A stem cell transplant is a procedure that is used in conjunction with high-dose chemotherapy, which is frequently more effective than conventional chemotherapy in destroying myeloma cells. Because high-dose chemotherapy also destroys normal blood-producing stem cells in the bone marrow, these cells must be replaced in order to restore blood cell production.
The first step in the process of stem cell transplantation is the collection of stem cells from a patient or a donor. When a patient's own stem cells are used, they are frozen and stored until needed. Stem cells can be collected from a donor when they are needed. The patient then receives high-dose chemotherapy and the stem cells are infused into the patient's bloodstream. The stem cells travel to the bone marrow and begin to produce new blood cells, replacing the normal cells lost during high-dose chemotherapy.
Stem cells are a remarkable type of cell that can divide and develop into any one of the three main types of cells found in the blood: Red Blood Cells, White Blood Cells and Platelets. There are mainly three sources of obtaining stem cells---Bone Marrow, peripheral Blood and Umbilical Cord Blood. Stem cells constitute only a small fraction (less than 1%) of all cells in the bone marrow and an even smaller percentage of cells in the peripheral blood. These days many Medical Practitioners suggest retrieving stem cells from the cord blood.
Without stem cells, blood cell production would cease. Therefore, stem cells that are lost during high-dose chemotherapy are replenished with a stem cell transplant, thus restoring blood cell production.
There are Three types of Stem Cell Transplantations
a) Autologous stem cell transplants (autografts) refer to stem cells that are collected from an individual and given back to that same individual. Most stem cell transplants in myeloma are autologous transplants.
b) Allogeneic stem cell transplants (allografts) refer to stem cells that are taken from one person and given to another. Currently, these types of transplant are performed much less frequently in myeloma in the US and are usually performed in the context of clinical trials.
c) Syngeneic stem cell transplants refer to stem cells that are taken from an identical twin of the recipient. These types of transplants are quite rare.
Lastly, there are also several types of transplants under investigation in clinical trials.
A tandem autologous transplant, also known as a double autologous transplant, requires the patient to undergo two autologous stem cell transplants within 6 months.
A mini (nonmyeloablative) allogeneic transplant involves the use of moderately high-dose chemotherapy in combination with an allogeneic stem cell transplant.
The Stem Cell Transplant Process
Stem cell transplantation is a complex process that involves several steps. The process is similar for both autologous and allogeneic stem cell transplants. However, in the case of autologous transplants, the patient will undergo the stem cell collection procedure prior to receiving high-dose chemotherapy and their cells will be frozen and stored until needed. In allogeneic transplants, a stem cell donor will typically undergo the collection procedure just before the transplant will be performed.
Stem Cell Collection:
Most of the stem cells in the human body reside in the bone marrow. Until recently, the only way to obtain stem cells for transplantation was to remove a portion of the bone marrow. However, through recent medical advances, it is now possible to collect stem cells from a person's peripheral blood (that is, from the arm or another site outside the bone marrow) and through the Umbilical Cord Blood (The Blood found in the cord after it has been clamped following the birth of baby). Today, most autologous transplants utilize peripheral blood stem cells (PBSCs). Bone marrow stem cells are more often used in allogeneic transplants, but PBSCs and Stem cells from the cord blood are beginning to be used more frequently
After the bone marrow or stem cells are collected, or at some later date, the patient will receive high-dose chemotherapy. The higher doses of chemotherapy are designed to destroy cancer cells more effectively than standard chemotherapy. Depending on the type of cancer and other factors, some patients may receive one or more treatments of high-dose chemotherapy, possibly in combination with radiation therapy, over a period of several days. This combination of treatments is also referred to as a conditioning regimen. These treatments, in addition to killing cancer cells, also destroy the blood-producing cells in the bone marrow, hence the need for the stem cell transplant. The chemotherapy drug melphalan is the most commonly used conditioning regimen in myeloma. Some patients may receive their high-dose chemotherapy on an outpatient basis.
Within a few days after completing the high-dose chemotherapy, the stored blood or bone marrow (or recently harvested allogeneic) stem cells are transplanted, or infused, into the patient's bloodstream. The infusion process is similar to a blood transfusion, and can be done on an outpatient basis in some cases. The frozen bags of bone marrow or blood cells are thawed in a warm water bath and infused into a vein over a period of 2 to 4 hours. The infused stem cells travel through the bloodstream and settle in the bone marrow, where they begin to produce new white blood cells, red blood cells, and platelets.
Potential Side Effects
Most of the significant potential side effects of stem cell transplantation are a result of the high-dose chemotherapy. Some of the more common temporary side effects include nausea, vomiting, diarrhea, mouth sores (oral mucositis), skin rash, and hair loss. Because the high-dose chemotherapy destroys blood-producing cells in the bone marrow, a patient is susceptible to infection, anemia, and bleeding caused by low blood cell counts until engraftment is complete. Graft-versus-host disease (GVHD) is a serious complication that can occur with allogeneic transplants.
Stem cell transplantation is all about collection and infusion of stem cells from the donor to recipient.
For more details on cord blood and cord blood transplantation log onto http://www.cordbloodinfo.org/cord-blood-transplant.html
