Bone Marrow Transplantation and Peripheral Blood Stem Cell Transplantation: Questions and Answers
- Hematopoietic or blood-forming stem cells are immature cells that can mature into blood cells. These stem cells are found in the bone marrow, bloodstream, or umbilical cord blood (see Question 1).
- Bone marrow transplantation (BMT) and peripheral blood stem cell transplantation (PBSCT) are procedures that restore stem cells that were destroyed by high doses of chemotherapy and/or radiation therapy (see Questions 2 and 3).
- In general, patients are less likely to develop a complication known as graft-versus-host disease (GVHD) if the stem cells of the donor and patient are closely matched (see Question 5).
- After being treated with high-dose anticancer drugs and/or radiation, the patient receives the harvested stem cells, which travel to the bone marrow and begin to produce new blood cells (see Questions 11 to 13).
- A "mini-transplant" uses lower, less toxic doses of chemotherapy and/or radiation to prepare the patient for transplant (see Question 15).
- A "tandem transplant" involves two sequential courses of high-dose chemotherapy and stem cell transplant (see Question 16).
- The National Marrow Donor ProgramÂ® (NMDP) maintains an international registry of volunteer stem cell donors (see Question 19).
1. What are bone marrow and hematopoietic stem cells?
Bone marrow is the soft, sponge-like material found inside bones. It contains immature cells known as hematopoietic or blood-forming stem cells. (Hematopoietic stem cells are different from embryonic stem cells. Embryonic stem cells can develop into every type of cell in the body.) Hematopoietic stem cells divide to form more blood-forming stem cells, or they mature into one of three types of blood cells: white blood cells, which fight infection; red blood cells, which carry oxygen; and platelets, which help the blood to clot. Most hematopoietic stem cells are found in the bone marrow, but some cells, called peripheral blood stem cells (PBSCs), are found in the bloodstream. Blood in the umbilical cord also contains hematopoietic stem cells. Cells from any of these sources can be used in transplants.
2. What are bone marrow transplantation and peripheral blood stem cell transplantation?
Bone marrow transplantation (BMT) and peripheral blood stem cell transplantation (PBSCT) are procedures that restore stem cells that have been destroyed by high doses of chemotherapy and/or radiation therapy. There are three types of transplants:
- In autologoustransplants, patients receive their own stem cells.
- In syngeneic transplants, patients receive stem cells from their identical twin.
- In allogeneictransplants, patients receive stem cells from their brother, sister, or parent. A person who is not related to the patient (an unrelated donor) also may be used.
3. Why are BMT and PBSCT used in cancer treatment?
One reason BMT and PBSCT are used in cancer treatment is to make it possible for patients to receive very high doses of chemotherapy and/or radiation therapy. To understand more about why BMT and PBSCT are used, it is helpful to understand how chemotherapy and radiation therapy work.