What is a stem cell transplant?
Your oncologist has recommended that you receive very high-dose therapy to treat your cancer. This will include high-dose chemotherapy and possibly total body irradiation (TBI). This will destroy cancer cells, but unfortunately the treatment cannot tell the difference between cancerous cells and healthy cells.
High-dose therapy destroys many types of cells that divide and reproduce rapidly; including healthy cells that produce red blood cells, white blood cells and platelets. Without these blood cells, there is higher risk for infections, bleeding problems and lower amounts of oxygen in the blood.
Your own stem cells can be collected before high-dose therapy is given and returned to you intravenously afterwards to replace the stem cells that were destroyed. These stem cells may come from either the peripheral blood or bone marrow.
What is a stem cell?
A stem cell is the cell from which all blood cells develop. Blood cells are essential to life. The different types of blood cells are red blood cells, white blood cells and platelets.
White blood cells
White blood cells are the body's primary defense against infections. They are produced mainly in the bone marrow. White blood cells divide rapidly, have a relatively short life span and are very sensitive to therapy. While receiving high-dose chemotherapy, your white blood cell count will drop below normal.
- Normal white blood cell count: 3,000 to 10,000
Red blood cells
Red blood cells carry oxygen to the body's cells and tissues. When your red cell count is low, you may be considered anemic. The bone marrow is responsible for producing red blood cells. They generally live approximately 120 days. Because of their long life span, they are less affected by the high-dose therapy. Other measurements of red blood cell function are the hemoglobin and hematocrit. The hemoglobin is often used to determine whether you will need a red blood cell transfusion.
- Normal red blood cell count: 3.8 to 5.9 million
- Normal hemoglobin: 12 to 17 grams
- Normal hematocrit: 35 to 51
Platelets are small cells with a relatively short life span. They are produced in the bone marrow and help form clots that stop bleeding when tissues are damaged. While receiving high-dose therapy, your platelet count will also drop below normal.
- Normal platelet count: 140,000 to 420,000
What is the difference between bone marrow transplant and stem cell transplant?
A peripheral blood stem cell transplant is done to replace the same type of cell (stem cell) that is replaced in a bone marrow transplant. The difference is the method of stem cell collection. You will often hear stem cell transplant and bone marrow transplant used interchangeably.
To collect or "harvest" bone marrow stem cells for a bone marrow transplant, the patient is taken into the operating room and given general anesthesia. A needle can be inserted into the pelvic (hip) bones to draw out the bone marrow. This is repeated until enough bone marrow is obtained for the transplant. The area from which the marrow is drawn may be sore for several days.
In contrast to a bone marrow harvest, stem cell collection is done by a procedure called apheresis; without general anesthesia, involves little discomfort, can be performed in an outpatient setting, and offers a faster recovery. This is discussed in more detail in Stem Cell Collection.