Stem Cell Transplant
What is a stem cell/bone marrow transplant?
- A transplant, at its most basic level, is a procedure where an individual receives healthy stem cells to replace stem cells that were damaged either because of disease or treatment. Stem cells are the source of the different types of blood cells in our body, including the white blood cells, which fight infection. As such, stem cells play a key role in the functioning of our immune system. Stem cells also give rise to the red blood cells, which carry oxygen, and the platelets, which aid in blood clotting.
Stem cells are found in the spongy center of our bones but can be collected from different places in the body.
The type of transplant a person receives depends in part on where the stem cells are collected.
- If the stem cells are collected from the bone marrow, which is the spongy tissue found in the cavities of the body’s bones, the procedure is referred to as a bone marrow transplant.
- If the stem cells are collected from the circulating blood, instead of from the bone marrow, the procedure is referred to as a peripheral blood stem cell (PBSC) transplant.
- If the stem cells are collected from the umbilical cord of a baby immediately after it is born, the procedure is referred to as a cord blood transplant.
The type of transplant also depends on who donates the stem cells:
- In an autologous transplant, the patient donates his/her own stem cells prior to treatment for reinfusion later.
- In an allogeneic related transplant, the person donating the stem cells is a biologically-related family member (usually a brother or sister).
- In an allogeneic unrelated transplant, the person donating the stem cells is not related to the patient but has been adequately tissue-matched.
- In a syngeneic transplant, the person donating the stem cells is an identical twin.
- Haploidentical transplant is a type of allogeneic transplant. It uses healthy, blood-forming cells from a half- matched donor to replace the unhealthy ones. The donor is typically a family member. For allogeneic transplants, your doctor tests your blood to find out your human leukocyte antigen (HLA) type.
Overview of the Transplantation Process
The autologous transplant is not necessarily performed because there is something wrong with the bone marrow or stem cells. It is performed because the dose of chemotherapy and radiation needed to treat the cancer in the body is so high that it will destroy the patient’s existing stem cells in the bone marrow. And without stem cells, the body cannot produce blood cells or an immune system. So, in cases where the patient’s stem cells are healthy, they are collected prior to the high dose chemotherapy/radiation and are stored for safekeeping. After receiving high doses of chemotherapy and/or radiation to treat the cancer, the stem cells are then re-infused into the patient’s body through a vein, just as in the case of a blood transfusion. The patient’s own cells thus “rescue” or restore blood cell production and the immune system. In most cases, it is recommended that the patient be in a full remission for the autologous transplant to be successful. However, in the case of some malignancies, patients with minimal disease can also be transplanted with their own stem cells. The chemotherapy given for transplant often destroys any remaining diseased cells. Even when the patient is in remission, it’s possible for some cancer cells to remain in the bone marrow or peripheral blood. In order to deal with this, some transplant centers have developed methods of purging or cleansing the stem cell product in an attempt to remove any remaining cancerous cells. The goal is to destroy enough diseased cells so that the body’s defense system will be able to destroy them after re-infusion. Purging is done differently from center to center, and many centers don’t do it at all. Bring up any questions you have about this procedure and the different methods used at different hospitals with your doctor and other medical professionals.
An allogeneic transplant is usually done when a patient has a disease or condition that affects their stem cells, such as leukemia or aplastic anemia or some genetic conditions. In these cases, the healthy stem cells of a donor are used to replace the patient’s damaged stem cells. Donors are all carefully screened to make sure that they are a good genetic match. Donors can be identical twins, siblings, or unrelated strangers. Once infused into the patient’s body, the new healthy stem cells from the donor will then migrate to the spongy tissue in the bone and generate new blood cells, including a new immune system. This can be important in preventing relapse after transplant because the donor’s immune cells can destroy any remaining cancer cells in the patient, thus reducing the risk of relapse. This is referred to as graft-versus-tumor (GVT) or graft-versus leukemia (GVL) effect. This graft-versus-tumor effect is one of the important treatment benefits of allogeneic stem cell transplantation.
To prepare for an allogeneic transplant, patients receive a conditioning treatment which involves chemotherapy with or without radiation. The purpose of conditioning treatment is to destroy any remaining cancerous cells in the body and also to weaken the patient’s immune system so that the new donor cells are not rejected and can grow and reproduce in the body. The duration and intensity of the conditioning treatment varies depending on the disease being treated and the age of the patient. Patients who are older or who have certain immune deficiencies may not require as intensive a conditioning regimen prior to transplant.
In cases where the conditioning treatment involves high doses of chemotherapy and/or radiation and destroys the stem cells in the body, the process is referred to as myeloablative (marrow destroying). In this type of transplant, the patient receives high doses of chemotherapy and/or radiation that will destroy the host immune system along with as many remaining cancer cells as possible. The process of destroying the stem cells in the marrow creates “marrow space” for the new donor stem cells to grow in. This type of transplant is associated with greater side effects because of the high-dose chemotherapy and/or radiation. However, it can lead to a lower risk of relapse (the cancer coming back).
Non-Myeloablative Transplant/Reduced Intensity Transplant
In cases where the conditioning is less intensive and only weakens the immune system, the conditioning treatment is called non-myeloablative (non-marrow destroying). In this type of transplant, the patient receives lower doses of chemotherapy and/or radiation that will not destroy his or her marrow completely. Instead, the treatment weakens the patient’s immune system just enough so that the donor’s stem cells are not rejected by the existing immune system. After this type of transplant, both the donor’s stem cells and the patient’s own stem cells can coexist (also called “mixed chimerism”). In a successful transplant, the donor cells will gradually fight off the patient’s blood and immune cells and establish a new donor immune system.
The National Bone Marrow Transplant Link, established in 1992, strives to help patients, caregivers, and families cope with the social and emotional challenges of bone marrow/stem cell transplant from diagnosis through survivorship by providing free programs and personalized support services.
Bone Marrow/Stem Cell Transplant Frequently Asked Questions
This booklet is intended for patients, caregivers, and families as they prepare for and enter the world of bone marrow/stem cell transplant. It was written as a helpful resource to give patients and families tools, information, encouragement, and support during their transplant journey.
Book contains both English and Spanish versions
Guide to Bone Marrow and Stem Cell Transplant, What to Expect and How to Move ForwardThis revised book, updated by Keren Stronach will guide patients, caregivers and health care professionals with much-needed guidance and support through the bone marrow and stem cell transplant journey before, during and after the procedure.
If I Am over 60, Am I Too Old for a Bone Marrow/Stem Cell Transplant?
Age is nothing but a number. However, some patients mistakenly think they are too old for a bone marrow or stem cell transplant. Dr. Marco Mielcarek busts that myth, and talks about different types of transplants and the patients who have benefited from them.
Addressing the Many Physical and Emotional Issues Following a Bone Marrow/Stem Cell TransplantThis webinar addresses the many issues that relate to survivorship including risks, treatments, bone health, cGVHD, steroids, secondary cancer, PTSD, meditation, mindfulness, healthy habits post-transplant and much more. (Caregivers and Health Care Professionals are also invited to join this webinar.)
We are here for you one on one or in a group setting, through a Coffee Klatch. Please email email@example.com should you want to talk to our licensed staff social worker, Jen Gillette or be placed on the list for a future Coffee Klatch, which is a 1.5 hour Zoom platform for up to 10 people, not recorded and intended to offer each other support and comfort on designated topics related to survivorship.
The information in these resources should not be construed as medical advice. Please consult with your health care provider regarding your medical decisions and treatment. The listed resources are not intended to be endorsements.