Pediatric stem cell transplants: What to know

When chemotherapy alone isn’t successful in treating blood cancers like leukemia and lymphoma in pediatric patients, a stem cell transplant may be an option. They can also help treat some non-cancerous bone marrow diseases, like sickle cell disease, thalassemia, severe aplastic anemia and Kostmann syndrome.

To learn about pediatric stem cell transplants and what parents should know, we spoke with Priti Tewari, M.D.

What is a stem cell transplant?

Stem cells are produced in our bone marrow; they mature to become our red blood cells, white blood cells, platelets and the cells of our immune system.

Stem cell transplants replace damaged or defective stem cells with healthy cells. They can also help replace a weakened immune system. There are two types:

• Autologous stem cell transplants use a patient’s own stem cells to help fight cancers like high-risk Hodgkin lymphoma, Ewing’s sarcoma, medulloblastoma and neuroblastoma. These cancers may require high doses of chemotherapy. Autologous transplants use patients’ own healthy stem cells to help with recovery.
• Allogeneic transplants replace patients’ stem cells with healthy cells from a donor.

Are stem cells transplants safe for kids?

Stem cell transplants come with risks, but they can be an option for patients as young as only a couple months old.

With some non-cancerous diseases like severe combined immunodeficiency, the transplant should take place as soon as possible. Pediatric patients with this condition often have weaker immune systems and are at greater risk for infection.

With some inherited disorders, we may watch your child for a few years and allow the organs to mature a little bit before moving ahead with a stem cell transplant.

What are allogeneic stem cell donor options for pediatric patients?

Suitable donated stem cells should match your child’s cells. Siblings are sometimes -- but not always -- a match. If a sibling isn’t an option, we can look for a matched unrelated donor through the National Marrow Donor Program.

If we can’t find a matched donor, we can use an alternate donor. That could be a mismatched unrelated donor, an umbilical cord blood donation or a haploidentical donation, which is a half-matched family member like a parent or sometimes a sibling.

If you have a child with a condition that may require a stem cell transplant and you’re expecting a baby, it could be beneficial to preserve the baby’s umbilical cord in a process called umbilical cord blood banking. If the siblings’ cells are a match, the banked cord may be used for a transplant later.

How are donated stem cells extracted?

They’re extracted in two ways. With peripheral withdrawal, the donor receives growth factor shots to stimulate stem cell production. The cells are then removed intravenously by apheresis, a process like blood donation.

The second approach is called bone marrow harvesting. It removes the stem cells from the pelvic bone through a surgery; it requires general anesthesia. 

We decide which approach is best based on the diagnosis, the donor’s physical size and the child’s overall health. If the donor is another child, we take special precautions. We want to ensure the donor is willingly entering this process. At MD Anderson, the donating child meets with a separate doctor on our team, a psychologist, our ethicist and a child life specialist to ensure they understand the procedure.

How do patients prepare for a stem cell transplant?

To wipe out cancer cells and to help make space for the new stem cells, patients receive chemotherapy before the transplant. Some high-risk acute lymphoblastic leukemia patients may also receive total body irradiation, a type of radiation therapy.

If your child is receiving an allogeneic transplant, we often use immunosuppressive agents to help lower the risk of a side effect called graft-versus-host disease, which is when the patient’s body rejects the donated cells.

What are the side effects of a pediatric stem cell transplant?

Many patients experience pancytopenia, which is a decrease in red blood cells, white blood cells and platelet counts.

The conditioning chemotherapy and radiation therapy commonly cause mucositis, which is irritation and ulcers throughout the digestive tract and mouth. Patients also can have painful sores, stomach discomfort and diarrhea, but medications can help.

Also, it’s rare, but the organs that help process chemotherapy -- such as the kidneys, liver and lungs -- are at risk for failure.

Another risk is infection. During and following a stem cell transplant, patients have no immune system to help fight infections. So, even a cold can be dangerous.

But we closely monitor patients to identify side effects before they become life-threatening. That’s one of the reasons why patients stay in the hospital for about four to six weeks, but sometimes it’s more. Our goal before your child leaves the hospital is for the new stem cells to start growing inside the body. We also want to get your child comfortable and walking, taking sips of water and sleeping comfortably until their blood counts are up again. Once they’re well enough to leave the hospital, they’ll start coming in for checkups three to five days a week.

Do stem cell transplants affect fertility?

Cancer and its treatment can affect fertility. Every patient who’s beyond puberty sees our fertility specialists to learn about their risks and options.

It’s also very important to discuss fertility with patients with non-cancerous diseases since these conditions are often hereditary. We want to make sure patients understand what that means for their future children and what options they have for starting a family.

What does life look like after a stem cell transplant?

If all goes well, life typically starts feeling normal about a year after the transplant.

During that year, we’re weaning down the immunosuppressive agents to help build up your child’s immune system. So, if they go back to a traditional school and they get a virus from somebody, their bodies can fight it.

If your child has siblings in school, they’ll be exposed to germs. It can be challenging, but it’s important for everyone to wash their hands and avoid sharing cups, utensils and food. It’s very important to avoid being around others with colds or the flu, too.

What research is underway in kids with blood diseases?

CAR T cell therapy is a new type of immunotherapy that’s given like a stem cell transplant. It’s being used to treat B-cell acute lymphoblastic leukemia and certain lymphomas in patients ages 25 and younger. But the side effects can be severe. MD Anderson has developed the first guidelines for managing these side effects in kids to help more patients receive CAR T cell therapy more safely.

What's your advice for families considering a stem cell transplant?

There's a lot to learn, and it can be overwhelming. Ask your care team for resources to learn more at your own pace.

Request an appointment at MD Anderson online or by calling 1-877-632-6789.