiation therapy.
There are three sources where stem cells can be found.
Bone Marrow - Stem cells were first collected from the bone marrow. This is how the name “bone marrow transplant” came about.
Blood Stream - More recently, researchers learned how to stimulate the stem cells in the bone marrow to move out into the blood stream where they can be collected. This procedure is called “peripheral blood stem cell transplant”.
Umbilical Cord - Stem cells are also found in the umbilical cord of the newborn baby. This procedure is called “umbilical cord stem cell transplant”. The umbilical cord is a rich source of stem cells; however, there are only enough stem cells in the umbilical cord to be used in a transplant for a child or small adult. Research is underway to learn how to stimulate the reproduction of these stem cells to a greater number to allow a transplant for an average size or large adult.
When Stem Cell Transplants are Needed
Stem cell transplants are performed when:
A disease affects the bone marrow causing the bone marrow to not be able to produce all the blood cells needed, because it either makes too many of one cell, as in leukemia, or too few cells as in aplastic anemia. The new stem cells given at the time of the transplant will divide and produce healthy new blood cells.
Chemotherapy and radiation are needed to treat a disease such as lymphoma which not only destroys the disease but the bone marrow. The transplant allows the bone marrow to be “rescued” by the stem cells given at the time of the transplant.