Stem cell vs bone marrow transplant: are they the same?

A stem cell transplant gives a patient healthy blood-forming stem cells. These are young cells that grow into red cells, white cells and platelets. The transplant restores them after very high doses of chemotherapy or radiation have destroyed the patient’s own.

The patient receives the cells through a needle in a vein, not through surgery. Once in the bloodstream, the cells travel to the bone marrow, the soft tissue inside bones, and take the place of the cells that were destroyed.

The name often tells you where the cells came from. When they come from the bone marrow, it may be called a bone marrow transplant, or BMT. When they come from the blood, it may be called a peripheral blood stem cell transplant. When they come from cord blood, it may be called a cord blood transplant.

Bloodstream. Most stem cells used in transplants come from the blood. This is called peripheral blood, meaning the blood that flows through the body. For 4 or 5 days first, the person giving the cells gets a medicine that increases the number of stem cells in the blood. Doctors call this step mobilization.

Bone marrow. Marrow is drawn out with a needle from the back of the pelvic (hip) bone. The person giving marrow has anesthesia for this, usually general anesthesia, which puts them to sleep.

Umbilical cord blood. After a baby is born and the cord is cut, blood can be collected from the umbilical cord and placenta, then frozen and stored. Only a small amount can be collected, so cord blood is most often used for children or small adults.

The patient’s transplant doctor decides. NMDP, which runs the national donor registry in the United States, says the doctor chooses the method that is best for the patient’s health and the success of the transplant.

Each source has trade-offs. A trial compared them in 551 people under 66 with leukemia or related blood cancers and unrelated donors, treated at 48 centers in the US and Canada from 2004 to 2009. Two-year survival was not significantly different. Graft failure, when the new cells do not take hold, was less common with cells from the blood, while long-term (chronic) graft-versus-host disease, when donor immune cells attack the patient’s healthy tissue, was less common with marrow.

NMDP says doctors may choose marrow when a patient is at higher risk of chronic graft-versus-host disease, or when the patient is a child. A 2004 study from an international transplant registry looked at children and teens aged 8 to 20 with acute leukemia whose donor was a matched brother or sister. After adjusting for other risk factors, it found higher death rates after blood stem cell transplants than after marrow.

Acquired aplastic anemia is a rare, serious condition in which the bone marrow cannot make enough new blood cells. An international study by the European Group for Blood and Marrow Transplantation (EBMT) looked at 1,886 people with it who had a first transplant from a matched brother or sister between 1999 and 2009. Survival was better with marrow in every age group studied, and the authors concluded marrow should be the preferred source for these transplants.

Blood stem cell donation, often called PBSC donation, is not surgery. For 5 days before, the donor gets injections of filgrastim (or a similar approved medicine), which moves stem cells into the bloodstream. Some donors have mild bone or muscle aches, headaches or flu-like symptoms from it, which go away after donation.

On donation day, blood is drawn from one arm, passed through a machine that collects the stem cells, and returned through the other arm. This is called apheresis. NMDP says most PBSC donations take 4 to 8 hours and are done in one session, and donors can go home the same day.

Marrow donation is a surgical procedure done in a hospital. Nearly all donors have general anesthesia, so they are asleep. Doctors use a sterile needle to draw liquid marrow from both sides of the back of the pelvic bone, which usually takes 1 to 2 hours. Soreness in the lower back or hips afterward is common, and the body replaces the marrow within a few weeks.

NMDP says most blood stem cell donors return to their regular activities within 1 to 7 days, and most marrow donors within 2 to 7 days. Donations happen at collection centers and hospitals that work with the registry. The Jada Bascom Foundation does not collect cells. It helps people find the official registry where they live.

Where the cells are collected is a separate question from whose cells they are. In an autologous transplant, the cells come from the patient. They are collected before treatment starts and given back afterward, so no donor is needed.

In an allogeneic transplant, the cells come from someone else. That can be a relative, an unrelated volunteer found through a registry, or donated cord blood. The cells need to match the patient’s tissue type as closely as possible. Rarely, the donor is an identical twin.

Both kinds can use cells from the blood or the marrow. Our page on autologous and allogeneic transplants explains how the two differ in purpose and risk.