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Resource Guide for Bone Marrow/Stem Cell Transplant
Understanding the Process
Bone marrow is the spongy tissue found in the cavities of the body’s bones where all of the blood cells are produced. Every type of blood cell in the marrow begins its life as a stem cell. A stem cell is often defined as a “parent cell” which divides and forms the different cells that make up the blood and immune system. Stem cells are found in the bone marrow, in cord blood, and, in smaller numbers, in the circulating (peripheral) blood. Stem cells produce:
The goal of a stem cell transplant is to cure many different types of cancer and disease. The type of transplant you have will depend on who donates the stem cells.
Stem cells can be collected from the following sources:
Many elements of your transplant are beyond your personal control. It may be a good time to shift your focus to those factors that can be controlled or influenced by you. You should begin to investigate what resources you will have available to you before, during, and after transplant. It is important that you educate yourself about the transplant procedure.
Oddly enough, however, cancers that originate in the bone marrow, such as certain types of leukemia, are sometimes treated with autologous stem cell transplants, particularly if it is not possible to use the stem cells of a donor. Since the marrow is where the cancer originates, it is difficult to obtain totally unaffected stem cells. Even when the patient is in remission, it’s possible for some cancer cells to remain in the body. In order to deal with this, many transplant centers have developed methods of purging or cleansing the stem cell product and ridding it of most of the cancerous cells. The goal is to keep the diseased cells in such a small number that the body’s defense system will be able to destroy them. Purging is done differently from center to center. Some centers, in fact, don’t do it at all. If you have questions about these issues, ask them. Your doctor and other medical professionals should be able to get you the information that you need.
Allogeneic SCT patients must have a donor identified for them in order to receive new stem cells. The choice of donor and source of stem cells will be determined by your physician. You should understand the rationale for choosing a particular donor and source of stem cells. Often a donor is a brother, sister, or another family member. Each sibling offers a 25% chance of being a match. Having an identical twin sets you up for a perfectly matched syngeneic transplant.
When there’s no related donor match for you, a search is initiated to locate a “matched unrelated donor” (MUD). How are unrelated matches found? There are a number of donor and cord blood registries worldwide. The National Marrow Donor Program is one of the largest computerized registries and keeps an extensive database of potential donors and cord blood units. The chance of finding an unrelated donor from the general population depends on the uniqueness of your tissue type. Genetic and ethnic background may also affect the likelihood of finding a donor. With the availability of more accurate laboratory tests, the ability to identify closely matched donors is improving.
Knowing who should and should not be tested as a donor is often a topic of concern. Friends, coworkers and others interested in becoming a stem cell donor may either contact a local donor center or one of the large registries like the National Marrow Donor Program (see Resource Listing). These organizations will be aware of when and where donor drives are occurring. The general criteria for becoming a donor include factors such as general health status, weight, and age. Those who will generally not be able to serve as a stem cell donor include people with a history of severe heart problems, cancer, hepatitis, insulin dependent diabetes, or HIV. Cord blood units undergo a similar screening process. Donors are screened for conditions that would put them at too great a risk to donate as well as for illnesses that could be harmful to the patient.
Your transplant center contacts the registries to begin a preliminary donor search. There is no cost for a preliminary search. Charges for a formal search vary, so check with your insurance company to find out what coverage is offered regarding donor searches. If you have questions about any part of the donor search process, speak to your doctor or transplant coordinator. Don’t be in the dark about the status of your search.
Two factors are important in locating a match. The first is a test known as HLA (human leukocyte antigen) typing. The antigen is a substance, acting like a marker, unique to you, not unlike a set of fingerprints. A simple blood test is all it takes to begin the process of HLA typing. Most HLA typing today is performed using a DNA based method to match patients and donors. DNA testing allows patients and donors to be more closely matched. The goal is to find a match for at least six key antigens. The ability to identify donors is improving and some transplant centers are trying to match even more antigens.
The second factor in finding a matched unrelated donor may be the amount of representation of your ethnic or racial group in the registries. Because these antigen/tissue types are inherited, and some are unique to racial or ethnic backgrounds, the greatest chance of locating a donor may come from the same group. A lack of donors in your ethnic or racial group may make it more difficult to locate a match. Ambitious efforts to increase the number of minority donors on the registries are underway.
You do not have to have the same blood type as your donor to be a suitable match. If blood types are different, the patient will become the donor’s blood type after the transplant. This is because the stem cells from a donor have been “programmed” to produce the donor’s blood type and will continue to do that in their new environment.
A cord blood transplant may be a possibility if you meet specific criteria. The use of cord blood is based on the size of the unit as the number of stem cells required is based on the patient’s weight. Some transplant centers are conducting research to combine multiple cord units for transplant in order to provide the necessary number of stem cells.
It is important to remember that it takes time to carry out a donor search. Your transplant center manages the search and will inform you of the results. If you’ve been told there are potential unrelated donor matches for you, more time is required to identify the best matched donor. A formal search begins to narrow down candidates and generally takes several weeks or months (a cord blood search usually takes less time). If a donor is located, willing, and eligible, then final evaluation begins. If no suitable matches are found, other strategies need to be discussed with your doctor.
Bone Marrow Stem Cell Transplant
Peripheral Blood Stem Cell Transplant
Cord Blood Transplant
Umbilical cord blood is a rich source of stem cells. The umbilical cord stem cells, instead of being discarded, may be removed from the placenta and attached umbilical cord after delivery of a baby. This procedure poses no danger to the mother or child’s health. The cord blood unit can then be frozen and stored for future transplant. Arrangements for the collection of the cord blood unit must be made several months prior to the expected date of delivery. Unless there is an existing reason to save a cord blood unit for a family member, the current medical recommendation advises against long-term cord blood storage. However, some hospitals allow parents the opportunity to donate their child’s umbilical cord blood to an unrelated donor registry. Interested parents should speak with their doctor about this option. Improved coordination of the cord blood registries and increased cord blood unit donation will help in identifying suitable cord blood products. CBT may be particularly valuable in meeting the desperate need for stem cell donors in minority groups. Readers are advised to discuss the most recent recommendations for CBT or cord blood donation with their physician to keep up with the latest findings.
However, T-lymphocytes are also beneficial as they help the donated stem cells take hold or engraft, and they play a role in reducing the risk of relapse. Although T-lymphocytes pose a risk to the patient because they attack healthy cells — as in GVHD — they also attack residual cancer cells in a process known as graft versus leukemia effect, thus reducing the risk of relapse.
Donor Lymphocyte Infusion (DLI)
In the future, DNA technology (gene testing) will lead to a better understanding of what triggers malignancies in the body’s cells, and high doses of chemotherapy may be replaced with new treatment options.
Your doctor will discuss with you what type of transplant and what source of stem cells is best for you. Many factors determine the type of transplant including the disease being treated, previous treatments, age, general health, donor availability, and method of stem cell collection. It will be up to you and your doctor to decide how the transplant is handled. Whatever method is used for the stem cell collection, the desired outcome is the same—that the retrieved stem cells will flourish in the recipient.
Clinical research studies validate new treatment in three phases. Phase I research studies establish optimal dosage. In phase II research, safety and effectiveness are carefully defined. Phase III studies compare and contrast a new treatment with standard treatment. In this phase, patients who participate are randomly assigned to receive one treatment or the other.
The potential benefits of participation in a clinical trial include:
The potential drawbacks of participation may include:
Ask your doctor or medical center to locate where clinical research studies are being conducted. One source for a listing of independent clinical trials is the Physician’s Data Query (PDQ). It is a computer database focusing on cancer treatment information. To find out about these studies, contact the National Cancer Institute (see Resource Listing).
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