Sources of stem cells for transplant – American Cancer Society

There are 3 possible sources of stem cells to use for transplants:

Bone marrow is the spongy tissue in the center of some bones. Its main job is to make blood cells that circulate in your body, which includes immune cells that recognize invaders and fight infection.

Bone marrow has a rich supply of stem cells. The bones of the pelvis (hip) contain the most marrow and have large numbers of stem cells in them. For this reason, cells from the pelvic bone are used most often for a bone marrow transplant. Enough marrow must be removed to collect a large number of healthy stem cells.

When the bone marrow is removed (harvested), the donor gets general anesthesia (drugs are used to put the patient into a deep sleep so they dont feel pain). A large needle is put through the skin and into the back of the hip bone. The thick liquid marrow is pulled out through the needle. This is repeated several times until enough marrow has been taken out or harvested. (For more on this, see the section called Whats it like to donate stem cells?)

The harvested marrow is filtered, stored in a special solution in bags, and then frozen. When the marrow is to be used, its thawed and then given into the vein just like a blood transfusion. The stem cells travel to the recipients bone marrow. Over time, they engraft or take and begin to make blood cells. Signs of the new blood cells usually can be measured in the patients blood tests in about 2 to 4 weeks.

Normally, few stem cells are found in the blood. But giving hormone-like substances called growth factors to stem cell donors a few days before the harvest causes their stem cells to grow faster and move from the bone marrow into the blood.

For a peripheral blood stem cell transplant, the stem cells are taken from blood. A special thin flexible tube (called a catheter) is put into a large vein in the donor and attached to tubing that carries the blood to a special machine. The machine separates the stem cells from the rest of the blood, which is given back to the donor during the same procedure. This takes several hours, and may need to be repeated for a few days to get enough stem cells. The stem cells are filtered, stored in bags, and frozen until the patient is ready for them. (For more on this, see the section called Whats it like to donate stem cells?)

After the patient is treated with chemotherapy and/or radiation, the stem cells are infused into the vein, much like a blood transfusion. The stem cells travel to the bone marrow, engraft, and then start making new, normal blood cells. The new cells are usually found in the patients blood a few days sooner than when bone marrow stem cells are used, usually in about 10 to 20 days.

Not everyone who needs an allogeneic stem cell transplant can find a well-matched donor among family members or among the people who have signed up to donate. For these patients, umbilical cord blood may be a source of stem cells. About 1 in 3 unrelated hematopoietic stem cell transplants are done with cord blood.

A large number of stem cells are normally found in the blood of newborn babies. After birth, the blood that is left behind in the placenta and umbilical cord (known as cord blood) can be taken and stored for later use in a stem cell transplant. The cord blood is frozen until needed. A cord blood transplant uses blood that normally is thrown out after a baby is born.

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Sources of stem cells for transplant - American Cancer Society