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 to the blood from the bone marrow, you may have chemotherapy followed by daily injections of a drug called a growth factor (or G-CSF). Or you may have only G-CSF injections.
Growth factors stimulate the bone marrow and increase the number of stem cells and white blood cells in the blood. The growth factor is usually given as an injection under the skin (subcutaneously).
A nurse can show you, a family member or a friend how to give these injections. Or your practice nurse or district nurse can give them to you.
Your blood will be tested 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. Different things can be tried to get more stem cells. Some people may have a drug called plerixafor (Mozobil®) to help increase the number of stem cells that are released into the blood stream. It is given as an injection under the skin. You will have this at the hospital.
Your stem cells will usually be collected at least 2 weeks before you have high-dose treatment. It is usually done as a day patient procedure. It takes 3 to 5 hours. You will be sitting or lying down, so it can help to wear loose, comfortable clothing. You may want to take some books, magazines or music to help pass the time.
A nurse will make sure you are comfortable on a chair or bed. They will put a short, thin tube called a cannula into a vein in each arm. Sometimes a vein at the top of your leg is used. You may have a local anaesthetic injection to numb the area where the cannulas are inserted.
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. The cells are collected in a bag. The rest of your blood and blood cells are then given back to you through the cannula in your other arm.
When stem cells are being collected some people:
- feel dizzy or light-headed
- have a numb or cold feeling in their lips, fingers or toes.
This is caused by a drug called citrate which lowers calcium levels in the blood. Citrate is added to the blood while it is out of the body to prevent it from clotting. You may be given a calcium tablet to chew or as a drip, which can treat or prevent this.
You may feel very tired afterwards, so it is a good idea to arrange for a family member or friend to take you home.
Collecting stem cells from the bone marrow
Rarely stem cells are collected from the bone marrow instead of the blood. This is usually done a few days or weeks before you have the transplant. You will have a general anaesthetic or an anaesthetic given into the spine, so you will not feel any pain. Usually, bone marrow is taken from the back of the hip bones (pelvis).
The doctor inserts a needle through the skin and into the bone. Bone marrow is then drawn into a syringe and placed in a sterile container. The doctor may do this a number of times during the collection, taking bone marrow from more than one area of the pelvis.
For an adult, about one litre of bone marrow is removed. This is about 10% to 15% of the body’s total bone marrow. This leaves plenty for your body’s needs. The body quickly replaces the bone marrow that has been removed.
You may have to stay in hospital overnight after the collection. It is common to feel sore for a few days, but regular painkillers can help. You will be given a supply to take home if you need it. There may also be some bruising from where the bone marrow was taken, which may last for a few weeks. Some people may need a blood transfusion after the collection to increase the number of red blood cells in their blood. You may also be given iron tablets.
The collected stem cells are counted to make sure there are enough. Some people need to come back over 2 or 3 days to collect enough stem cells. The stem cells are frozen and stored until you need them for your transplant.
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 may give you:
- another course of chemotherapy with G-CSF either alone or with plerixafor
- G-CSF either on its own or along with plerixafor.
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. Irradiated blood is not radioactive and will not harm you or anyone you come into contact with.
For at least 3 months after your stem cell transplant you will continue to have irradiated blood for any transfusions you need. Some people may have it for longer.