How Do Stem Cell Transplants Work?

by Judi Ebbert, PhD, MPH, RN Health Writer

A stem cell transplant is a medical procedure to help or cure people suffering from certain types of cancer. The procedure starts with removal of healthy blood or marrow stem cells from a matched donor (or, in some cases, themselves). The cells are safely stored, usually by freezing. The donated stem cells are given by infusion to the person with cancer.

Stem cells.
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What are stem cells?

Stem cells are uniquely special cells. That’s because stem cells can transform into different types of cells, repairing and healing tissue. We all have stem cells in various organs. Many lie dormant for years until awakened to repair an injury. Remember the aftermath of the insult you wrongly thought fell on deaf ears? Stem cells to the rescue!

Stem cell diagram.
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Where do stem cells come from?

Adult stem cells are in bone marrow, blood, muscles, and organs like the brain and liver. Another source of stem cells is called cord blood. That’s the blood in a newborn’s umbilical cord, the part that’s discarded after a baby is born. Parents can donate their newborn’s cord blood. For information, call 1-800-627-7692 or visit Be the Match.

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Are there other names for a stem cell transplant?

Yes. A stem cell transplant can be called bone marrow transplantation, blood and marrow transplant, peripheral blood stem cell transplantation, and blood-forming stem cell transplant. They refer to the same procedure. Transplant and transplantation mean to move from one source to another. Bone marrow, which is inside bones, produces blood cells.

People with connections.
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How are donors and recipients “matched”?

Donor and donee require at least six matched markers in their Human Leukocyte Antigen (HLA). HLA is a protein that helps the immune system detect troublemakers. Think of it like this. Dating services predict great matches when pairs score high on shared behavioral traits. Transplant teams see better outcomes in pairs with the most shared markers.

DNA mouth swab.
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How can you donate?

It’s easy. HLA analysis requires a blood sample or a swab of cheek cells. Donor matching resources include Be the Match, sponsored by the National Marrow Donor Program. The Gift of Life provides information on donating and has a convenient link for ordering a swab kit. You can view a video of the cheek swab procedure here.

Blood donation.
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What happens when you donate stem cells from blood?

You get several daily injections of filgrastim, a growth-factor drug that speeds up bone marrow production of stem cells, which go into the bloodstream. Blood is removed by a catheter in the arm over 2 to 4 hours. This may be repeated over a few days. Stem cells are separated from the blood, which is returned through the same or a second catheter.

Bone marrow extraction.
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What happens when you donate stem cells from bone marrow?

A bone marrow harvest is done in an operating room under general anesthesia. The doctor uses a needle to penetrate the back of the hip bone, extracting 2 pints of marrow. It can take 2 hours, and the body replaces the donated amount in about a month. The donor can leave the hospital within a day, and soreness in the hip lasts a few days.

Blood cells.
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Which cancers can be treated by stem cell transplants (SCTs)?

  • Multiple myeloma: abnormal plasma cells cluster in bones or marrow.
  • Leukemia: abnormal bone marrow cells overproduce a type of blood cell.
  • Lymphoma: white blood cells grow out of control, weakening the immune system.
  • Neuroblastoma: nerve cell overgrowth impedes brain signals to the body.
  • The impact of SCTs on other cancers is being studied.
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Are there different types of stem cell transplants?

Yes, three to be exact. An autologous transplant means a person receives his or her own cells —the donor and donee are the same person. In a syngeneic transplant, the recipient get cells from an identical twin. In an allogeneic transplant, the recipient gets stems cells from a parent, sister, brother, or matched non-blood-related donor.

Patients in a waiting room.
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Where are stem cell transplants done?

Surprisingly, some transplants can be done in an outpatient setting. Others require an inpatient stay in the hospital. The transplant team will decide which setting is appropriate on a case by case basis.

Doctor using a stethoscope on a patient.
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What happens before the transplant?

A complete exam precedes imaging, blood, heart, and lung function tests. Next is conditioning: chemo- or radiation therapy over 1 week to 2 weeks. Conditioning kills cancer cells and makes room for the new stem cells in the recipient’s bone marrow. It also suppresses the immune system to reduce risk for rejection of the stem cells.

Blood transfusion.
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What happens during the transplant?

Receiving stem cells is similar to a blood transfusion. Rigorous behind-the-scenes preparation ensures that the stem cells are ready for the recipient, who will be awake and feel no pain. Side effects are rare and may include fever or chills, shortness of breath, hives, and low blood pressure. The detailed procedure is at this ACS link.

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How effective are stem cell transplants?

Very effective. The U.S. Patient Survival Report predicts length of survival (LOS) for nearly 140 disorders. Pick a disorder, and select total remissions and donor type alone or with age, sex, race, and cell source. LOS estimates the number of patients living for specified lengths of time after a bone marrow or cord blood transplant.

Patient giving a blood donation.
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What’s a stem cell transplant priority?

The Institute for Justice asserts that only 30 percent of people who need a BMT have a matching donor in their family. The other 70 percent need a matching donor. At any moment, 7,500 Americans seek an unrelated matching donor, yet only 2 percent of the population is in the national registry. The way to help is to join the registry. Be the Match to save a life.

Judi Ebbert, PhD, MPH, RN
Meet Our Writer
Judi Ebbert, PhD, MPH, RN

Judi Ebbert earned her PhD at the University of South Florida’s College of Public Health. She has worked at three NCI-designated comprehensive cancer centers and is a writer/editor at Moffitt Cancer Center. Judi has great interest in chronic disease prevention and treatment, and is an advocate for equitable access to care and optimal quality of life for all people. She loves swimming, her dogs and cats, great food, art, humor, and cinematic thrillers. She’s on Twitter @judithebbert.