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A stem cell transplant (also known as a bone marrow transplant) replaces defective or cancerous bone marrow with new, healthy bone marrow cells. This procedure is used to treat certain cancers, including leukemia and lymphoma. It can also help patients recover from or better tolerate cancer treatment.

What is a stem cell?

Stem cells are specialized cells that can mature into different kinds of cells, depending on what your body needs. They are located in various places throughout your body, including your bone marrow. Bone marrow contains hematopoietic stem cells that constantly divide to produce all the different kinds of blood cells. Young hematopoietic stem cells can mature into any of the following cell types:

• Red blood cells, which carry oxygen
• Platelets, which help the blood clot
• White blood cells, which help fight infection

Any disease or condition that impacts the ability of your bone marrow to produce new blood cells can have serious health consequences. Stem cell transplantation may be an effective treatment for such conditions.

What diseases do stem cell transplants treat?

Stem cell transplants are used to treat cancers and blood disorders that affect the bone marrow. Some of the most common conditions include:

• Blood cancers like leukemia, lymphoma, myelodysplastic syndromes, myeloproliferative disorders and multiple myeloma
• Bone marrow disorders like aplastic anemia
• Genetic blood diseases such as sickle cell anemia, and autoimmune diseases, like multiple sclerosis.

If your doctor recommends a stem cell transplant, it¡¯s often because other treatments haven't worked well enough or because your condition requires a stronger approach.

Who gets stem cell transplants?

A stem cell transplant might be an option if:

• You have a blood cancer that has come back or isn¡¯t responding to treatment
• Your bone marrow isn¡¯t making enough healthy blood cells
• You have a genetic or immune disorder that affects your blood or bone marrow

Your doctor will consider factors like your overall health, age, and type of disease to decide if a stem cell transplant is right for you.

What happens during a stem cell transplant procedure?

The process requires a hospital stay, careful monitoring, and protective measures due to the patient's vulnerable immune state. A stem cell transplant is a step-by-step process:

• Harvesting: Generally, the first step to a successful stem cell transplant is harvesting healthy bone marrow, either from the patient or from a donor. This procedure is often done at an outpatient clinic. This involves putting the patient or donor under general anesthesia and using a large needle to remove bone marrow from their pelvis. The bone marrow can then be frozen and stored.

Alternatively, stem cells can be collected from a patient's or donor¡¯s blood using a process called leukapheresis. This requires an injection that causes blood stem cells to move from the bone marrow into the bloodstream. During this process, blood is drawn, stem cells are separated and stored, and the remaining blood is returned to the patient. These stem cells are later infused back after high-dose treatment (the preparation phase) to help restore bone marrow function.

• Preparation (Conditioning Therapy): You¡¯ll receive high-dose chemotherapy (and sometimes radiation) to destroy diseased bone marrow cells and make room for new, healthy stem cells.
• Stem Cell Infusion: When it is time for the procedure, the donated marrow is thawed. The healthy stem cells are then given through an IV, much like a blood transfusion.
• Recovery & Engraftment: The new stem cells travel to your bone marrow and start making healthy blood cells. This can take a few weeks.
• Monitoring: You¡¯ll be closely watched for infections, side effects and complications. While you will be discharged from the hospital when your blood counts initially recover, full immune system recovery can take several months to a year.

Below are answers to common questions about what to expect during your hospital stay:

When will I be admitted to the hospital?

You¡¯ll usually check into the hospital a few days before the actual transplant. This is when you¡¯ll begin the conditioning therapy to prepare your body for the new stem cells.

How long will I be in the hospital?

• If you¡¯re getting your own stem cells (autologous transplant), you¡¯ll likely stay in the hospital for about two to three weeks.
• If you¡¯re receiving donor stem cells (allogeneic transplant), the stay is often a bit longer ¡ª around three to five weeks, depending on how your body responds.

When can I go home?

You can usually go home when:

• Your immune system has started to recover, especially your white blood cell counts.
• You can eat and drink enough, and don¡¯t need IV fluids or medications.
• There are no signs of serious infection or other complications.

Will I be in isolation during my stay?

Yes, you¡¯ll be in protective isolation while your immune system is very weak.

