What are hematopoietic cell transplantation (HCT) and peripheral blood stem cell transplantation (PBSCT)?
HCT and PBSCT are procedures that use stem cells to treat a patient's malignancy or to repair diseased or defective bone marrow. A patient receives intensive chemotherapy with or without total body irradiation therapy in an attempt to kill all cancerous cells, but which also destroy his/her own bone marrow function. This therapy also causes immunosuppression, which prevents rejection of the newly transplanted stem cells from a related or unrelated donor.
There is little risk of rejection of a patient's own stem cells following autologous transplant. After transplantation, the new stem cells replace the damaged bone marrow and cells of the immune system.
How do HCT and PBSCT help patients?
HCT and PBSCT allow a patient to receive very high doses of chemotherapy and radiation designed to kill cancer cells. The high doses of therapy lead to the destruction of a patient's own marrow and immune system, which is then replaced by marrow from a donor or from peripheral blood stem cells that have been harvested before therapy.
How many HCTs and PBSCTs are performed at City of Hope?
City of Hope has performed more than 12,000 transplants for patients from virtually every state as well as from numerous countries. HCT and PBSCT patients at City of Hope have ranged in age from less than 1 year old to 79 years old. City of Hope's HCT program is one of America's largest, dedicated solely to the traditional and newer uses of this procedure.
Which diseases are HCT and PBSCT most frequently used to treat?
What is the difference between autologous and allogeneic HCT?
Patients receive one of two types of stem cell-based transplants: autologous, in which a patient donates and receives back his/her own stem cells; or allogeneic, in which bone marrow-derived stem cells come from a related or unrelated donor whose human leukocyte antigens (HLA) are genetically matched with those of a patient.
Peripheral blood stem cells are generally used in autologous transplantations, while either marrow or peripheral blood stem cells are used in allogeneic transplantations.
How long have HCTs and PBSCTs been done?
This process was first used in the early 1970s. City of Hope's HCT Program began in 1976. City of Hope began performing PBSCTs in 1988.
How are donors for allogeneic transplantations found?
About 30 percent of patients needing a transplant get one from a family member whose HLA testing has identified compatibility between a patient and donor. This matching of donor and recipient reduces the chance of marrow rejection and greatly increases the likelihood of a successful transplant. The remaining 70 percent of patients must find an unrelated donor whose marrow is compatible.
Currently, there are nearly 5 million volunteer donors in the National Marrow Donor Program (NMDP) Be The Match Registry. Almost 50 percent of patients searching the registry have at least one identically matched, unrelated donor. The NMDP is conducting a major effort at the 97 donor centers around the United States (of which City of Hope is one) to increase minority registration.
As of January 2001, only 25 percent of the potential donors registered were from racial or ethnic minorities. Because HLA types vary greatly between people of different ethnic backgrounds, increasing minority and ethnic representation will increase minority patients' chances of finding matches.
What is a mini-HCT?
Mini-HCT is a procedure that allows successful transplant of bone marrow without the use of high-dose chemo and radiation therapy. It is less intensive but allows transplant to be utilized in the treatment of older patients who may not be able to endure the intensity of traditional HCT transplant regimens.
Because many diseases, such as leukemia, lymphoma, myeloma and myelodysplasia, are more common in older patients, mini-HCTs allow these patients to potentially benefit from transplant.
What is bone marrow?
Bone marrow is the soft, spongy material found inside bones. Bone marrow contains stem cells that give rise to white blood cells (to fight infections), red blood cells (for oxygenation) and platelets (to prevent hemorrhaging). The chief function of bone marrow is to produce blood cells.
What are platelets?
Platelets are critical in the clotting process and to help control bleeding. Platelets are commonly used to treat leukemia and cancer patients undergoing chemotherapy and bone marrow transplants. Platelets are also used for trauma patients.
What are stem cells?
All blood cells develop from very immature cells called stem cells. Most stem cells are found in the bone marrow, although some, called peripheral blood stem cells, circulate in blood vessels throughout the body. Stem cells can divide to form more stem cells, or they can go through a series of cell divisions by which they become fully mature blood cells.
Who can donate bone marrow or peripheral blood stem cells?
Donating bone marrow or stem cell to someone suffering from a life-threatening disease is one of the greatest gifts you can provide, the gift of life. The first step is to join the National Marrow Donor Program (NMDP) Be The Match Registry. The NMDP maintains the registry of potential donors and searches this when people need a match. To join the registry, you need to complete a brief health questionnaire, sign a consent form, and provide a small blood sample to determine your tissue type.
At City of Hope, we ask that you donate a unit of blood or platelets to help offset the cost of a tissue-type test. Your tissue type will be compared to the tissue types of thousands of patients awaiting a bone marrow transplant. If you are ever a potential match, the City of Hope Donor Center will notify you to see if you are still interested in continuing with the process. If you are, a City of Hope staff member will request an additional blood sample. This sample will determine if the donor matches well enough to continue with the process.
Will patients need blood and platelet donations?
Blood donations from friends and family are a great source of encouragement and support for a patient needing transfusions. If your blood type is compatible with the patient, your donated blood can be given directly to your loved one. If your blood is not the same type, it is still important that you donate to help other City of Hope patients who are a blood type match and seriously in need of your help.
In most circumstances, platelet donations do not need be the same blood type. Therefore, most friends and family members can direct their platelet donations to their loved one. Because platelets can only be stored for 3-5 days, consistent support for our patients is crucial. You can help rally friends and family members by sponsoring blood drives for patients as well as arranging for group donations in our Donor Center.
Encourage friends and family members to call the City of Hope Blood Donor Center at (626) 471-7171 and schedule an appointment to donate blood and/or platelets or make arrangements for a blood drive in your community. To find a blood drive in your community, please call 626-301-8385.
Why do patients need platelets?
Before a patient receives a donor's marrow, his or her own marrow must be destroyed by a rigorous treatment of chemotherapy and/or radiation. Once the patient receives the donated marrow, it takes about 4 to 8 weeks for the new marrow to produce platelets. During that time period, the patient needs transfusions of platelets to help his/her blood to clot. City of Hope patients sometimes receive platelet transfusion on a daily basis.
What are the risks to marrow donors?
Virtually none. Bone marrow is extracted under general anesthesia in a procedure that takes less than an hour. Donors have commented that their buttocks felt sore for several days after aspiration. Contrary to organ donations, marrow is completely replenished by the body within a couple of weeks. There are no increased risks to the donor during this period. Historically, at HCT centers around the world, marrow has been donated by individuals less than 1 year old to 60 or 70 years old.
What are the possible complications associated with HCT and PBSCT?
Immediately following allogeneic transplantation, patients are immunosuppressed and unable to fight infection. Different drugs are administered during this critical period and isolation is sometimes necessary for the patient.
Another possible complication for patients receiving allogeneic transplantation is known as graft-versus-host disease (GvHD). Despite the close match between patient and donor, in GvHD, the donated marrow may recognize its new home as foreign and react against the host.
In addition, patients can acquire post-transplant cytomegalovirus (CMV) pneumonia. City of Hope has pioneered several outstanding advances for the prevention and treatment of this potentially fatal complication. Recurrent disease also is possible if the pre-transplant chemotherapy and irradiation therapy were not successful in killing all malignant cells.
In autologous transplantations there are few complications once the patient leaves the hospital, and the only risk is whether the disease will return, causing relapse.