How stem cells are collected

For an autologous stem cell transplant, your stem cells are usually collected at least 2 weeks before the high-dose treatment, when the cancer is in remission.

Collecting stem cells for autologous transplant

Before high-dose treatment and autologous stem cell transplant, your stem cells will be collected and stored. This usually happens at least 2 weeks before the high‑dose treatment, when the cancer is in remission.

Your stem cells are usually collected from the blood.  

Mobilising the stem cells

Stem cells usually live in the bone marrow and produce all our blood cells. The first part of collecting stem cells from the blood is making them move from the bone marrow into the blood. This is called mobilising the stem cells.

To get the stem cells to travel from the bone marrow to the blood, you may have chemotherapy. This is followed by daily injections of a drug called a growth factor (or G-CSF). Or you may only have the G-CSF injections.

G-CSF stimulates the bone marrow. It increases the number of stem cells and white blood cells in the blood. You have it as an injection under the skin (subcutaneously).

You can have the injections at home. Your nurse can show you, a relative or a friend how to give them. Or your practice nurse or community (district) nurse can give them to you. Some side effects of the injections include:

  • flu-like symptoms
  • bone pain
  • redness where the injection was given.

Your doctor or nurse will explain how many days you have the injections for. They will also explain the side effects and what type of painkiller will help.

They will test your blood regularly to check the level of stem cells. Once there are enough stem cells in the blood, they will be collected.

In a small number of people, not enough stem cells move into the blood for collection. If this happens, you may have a drug called plerixafor (Mozobil®). This helps to increase the number of stem cells released into the blood. The nurses at the hospital will give it to you as an injection under the skin.

Collecting the stem cells

You usually have stem cells collected as a day patient. It takes 3 to 5 hours. You will be sitting or lying down, so wear some loose, comfortable clothing. You may want to take some books, magazines or music to help pass the time.

The nurse will make sure you are comfortable on a chair or bed. They will put a tube (cannula) into a vein in each arm. Each cannula is connected by tubing to a machine called a cell separator.

Blood goes from one of your arms through the tubing into the cell separator. As the blood travels through the cell separator, it is spun to separate out the stem cells. These are collected in a bag. The rest of your blood is given back through the cannula in your other arm.

If you have a central line or a PICC line, the nurses may use this instead. Less commonly, your doctor or nurse may suggest putting a thin tube (line) into a vein at the top of your leg. This happens if they cannot use the veins in your arms. Your healthcare team can tell you more about this.

You will not usually feel anything while you are having your stem cells collected. But sometimes people feel dizzy or light-headed.

A drug called citrate is used to stop the blood from clotting as it passes through the separator machine. A small amount of this drug gets into your blood. It can reduce the level of calcium. This can cause:

  • muscle cramps
  • tingling
  • numbness or a cold feeling in your lips, fingers or toes.

This is common but is usually mild. The nurse may give you a calcium tablet to chew or calcium as a drip to treat or prevent low calcium.

Sometimes not enough stem cells are collected on the first day. If this happens, you may need to have them collected again the following day.

What happens after the stem cells are collected?

The collected stem cells are counted to make sure there are enough. Some people need to come back over 2, or sometimes 3 days to collect enough stem cells. The stem cells are frozen and stored until you need them.

Sometimes not enough stem cells are collected over this period. There are different things your doctor can do to try to get more stem cells. They can arrange another stem cell transplant when they may give you:

  • more chemotherapy with G-CSF, and sometimes with a drug called plerixafor
  • G-CSF either on its own, or along with plerixafor.

Irradiated blood

For at least 2 weeks before stem cells are collected, any blood or platelet transfusions you have will be treated with radiation (irradiated). This is to prevent any problems caused by white blood cells in the donated blood.

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About our information

  • References

    Below is a sample of the sources used in our stem cell and bone marrow transplants information. If you would like more information about the sources we use, please contact us at

    Carreras, Dunfour, Mohty and Kröger. The European Society for Blood and Bone Marrow Transplantation: Hematopoietic stem cell transplantation and cellular therapies. Springer, Switzerland. 2019. 

    FACT-JACIE International Standards for Hematopoietic Cellular Therapy – product collection, processing and administration. 7th edition. 2018. 

    Anthony Nolan. Operations and patient services user guide. Available from Accessed January 2019.

  • Reviewers

    This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer. It has been approved by Senior Medical Editor, Dr Anne Parker, Consultant Haematologist.

    Our cancer information has been awarded the PIF TICK. Created by the Patient Information Forum, this quality mark shows we meet PIF’s 10 criteria for trustworthy health information.

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