Bone Marrow/Stem Cell Transplantation: About Bone Marrow/Stem Cell Transplantation

Bone Marrow

Bone marrow is found in the spaces in the center of your long bones in your body. Blood cells are made in the bone marrow: white blood cells (WBC) fight infection; red blood cells (RBC) carry oxygen; and platelets (PLT) help form clots to prevent bleeding. Stem cells are blood cells that have not yet become a specific kind of blood cell. All cells begin as stem cells. By transplanting stem cells we can regenerate your blood cell forming ability. Stem cells tend to remain in the bone marrow, where they can become any type of blood cell the body needs, but some go into general circulation in the blood vessels.

Bone Marrow or Stem Cell Transplant

A bone marrow transplant can also be referred to as a stem cell transplant and is a method of treating patients with specific types of cancers or bone marrow diseases. Examples of cancers and diseases that are treated with a stem cell transplant include leukemia, lymphoma, and multiple myeloma, amyloidosis and various inherited blood diseases like sickle cell anemia.

The decision to transplant and the type of transplant that a patient receives depend on a number of factors. These factors include the type and stage of cancer or disease, the availability of a suitable donor, and the potential risks and benefits for the patient.

There are two basic types of stem cell transplants. The types of transplants are named according to who donated the stem cells. If the person donating the stem cells is the patient, the transplant is called an autologous transplant or Auto for short (Auto means self). If the stem cells are donated by someone other than the patient, the transplant is called an allogeneic transplant or Allo for short (Allo means other). The person donating stem cells for an allo transplant can be a relative of the patient or someone not related to the patient. Before either type of transplant, a patient will receive high-dose chemotherapy, or a combination of chemotherapy and radiation. This prepares the body for the transplant by eliminating any abnormal or cancer cells in the patient’s blood stream and by destroying blood-forming cells in the marrow, to make room for new cells.

Autologous Stem Cell Transplant

Autologous means “from yourself.” Stem cells will form your new bone marrow after you have been treated. The stem cells in your blood are collected (harvested) before you are treated with high-dose chemotherapy called the “conditioning regimen.” We call this stem cell harvesting. You will have injections of G-CSF (Neupogen©) to help your body make more stem cells.
Stem cell harvesting is done in the Blood Donor Room and is very similar to giving blood. You will sit in a chair or lie in a bed. You can read or listen to music throughout your time there. It takes between three to four hours for each collection day. Several harvesting procedures (1 – 5) may be required to get enough stem cells to support an autologous stem cell transplant. With an Autologous Transplant, we know that your type of cancer responds to high doses of chemotherapy, radiation or both. A side effect of these is that your bone marrow will be wiped out. When your treatments are finished, the stem cells will be given back to you (“transplanted”) Diseases that we treat with Autologous Stem Cell Transplant include Lymphoma, Multiple Myeloma, Amyloidosis.

Allogeneic Stem Cell Transplant

An allogeneic stem cell transplant replaces your stem cells with new, healthy ones from a donor.  “Allogeneic” means that the stem cells come from a donor other than you.  You will have chemotherapy, radiation, or both to treat your cancer and/or suppress your immune system.  This will damage your normal bone marrow. You will then receive the transplant of the donor stem cells.

Allogeneic transplants are used to treat many diseases.  These include Leukemia, Lymphoma, Aplastic Anemia, Sickle Cell Anemia or other tumors and immune deficiencies that are present form birth.  The care you need before a transplant depends on your disease.  Your doctor will tell you why a transplant is used, why you cannot use your own stem cells, and what treatment plan is best for you.

 

Your Doctor will decide which type of donor is best for you.  It can be a related or unrelated donor.  The right donor is someone whose tissue type most closely matches yours. Family members will have a blood test to see what tissue type they have.  If no family member is a close match, your doctor will start a search with a donor registry. Depending on the situation a half-matched or haploidentical family donor may be utilized if a fully matched unrelated donor cannot be identified.

Myeloablative Transplant versus Non-Myeloablative Transplant

There are two approaches to treatment before an allogeneic transplant. One is called myeloablative. With this approach you receive high doses of chemotherapy with or without radiation. These treatments aim to kill your cancer but also kill (myeloablate) all stem cells in your bone marrow. The donor stem cells will then replace the ones killed by the treatment. This form of treatment is very strong and it may not be suitable for all patients.

Another approach involves a less intense treatment. It uses lower doses of chemotherapy with or without low doses of radiation. It also includes drugs that suppress your immune system. This type of transplant is called non-myeloablative or reduced-intensity conditioning. It aims to weaken your immune system and destroy enough stem cells to allow the donor stem cells to take over.
Your doctor will consider many factors when choosing which type of transplant is best for you. These include your disease, other treatments you have received, and your general health status.

How is a bone marrow/stem cell transplant done?

The transplant itself is not considered a surgery. Stem cells are infused into the patient's bloodstream intravenously much in the same way a blood transfusion is given.
It takes about a week for the new stem cells to find their way to the bone marrow. Once there, they begin to manufacture healthy cells, including red and white blood cells and platelets.

After several weeks, the body’s blood supply is replenished, and if the transplant is a success, the patient’s bone marrow is restored and begins making mature blood cells. Until that happens, however, the individual must be protected from infections and any activity or injury that might cause bleeding. As a result, Autologous transplant patients are usually hospitalized and carefully monitored for 2-3 weeks and Allogeneic transplants about 4 weeks. You will also be monitored very closely once you are discharged from the hospital.