After the transplant, your body can't fight infections like it normally would. Isolation helps protect you from germs that could cause serious illness during this time.

What does that mean for me?

You¡¯ll have your own private hospital room with special air filters.

Nurses, doctors and visitors may wear masks, gowns and gloves to help keep you safe.

Certain items, such as fresh flowers, are not permitted in your room. However, thoroughly washed raw fruits or vegetables and outside food are allowed.

What are the two types of stem cell transplants?

There are two types of stem cell transplant: autologous and allogeneic.

Autologous stem cell transplant

In an autologous stem cell transplant, the patient¡¯s own healthy stem cells are collected through a process called leukapheresis. Autologous transplantation is most often used to treat diseases like lymphoma and multiple myeloma. Because autologous transplants use the cells of a patient, they have little to no risk of rejection or graft-versus-host disease (GVHD). This makes them safer than allogeneic transplants.

Allogeneic stem cell transplant

An allogeneic bone marrow or stem cell transplant uses donor stem cells to treat blood cancers that affect the bone marrow, like leukemia. The stem cells come from a donor whose tissue closely matches that patient. The donor cells are infused after the patient has undergone chemotherapy and, in some cases, total body irradiation. But beyond restoring the blood-producing ability of the body, allogeneic stem cell transplantation can help fight cancer directly. The donated cells generate a new immune response, meaning they find and kill cancer cells, sometimes better than the original immune cells of the patient. This is called the graft-versus-cancer effect, and it can help fight cancer.

Unfortunately, allogeneic stem cells come with an increased risk of rejection or graft-versus-host disease.

What are the side effects of a stem cell transplant?

Before the transplant, your doctors will need to prepare your body to receive the new stem cells. This is called the preparative or conditioning regimen. It consists of chemotherapy and radiation given several days before your transplant. Stem cell transplant side effects can be caused by the preparative regimen or by the transplant itself. 

Side effects can vary, but common ones include:

• Short-term: Fatigue, nausea, vomiting, mouth sores, hair loss and infections due to low immunity.
• Long-term: Weakened immune system, infertility, organ damage and a higher risk of developing another cancer.

Graft-versus-host disease

If you receive donor stem cells, your immune system may react to them, causing graft-versus-host disease (GVHD). This happens when the new immune cells from the donor see the patient¡¯s body as something to attack. GVHD can affect different parts of the body like the skin, liver and stomach, causing reactions like rashes, yellowing skin and stomach pain. There are two forms: acute GVHD, which appears shortly after the transplant, and chronic GVHD, which develops later and may be long-lasting. Doctors may use drugs to calm down the immune system and help manage these symptoms.

Finding stem cell donors

For allogeneic transplants to work, a patient needs to be matched with a donor whose human leukocyte antigen (HLA) proteins closely match theirs. HLA proteins dot your cells' surface and help your body distinguish normal cells from foreign cells. If the HLA proteins of a donor are a poor match to a patient, there is an increased risk of GVHD. 

HLA typing matches stem cell transplant patients with eligible donors. In HLA typing, a blood sample from a patient is compared with samples from family members or a donor registry. The best match is usually a sibling. However, about 75% of patients do not have a suitable matching donor in their family and require cells from a matched unrelated donor (MUD). Stem cell donors are located through registries such as the . It can sometimes take several weeks or longer to find a suitable donor.

If a suitable donor cannot be found, there are other options, including:

• Haploidentical transplants: This type of transplant uses bone marrow or peripheral blood stem cells from a first-degree relative (such as a parent, sibling or child) who is a half-match for a patient. Haploidentical transplants have become safer over time, and they have the benefit of decreased wait time. Safety has improved with changes to treatment plans before the transplant, medicines to help prevent GVHD, careful monitoring during the transplant process and additional medications to manage side effects.
• Umbilical cord blood transplant: The umbilical cord connects a fetus to the placenta during pregnancy. It contains hematopoietic stem cells. Once the baby is born, the umbilical cord is no longer needed. Its stem cells can be harvested and saved in a cord blood bank for use in cancer treatments. The MD Anderson Cord Blood Bank actively seeks donations of umbilical cords.